text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2015 The Bitcoin Core developers
  // Copyright (c) 2014-2017 The Dash Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include "validation.h"
  
  #include "alert.h"
  #include "arith_uint256.h"
  #include "chainparams.h"
  #include "checkpoints.h"
  #include "checkqueue.h"
  #include "consensus/consensus.h"
  #include "consensus/merkle.h"
  #include "consensus/validation.h"
  #include "hash.h"
  #include "init.h"
  #include "policy/policy.h"
  #include "pow.h"
  #include "primitives/block.h"
  #include "primitives/transaction.h"
  #include "script/script.h"
  #include "script/sigcache.h"
  #include "script/standard.h"
  #include "timedata.h"
  #include "tinyformat.h"
  #include "txdb.h"
  #include "txmempool.h"
  #include "ui_interface.h"
  #include "undo.h"
  #include "util.h"
  #include "spork.h"
  #include "utilmoneystr.h"
  #include "utilstrencodings.h"
  #include "validationinterface.h"
  #include "versionbits.h"
  #include "dag_singleton.h"
  
  #include "instantx.h"
  #include "masternodeman.h"
  #include "masternode-payments.h"
  
  #include <sstream>
  
  #include <boost/algorithm/string/replace.hpp>
  #include <boost/filesystem.hpp>
  #include <boost/filesystem/fstream.hpp>
  #include <boost/lexical_cast.hpp>
  #include <boost/math/distributions/poisson.hpp>
  #include <boost/thread.hpp>
  
  using namespace std;
  
  #if defined(NDEBUG)
  # error "Energi Core cannot be compiled without assertions."
  #endif
  
  /**
   * Global state
   */
  
  CCriticalSection cs_main;
  
  BlockMap mapBlockIndex;
  CChain chainActive;
  CBlockIndex *pindexBestHeader = NULL;
  CWaitableCriticalSection csBestBlock;
  CConditionVariable cvBlockChange;
  int nScriptCheckThreads = 0;
  bool fImporting = false;
  bool fReindex = false;
  bool fTxIndex = true;
  bool fAddressIndex = false;
  bool fTimestampIndex = false;
  bool fSpentIndex = false;
  bool fHavePruned = false;
  bool fPruneMode = false;
  bool fIsBareMultisigStd = DEFAULT_PERMIT_BAREMULTISIG;
  bool fRequireStandard = true;
  unsigned int nBytesPerSigOp = DEFAULT_BYTES_PER_SIGOP;
  bool fCheckBlockIndex = false;
  bool fCheckpointsEnabled = DEFAULT_CHECKPOINTS_ENABLED;
  size_t nCoinCacheUsage = 5000 * 300;
  uint64_t nPruneTarget = 0;
  bool fAlerts = DEFAULT_ALERTS;
  bool fEnableReplacement = DEFAULT_ENABLE_REPLACEMENT;
  
  std::atomic<bool> fDIP0001WasLockedIn{false};
  std::atomic<bool> fDIP0001ActiveAtTip{false};
  
  uint256 hashAssumeValid;
  
  /** Fees smaller than this (in atoms) are considered zero fee (for relaying, mining and transaction creation) */
  CFeeRate minRelayTxFee = CFeeRate(DEFAULT_LEGACY_MIN_RELAY_TX_FEE);
  
  CTxMemPool mempool(::minRelayTxFee);
  map<uint256, int64_t> mapRejectedBlocks GUARDED_BY(cs_main);
  
  /**
   * Returns true if there are nRequired or more blocks of minVersion or above
   * in the last Consensus::Params::nMajorityWindow blocks, starting at pstart and going backwards.
   */
  static bool IsSuperMajority(int minVersion, const CBlockIndex* pstart, unsigned nRequired, const Consensus::Params& consensusParams);
  static void CheckBlockIndex(const Consensus::Params& consensusParams);
  
  /** Constant stuff for coinbase transactions we create: */
  CScript COINBASE_FLAGS;
  
  const string strMessageMagic = "DarkCoin Signed Message:\n";
  
  // Internal stuff
  namespace {
  
      struct CBlockIndexWorkComparator
      {
          bool operator()(CBlockIndex *pa, CBlockIndex *pb) const {
              // First sort by most total work, ...
              if (pa->nChainWork > pb->nChainWork) return false;
              if (pa->nChainWork < pb->nChainWork) return true;
  
              // ... then by earliest time received, ...
              if (pa->nSequenceId < pb->nSequenceId) return false;
              if (pa->nSequenceId > pb->nSequenceId) return true;
  
              // Use pointer address as tie breaker (should only happen with blocks
              // loaded from disk, as those all have id 0).
              if (pa < pb) return false;
              if (pa > pb) return true;
  
              // Identical blocks.
              return false;
          }
      };
  
      CBlockIndex *pindexBestInvalid;
  
      /**
       * The set of all CBlockIndex entries with BLOCK_VALID_TRANSACTIONS (for itself and all ancestors) and
       * as good as our current tip or better. Entries may be failed, though, and pruning nodes may be
       * missing the data for the block.
       */
      set<CBlockIndex*, CBlockIndexWorkComparator> setBlockIndexCandidates;
      /** All pairs A->B, where A (or one of its ancestors) misses transactions, but B has transactions.
       * Pruned nodes may have entries where B is missing data.
       */
      multimap<CBlockIndex*, CBlockIndex*> mapBlocksUnlinked;
  
      CCriticalSection cs_LastBlockFile;
      std::vector<CBlockFileInfo> vinfoBlockFile;
      int nLastBlockFile = 0;
      /** Global flag to indicate we should check to see if there are
       *  block/undo files that should be deleted.  Set on startup
       *  or if we allocate more file space when we're in prune mode
       */
      bool fCheckForPruning = false;
  
      /**
       * Every received block is assigned a unique and increasing identifier, so we
       * know which one to give priority in case of a fork.
       */
      CCriticalSection cs_nBlockSequenceId;
      /** Blocks loaded from disk are assigned id 0, so start the counter at 1. */
      uint32_t nBlockSequenceId = 1;
  
      /** Dirty block index entries. */
      set<CBlockIndex*> setDirtyBlockIndex;
  
      /** Dirty block file entries. */
      set<int> setDirtyFileInfo;
  } // anon namespace
  
  CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator)
  {
      // Find the first block the caller has in the main chain
      BOOST_FOREACH(const uint256& hash, locator.vHave) {
          BlockMap::iterator mi = mapBlockIndex.find(hash);
          if (mi != mapBlockIndex.end())
          {
              CBlockIndex* pindex = (*mi).second;
              if (chain.Contains(pindex))
                  return pindex;
          }
      }
      return chain.Genesis();
  }
  
  CCoinsViewCache *pcoinsTip = NULL;
  CBlockTreeDB *pblocktree = NULL;
  
  enum FlushStateMode {
      FLUSH_STATE_NONE,
      FLUSH_STATE_IF_NEEDED,
      FLUSH_STATE_PERIODIC,
      FLUSH_STATE_ALWAYS
  };
  
  // See definition for documentation
  bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode);
  
  bool IsFinalTx(const CTransaction &tx, int nBlockHeight, int64_t nBlockTime)
  {
      if (tx.nLockTime == 0)
          return true;
      if ((int64_t)tx.nLockTime < ((int64_t)tx.nLockTime < LOCKTIME_THRESHOLD ? (int64_t)nBlockHeight : nBlockTime))
          return true;
      BOOST_FOREACH(const CTxIn& txin, tx.vin) {
          if (!(txin.nSequence == CTxIn::SEQUENCE_FINAL))
              return false;
      }
      return true;
  }
  
  bool CheckFinalTx(const CTransaction &tx, int flags)
  {
      AssertLockHeld(cs_main);
  
      // By convention a negative value for flags indicates that the
      // current network-enforced consensus rules should be used. In
      // a future soft-fork scenario that would mean checking which
      // rules would be enforced for the next block and setting the
      // appropriate flags. At the present time no soft-forks are
      // scheduled, so no flags are set.
      flags = std::max(flags, 0);
  
      // CheckFinalTx() uses chainActive.Height()+1 to evaluate
      // nLockTime because when IsFinalTx() is called within
      // CBlock::AcceptBlock(), the height of the block *being*
      // evaluated is what is used. Thus if we want to know if a
      // transaction can be part of the *next* block, we need to call
      // IsFinalTx() with one more than chainActive.Height().
      const int nBlockHeight = chainActive.Height() + 1;
  
      // BIP113 will require that time-locked transactions have nLockTime set to
      // less than the median time of the previous block they're contained in.
      // When the next block is created its previous block will be the current
      // chain tip, so we use that to calculate the median time passed to
      // IsFinalTx() if LOCKTIME_MEDIAN_TIME_PAST is set.
      const int64_t nBlockTime = (flags & LOCKTIME_MEDIAN_TIME_PAST)
                               ? chainActive.Tip()->GetMedianTimePast()
                               : GetAdjustedTime();
  
      return IsFinalTx(tx, nBlockHeight, nBlockTime);
  }
  
  /**
   * Calculates the block height and previous block's median time past at
   * which the transaction will be considered final in the context of BIP 68.
   * Also removes from the vector of input heights any entries which did not
   * correspond to sequence locked inputs as they do not affect the calculation.
   */
  static std::pair<int, int64_t> CalculateSequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block)
  {
      assert(prevHeights->size() == tx.vin.size());
  
      // Will be set to the equivalent height- and time-based nLockTime
      // values that would be necessary to satisfy all relative lock-
      // time constraints given our view of block chain history.
      // The semantics of nLockTime are the last invalid height/time, so
      // use -1 to have the effect of any height or time being valid.
      int nMinHeight = -1;
      int64_t nMinTime = -1;
  
      // tx.nVersion is signed integer so requires cast to unsigned otherwise
      // we would be doing a signed comparison and half the range of nVersion
      // wouldn't support BIP 68.
      bool fEnforceBIP68 = static_cast<uint32_t>(tx.nVersion) >= 2
                        && flags & LOCKTIME_VERIFY_SEQUENCE;
  
      // Do not enforce sequence numbers as a relative lock time
      // unless we have been instructed to
      if (!fEnforceBIP68) {
          return std::make_pair(nMinHeight, nMinTime);
      }
  
      for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
          const CTxIn& txin = tx.vin[txinIndex];
  
          // Sequence numbers with the most significant bit set are not
          // treated as relative lock-times, nor are they given any
          // consensus-enforced meaning at this point.
          if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_DISABLE_FLAG) {
              // The height of this input is not relevant for sequence locks
              (*prevHeights)[txinIndex] = 0;
              continue;
          }
  
          int nCoinHeight = (*prevHeights)[txinIndex];
  
          if (txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_TYPE_FLAG) {
              int64_t nCoinTime = block.GetAncestor(std::max(nCoinHeight-1, 0))->GetMedianTimePast();
              // NOTE: Subtract 1 to maintain nLockTime semantics
              // BIP 68 relative lock times have the semantics of calculating
              // the first block or time at which the transaction would be
              // valid. When calculating the effective block time or height
              // for the entire transaction, we switch to using the
              // semantics of nLockTime which is the last invalid block
              // time or height.  Thus we subtract 1 from the calculated
              // time or height.
  
              // Time-based relative lock-times are measured from the
              // smallest allowed timestamp of the block containing the
              // txout being spent, which is the median time past of the
              // block prior.
              nMinTime = std::max(nMinTime, nCoinTime + (int64_t)((txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) << CTxIn::SEQUENCE_LOCKTIME_GRANULARITY) - 1);
          } else {
              nMinHeight = std::max(nMinHeight, nCoinHeight + (int)(txin.nSequence & CTxIn::SEQUENCE_LOCKTIME_MASK) - 1);
          }
      }
  
      return std::make_pair(nMinHeight, nMinTime);
  }
  
  static bool EvaluateSequenceLocks(const CBlockIndex& block, std::pair<int, int64_t> lockPair)
  {
      assert(block.pprev);
      int64_t nBlockTime = block.pprev->GetMedianTimePast();
      if (lockPair.first >= block.nHeight || lockPair.second >= nBlockTime)
          return false;
  
      return true;
  }
  
  bool SequenceLocks(const CTransaction &tx, int flags, std::vector<int>* prevHeights, const CBlockIndex& block)
  {
      return EvaluateSequenceLocks(block, CalculateSequenceLocks(tx, flags, prevHeights, block));
  }
  
  bool TestLockPointValidity(const LockPoints* lp)
  {
      AssertLockHeld(cs_main);
      assert(lp);
      // If there are relative lock times then the maxInputBlock will be set
      // If there are no relative lock times, the LockPoints don't depend on the chain
      if (lp->maxInputBlock) {
          // Check whether chainActive is an extension of the block at which the LockPoints
          // calculation was valid.  If not LockPoints are no longer valid
          if (!chainActive.Contains(lp->maxInputBlock)) {
              return false;
          }
      }
  
      // LockPoints still valid
      return true;
  }
  
  bool CheckSequenceLocks(const CTransaction &tx, int flags, LockPoints* lp, bool useExistingLockPoints)
  {
      AssertLockHeld(cs_main);
      AssertLockHeld(mempool.cs);
  
      CBlockIndex* tip = chainActive.Tip();
      CBlockIndex index;
      index.pprev = tip;
      // CheckSequenceLocks() uses chainActive.Height()+1 to evaluate
      // height based locks because when SequenceLocks() is called within
      // ConnectBlock(), the height of the block *being*
      // evaluated is what is used.
      // Thus if we want to know if a transaction can be part of the
      // *next* block, we need to use one more than chainActive.Height()
      index.nHeight = tip->nHeight + 1;
  
      std::pair<int, int64_t> lockPair;
      if (useExistingLockPoints) {
          assert(lp);
          lockPair.first = lp->height;
          lockPair.second = lp->time;
      }
      else {
          // pcoinsTip contains the UTXO set for chainActive.Tip()
          CCoinsViewMemPool viewMemPool(pcoinsTip, mempool);
          std::vector<int> prevheights;
          prevheights.resize(tx.vin.size());
          for (size_t txinIndex = 0; txinIndex < tx.vin.size(); txinIndex++) {
              const CTxIn& txin = tx.vin[txinIndex];
              CCoins coins;
              if (!viewMemPool.GetCoins(txin.prevout.hash, coins)) {
                  return error("%s: Missing input", __func__);
              }
              if (coins.nHeight == MEMPOOL_HEIGHT) {
                  // Assume all mempool transaction confirm in the next block
                  prevheights[txinIndex] = tip->nHeight + 1;
              } else {
                  prevheights[txinIndex] = coins.nHeight;
              }
          }
          lockPair = CalculateSequenceLocks(tx, flags, &prevheights, index);
          if (lp) {
              lp->height = lockPair.first;
              lp->time = lockPair.second;
              // Also store the hash of the block with the highest height of
              // all the blocks which have sequence locked prevouts.
              // This hash needs to still be on the chain
              // for these LockPoint calculations to be valid
              // Note: It is impossible to correctly calculate a maxInputBlock
              // if any of the sequence locked inputs depend on unconfirmed txs,
              // except in the special case where the relative lock time/height
              // is 0, which is equivalent to no sequence lock. Since we assume
              // input height of tip+1 for mempool txs and test the resulting
              // lockPair from CalculateSequenceLocks against tip+1.  We know
              // EvaluateSequenceLocks will fail if there was a non-zero sequence
              // lock on a mempool input, so we can use the return value of
              // CheckSequenceLocks to indicate the LockPoints validity
              int maxInputHeight = 0;
              BOOST_FOREACH(int height, prevheights) {
                  // Can ignore mempool inputs since we'll fail if they had non-zero locks
                  if (height != tip->nHeight+1) {
                      maxInputHeight = std::max(maxInputHeight, height);
                  }
              }
              lp->maxInputBlock = tip->GetAncestor(maxInputHeight);
          }
      }
      return EvaluateSequenceLocks(index, lockPair);
  }
  
  
  unsigned int GetLegacySigOpCount(const CTransaction& tx)
  {
      unsigned int nSigOps = 0;
      BOOST_FOREACH(const CTxIn& txin, tx.vin)
      {
          nSigOps += txin.scriptSig.GetSigOpCount(false);
      }
      BOOST_FOREACH(const CTxOut& txout, tx.vout)
      {
          nSigOps += txout.scriptPubKey.GetSigOpCount(false);
      }
      return nSigOps;
  }
  
  unsigned int GetP2SHSigOpCount(const CTransaction& tx, const CCoinsViewCache& inputs)
  {
      if (tx.IsCoinBase())
          return 0;
  
      unsigned int nSigOps = 0;
      for (unsigned int i = 0; i < tx.vin.size(); i++)
      {
          const CTxOut &prevout = inputs.GetOutputFor(tx.vin[i]);
          if (prevout.scriptPubKey.IsPayToScriptHash())
              nSigOps += prevout.scriptPubKey.GetSigOpCount(tx.vin[i].scriptSig);
      }
      return nSigOps;
  }
  
  bool GetUTXOCoins(const COutPoint& outpoint, CCoins& coins)
  {
      LOCK(cs_main);
      return !(!pcoinsTip->GetCoins(outpoint.hash, coins) ||
               (unsigned int)outpoint.n>=coins.vout.size() ||
               coins.vout[outpoint.n].IsNull());
  }
  
  int GetUTXOHeight(const COutPoint& outpoint)
  {
      // -1 means UTXO is yet unknown or already spent
      CCoins coins;
      return GetUTXOCoins(outpoint, coins) ? coins.nHeight : -1;
  }
  
  int GetUTXOConfirmations(const COutPoint& outpoint)
  {
      // -1 means UTXO is yet unknown or already spent
      LOCK(cs_main);
      int nPrevoutHeight = GetUTXOHeight(outpoint);
      return (nPrevoutHeight > -1 && chainActive.Tip()) ? chainActive.Height() - nPrevoutHeight + 1 : -1;
  }
  
  
  bool CheckTransaction(const CTransaction& tx, CValidationState &state)
  {
      // Basic checks that don't depend on any context
      if (tx.vin.empty())
          return state.DoS(10, false, REJECT_INVALID, "bad-txns-vin-empty");
      if (tx.vout.empty())
          return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty");
      // Size limits
      if (::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION) > MAX_LEGACY_BLOCK_SIZE)
          return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
  
      // Check for negative or overflow output values
      CAmount nValueOut = 0;
      BOOST_FOREACH(const CTxOut& txout, tx.vout)
      {
          if (txout.nValue < 0)
              return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-negative");
          if (txout.nValue > MAX_MONEY)
              return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-toolarge");
          nValueOut += txout.nValue;
          if (!MoneyRange(nValueOut))
              return state.DoS(100, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge");
      }
  
      // Check for duplicate inputs
      set<COutPoint> vInOutPoints;
      BOOST_FOREACH(const CTxIn& txin, tx.vin)
      {
          if (vInOutPoints.count(txin.prevout))
              return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
          vInOutPoints.insert(txin.prevout);
      }
  
      if (tx.IsCoinBase())
      {
          if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)
              return state.DoS(100, false, REJECT_INVALID, "bad-cb-length");
      }
      else
      {
          BOOST_FOREACH(const CTxIn& txin, tx.vin)
              if (txin.prevout.IsNull())
                  return state.DoS(10, false, REJECT_INVALID, "bad-txns-prevout-null");
      }
  
      return true;
  }
  
  bool ContextualCheckTransaction(const CTransaction& tx, CValidationState &state, CBlockIndex * const pindexPrev)
  {
      bool fDIP0001Active_context = (VersionBitsState(pindexPrev, Params().GetConsensus(), Consensus::DEPLOYMENT_DIP0001, versionbitscache) == THRESHOLD_ACTIVE);
  
      // Size limits
      if (fDIP0001Active_context && ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION) > MAX_STANDARD_TX_SIZE)
          return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
  
      return true;
  }
  
  void LimitMempoolSize(CTxMemPool& pool, size_t limit, unsigned long age) {
      int expired = pool.Expire(GetTime() - age);
      if (expired != 0)
          LogPrint("mempool", "Expired %i transactions from the memory pool\n", expired);
  
      std::vector<uint256> vNoSpendsRemaining;
      pool.TrimToSize(limit, &vNoSpendsRemaining);
      BOOST_FOREACH(const uint256& removed, vNoSpendsRemaining)
          pcoinsTip->Uncache(removed);
  }
  
  /** Convert CValidationState to a human-readable message for logging */
  std::string FormatStateMessage(const CValidationState &state)
  {
      return strprintf("%s%s (code %i)",
          state.GetRejectReason(),
          state.GetDebugMessage().empty() ? "" : ", "+state.GetDebugMessage(),
          state.GetRejectCode());
  }
  
  bool AcceptToMemoryPoolWorker(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
                                bool* pfMissingInputs, bool fOverrideMempoolLimit, bool fRejectAbsurdFee,
                                std::vector<uint256>& vHashTxnToUncache, bool fDryRun)
  {
      AssertLockHeld(cs_main);
      if (pfMissingInputs)
          *pfMissingInputs = false;
  
      if (!CheckTransaction(tx, state) || !ContextualCheckTransaction(tx, state, chainActive.Tip()))
          return false;
  
      // Coinbase is only valid in a block, not as a loose transaction
      if (tx.IsCoinBase())
          return state.DoS(100, false, REJECT_INVALID, "coinbase");
  
      // Rather not work on nonstandard transactions (unless -testnet/-regtest)
      string reason;
      if (fRequireStandard && !IsStandardTx(tx, reason))
          return state.DoS(0, false, REJECT_NONSTANDARD, reason);
  
      // Don't relay version 2 transactions until CSV is active, and we can be
      // sure that such transactions will be mined (unless we're on
      // -testnet/-regtest).
      const CChainParams& chainparams = Params();
      if (fRequireStandard && tx.nVersion >= 2 && VersionBitsTipState(chainparams.GetConsensus(), Consensus::DEPLOYMENT_CSV) != THRESHOLD_ACTIVE) {
          return state.DoS(0, false, REJECT_NONSTANDARD, "premature-version2-tx");
      }
  
      // Only accept nLockTime-using transactions that can be mined in the next
      // block; we don't want our mempool filled up with transactions that can't
      // be mined yet.
      if (!CheckFinalTx(tx, STANDARD_LOCKTIME_VERIFY_FLAGS))
          return state.DoS(0, false, REJECT_NONSTANDARD, "non-final");
  
      // is it already in the memory pool?
      uint256 hash = tx.GetHash();
      if (pool.exists(hash))
          return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-in-mempool");
  
      // If this is a Transaction Lock Request check to see if it's valid
      if(instantsend.HasTxLockRequest(hash) && !CTxLockRequest(tx).IsValid())
          return state.DoS(10, error("AcceptToMemoryPool : CTxLockRequest %s is invalid", hash.ToString()),
                              REJECT_INVALID, "bad-txlockrequest");
  
      // Check for conflicts with a completed Transaction Lock
      BOOST_FOREACH(const CTxIn &txin, tx.vin)
      {
          uint256 hashLocked;
          if(instantsend.GetLockedOutPointTxHash(txin.prevout, hashLocked) && hash != hashLocked)
              return state.DoS(10, error("AcceptToMemoryPool : Transaction %s conflicts with completed Transaction Lock %s",
                                      hash.ToString(), hashLocked.ToString()),
                              REJECT_INVALID, "tx-txlock-conflict");
      }
  
      // Check for conflicts with in-memory transactions
      set<uint256> setConflicts;
      {
      LOCK(pool.cs); // protect pool.mapNextTx
      BOOST_FOREACH(const CTxIn &txin, tx.vin)
      {
          if (pool.mapNextTx.count(txin.prevout))
          {
              const CTransaction *ptxConflicting = pool.mapNextTx[txin.prevout].ptx;
              if (!setConflicts.count(ptxConflicting->GetHash()))
              {
                  // InstantSend txes are not replacable
                  if(instantsend.HasTxLockRequest(ptxConflicting->GetHash())) {
                      // this tx conflicts with a Transaction Lock Request candidate
                      return state.DoS(0, error("AcceptToMemoryPool : Transaction %s conflicts with Transaction Lock Request %s",
                                              hash.ToString(), ptxConflicting->GetHash().ToString()),
                                      REJECT_INVALID, "tx-txlockreq-mempool-conflict");
                  } else if (instantsend.HasTxLockRequest(hash)) {
                      // this tx is a tx lock request and it conflicts with a normal tx
                      return state.DoS(0, error("AcceptToMemoryPool : Transaction Lock Request %s conflicts with transaction %s",
                                              hash.ToString(), ptxConflicting->GetHash().ToString()),
                                      REJECT_INVALID, "txlockreq-tx-mempool-conflict");
                  }
                  // Allow opt-out of transaction replacement by setting
                  // nSequence >= maxint-1 on all inputs.
                  //
                  // maxint-1 is picked to still allow use of nLockTime by
                  // non-replacable transactions. All inputs rather than just one
                  // is for the sake of multi-party protocols, where we don't
                  // want a single party to be able to disable replacement.
                  //
                  // The opt-out ignores descendants as anyone relying on
                  // first-seen mempool behavior should be checking all
                  // unconfirmed ancestors anyway; doing otherwise is hopelessly
                  // insecure.
                  bool fReplacementOptOut = true;
                  if (fEnableReplacement)
                  {
                      BOOST_FOREACH(const CTxIn &txin, ptxConflicting->vin)
                      {
                          if (txin.nSequence < std::numeric_limits<unsigned int>::max()-1)
                          {
                              fReplacementOptOut = false;
                              break;
                          }
                      }
                  }
                  if (fReplacementOptOut)
                      return state.Invalid(false, REJECT_CONFLICT, "txn-mempool-conflict");
  
                  setConflicts.insert(ptxConflicting->GetHash());
              }
          }
      }
      }
  
      {
          CCoinsView dummy;
          CCoinsViewCache view(&dummy);
  
          CAmount nValueIn = 0;
          LockPoints lp;
          {
          LOCK(pool.cs);
          CCoinsViewMemPool viewMemPool(pcoinsTip, pool);
          view.SetBackend(viewMemPool);
  
          // do we already have it?
          bool fHadTxInCache = pcoinsTip->HaveCoinsInCache(hash);
          if (view.HaveCoins(hash)) {
              if (!fHadTxInCache)
                  vHashTxnToUncache.push_back(hash);
              return state.Invalid(false, REJECT_ALREADY_KNOWN, "txn-already-known");
          }
  
          // do all inputs exist?
          // Note that this does not check for the presence of actual outputs (see the next check for that),
          // and only helps with filling in pfMissingInputs (to determine missing vs spent).
          BOOST_FOREACH(const CTxIn txin, tx.vin) {
              if (!pcoinsTip->HaveCoinsInCache(txin.prevout.hash))
                  vHashTxnToUncache.push_back(txin.prevout.hash);
              if (!view.HaveCoins(txin.prevout.hash)) {
                  if (pfMissingInputs)
                      *pfMissingInputs = true;
                  return false; // fMissingInputs and !state.IsInvalid() is used to detect this condition, don't set state.Invalid()
              }
          }
  
          // are the actual inputs available?
          if (!view.HaveInputs(tx))
              return state.Invalid(false, REJECT_DUPLICATE, "bad-txns-inputs-spent");
  
          // Bring the best block into scope
          view.GetBestBlock();
  
          nValueIn = view.GetValueIn(tx);
  
          // we have all inputs cached now, so switch back to dummy, so we don't need to keep lock on mempool
          view.SetBackend(dummy);
  
          // Only accept BIP68 sequence locked transactions that can be mined in the next
          // block; we don't want our mempool filled up with transactions that can't
          // be mined yet.
          // Must keep pool.cs for this unless we change CheckSequenceLocks to take a
          // CoinsViewCache instead of create its own
          if (!CheckSequenceLocks(tx, STANDARD_LOCKTIME_VERIFY_FLAGS, &lp))
              return state.DoS(0, false, REJECT_NONSTANDARD, "non-BIP68-final");
          }
  
          // Check for non-standard pay-to-script-hash in inputs
          if (fRequireStandard && !AreInputsStandard(tx, view))
              return state.Invalid(false, REJECT_NONSTANDARD, "bad-txns-nonstandard-inputs");
  
          unsigned int nSigOps = GetLegacySigOpCount(tx);
          nSigOps += GetP2SHSigOpCount(tx, view);
  
          CAmount nValueOut = tx.GetValueOut();
          CAmount nFees = nValueIn-nValueOut;
          // nModifiedFees includes any fee deltas from PrioritiseTransaction
          CAmount nModifiedFees = nFees;
          double nPriorityDummy = 0;
          pool.ApplyDeltas(hash, nPriorityDummy, nModifiedFees);
  
          CAmount inChainInputValue;
          double dPriority = view.GetPriority(tx, chainActive.Height(), inChainInputValue);
  
          // Keep track of transactions that spend a coinbase, which we re-scan
          // during reorgs to ensure COINBASE_MATURITY is still met.
          bool fSpendsCoinbase = false;
          BOOST_FOREACH(const CTxIn &txin, tx.vin) {
              const CCoins *coins = view.AccessCoins(txin.prevout.hash);
              if (coins->IsCoinBase()) {
                  fSpendsCoinbase = true;
                  break;
              }
          }
  
          CTxMemPoolEntry entry(tx, nFees, GetTime(), dPriority, chainActive.Height(), pool.HasNoInputsOf(tx), inChainInputValue, fSpendsCoinbase, nSigOps, lp);
          unsigned int nSize = entry.GetTxSize();
  
          // Check that the transaction doesn't have an excessive number of
          // sigops, making it impossible to mine. Since the coinbase transaction
          // itself can contain sigops MAX_STANDARD_TX_SIGOPS is less than
          // MAX_BLOCK_SIGOPS; we still consider this an invalid rather than
          // merely non-standard transaction.
          if ((nSigOps > MAX_STANDARD_TX_SIGOPS) || (nBytesPerSigOp && nSigOps > nSize / nBytesPerSigOp))
              return state.DoS(0, false, REJECT_NONSTANDARD, "bad-txns-too-many-sigops", false,
                  strprintf("%d", nSigOps));
  
          CAmount mempoolRejectFee = pool.GetMinFee(GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000).GetFee(nSize);
          if (mempoolRejectFee > 0 && nModifiedFees < mempoolRejectFee) {
              return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool min fee not met", false, strprintf("%d < %d", nFees, mempoolRejectFee));
          } else if (GetBoolArg("-relaypriority", DEFAULT_RELAYPRIORITY) && nModifiedFees < ::minRelayTxFee.GetFee(nSize) && !AllowFree(entry.GetPriority(chainActive.Height() + 1))) {
              // Require that free transactions have sufficient priority to be mined in the next block.
              return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "insufficient priority");
          }
  
          // Continuously rate-limit free (really, very-low-fee) transactions
          // This mitigates 'penny-flooding' -- sending thousands of free transactions just to
          // be annoying or make others' transactions take longer to confirm.
          if (fLimitFree && nModifiedFees < ::minRelayTxFee.GetFee(nSize))
          {
              static CCriticalSection csFreeLimiter;
              static double dFreeCount;
              static int64_t nLastTime;
              int64_t nNow = GetTime();
  
              LOCK(csFreeLimiter);
  
              // Use an exponentially decaying ~10-minute window:
              dFreeCount *= pow(1.0 - 1.0/600.0, (double)(nNow - nLastTime));
              nLastTime = nNow;
              // -limitfreerelay unit is thousand-bytes-per-minute
              // At default rate it would take over a month to fill 1GB
              if (dFreeCount >= GetArg("-limitfreerelay", DEFAULT_LIMITFREERELAY) * 10 * 1000)
                  return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "rate limited free transaction");
              LogPrint("mempool", "Rate limit dFreeCount: %g => %g\n", dFreeCount, dFreeCount+nSize);
              dFreeCount += nSize;
          }
  
          if (fRejectAbsurdFee && nFees > ::minRelayTxFee.GetFee(nSize) * 10000)
              return state.Invalid(false,
                  REJECT_HIGHFEE, "absurdly-high-fee",
                  strprintf("%d > %d", nFees, ::minRelayTxFee.GetFee(nSize) * 10000));
  
          // Calculate in-mempool ancestors, up to a limit.
          CTxMemPool::setEntries setAncestors;
          size_t nLimitAncestors = GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
          size_t nLimitAncestorSize = GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT)*1000;
          size_t nLimitDescendants = GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
          size_t nLimitDescendantSize = GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT)*1000;
          std::string errString;
          if (!pool.CalculateMemPoolAncestors(entry, setAncestors, nLimitAncestors, nLimitAncestorSize, nLimitDescendants, nLimitDescendantSize, errString)) {
              return state.DoS(0, false, REJECT_NONSTANDARD, "too-long-mempool-chain", false, errString);
          }
  
          // A transaction that spends outputs that would be replaced by it is invalid. Now
          // that we have the set of all ancestors we can detect this
          // pathological case by making sure setConflicts and setAncestors don't
          // intersect.
          BOOST_FOREACH(CTxMemPool::txiter ancestorIt, setAncestors)
          {
              const uint256 &hashAncestor = ancestorIt->GetTx().GetHash();
              if (setConflicts.count(hashAncestor))
              {
                  return state.DoS(10, error("AcceptToMemoryPool: %s spends conflicting transaction %s",
                                             hash.ToString(),
                                             hashAncestor.ToString()),
                                   REJECT_INVALID, "bad-txns-spends-conflicting-tx");
              }
          }
  
          // Check if it's economically rational to mine this transaction rather
          // than the ones it replaces.
          CAmount nConflictingFees = 0;
          size_t nConflictingSize = 0;
          uint64_t nConflictingCount = 0;
          CTxMemPool::setEntries allConflicting;
  
          // If we don't hold the lock allConflicting might be incomplete; the
          // subsequent RemoveStaged() and addUnchecked() calls don't guarantee
          // mempool consistency for us.
          LOCK(pool.cs);
          if (setConflicts.size())
          {
              CFeeRate newFeeRate(nModifiedFees, nSize);
              set<uint256> setConflictsParents;
              const int maxDescendantsToVisit = 100;
              CTxMemPool::setEntries setIterConflicting;
              BOOST_FOREACH(const uint256 &hashConflicting, setConflicts)
              {
                  CTxMemPool::txiter mi = pool.mapTx.find(hashConflicting);
                  if (mi == pool.mapTx.end())
                      continue;
  
                  // Save these to avoid repeated lookups
                  setIterConflicting.insert(mi);
  
                  // If this entry is "dirty", then we don't have descendant
                  // state for this transaction, which means we probably have
                  // lots of in-mempool descendants.
                  // Don't allow replacements of dirty transactions, to ensure
                  // that we don't spend too much time walking descendants.
                  // This should be rare.
                  if (mi->IsDirty()) {
                      return state.DoS(0,
                              error("AcceptToMemoryPool: rejecting replacement %s; cannot replace tx %s with untracked descendants",
                                  hash.ToString(),
                                  mi->GetTx().GetHash().ToString()),
                              REJECT_NONSTANDARD, "too many potential replacements");
                  }
  
                  // Don't allow the replacement to reduce the feerate of the
                  // mempool.
                  //
                  // We usually don't want to accept replacements with lower
                  // feerates than what they replaced as that would lower the
                  // feerate of the next block. Requiring that the feerate always
                  // be increased is also an easy-to-reason about way to prevent
                  // DoS attacks via replacements.
                  //
                  // The mining code doesn't (currently) take children into
                  // account (CPFP) so we only consider the feerates of
                  // transactions being directly replaced, not their indirect
                  // descendants. While that does mean high feerate children are
                  // ignored when deciding whether or not to replace, we do
                  // require the replacement to pay more overall fees too,
                  // mitigating most cases.
                  CFeeRate oldFeeRate(mi->GetModifiedFee(), mi->GetTxSize());
                  if (newFeeRate <= oldFeeRate)
                  {
                      return state.DoS(0,
                              error("AcceptToMemoryPool: rejecting replacement %s; new feerate %s <= old feerate %s",
                                    hash.ToString(),
                                    newFeeRate.ToString(),
                                    oldFeeRate.ToString()),
                              REJECT_INSUFFICIENTFEE, "insufficient fee");
                  }
  
                  BOOST_FOREACH(const CTxIn &txin, mi->GetTx().vin)
                  {
                      setConflictsParents.insert(txin.prevout.hash);
                  }
  
                  nConflictingCount += mi->GetCountWithDescendants();
              }
              // This potentially overestimates the number of actual descendants
              // but we just want to be conservative to avoid doing too much
              // work.
              if (nConflictingCount <= maxDescendantsToVisit) {
                  // If not too many to replace, then calculate the set of
                  // transactions that would have to be evicted
                  BOOST_FOREACH(CTxMemPool::txiter it, setIterConflicting) {
                      pool.CalculateDescendants(it, allConflicting);
                  }
                  BOOST_FOREACH(CTxMemPool::txiter it, allConflicting) {
                      nConflictingFees += it->GetModifiedFee();
                      nConflictingSize += it->GetTxSize();
                  }
              } else {
                  return state.DoS(0,
                          error("AcceptToMemoryPool: rejecting replacement %s; too many potential replacements (%d > %d)\n",
                              hash.ToString(),
                              nConflictingCount,
                              maxDescendantsToVisit),
                          REJECT_NONSTANDARD, "too many potential replacements");
              }
  
              for (unsigned int j = 0; j < tx.vin.size(); j++)
              {
                  // We don't want to accept replacements that require low
                  // feerate junk to be mined first. Ideally we'd keep track of
                  // the ancestor feerates and make the decision based on that,
                  // but for now requiring all new inputs to be confirmed works.
                  if (!setConflictsParents.count(tx.vin[j].prevout.hash))
                  {
                      // Rather than check the UTXO set - potentially expensive -
                      // it's cheaper to just check if the new input refers to a
                      // tx that's in the mempool.
                      if (pool.mapTx.find(tx.vin[j].prevout.hash) != pool.mapTx.end())
                          return state.DoS(0, error("AcceptToMemoryPool: replacement %s adds unconfirmed input, idx %d",
                                                    hash.ToString(), j),
                                           REJECT_NONSTANDARD, "replacement-adds-unconfirmed");
                  }
              }
  
              // The replacement must pay greater fees than the transactions it
              // replaces - if we did the bandwidth used by those conflicting
              // transactions would not be paid for.
              if (nModifiedFees < nConflictingFees)
              {
                  return state.DoS(0, error("AcceptToMemoryPool: rejecting replacement %s, less fees than conflicting txs; %s < %s",
                                            hash.ToString(), FormatMoney(nModifiedFees), FormatMoney(nConflictingFees)),
                                   REJECT_INSUFFICIENTFEE, "insufficient fee");
              }
  
              // Finally in addition to paying more fees than the conflicts the
              // new transaction must pay for its own bandwidth.
              CAmount nDeltaFees = nModifiedFees - nConflictingFees;
              if (nDeltaFees < ::minRelayTxFee.GetFee(nSize))
              {
                  return state.DoS(0,
                          error("AcceptToMemoryPool: rejecting replacement %s, not enough additional fees to relay; %s < %s",
                                hash.ToString(),
                                FormatMoney(nDeltaFees),
                                FormatMoney(::minRelayTxFee.GetFee(nSize))),
                          REJECT_INSUFFICIENTFEE, "insufficient fee");
              }
          }
  
          // If we aren't going to actually accept it but just were verifying it, we are fine already
          if(fDryRun) return true;
  
          // Check against previous transactions
          // This is done last to help prevent CPU exhaustion denial-of-service attacks.
          if (!CheckInputs(tx, state, view, true, STANDARD_SCRIPT_VERIFY_FLAGS, true))
              return false;
  
          // Check again against just the consensus-critical mandatory script
          // verification flags, in case of bugs in the standard flags that cause
          // transactions to pass as valid when they're actually invalid. For
          // instance the STRICTENC flag was incorrectly allowing certain
          // CHECKSIG NOT scripts to pass, even though they were invalid.
          //
          // There is a similar check in CreateNewBlock() to prevent creating
          // invalid blocks, however allowing such transactions into the mempool
          // can be exploited as a DoS attack.
          if (!CheckInputs(tx, state, view, true, MANDATORY_SCRIPT_VERIFY_FLAGS, true))
          {
              return error("%s: BUG! PLEASE REPORT THIS! ConnectInputs failed against MANDATORY but not STANDARD flags %s, %s",
                  __func__, hash.ToString(), FormatStateMessage(state));
          }
  
          // Remove conflicting transactions from the mempool
          BOOST_FOREACH(const CTxMemPool::txiter it, allConflicting)
          {
              LogPrint("mempool", "replacing tx %s with %s for %s BTC additional fees, %d delta bytes\n",
                      it->GetTx().GetHash().ToString(),
                      hash.ToString(),
                      FormatMoney(nModifiedFees - nConflictingFees),
                      (int)nSize - (int)nConflictingSize);
          }
          pool.RemoveStaged(allConflicting);
  
          // Store transaction in memory
          pool.addUnchecked(hash, entry, setAncestors, !IsInitialBlockDownload());
  
          // Add memory address index
          if (fAddressIndex) {
              pool.addAddressIndex(entry, view);
          }
  
          // Add memory spent index
          if (fSpentIndex) {
              pool.addSpentIndex(entry, view);
          }
  
          // trim mempool and check if tx was trimmed
          if (!fOverrideMempoolLimit) {
              LimitMempoolSize(pool, GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
              if (!pool.exists(hash))
                  return state.DoS(0, false, REJECT_INSUFFICIENTFEE, "mempool full");
          }
      }
  
      if(!fDryRun)
          GetMainSignals().SyncTransaction(tx, NULL);
  
      return true;
  }
  
  bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransaction &tx, bool fLimitFree,
                          bool* pfMissingInputs, bool fOverrideMempoolLimit, bool fRejectAbsurdFee, bool fDryRun)
  {
      std::vector<uint256> vHashTxToUncache;
      bool res = AcceptToMemoryPoolWorker(pool, state, tx, fLimitFree, pfMissingInputs, fOverrideMempoolLimit, fRejectAbsurdFee, vHashTxToUncache, fDryRun);
      if (!res || fDryRun) {
          if(!res) LogPrint("mempool", "%s: %s %s\n", __func__, tx.GetHash().ToString(), state.GetRejectReason());
          BOOST_FOREACH(const uint256& hashTx, vHashTxToUncache)
              pcoinsTip->Uncache(hashTx);
      }
      // After we've (potentially) uncached entries, ensure our coins cache is still within its size limits
      CValidationState stateDummy;
      FlushStateToDisk(stateDummy, FLUSH_STATE_PERIODIC);
      return res;
  }
  
  bool GetTimestampIndex(const unsigned int &high, const unsigned int &low, std::vector<uint256> &hashes)
  {
      if (!fTimestampIndex)
          return error("Timestamp index not enabled");
  
      if (!pblocktree->ReadTimestampIndex(high, low, hashes))
          return error("Unable to get hashes for timestamps");
  
      return true;
  }
  
  bool GetSpentIndex(CSpentIndexKey &key, CSpentIndexValue &value)
  {
      if (!fSpentIndex)
          return false;
  
      if (mempool.getSpentIndex(key, value))
          return true;
  
      if (!pblocktree->ReadSpentIndex(key, value))
          return false;
  
      return true;
  }
  
  bool GetAddressIndex(uint160 addressHash, int type,
                       std::vector<std::pair<CAddressIndexKey, CAmount> > &addressIndex, int start, int end)
  {
      if (!fAddressIndex)
          return error("address index not enabled");
  
      if (!pblocktree->ReadAddressIndex(addressHash, type, addressIndex, start, end))
          return error("unable to get txids for address");
  
      return true;
  }
  
  bool GetAddressUnspent(uint160 addressHash, int type,
                         std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> > &unspentOutputs)
  {
      if (!fAddressIndex)
          return error("address index not enabled");
  
      if (!pblocktree->ReadAddressUnspentIndex(addressHash, type, unspentOutputs))
          return error("unable to get txids for address");
  
      return true;
  }
  
  /** Return transaction in tx, and if it was found inside a block, its hash is placed in hashBlock */
  bool GetTransaction(const uint256 &hash, CTransaction &txOut, const Consensus::Params& consensusParams, uint256 &hashBlock, bool fAllowSlow)
  {
      CBlockIndex *pindexSlow = NULL;
  
      LOCK(cs_main);
  
      if (mempool.lookup(hash, txOut))
      {
          return true;
      }
  
      if (fTxIndex) {
          CDiskTxPos postx;
          if (pblocktree->ReadTxIndex(hash, postx)) {
              CAutoFile file(OpenBlockFile(postx, true), SER_DISK, CLIENT_VERSION);
              if (file.IsNull())
                  return error("%s: OpenBlockFile failed", __func__);
              CBlockHeader header;
              try {
                  file >> header;
                  fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
                  file >> txOut;
              } catch (const std::exception& e) {
                  return error("%s: Deserialize or I/O error - %s", __func__, e.what());
              }
              hashBlock = header.GetHash();
              if (txOut.GetHash() != hash)
                  return error("%s: txid mismatch", __func__);
              return true;
          }
      }
  
      if (fAllowSlow) { // use coin database to locate block that contains transaction, and scan it
          int nHeight = -1;
          {
              CCoinsViewCache &view = *pcoinsTip;
              const CCoins* coins = view.AccessCoins(hash);
              if (coins)
                  nHeight = coins->nHeight;
          }
          if (nHeight > 0)
              pindexSlow = chainActive[nHeight];
      }
  
      if (pindexSlow) {
          CBlock block;
          if (ReadBlockFromDisk(block, pindexSlow, consensusParams)) {
              BOOST_FOREACH(const CTransaction &tx, block.vtx) {
                  if (tx.GetHash() == hash) {
                      txOut = tx;
                      hashBlock = pindexSlow->GetBlockHash();
                      return true;
                  }
              }
          }
      }
  
      return false;
  }
  
  
  
  
  
  
  //////////////////////////////////////////////////////////////////////////////
  //
  // CBlock and CBlockIndex
  //
  
  bool WriteBlockToDisk(const CBlock& block, CDiskBlockPos& pos, const CMessageHeader::MessageStartChars& messageStart)
  {
      // Open history file to append
      CAutoFile fileout(OpenBlockFile(pos), SER_DISK, CLIENT_VERSION);
      if (fileout.IsNull())
          return error("WriteBlockToDisk: OpenBlockFile failed");
  
      // Write index header
      unsigned int nSize = fileout.GetSerializeSize(block);
      fileout << FLATDATA(messageStart) << nSize;
  
      // Write block
      long fileOutPos = ftell(fileout.Get());
      if (fileOutPos < 0)
          return error("WriteBlockToDisk: ftell failed");
      pos.nPos = (unsigned int)fileOutPos;
      fileout << block;
  
      return true;
  }
  
  bool ReadBlockFromDisk(CBlock& block, const CDiskBlockPos& pos, const Consensus::Params& consensusParams)
  {
      block.SetNull();
  
      // Open history file to read
      CAutoFile filein(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION);
      if (filein.IsNull())
          return error("ReadBlockFromDisk: OpenBlockFile failed for %s", pos.ToString());
  
      // Read block
      try {
          filein >> block;
      }
      catch (const std::exception& e) {
          return error("%s: Deserialize or I/O error - %s at %s", __func__, e.what(), pos.ToString());
      }
  
      // Check the header
      if (!CheckProofOfWork(block.GetPOWHash(), block.nBits, consensusParams))
          return error("ReadBlockFromDisk: Errors in block header at %s", pos.ToString());
  
      return true;
  }
  
  bool ReadBlockFromDisk(CBlock& block, const CBlockIndex* pindex, const Consensus::Params& consensusParams)
  {
      if (!ReadBlockFromDisk(block, pindex->GetBlockPos(), consensusParams))
          return false;
      if (block.GetHash() != pindex->GetBlockHash())
          return error("ReadBlockFromDisk(CBlock&, CBlockIndex*): GetHash() doesn't match index for %s at %s",
                  pindex->ToString(), pindex->GetBlockPos().ToString());
      return true;
  }
  
  double ConvertBitsToDouble(unsigned int nBits)
  {
      int nShift = (nBits >> 24) & 0xff;
  
      double dDiff = (double)0x0000ffff / (double)(nBits & 0x00ffffff);
  
      while (nShift < 29)
      {
          dDiff *= 256.0;
          nShift++;
      }
      while (nShift > 29)
      {
          dDiff /= 256.0;
          nShift--;
      }
  
      return dDiff;
  }
  
  CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams)
  {
      // before the nMasternodePaymentsStartBlock we only pay the miner reward & the Energi Backbone
      if (nHeight < consensusParams.nMasternodePaymentsStartBlock)
      {
          return consensusParams.nBlockSubsidyBackbone + consensusParams.nBlockSubsidyMiners;
      }
  
      return consensusParams.nBlockSubsidy;
  }
  
  CAmount GetMasternodePayment(int nHeight, CAmount blockReward)
  {
      CAmount ret = 0;
      const Consensus::Params& consensusParams = Params().GetConsensus();
      if (nHeight >= consensusParams.nMasternodePaymentsStartBlock) {
          //Masternodes get their assigned block subsidy plus 50% of the tx fees
          CAmount txFees = blockReward - GetBlockSubsidy(nHeight, consensusParams);
          ret = consensusParams.nBlockSubsidyMasternodes + (0.5 * txFees);
      }
      return ret;
  }
  
  bool IsInitialBlockDownload()
  {
      static bool lockIBDState = false;
      if (lockIBDState)
          return false;
      if (fImporting || fReindex)
          return true;
      LOCK(cs_main);
      const CChainParams& chainParams = Params();
      if (chainActive.Tip() == NULL)
          return true;
      if (chainActive.Tip()->nChainWork < UintToArith256(chainParams.GetConsensus().nMinimumChainWork))
          return true;
      if (chainActive.Tip()->GetBlockTime() < (GetTime() - chainParams.MaxTipAge()))
          return true;
      lockIBDState = true;
      return false;
  }
  
  bool fLargeWorkForkFound = false;
  bool fLargeWorkInvalidChainFound = false;
  CBlockIndex *pindexBestForkTip = NULL, *pindexBestForkBase = NULL;
  
  void CheckForkWarningConditions()
  {
      AssertLockHeld(cs_main);
      // Before we get past initial download, we cannot reliably alert about forks
      // (we assume we don't get stuck on a fork before finishing our initial sync)
      if (IsInitialBlockDownload())
          return;
  
      // If our best fork is no longer within 72 blocks (+/- 3 hours if no one mines it)
      // of our head, drop it
      if (pindexBestForkTip && chainActive.Height() - pindexBestForkTip->nHeight >= 72)
          pindexBestForkTip = NULL;
  
      if (pindexBestForkTip || (pindexBestInvalid && pindexBestInvalid->nChainWork > chainActive.Tip()->nChainWork + (GetBlockProof(*chainActive.Tip()) * 6)))
      {
          if (!fLargeWorkForkFound && pindexBestForkBase)
          {
              if(pindexBestForkBase->phashBlock){
                  std::string warning = std::string("'Warning: Large-work fork detected, forking after block ") +
                      pindexBestForkBase->phashBlock->ToString() + std::string("'");
                  CAlert::Notify(warning, true);
              }
          }
          if (pindexBestForkTip && pindexBestForkBase)
          {
              if(pindexBestForkBase->phashBlock){
                  LogPrintf("%s: Warning: Large valid fork found\n  forking the chain at height %d (%s)\n  lasting to height %d (%s).\nChain state database corruption likely.\n", __func__,
                         pindexBestForkBase->nHeight, pindexBestForkBase->phashBlock->ToString(),
                         pindexBestForkTip->nHeight, pindexBestForkTip->phashBlock->ToString());
                  fLargeWorkForkFound = true;
              }
          }
          else
          {
              if(pindexBestInvalid->nHeight > chainActive.Height() + 6)
                  LogPrintf("%s: Warning: Found invalid chain at least ~6 blocks longer than our best chain.\nChain state database corruption likely.\n", __func__);
              else
                  LogPrintf("%s: Warning: Found invalid chain which has higher work (at least ~6 blocks worth of work) than our best chain.\nChain state database corruption likely.\n", __func__);
              fLargeWorkInvalidChainFound = true;
          }
      }
      else
      {
          fLargeWorkForkFound = false;
          fLargeWorkInvalidChainFound = false;
      }
  }
  
  void CheckForkWarningConditionsOnNewFork(CBlockIndex* pindexNewForkTip)
  {
      AssertLockHeld(cs_main);
      // If we are on a fork that is sufficiently large, set a warning flag
      CBlockIndex* pfork = pindexNewForkTip;
      CBlockIndex* plonger = chainActive.Tip();
      while (pfork && pfork != plonger)
      {
          while (plonger && plonger->nHeight > pfork->nHeight)
              plonger = plonger->pprev;
          if (pfork == plonger)
              break;
          pfork = pfork->pprev;
      }
  
      // We define a condition where we should warn the user about as a fork of at least 7 blocks
      // with a tip within 72 blocks (+/- 3 hours if no one mines it) of ours
      // or a chain that is entirely longer than ours and invalid (note that this should be detected by both)
      // We use 7 blocks rather arbitrarily as it represents just under 10% of sustained network
      // hash rate operating on the fork.
      // We define it this way because it allows us to only store the highest fork tip (+ base) which meets
      // the 7-block condition and from this always have the most-likely-to-cause-warning fork
      if (pfork && (!pindexBestForkTip || (pindexBestForkTip && pindexNewForkTip->nHeight > pindexBestForkTip->nHeight)) &&
              pindexNewForkTip->nChainWork - pfork->nChainWork > (GetBlockProof(*pfork) * 7) &&
              chainActive.Height() - pindexNewForkTip->nHeight < 72)
      {
          pindexBestForkTip = pindexNewForkTip;
          pindexBestForkBase = pfork;
      }
  
      CheckForkWarningConditions();
  }
  
  void static InvalidChainFound(CBlockIndex* pindexNew)
  {
      if (!pindexBestInvalid || pindexNew->nChainWork > pindexBestInvalid->nChainWork)
          pindexBestInvalid = pindexNew;
  
      LogPrintf("%s: invalid block=%s  height=%d  log2_work=%.8g  date=%s\n", __func__,
              pindexNew->GetBlockHash().ToString(), pindexNew->nHeight,
              log(pindexNew->nChainWork.getdouble())/log(2.0), DateTimeStrFormat("%Y-%m-%d %H:%M:%S",
                  pindexNew->GetBlockTime()));
      CBlockIndex *tip = chainActive.Tip();
      assert (tip);
      LogPrintf("%s:  current best=%s  height=%d  log2_work=%.8g  date=%s\n", __func__,
              tip->GetBlockHash().ToString(), chainActive.Height(), log(tip->nChainWork.getdouble())/log(2.0),
              DateTimeStrFormat("%Y-%m-%d %H:%M:%S", tip->GetBlockTime()));
      CheckForkWarningConditions();
  }
  
  void static InvalidBlockFound(CBlockIndex *pindex, const CValidationState &state) {
      if (!state.CorruptionPossible()) {
          pindex->nStatus |= BLOCK_FAILED_VALID;
          setDirtyBlockIndex.insert(pindex);
          setBlockIndexCandidates.erase(pindex);
          InvalidChainFound(pindex);
      }
  }
  
  void UpdateCoins(const CTransaction& tx, CValidationState &state, CCoinsViewCache &inputs, CTxUndo &txundo, int nHeight)
  {
      // mark inputs spent
      if (!tx.IsCoinBase()) {
          txundo.vprevout.reserve(tx.vin.size());
          BOOST_FOREACH(const CTxIn &txin, tx.vin) {
              CCoinsModifier coins = inputs.ModifyCoins(txin.prevout.hash);
              unsigned nPos = txin.prevout.n;
  
              if (nPos >= coins->vout.size() || coins->vout[nPos].IsNull())
                  assert(false);
              // mark an outpoint spent, and construct undo information
              txundo.vprevout.push_back(CTxInUndo(coins->vout[nPos]));
              coins->Spend(nPos);
              if (coins->vout.size() == 0) {
                  CTxInUndo& undo = txundo.vprevout.back();
                  undo.nHeight = coins->nHeight;
                  undo.fCoinBase = coins->fCoinBase;
                  undo.nVersion = coins->nVersion;
              }
          }
          // add outputs
          inputs.ModifyNewCoins(tx.GetHash())->FromTx(tx, nHeight);
      }
      else {
          // add outputs for coinbase tx
          // In this case call the full ModifyCoins which will do a database
          // lookup to be sure the coins do not already exist otherwise we do not
          // know whether to mark them fresh or not.  We want the duplicate coinbases
          // before BIP30 to still be properly overwritten.
          inputs.ModifyCoins(tx.GetHash())->FromTx(tx, nHeight);
      }
  }
  
  void UpdateCoins(const CTransaction& tx, CValidationState &state, CCoinsViewCache &inputs, int nHeight)
  {
      CTxUndo txundo;
      UpdateCoins(tx, state, inputs, txundo, nHeight);
  }
  
  bool CScriptCheck::operator()() {
      const CScript &scriptSig = ptxTo->vin[nIn].scriptSig;
      if (!VerifyScript(scriptSig, scriptPubKey, nFlags, CachingTransactionSignatureChecker(ptxTo, nIn, cacheStore), &error)) {
          return false;
      }
      return true;
  }
  
  int GetSpendHeight(const CCoinsViewCache& inputs)
  {
      LOCK(cs_main);
      CBlockIndex* pindexPrev = mapBlockIndex.find(inputs.GetBestBlock())->second;
      return pindexPrev->nHeight + 1;
  }
  
  namespace Consensus {
  bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight)
  {
          // This doesn't trigger the DoS code on purpose; if it did, it would make it easier
          // for an attacker to attempt to split the network.
          if (!inputs.HaveInputs(tx))
              return state.Invalid(false, 0, "", "Inputs unavailable");
  
          CAmount nValueIn = 0;
          CAmount nFees = 0;
          for (unsigned int i = 0; i < tx.vin.size(); i++)
          {
              const COutPoint &prevout = tx.vin[i].prevout;
              const CCoins *coins = inputs.AccessCoins(prevout.hash);
              assert(coins);
  
              // If prev is coinbase, check that it's matured
              if (coins->IsCoinBase()) {
                  if (nSpendHeight - coins->nHeight < COINBASE_MATURITY)
                      return state.Invalid(false,
                          REJECT_INVALID, "bad-txns-premature-spend-of-coinbase",
                          strprintf("tried to spend coinbase at depth %d", nSpendHeight - coins->nHeight));
              }
  
              // Check for negative or overflow input values
              nValueIn += coins->vout[prevout.n].nValue;
              if (!MoneyRange(coins->vout[prevout.n].nValue) || !MoneyRange(nValueIn))
                  return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputvalues-outofrange");
  
          }
  
          if (nValueIn < tx.GetValueOut())
              return state.DoS(100, false, REJECT_INVALID, "bad-txns-in-belowout", false,
                  strprintf("value in (%s) < value out (%s)", FormatMoney(nValueIn), FormatMoney(tx.GetValueOut())));
  
          // Tally transaction fees
          CAmount nTxFee = nValueIn - tx.GetValueOut();
          if (nTxFee < 0)
              return state.DoS(100, false, REJECT_INVALID, "bad-txns-fee-negative");
          nFees += nTxFee;
          if (!MoneyRange(nFees))
              return state.DoS(100, false, REJECT_INVALID, "bad-txns-fee-outofrange");
      return true;
  }
  }// namespace Consensus
  
  bool CheckInputs(const CTransaction& tx, CValidationState &state, const CCoinsViewCache &inputs, bool fScriptChecks, unsigned int flags, bool cacheStore, std::vector<CScriptCheck> *pvChecks)
  {
      if (!tx.IsCoinBase())
      {
          if (!Consensus::CheckTxInputs(tx, state, inputs, GetSpendHeight(inputs)))
              return false;
  
          if (pvChecks)
              pvChecks->reserve(tx.vin.size());
  
          // The first loop above does all the inexpensive checks.
          // Only if ALL inputs pass do we perform expensive ECDSA signature checks.
          // Helps prevent CPU exhaustion attacks.
  
          // Skip script verification when connecting blocks under the
          // assumedvalid block. Assuming the assumedvalid block is valid this
          // is safe because block merkle hashes are still computed and checked,
          // Of course, if an assumed valid block is invalid due to false scriptSigs
          // this optimization would allow an invalid chain to be accepted.
          if (fScriptChecks) {
              for (unsigned int i = 0; i < tx.vin.size(); i++) {
                  const COutPoint &prevout = tx.vin[i].prevout;
                  const CCoins* coins = inputs.AccessCoins(prevout.hash);
                  assert(coins);
  
                  // Verify signature
                  CScriptCheck check(*coins, tx, i, flags, cacheStore);
                  if (pvChecks) {
                      pvChecks->push_back(CScriptCheck());
                      check.swap(pvChecks->back());
                  } else if (!check()) {
                      if (flags & STANDARD_NOT_MANDATORY_VERIFY_FLAGS) {
                          // Check whether the failure was caused by a
                          // non-mandatory script verification check, such as
                          // non-standard DER encodings or non-null dummy
                          // arguments; if so, don't trigger DoS protection to
                          // avoid splitting the network between upgraded and
                          // non-upgraded nodes.
                          CScriptCheck check2(*coins, tx, i,
                                  flags & ~STANDARD_NOT_MANDATORY_VERIFY_FLAGS, cacheStore);
                          if (check2())
                              return state.Invalid(false, REJECT_NONSTANDARD, strprintf("non-mandatory-script-verify-flag (%s)", ScriptErrorString(check.GetScriptError())));
                      }
                      // Failures of other flags indicate a transaction that is
                      // invalid in new blocks, e.g. a invalid P2SH. We DoS ban
                      // such nodes as they are not following the protocol. That
                      // said during an upgrade careful thought should be taken
                      // as to the correct behavior - we may want to continue
                      // peering with non-upgraded nodes even after a soft-fork
                      // super-majority vote has passed.
                      return state.DoS(100,false, REJECT_INVALID, strprintf("mandatory-script-verify-flag-failed (%s)", ScriptErrorString(check.GetScriptError())));
                  }
              }
          }
      }
  
      return true;
  }
  
  namespace {
  
  bool UndoWriteToDisk(const CBlockUndo& blockundo, CDiskBlockPos& pos, const uint256& hashBlock, const CMessageHeader::MessageStartChars& messageStart)
  {
      // Open history file to append
      CAutoFile fileout(OpenUndoFile(pos), SER_DISK, CLIENT_VERSION);
      if (fileout.IsNull())
          return error("%s: OpenUndoFile failed", __func__);
  
      // Write index header
      unsigned int nSize = fileout.GetSerializeSize(blockundo);
      fileout << FLATDATA(messageStart) << nSize;
  
      // Write undo data
      long fileOutPos = ftell(fileout.Get());
      if (fileOutPos < 0)
          return error("%s: ftell failed", __func__);
      pos.nPos = (unsigned int)fileOutPos;
      fileout << blockundo;
  
      // calculate & write checksum
      CHashWriter hasher(SER_GETHASH, PROTOCOL_VERSION);
      hasher << hashBlock;
      hasher << blockundo;
      fileout << hasher.GetHash();
  
      return true;
  }
  
  bool UndoReadFromDisk(CBlockUndo& blockundo, const CDiskBlockPos& pos, const uint256& hashBlock)
  {
      // Open history file to read
      CAutoFile filein(OpenUndoFile(pos, true), SER_DISK, CLIENT_VERSION);
      if (filein.IsNull())
          return error("%s: OpenBlockFile failed", __func__);
  
      // Read block
      uint256 hashChecksum;
      try {
          filein >> blockundo;
          filein >> hashChecksum;
      }
      catch (const std::exception& e) {
          return error("%s: Deserialize or I/O error - %s", __func__, e.what());
      }
  
      // Verify checksum
      CHashWriter hasher(SER_GETHASH, PROTOCOL_VERSION);
      hasher << hashBlock;
      hasher << blockundo;
      if (hashChecksum != hasher.GetHash())
          return error("%s: Checksum mismatch", __func__);
  
      return true;
  }
  
  /** Abort with a message */
  bool AbortNode(const std::string& strMessage, const std::string& userMessage="")
  {
      strMiscWarning = strMessage;
      LogPrintf("*** %s\n", strMessage);
      uiInterface.ThreadSafeMessageBox(
          userMessage.empty() ? _("Error: A fatal internal error occurred, see debug.log for details") : userMessage,
          "", CClientUIInterface::MSG_ERROR);
      StartShutdown();
      return false;
  }
  
  bool AbortNode(CValidationState& state, const std::string& strMessage, const std::string& userMessage="")
  {
      AbortNode(strMessage, userMessage);
      return state.Error(strMessage);
  }
  
  } // anon namespace
  
  /**
   * Apply the undo operation of a CTxInUndo to the given chain state.
   * @param undo The undo object.
   * @param view The coins view to which to apply the changes.
   * @param out The out point that corresponds to the tx input.
   * @return True on success.
   */
  static bool ApplyTxInUndo(const CTxInUndo& undo, CCoinsViewCache& view, const COutPoint& out)
  {
      bool fClean = true;
  
      CCoinsModifier coins = view.ModifyCoins(out.hash);
      if (undo.nHeight != 0) {
          // undo data contains height: this is the last output of the prevout tx being spent
          if (!coins->IsPruned())
              fClean = fClean && error("%s: undo data overwriting existing transaction", __func__);
          coins->Clear();
          coins->fCoinBase = undo.fCoinBase;
          coins->nHeight = undo.nHeight;
          coins->nVersion = undo.nVersion;
      } else {
          if (coins->IsPruned())
              fClean = fClean && error("%s: undo data adding output to missing transaction", __func__);
      }
      if (coins->IsAvailable(out.n))
          fClean = fClean && error("%s: undo data overwriting existing output", __func__);
      if (coins->vout.size() < out.n+1)
          coins->vout.resize(out.n+1);
      coins->vout[out.n] = undo.txout;
  
      return fClean;
  }
  
  bool DisconnectBlock(const CBlock& block, CValidationState& state, const CBlockIndex* pindex, CCoinsViewCache& view, bool* pfClean)
  {
      assert(pindex->GetBlockHash() == view.GetBestBlock());
  
      if (pfClean)
          *pfClean = false;
  
      bool fClean = true;
  
      CBlockUndo blockUndo;
      CDiskBlockPos pos = pindex->GetUndoPos();
      if (pos.IsNull())
          return error("DisconnectBlock(): no undo data available");
      if (!UndoReadFromDisk(blockUndo, pos, pindex->pprev->GetBlockHash()))
          return error("DisconnectBlock(): failure reading undo data");
  
      if (blockUndo.vtxundo.size() + 1 != block.vtx.size())
          return error("DisconnectBlock(): block and undo data inconsistent");
  
      std::vector<std::pair<CAddressIndexKey, CAmount> > addressIndex;
      std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> > addressUnspentIndex;
      std::vector<std::pair<CSpentIndexKey, CSpentIndexValue> > spentIndex;
  
      // undo transactions in reverse order
      for (int i = block.vtx.size() - 1; i >= 0; i--) {
          const CTransaction &tx = block.vtx[i];
          uint256 hash = tx.GetHash();
  
          if (fAddressIndex) {
  
              for (unsigned int k = tx.vout.size(); k-- > 0;) {
                  const CTxOut &out = tx.vout[k];
  
                  if (out.scriptPubKey.IsPayToScriptHash()) {
                      vector<unsigned char> hashBytes(out.scriptPubKey.begin()+2, out.scriptPubKey.begin()+22);
  
                      // undo receiving activity
                      addressIndex.push_back(make_pair(CAddressIndexKey(2, uint160(hashBytes), pindex->nHeight, i, hash, k, false), out.nValue));
  
                      // undo unspent index
                      addressUnspentIndex.push_back(make_pair(CAddressUnspentKey(2, uint160(hashBytes), hash, k), CAddressUnspentValue()));
  
                  } else if (out.scriptPubKey.IsPayToPublicKeyHash()) {
                      vector<unsigned char> hashBytes(out.scriptPubKey.begin()+3, out.scriptPubKey.begin()+23);
  
                      // undo receiving activity
                      addressIndex.push_back(make_pair(CAddressIndexKey(1, uint160(hashBytes), pindex->nHeight, i, hash, k, false), out.nValue));
  
                      // undo unspent index
                      addressUnspentIndex.push_back(make_pair(CAddressUnspentKey(1, uint160(hashBytes), hash, k), CAddressUnspentValue()));
  
                  } else {
                      continue;
                  }
  
              }
  
          }
  
          // Check that all outputs are available and match the outputs in the block itself
          // exactly.
          {
          CCoinsModifier outs = view.ModifyCoins(hash);
          outs->ClearUnspendable();
  
          CCoins outsBlock(tx, pindex->nHeight);
          // The CCoins serialization does not serialize negative numbers.
          // No network rules currently depend on the version here, so an inconsistency is harmless
          // but it must be corrected before txout nversion ever influences a network rule.
          if (outsBlock.nVersion < 0)
              outs->nVersion = outsBlock.nVersion;
          if (*outs != outsBlock)
              fClean = fClean && error("DisconnectBlock(): added transaction mismatch? database corrupted");
  
          // remove outputs
          outs->Clear();
          }
  
          // restore inputs
          if (i > 0) { // not coinbases
              const CTxUndo &txundo = blockUndo.vtxundo[i-1];
              if (txundo.vprevout.size() != tx.vin.size())
                  return error("DisconnectBlock(): transaction and undo data inconsistent");
              for (unsigned int j = tx.vin.size(); j-- > 0;) {
                  const COutPoint &out = tx.vin[j].prevout;
                  const CTxInUndo &undo = txundo.vprevout[j];
                  if (!ApplyTxInUndo(undo, view, out))
                      fClean = false;
  
                  const CTxIn input = tx.vin[j];
  
                  if (fSpentIndex) {
                      // undo and delete the spent index
                      spentIndex.push_back(make_pair(CSpentIndexKey(input.prevout.hash, input.prevout.n), CSpentIndexValue()));
                  }
  
                  if (fAddressIndex) {
                      const CTxOut &prevout = view.GetOutputFor(tx.vin[j]);
                      if (prevout.scriptPubKey.IsPayToScriptHash()) {
                          vector<unsigned char> hashBytes(prevout.scriptPubKey.begin()+2, prevout.scriptPubKey.begin()+22);
  
                          // undo spending activity
                          addressIndex.push_back(make_pair(CAddressIndexKey(2, uint160(hashBytes), pindex->nHeight, i, hash, j, true), prevout.nValue * -1));
  
                          // restore unspent index
                          addressUnspentIndex.push_back(make_pair(CAddressUnspentKey(2, uint160(hashBytes), input.prevout.hash, input.prevout.n), CAddressUnspentValue(prevout.nValue, prevout.scriptPubKey, undo.nHeight)));
  
  
                      } else if (prevout.scriptPubKey.IsPayToPublicKeyHash()) {
                          vector<unsigned char> hashBytes(prevout.scriptPubKey.begin()+3, prevout.scriptPubKey.begin()+23);
  
                          // undo spending activity
                          addressIndex.push_back(make_pair(CAddressIndexKey(1, uint160(hashBytes), pindex->nHeight, i, hash, j, true), prevout.nValue * -1));
  
                          // restore unspent index
                          addressUnspentIndex.push_back(make_pair(CAddressUnspentKey(1, uint160(hashBytes), input.prevout.hash, input.prevout.n), CAddressUnspentValue(prevout.nValue, prevout.scriptPubKey, undo.nHeight)));
  
                      } else {
                          continue;
                      }
                  }
  
              }
          }
      }
  
  
      // move best block pointer to prevout block
      view.SetBestBlock(pindex->pprev->GetBlockHash());
  
      if (pfClean) {
          *pfClean = fClean;
          return true;
      }
  
      if (fAddressIndex) {
          if (!pblocktree->EraseAddressIndex(addressIndex)) {
              return AbortNode(state, "Failed to delete address index");
          }
          if (!pblocktree->UpdateAddressUnspentIndex(addressUnspentIndex)) {
              return AbortNode(state, "Failed to write address unspent index");
          }
      }
  
      return fClean;
  }
  
  void static FlushBlockFile(bool fFinalize = false)
  {
      LOCK(cs_LastBlockFile);
  
      CDiskBlockPos posOld(nLastBlockFile, 0);
  
      FILE *fileOld = OpenBlockFile(posOld);
      if (fileOld) {
          if (fFinalize)
              TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nSize);
          FileCommit(fileOld);
          fclose(fileOld);
      }
  
      fileOld = OpenUndoFile(posOld);
      if (fileOld) {
          if (fFinalize)
              TruncateFile(fileOld, vinfoBlockFile[nLastBlockFile].nUndoSize);
          FileCommit(fileOld);
          fclose(fileOld);
      }
  }
  
  bool FindUndoPos(CValidationState &state, int nFile, CDiskBlockPos &pos, unsigned int nAddSize);
  
  static CCheckQueue<CScriptCheck> scriptcheckqueue(128);
  
  void ThreadScriptCheck() {
      RenameThread("energi-scriptch");
      scriptcheckqueue.Thread();
  }
  
  // Protected by cs_main
  VersionBitsCache versionbitscache;
  
  int32_t ComputeBlockVersion(const CBlockIndex* pindexPrev, const Consensus::Params& params, bool fAssumeMasternodeIsUpgraded)
  {
      LOCK(cs_main);
      int32_t nVersion = VERSIONBITS_TOP_BITS;
  
      for (int i = 0; i < (int)Consensus::MAX_VERSION_BITS_DEPLOYMENTS; i++) {
          Consensus::DeploymentPos pos = Consensus::DeploymentPos(i);
          ThresholdState state = VersionBitsState(pindexPrev, params, pos, versionbitscache);
          const struct BIP9DeploymentInfo& vbinfo = VersionBitsDeploymentInfo[pos];
          if (vbinfo.check_mn_protocol && state == THRESHOLD_STARTED && !fAssumeMasternodeIsUpgraded) {
              CScript payee;
              masternode_info_t mnInfo;
              if (!mnpayments.GetBlockPayee(pindexPrev->nHeight + 1, payee)) {
                  // no votes for this block
                  continue;
              }
              if (!mnodeman.GetMasternodeInfo(payee, mnInfo)) {
                  // unknown masternode
                  continue;
              }
              if (mnInfo.nProtocolVersion < DIP0001_PROTOCOL_VERSION) {
                  // masternode is not upgraded yet
                  continue;
              }
          }
          if (state == THRESHOLD_LOCKED_IN || state == THRESHOLD_STARTED) {
              nVersion |= VersionBitsMask(params, (Consensus::DeploymentPos)i);
          }
      }
  
      return nVersion;
  }
  
  bool GetBlockHash(uint256& hashRet, int nBlockHeight)
  {
      LOCK(cs_main);
      if(chainActive.Tip() == NULL) return false;
      if(nBlockHeight < -1 || nBlockHeight > chainActive.Height()) return false;
      if(nBlockHeight == -1) nBlockHeight = chainActive.Height();
      hashRet = chainActive[nBlockHeight]->GetBlockHash();
      return true;
  }
  
  /**
   * Threshold condition checker that triggers when unknown versionbits are seen on the network.
   */
  class WarningBitsConditionChecker : public AbstractThresholdConditionChecker
  {
  private:
      int bit;
  
  public:
      WarningBitsConditionChecker(int bitIn) : bit(bitIn) {}
  
      int64_t BeginTime(const Consensus::Params& params) const { return 0; }
      int64_t EndTime(const Consensus::Params& params) const { return std::numeric_limits<int64_t>::max(); }
      int Period(const Consensus::Params& params) const { return params.nMinerConfirmationWindow; }
      int Threshold(const Consensus::Params& params) const { return params.nRuleChangeActivationThreshold; }
  
      bool Condition(const CBlockIndex* pindex, const Consensus::Params& params) const
      {
          return ((pindex->nVersion & VERSIONBITS_TOP_MASK) == VERSIONBITS_TOP_BITS) &&
                 ((pindex->nVersion >> bit) & 1) != 0 &&
                 ((ComputeBlockVersion(pindex->pprev, params) >> bit) & 1) == 0;
      }
  };
  
  // Protected by cs_main
  static ThresholdConditionCache warningcache[VERSIONBITS_NUM_BITS];
  
  static int64_t nTimeCheck = 0;
  static int64_t nTimeForks = 0;
  static int64_t nTimeVerify = 0;
  static int64_t nTimeConnect = 0;
  static int64_t nTimeIndex = 0;
  static int64_t nTimeCallbacks = 0;
  static int64_t nTimeTotal = 0;
  
  bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pindex, CCoinsViewCache& view, bool fJustCheck)
  {
      const CChainParams& chainparams = Params();
      AssertLockHeld(cs_main);
  
      int64_t nTimeStart = GetTimeMicros();
  
      // Check it again in case a previous version let a bad block in
      if (!CheckBlock(block, state, !fJustCheck, !fJustCheck))
          return false;
  
      // verify that the view's current state corresponds to the previous block
      uint256 hashPrevBlock = pindex->pprev == NULL ? uint256() : pindex->pprev->GetBlockHash();
      assert(hashPrevBlock == view.GetBestBlock());
  
      // Special case for the genesis block, skipping connection of its transactions
      // (its coinbase is unspendable)
      if (block.GetHash() == chainparams.GetConsensus().hashGenesisBlock) {
          if (!fJustCheck)
              view.SetBestBlock(pindex->GetBlockHash());
          return true;
      }
  
      bool fScriptChecks = true;
      if (!hashAssumeValid.IsNull()) {
          // We've been configured with the hash of a block which has been externally verified to have a valid history.
          // A suitable default value is included with the software and updated from time to time.  Because validity
          //  relative to a piece of software is an objective fact these defaults can be easily reviewed.
          // This setting doesn't force the selection of any particular chain but makes validating some faster by
          //  effectively caching the result of part of the verification.
          BlockMap::const_iterator  it = mapBlockIndex.find(hashAssumeValid);
          if (it != mapBlockIndex.end()) {
              if (it->second->GetAncestor(pindex->nHeight) == pindex &&
                  pindexBestHeader->GetAncestor(pindex->nHeight) == pindex &&
                  pindexBestHeader->nChainWork >= UintToArith256(chainparams.GetConsensus().nMinimumChainWork)) {
                  // This block is a member of the assumed verified chain and an ancestor of the best header.
                  // The equivalent time check discourages hashpower from extorting the network via DOS attack
                  //  into accepting an invalid block through telling users they must manually set assumevalid.
                  //  Requiring a software change or burying the invalid block, regardless of the setting, makes
                  //  it hard to hide the implication of the demand.  This also avoids having release candidates
                  //  that are hardly doing any signature verification at all in testing without having to
                  //  artificially set the default assumed verified block further back.
                  // The test against nMinimumChainWork prevents the skipping when denied access to any chain at
                  //  least as good as the expected chain.
                  fScriptChecks = (GetBlockProofEquivalentTime(*pindexBestHeader, *pindex, *pindexBestHeader, chainparams.GetConsensus()) <= 60 * 60 * 24 * 7 * 2);
              }
          }
      }
  
      int64_t nTime1 = GetTimeMicros(); nTimeCheck += nTime1 - nTimeStart;
      LogPrint("bench", "    - Sanity checks: %.2fms [%.2fs]\n", 0.001 * (nTime1 - nTimeStart), nTimeCheck * 0.000001);
  
      // BIP16 didn't become active until Apr 1 2012
      int64_t nBIP16SwitchTime = 1333238400;
      bool fStrictPayToScriptHash = (pindex->GetBlockTime() >= nBIP16SwitchTime);
  
      unsigned int flags = fStrictPayToScriptHash ? SCRIPT_VERIFY_P2SH : SCRIPT_VERIFY_NONE;
  
      // Start enforcing the DERSIG (BIP66) rules, for block.nVersion=3 blocks,
      // when 75% of the network has upgraded:
      if (block.nVersion >= 3 && IsSuperMajority(3, pindex->pprev, chainparams.GetConsensus().nMajorityEnforceBlockUpgrade, chainparams.GetConsensus())) {
          flags |= SCRIPT_VERIFY_DERSIG;
      }
  
      // Start enforcing CHECKLOCKTIMEVERIFY, (BIP65) for block.nVersion=4
      // blocks, when 75% of the network has upgraded:
      if (block.nVersion >= 4 && IsSuperMajority(4, pindex->pprev, chainparams.GetConsensus().nMajorityEnforceBlockUpgrade, chainparams.GetConsensus())) {
          flags |= SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY;
      }
  
      // Start enforcing BIP68 (sequence locks) and BIP112 (CHECKSEQUENCEVERIFY) using versionbits logic.
      int nLockTimeFlags = 0;
      if (VersionBitsState(pindex->pprev, chainparams.GetConsensus(), Consensus::DEPLOYMENT_CSV, versionbitscache) == THRESHOLD_ACTIVE) {
          flags |= SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
          nLockTimeFlags |= LOCKTIME_VERIFY_SEQUENCE;
      }
  
      int64_t nTime2 = GetTimeMicros(); nTimeForks += nTime2 - nTime1;
      LogPrint("bench", "    - Fork checks: %.2fms [%.2fs]\n", 0.001 * (nTime2 - nTime1), nTimeForks * 0.000001);
  
      CBlockUndo blockundo;
  
      CCheckQueueControl<CScriptCheck> control(fScriptChecks && nScriptCheckThreads ? &scriptcheckqueue : NULL);
  
      std::vector<int> prevheights;
      CAmount nFees = 0;
      int nInputs = 0;
      unsigned int nSigOps = 0;
      CDiskTxPos pos(pindex->GetBlockPos(), GetSizeOfCompactSize(block.vtx.size()));
      std::vector<std::pair<uint256, CDiskTxPos> > vPos;
      vPos.reserve(block.vtx.size());
      blockundo.vtxundo.reserve(block.vtx.size() - 1);
      std::vector<std::pair<CAddressIndexKey, CAmount> > addressIndex;
      std::vector<std::pair<CAddressUnspentKey, CAddressUnspentValue> > addressUnspentIndex;
      std::vector<std::pair<CSpentIndexKey, CSpentIndexValue> > spentIndex;
  
      bool fDIP0001Active_context = (VersionBitsState(pindex->pprev, chainparams.GetConsensus(), Consensus::DEPLOYMENT_DIP0001, versionbitscache) == THRESHOLD_ACTIVE);
  
      for (unsigned int i = 0; i < block.vtx.size(); i++)
      {
          const CTransaction &tx = block.vtx[i];
          const uint256 txhash = tx.GetHash();
  
          nInputs += tx.vin.size();
          nSigOps += GetLegacySigOpCount(tx);
          if (nSigOps > MaxBlockSigOps(fDIP0001Active_context))
              return state.DoS(100, error("ConnectBlock(): too many sigops"),
                               REJECT_INVALID, "bad-blk-sigops");
  
          if (!tx.IsCoinBase())
          {
              if (!view.HaveInputs(tx))
                  return state.DoS(100, error("ConnectBlock(): inputs missing/spent"),
                                   REJECT_INVALID, "bad-txns-inputs-missingorspent");
  
              // Check that transaction is BIP68 final
              // BIP68 lock checks (as opposed to nLockTime checks) must
              // be in ConnectBlock because they require the UTXO set
              prevheights.resize(tx.vin.size());
              for (size_t j = 0; j < tx.vin.size(); j++) {
                  prevheights[j] = view.AccessCoins(tx.vin[j].prevout.hash)->nHeight;
              }
  
              if (!SequenceLocks(tx, nLockTimeFlags, &prevheights, *pindex)) {
                  return state.DoS(100, error("%s: contains a non-BIP68-final transaction", __func__),
                                   REJECT_INVALID, "bad-txns-nonfinal");
              }
  
              if (fAddressIndex || fSpentIndex)
              {
                  for (size_t j = 0; j < tx.vin.size(); j++) {
  
                      const CTxIn input = tx.vin[j];
                      const CTxOut &prevout = view.GetOutputFor(tx.vin[j]);
                      uint160 hashBytes;
                      int addressType;
  
                      if (prevout.scriptPubKey.IsPayToScriptHash()) {
                          hashBytes = uint160(vector <unsigned char>(prevout.scriptPubKey.begin()+2, prevout.scriptPubKey.begin()+22));
                          addressType = 2;
                      } else if (prevout.scriptPubKey.IsPayToPublicKeyHash()) {
                          hashBytes = uint160(vector <unsigned char>(prevout.scriptPubKey.begin()+3, prevout.scriptPubKey.begin()+23));
                          addressType = 1;
                      } else {
                          hashBytes.SetNull();
                          addressType = 0;
                      }
  
                      if (fAddressIndex && addressType > 0) {
                          // record spending activity
                          addressIndex.push_back(make_pair(CAddressIndexKey(addressType, hashBytes, pindex->nHeight, i, txhash, j, true), prevout.nValue * -1));
  
                          // remove address from unspent index
                          addressUnspentIndex.push_back(make_pair(CAddressUnspentKey(addressType, hashBytes, input.prevout.hash, input.prevout.n), CAddressUnspentValue()));
                      }
  
                      if (fSpentIndex) {
                          // add the spent index to determine the txid and input that spent an output
                          // and to find the amount and address from an input
                          spentIndex.push_back(make_pair(CSpentIndexKey(input.prevout.hash, input.prevout.n), CSpentIndexValue(txhash, j, pindex->nHeight, prevout.nValue, addressType, hashBytes)));
                      }
                  }
  
              }
  
              if (fStrictPayToScriptHash)
              {
                  // Add in sigops done by pay-to-script-hash inputs;
                  // this is to prevent a "rogue miner" from creating
                  // an incredibly-expensive-to-validate block.
                  nSigOps += GetP2SHSigOpCount(tx, view);
                  if (nSigOps > MaxBlockSigOps(fDIP0001Active_context))
                      return state.DoS(100, error("ConnectBlock(): too many sigops"),
                                       REJECT_INVALID, "bad-blk-sigops");
              }
  
              nFees += view.GetValueIn(tx)-tx.GetValueOut();
  
              std::vector<CScriptCheck> vChecks;
              bool fCacheResults = fJustCheck; /* Don't cache results if we're actually connecting blocks (still consult the cache, though) */
              if (!CheckInputs(tx, state, view, fScriptChecks, flags, fCacheResults, nScriptCheckThreads ? &vChecks : NULL))
                  return error("ConnectBlock(): CheckInputs on %s failed with %s",
                      tx.GetHash().ToString(), FormatStateMessage(state));
              control.Add(vChecks);
          }
  
          if (fAddressIndex) {
              for (unsigned int k = 0; k < tx.vout.size(); k++) {
                  const CTxOut &out = tx.vout[k];
  
                  if (out.scriptPubKey.IsPayToScriptHash()) {
                      vector<unsigned char> hashBytes(out.scriptPubKey.begin()+2, out.scriptPubKey.begin()+22);
  
                      // record receiving activity
                      addressIndex.push_back(make_pair(CAddressIndexKey(2, uint160(hashBytes), pindex->nHeight, i, txhash, k, false), out.nValue));
  
                      // record unspent output
                      addressUnspentIndex.push_back(make_pair(CAddressUnspentKey(2, uint160(hashBytes), txhash, k), CAddressUnspentValue(out.nValue, out.scriptPubKey, pindex->nHeight)));
  
                  } else if (out.scriptPubKey.IsPayToPublicKeyHash()) {
                      vector<unsigned char> hashBytes(out.scriptPubKey.begin()+3, out.scriptPubKey.begin()+23);
  
                      // record receiving activity
                      addressIndex.push_back(make_pair(CAddressIndexKey(1, uint160(hashBytes), pindex->nHeight, i, txhash, k, false), out.nValue));
  
                      // record unspent output
                      addressUnspentIndex.push_back(make_pair(CAddressUnspentKey(1, uint160(hashBytes), txhash, k), CAddressUnspentValue(out.nValue, out.scriptPubKey, pindex->nHeight)));
  
                  } else {
                      continue;
                  }
  
              }
          }
  
          CTxUndo undoDummy;
          if (i > 0) {
              blockundo.vtxundo.push_back(CTxUndo());
          }
          UpdateCoins(tx, state, view, i == 0 ? undoDummy : blockundo.vtxundo.back(), pindex->nHeight);
  
          vPos.push_back(std::make_pair(tx.GetHash(), pos));
          pos.nTxOffset += ::GetSerializeSize(tx, SER_DISK, CLIENT_VERSION);
      }
      int64_t nTime3 = GetTimeMicros(); nTimeConnect += nTime3 - nTime2;
      LogPrint("bench", "      - Connect %u transactions: %.2fms (%.3fms/tx, %.3fms/txin) [%.2fs]\n", (unsigned)block.vtx.size(), 0.001 * (nTime3 - nTime2), 0.001 * (nTime3 - nTime2) / block.vtx.size(), nInputs <= 1 ? 0 : 0.001 * (nTime3 - nTime2) / (nInputs-1), nTimeConnect * 0.000001);
  
  
      // It's possible that we simply don't have enough data and this could fail
      // (i.e. block itself could be a correct one and we need to store it),
      // that's why this is in ConnectBlock. Could be the other way around however -
      // the peer who sent us this block is missing some data and wasn't able
      // to recognize that block is actually invalid.
      // TODO: resync data (both ways?) and try to reprocess this block later.
      CAmount blockReward = nFees + GetBlockSubsidy(pindex->nHeight, chainparams.GetConsensus());
      std::string strError = "";
      if (!IsBlockValueValid(block, pindex->nHeight, blockReward, strError)) {
          return state.DoS(0, error("ConnectBlock(NRG): %s", strError), REJECT_INVALID, "bad-cb-amount");
      }
  
      if (!IsBlockPayeeValid(block.vtx[0], pindex->nHeight, blockReward)) {
          mapRejectedBlocks.insert(make_pair(block.GetHash(), GetTime()));
          return state.DoS(0, error("ConnectBlock(NRG): couldn't find masternode or superblock payments"),
                                  REJECT_INVALID, "bad-cb-payee");
      }
  
      if (!control.Wait())
          return state.DoS(100, false);
      int64_t nTime4 = GetTimeMicros(); nTimeVerify += nTime4 - nTime2;
      LogPrint("bench", "    - Verify %u txins: %.2fms (%.3fms/txin) [%.2fs]\n", nInputs - 1, 0.001 * (nTime4 - nTime2), nInputs <= 1 ? 0 : 0.001 * (nTime4 - nTime2) / (nInputs-1), nTimeVerify * 0.000001);
  
      if (fJustCheck)
          return true;
  
      // Write undo information to disk
      if (pindex->GetUndoPos().IsNull() || !pindex->IsValid(BLOCK_VALID_SCRIPTS))
      {
          if (pindex->GetUndoPos().IsNull()) {
              CDiskBlockPos pos;
              if (!FindUndoPos(state, pindex->nFile, pos, ::GetSerializeSize(blockundo, SER_DISK, CLIENT_VERSION) + 40))
                  return error("ConnectBlock(): FindUndoPos failed");
              if (!UndoWriteToDisk(blockundo, pos, pindex->pprev->GetBlockHash(), chainparams.MessageStart()))
                  return AbortNode(state, "Failed to write undo data");
  
              // update nUndoPos in block index
              pindex->nUndoPos = pos.nPos;
              pindex->nStatus |= BLOCK_HAVE_UNDO;
          }
  
          pindex->RaiseValidity(BLOCK_VALID_SCRIPTS);
          setDirtyBlockIndex.insert(pindex);
      }
  
      if (fTxIndex)
          if (!pblocktree->WriteTxIndex(vPos))
              return AbortNode(state, "Failed to write transaction index");
  
      if (fAddressIndex) {
          if (!pblocktree->WriteAddressIndex(addressIndex)) {
              return AbortNode(state, "Failed to write address index");
          }
  
          if (!pblocktree->UpdateAddressUnspentIndex(addressUnspentIndex)) {
              return AbortNode(state, "Failed to write address unspent index");
          }
      }
  
      if (fSpentIndex)
          if (!pblocktree->UpdateSpentIndex(spentIndex))
              return AbortNode(state, "Failed to write transaction index");
  
      if (fTimestampIndex)
          if (!pblocktree->WriteTimestampIndex(CTimestampIndexKey(pindex->nTime, pindex->GetBlockHash())))
              return AbortNode(state, "Failed to write timestamp index");
  
      // add this block to the view's block chain
      view.SetBestBlock(pindex->GetBlockHash());
  
      int64_t nTime5 = GetTimeMicros(); nTimeIndex += nTime5 - nTime4;
      LogPrint("bench", "    - Index writing: %.2fms [%.2fs]\n", 0.001 * (nTime5 - nTime4), nTimeIndex * 0.000001);
  
      // Watch for changes to the previous coinbase transaction.
      static uint256 hashPrevBestCoinBase;
      GetMainSignals().UpdatedTransaction(hashPrevBestCoinBase);
      hashPrevBestCoinBase = block.vtx[0].GetHash();
  
      int64_t nTime6 = GetTimeMicros(); nTimeCallbacks += nTime6 - nTime5;
      LogPrint("bench", "    - Callbacks: %.2fms [%.2fs]\n", 0.001 * (nTime6 - nTime5), nTimeCallbacks * 0.000001);
  
      return true;
  }
  
  /**
   * Update the on-disk chain state.
   * The caches and indexes are flushed depending on the mode we're called with
   * if they're too large, if it's been a while since the last write,
   * or always and in all cases if we're in prune mode and are deleting files.
   */
  bool static FlushStateToDisk(CValidationState &state, FlushStateMode mode) {
      const CChainParams& chainparams = Params();
      LOCK2(cs_main, cs_LastBlockFile);
      static int64_t nLastWrite = 0;
      static int64_t nLastFlush = 0;
      static int64_t nLastSetChain = 0;
      std::set<int> setFilesToPrune;
      bool fFlushForPrune = false;
      try {
      if (fPruneMode && fCheckForPruning && !fReindex) {
          FindFilesToPrune(setFilesToPrune, chainparams.PruneAfterHeight());
          fCheckForPruning = false;
          if (!setFilesToPrune.empty()) {
              fFlushForPrune = true;
              if (!fHavePruned) {
                  pblocktree->WriteFlag("prunedblockfiles", true);
                  fHavePruned = true;
              }
          }
      }
      int64_t nNow = GetTimeMicros();
      // Avoid writing/flushing immediately after startup.
      if (nLastWrite == 0) {
          nLastWrite = nNow;
      }
      if (nLastFlush == 0) {
          nLastFlush = nNow;
      }
      if (nLastSetChain == 0) {
          nLastSetChain = nNow;
      }
      size_t cacheSize = pcoinsTip->DynamicMemoryUsage();
      // The cache is large and close to the limit, but we have time now (not in the middle of a block processing).
      bool fCacheLarge = mode == FLUSH_STATE_PERIODIC && cacheSize * (10.0/9) > nCoinCacheUsage;
      // The cache is over the limit, we have to write now.
      bool fCacheCritical = mode == FLUSH_STATE_IF_NEEDED && cacheSize > nCoinCacheUsage;
      // It's been a while since we wrote the block index to disk. Do this frequently, so we don't need to redownload after a crash.
      bool fPeriodicWrite = mode == FLUSH_STATE_PERIODIC && nNow > nLastWrite + (int64_t)DATABASE_WRITE_INTERVAL * 1000000;
      // It's been very long since we flushed the cache. Do this infrequently, to optimize cache usage.
      bool fPeriodicFlush = mode == FLUSH_STATE_PERIODIC && nNow > nLastFlush + (int64_t)DATABASE_FLUSH_INTERVAL * 1000000;
      // Combine all conditions that result in a full cache flush.
      bool fDoFullFlush = (mode == FLUSH_STATE_ALWAYS) || fCacheLarge || fCacheCritical || fPeriodicFlush || fFlushForPrune;
      // Write blocks and block index to disk.
      if (fDoFullFlush || fPeriodicWrite) {
          // Depend on nMinDiskSpace to ensure we can write block index
          if (!CheckDiskSpace(0))
              return state.Error("out of disk space");
          // First make sure all block and undo data is flushed to disk.
          FlushBlockFile();
          // Then update all block file information (which may refer to block and undo files).
          {
              std::vector<std::pair<int, const CBlockFileInfo*> > vFiles;
              vFiles.reserve(setDirtyFileInfo.size());
              for (set<int>::iterator it = setDirtyFileInfo.begin(); it != setDirtyFileInfo.end(); ) {
                  vFiles.push_back(make_pair(*it, &vinfoBlockFile[*it]));
                  setDirtyFileInfo.erase(it++);
              }
              std::vector<const CBlockIndex*> vBlocks;
              vBlocks.reserve(setDirtyBlockIndex.size());
              for (set<CBlockIndex*>::iterator it = setDirtyBlockIndex.begin(); it != setDirtyBlockIndex.end(); ) {
                  vBlocks.push_back(*it);
                  setDirtyBlockIndex.erase(it++);
              }
              if (!pblocktree->WriteBatchSync(vFiles, nLastBlockFile, vBlocks)) {
                  return AbortNode(state, "Files to write to block index database");
              }
          }
          // Finally remove any pruned files
          if (fFlushForPrune)
              UnlinkPrunedFiles(setFilesToPrune);
          nLastWrite = nNow;
      }
      // Flush best chain related state. This can only be done if the blocks / block index write was also done.
      if (fDoFullFlush) {
          // Typical CCoins structures on disk are around 128 bytes in size.
          // Pushing a new one to the database can cause it to be written
          // twice (once in the log, and once in the tables). This is already
          // an overestimation, as most will delete an existing entry or
          // overwrite one. Still, use a conservative safety factor of 2.
          if (!CheckDiskSpace(128 * 2 * 2 * pcoinsTip->GetCacheSize()))
              return state.Error("out of disk space");
          // Flush the chainstate (which may refer to block index entries).
          if (!pcoinsTip->Flush())
              return AbortNode(state, "Failed to write to coin database");
          nLastFlush = nNow;
      }
      if (fDoFullFlush || ((mode == FLUSH_STATE_ALWAYS || mode == FLUSH_STATE_PERIODIC) && nNow > nLastSetChain + (int64_t)DATABASE_WRITE_INTERVAL * 1000000)) {
          // Update best block in wallet (so we can detect restored wallets).
          GetMainSignals().SetBestChain(chainActive.GetLocator());
          nLastSetChain = nNow;
      }
      } catch (const std::runtime_error& e) {
          return AbortNode(state, std::string("System error while flushing: ") + e.what());
      }
      return true;
  }
  
  void FlushStateToDisk() {
      CValidationState state;
      FlushStateToDisk(state, FLUSH_STATE_ALWAYS);
  }
  
  void PruneAndFlush() {
      CValidationState state;
      fCheckForPruning = true;
      FlushStateToDisk(state, FLUSH_STATE_NONE);
  }
  
  /** Update chainActive and related internal data structures. */
  void static UpdateTip(CBlockIndex *pindexNew) {
      const CChainParams& chainParams = Params();
      chainActive.SetTip(pindexNew);
  
      // New best block
      mempool.AddTransactionsUpdated(1);
  
      LogPrintf("%s: new best=%s  height=%d  log2_work=%.8g  tx=%lu  date=%s progress=%f  cache=%.1fMiB(%utx)\n", __func__,
        chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(), log(chainActive.Tip()->nChainWork.getdouble())/log(2.0), (unsigned long)chainActive.Tip()->nChainTx,
        DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),
        Checkpoints::GuessVerificationProgress(chainParams.Checkpoints(), chainActive.Tip()), pcoinsTip->DynamicMemoryUsage() * (1.0 / (1<<20)), pcoinsTip->GetCacheSize());
  
      cvBlockChange.notify_all();
  
      // Check the version of the last 100 blocks to see if we need to upgrade:
      static bool fWarned = false;
      if (!IsInitialBlockDownload())
      {
          int nUpgraded = 0;
          const CBlockIndex* pindex = chainActive.Tip();
          for (int bit = 0; bit < VERSIONBITS_NUM_BITS; bit++) {
              WarningBitsConditionChecker checker(bit);
              ThresholdState state = checker.GetStateFor(pindex, chainParams.GetConsensus(), warningcache[bit]);
              if (state == THRESHOLD_ACTIVE || state == THRESHOLD_LOCKED_IN) {
                  if (state == THRESHOLD_ACTIVE) {
                      strMiscWarning = strprintf(_("Warning: unknown new rules activated (versionbit %i)"), bit);
                      if (!fWarned) {
                          CAlert::Notify(strMiscWarning, true);
                          fWarned = true;
                      }
                  } else {
                      LogPrintf("%s: unknown new rules are about to activate (versionbit %i)\n", __func__, bit);
                  }
              }
          }
          for (int i = 0; i < 100 && pindex != NULL; i++)
          {
              int32_t nExpectedVersion = ComputeBlockVersion(pindex->pprev, chainParams.GetConsensus(), true);
              if (pindex->nVersion > VERSIONBITS_LAST_OLD_BLOCK_VERSION && (pindex->nVersion & ~nExpectedVersion) != 0)
                  ++nUpgraded;
              pindex = pindex->pprev;
          }
          if (nUpgraded > 0)
              LogPrintf("%s: %d of last 100 blocks have unexpected version\n", __func__, nUpgraded);
          if (nUpgraded > 100/2)
          {
              // strMiscWarning is read by GetWarnings(), called by Qt and the JSON-RPC code to warn the user:
              strMiscWarning = _("Warning: Unknown block versions being mined! It's possible unknown rules are in effect");
              if (!fWarned) {
                  CAlert::Notify(strMiscWarning, true);
                  fWarned = true;
              }
          }
      }
  }
  
  /** Disconnect chainActive's tip. You probably want to call mempool.removeForReorg and manually re-limit mempool size after this, with cs_main held. */
  bool static DisconnectTip(CValidationState& state, const Consensus::Params& consensusParams)
  {
      CBlockIndex *pindexDelete = chainActive.Tip();
      assert(pindexDelete);
      // Read block from disk.
      CBlock block;
      if (!ReadBlockFromDisk(block, pindexDelete, consensusParams))
          return AbortNode(state, "Failed to read block");
      // Apply the block atomically to the chain state.
      int64_t nStart = GetTimeMicros();
      {
          CCoinsViewCache view(pcoinsTip);
          if (!DisconnectBlock(block, state, pindexDelete, view))
              return error("DisconnectTip(): DisconnectBlock %s failed", pindexDelete->GetBlockHash().ToString());
          assert(view.Flush());
      }
      LogPrint("bench", "- Disconnect block: %.2fms\n", (GetTimeMicros() - nStart) * 0.001);
      // Write the chain state to disk, if necessary.
      if (!FlushStateToDisk(state, FLUSH_STATE_IF_NEEDED))
          return false;
      // Resurrect mempool transactions from the disconnected block.
      std::vector<uint256> vHashUpdate;
      BOOST_FOREACH(const CTransaction &tx, block.vtx) {
          // ignore validation errors in resurrected transactions
          list<CTransaction> removed;
          CValidationState stateDummy;
          if (tx.IsCoinBase() || !AcceptToMemoryPool(mempool, stateDummy, tx, false, NULL, true)) {
              mempool.remove(tx, removed, true);
          } else if (mempool.exists(tx.GetHash())) {
              vHashUpdate.push_back(tx.GetHash());
          }
      }
      // AcceptToMemoryPool/addUnchecked all assume that new mempool entries have
      // no in-mempool children, which is generally not true when adding
      // previously-confirmed transactions back to the mempool.
      // UpdateTransactionsFromBlock finds descendants of any transactions in this
      // block that were added back and cleans up the mempool state.
      mempool.UpdateTransactionsFromBlock(vHashUpdate);
      // Update chainActive and related variables.
      UpdateTip(pindexDelete->pprev);
      // Let wallets know transactions went from 1-confirmed to
      // 0-confirmed or conflicted:
      BOOST_FOREACH(const CTransaction &tx, block.vtx) {
          GetMainSignals().SyncTransaction(tx, NULL);
      }
      return true;
  }
  
  static int64_t nTimeReadFromDisk = 0;
  static int64_t nTimeConnectTotal = 0;
  static int64_t nTimeFlush = 0;
  static int64_t nTimeChainState = 0;
  static int64_t nTimePostConnect = 0;
  
  void CreateDAG(int height, egihash::progress_callback_type callback)
  {
      using namespace egihash;
  
      if (!GetBoolArg("-usedag", DEFAULT_USEDAG)) {
          LogPrint("nrghash", "Operating in light mode, not loading a DAG\n");
          return;
      }
  
      auto const epoch = height / constants::EPOCH_LENGTH;
      auto const & seedhash = cache_t::get_seedhash(height).to_hex();
      stringstream ss;
      ss << hex << setw(4) << setfill('0') << epoch << "-" << seedhash.substr(0, 12) << ".dag";
      auto const epoch_file = GetDataDir(false) / "dag" / ss.str();
  
      LogPrint("nrghash", "DAG file for epoch %u is \"%s\"\n", epoch, epoch_file.string());
      // try to load the DAG from disk
      try
      {
          unique_ptr<dag_t> new_dag(new dag_t(epoch_file.string(), callback));
          ActiveDAG(move(new_dag));
          LogPrint("nrghash", "DAG file \"%s\" loaded successfully.\n", epoch_file.string());
          return;
      }
      catch (hash_exception const & e)
      {
          LogPrint("nrghash", "DAG file \"%s\" not loaded, will be generated instead. Message: %s\n", epoch_file.string(), e.what());
      }
  
      // try to generate the DAG
      try
      {
          unique_ptr<dag_t> new_dag(new dag_t(height, callback));
          boost::filesystem::create_directories(epoch_file.parent_path());
          new_dag->save(epoch_file.string());
          ActiveDAG(move(new_dag));
          LogPrint("nrghash", "DAG generated successfully. Saved to \"%s\".\n", epoch_file.string());
      }
      catch (hash_exception const & e)
      {
          error("DAG for epoch %u could not be generated: %s\n", epoch, e.what());
      }
  }
  
  int GetHeight()
  {
      LOCK(cs_main);
      return chainActive.Height();
  }
  
  void InitDAG(egihash::progress_callback_type callback)
  {
      auto const & dag = ActiveDAG();
      if (!dag)
      {
          auto const height = (max)(GetHeight(), 0);
          CreateDAG(height, callback);
          LogPrint("nrghash", "Loaded or created DAG for epoch %d\n", height / egihash::constants::EPOCH_LENGTH);
      }
      LogPrint("nrghash", "DAG has been initialized already. Use ActiveDAG() to swap.\n");
  }
  
  /**
   * Connect a new block to chainActive. pblock is either NULL or a pointer to a CBlock
   * corresponding to pindexNew, to bypass loading it again from disk.
   */
  bool static ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const CBlock* pblock)
  {
      using namespace egihash;
  
      assert(pindexNew->pprev == chainActive.Tip());
      auto const height = pindexNew->nHeight;
      auto const epoch = height / constants::EPOCH_LENGTH;
  
      // if there have been EPOCH_LENGTH number of blocks since the last DAG was generated,
      // generate a new one
      auto const & active_dag = ActiveDAG();
      if (active_dag && (epoch > active_dag->epoch())) {
          CreateDAG(height, [](::std::size_t step, ::std::size_t max, int phase) -> bool
          {
              double progress = static_cast<double>(step) / static_cast<double>(max) * 100.0;
              switch(phase)
              {
                  case egihash::cache_seeding:
                      LogPrint("nrghash", "Seeding cache... %3.2lf\n", progress);
                      break;
                  case egihash::cache_generation:
                      LogPrint("nrghash", "Generating cache... %3.2lf\n", progress);
                      break;
                  case egihash::cache_saving:
                      LogPrint("nrghash", "Saving cache... %3.2lf\n", progress);
                      break;
                  case egihash::cache_loading:
                      LogPrint("nrghash", "Loading cache... %3.2lf\n", progress);
                      break;
                  case egihash::dag_generation:
                      LogPrint("nrghash", "Generating DAG... %3.2lf\n", progress);
                      break;
                  case egihash::dag_saving:
                      LogPrint("nrghash", "Saving DAG... %3.2lf\n", progress);
                      break;
                  case egihash::dag_loading:
                      LogPrint("nrghash", "Loading DAG... %3.2lf\n", progress);
                      break;
                  default:
                      break;
              }
              return true;
          });
      }
  
      // Read block from disk.
      int64_t nTime1 = GetTimeMicros();
      CBlock block;
      if (!pblock) {
          if (!ReadBlockFromDisk(block, pindexNew, chainparams.GetConsensus()))
              return AbortNode(state, "Failed to read block");
          pblock = &block;
      }
      // Apply the block atomically to the chain state.
      int64_t nTime2 = GetTimeMicros(); nTimeReadFromDisk += nTime2 - nTime1;
      int64_t nTime3;
      LogPrint("bench", "  - Load block from disk: %.2fms [%.2fs]\n", (nTime2 - nTime1) * 0.001, nTimeReadFromDisk * 0.000001);
      {
          CCoinsViewCache view(pcoinsTip);
          bool rv = ConnectBlock(*pblock, state, pindexNew, view);
          GetMainSignals().BlockChecked(*pblock, state);
          if (!rv) {
              if (state.IsInvalid())
                  InvalidBlockFound(pindexNew, state);
              return error("ConnectTip(): ConnectBlock %s failed", pindexNew->GetBlockHash().ToString());
          }
          nTime3 = GetTimeMicros(); nTimeConnectTotal += nTime3 - nTime2;
          LogPrint("bench", "  - Connect total: %.2fms [%.2fs]\n", (nTime3 - nTime2) * 0.001, nTimeConnectTotal * 0.000001);
          assert(view.Flush());
      }
      int64_t nTime4 = GetTimeMicros(); nTimeFlush += nTime4 - nTime3;
      LogPrint("bench", "  - Flush: %.2fms [%.2fs]\n", (nTime4 - nTime3) * 0.001, nTimeFlush * 0.000001);
      // Write the chain state to disk, if necessary.
      if (!FlushStateToDisk(state, FLUSH_STATE_IF_NEEDED))
          return false;
      int64_t nTime5 = GetTimeMicros(); nTimeChainState += nTime5 - nTime4;
      LogPrint("bench", "  - Writing chainstate: %.2fms [%.2fs]\n", (nTime5 - nTime4) * 0.001, nTimeChainState * 0.000001);
      // Remove conflicting transactions from the mempool.
      list<CTransaction> txConflicted;
      mempool.removeForBlock(pblock->vtx, pindexNew->nHeight, txConflicted, !IsInitialBlockDownload());
      // Update chainActive & related variables.
      UpdateTip(pindexNew);
      // Tell wallet about transactions that went from mempool
      // to conflicted:
      BOOST_FOREACH(const CTransaction &tx, txConflicted) {
          GetMainSignals().SyncTransaction(tx, NULL);
      }
      // ... and about transactions that got confirmed:
      BOOST_FOREACH(const CTransaction &tx, pblock->vtx) {
          GetMainSignals().SyncTransaction(tx, pblock);
      }
  
      int64_t nTime6 = GetTimeMicros(); nTimePostConnect += nTime6 - nTime5; nTimeTotal += nTime6 - nTime1;
      LogPrint("bench", "  - Connect postprocess: %.2fms [%.2fs]\n", (nTime6 - nTime5) * 0.001, nTimePostConnect * 0.000001);
      LogPrint("bench", "- Connect block: %.2fms [%.2fs]\n", (nTime6 - nTime1) * 0.001, nTimeTotal * 0.000001);
      return true;
  }
  
  bool DisconnectBlocks(int blocks)
  {
      LOCK(cs_main);
  
      CValidationState state;
      const CChainParams& chainparams = Params();
  
      LogPrintf("DisconnectBlocks -- Got command to replay %d blocks\n", blocks);
      for(int i = 0; i < blocks; i++) {
          if(!DisconnectTip(state, chainparams.GetConsensus()) || !state.IsValid()) {
              return false;
          }
      }
  
      return true;
  }
  
  void ReprocessBlocks(int nBlocks)
  {
      LOCK(cs_main);
  
      std::map<uint256, int64_t>::iterator it = mapRejectedBlocks.begin();
      while(it != mapRejectedBlocks.end()){
          //use a window twice as large as is usual for the nBlocks we want to reset
          if((*it).second  > GetTime() - (nBlocks*60*5)) {
              BlockMap::iterator mi = mapBlockIndex.find((*it).first);
              if (mi != mapBlockIndex.end() && (*mi).second) {
  
                  CBlockIndex* pindex = (*mi).second;
                  LogPrintf("ReprocessBlocks -- %s\n", (*it).first.ToString());
  
                  CValidationState state;
                  ReconsiderBlock(state, pindex);
              }
          }
          ++it;
      }
  
      DisconnectBlocks(nBlocks);
  
      CValidationState state;
      ActivateBestChain(state, Params());
  }
  
  /**
   * Return the tip of the chain with the most work in it, that isn't
   * known to be invalid (it's however far from certain to be valid).
   */
  static CBlockIndex* FindMostWorkChain() {
      do {
          CBlockIndex *pindexNew = NULL;
  
          // Find the best candidate header.
          {
              std::set<CBlockIndex*, CBlockIndexWorkComparator>::reverse_iterator it = setBlockIndexCandidates.rbegin();
              if (it == setBlockIndexCandidates.rend())
                  return NULL;
              pindexNew = *it;
          }
  
          // Check whether all blocks on the path between the currently active chain and the candidate are valid.
          // Just going until the active chain is an optimization, as we know all blocks in it are valid already.
          CBlockIndex *pindexTest = pindexNew;
          bool fInvalidAncestor = false;
          while (pindexTest && !chainActive.Contains(pindexTest)) {
              assert(pindexTest->nChainTx || pindexTest->nHeight == 0);
  
              // Pruned nodes may have entries in setBlockIndexCandidates for
              // which block files have been deleted.  Remove those as candidates
              // for the most work chain if we come across them; we can't switch
              // to a chain unless we have all the non-active-chain parent blocks.
              bool fFailedChain = pindexTest->nStatus & BLOCK_FAILED_MASK;
              bool fMissingData = !(pindexTest->nStatus & BLOCK_HAVE_DATA);
              if (fFailedChain || fMissingData) {
                  // Candidate chain is not usable (either invalid or missing data)
                  if (fFailedChain && (pindexBestInvalid == NULL || pindexNew->nChainWork > pindexBestInvalid->nChainWork))
                      pindexBestInvalid = pindexNew;
                  CBlockIndex *pindexFailed = pindexNew;
                  // Remove the entire chain from the set.
                  while (pindexTest != pindexFailed) {
                      if (fFailedChain) {
                          pindexFailed->nStatus |= BLOCK_FAILED_CHILD;
                      } else if (fMissingData) {
                          // If we're missing data, then add back to mapBlocksUnlinked,
                          // so that if the block arrives in the future we can try adding
                          // to setBlockIndexCandidates again.
                          mapBlocksUnlinked.insert(std::make_pair(pindexFailed->pprev, pindexFailed));
                      }
                      setBlockIndexCandidates.erase(pindexFailed);
                      pindexFailed = pindexFailed->pprev;
                  }
                  setBlockIndexCandidates.erase(pindexTest);
                  fInvalidAncestor = true;
                  break;
              }
              pindexTest = pindexTest->pprev;
          }
          if (!fInvalidAncestor)
              return pindexNew;
      } while(true);
  }
  
  /** Delete all entries in setBlockIndexCandidates that are worse than the current tip. */
  static void PruneBlockIndexCandidates() {
      // Note that we can't delete the current block itself, as we may need to return to it later in case a
      // reorganization to a better block fails.
      std::set<CBlockIndex*, CBlockIndexWorkComparator>::iterator it = setBlockIndexCandidates.begin();
      while (it != setBlockIndexCandidates.end() && setBlockIndexCandidates.value_comp()(*it, chainActive.Tip())) {
          setBlockIndexCandidates.erase(it++);
      }
      // Either the current tip or a successor of it we're working towards is left in setBlockIndexCandidates.
      assert(!setBlockIndexCandidates.empty());
  }
  
  /**
   * Try to make some progress towards making pindexMostWork the active block.
   * pblock is either NULL or a pointer to a CBlock corresponding to pindexMostWork.
   */
  static bool ActivateBestChainStep(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexMostWork, const CBlock* pblock, bool& fInvalidFound)
  {
      AssertLockHeld(cs_main);
      const CBlockIndex *pindexOldTip = chainActive.Tip();
      const CBlockIndex *pindexFork = chainActive.FindFork(pindexMostWork);
  
      // Disconnect active blocks which are no longer in the best chain.
      bool fBlocksDisconnected = false;
      while (chainActive.Tip() && chainActive.Tip() != pindexFork) {
          if (!DisconnectTip(state, chainparams.GetConsensus()))
              return false;
          fBlocksDisconnected = true;
      }
  
      // Build list of new blocks to connect.
      std::vector<CBlockIndex*> vpindexToConnect;
      bool fContinue = true;
      int nHeight = pindexFork ? pindexFork->nHeight : -1;
      while (fContinue && nHeight != pindexMostWork->nHeight) {
          // Don't iterate the entire list of potential improvements toward the best tip, as we likely only need
          // a few blocks along the way.
          int nTargetHeight = std::min(nHeight + 32, pindexMostWork->nHeight);
          vpindexToConnect.clear();
          vpindexToConnect.reserve(nTargetHeight - nHeight);
          CBlockIndex *pindexIter = pindexMostWork->GetAncestor(nTargetHeight);
          while (pindexIter && pindexIter->nHeight != nHeight) {
              vpindexToConnect.push_back(pindexIter);
              pindexIter = pindexIter->pprev;
          }
          nHeight = nTargetHeight;
  
          // Connect new blocks.
          BOOST_REVERSE_FOREACH(CBlockIndex *pindexConnect, vpindexToConnect) {
              if (!ConnectTip(state, chainparams, pindexConnect, pindexConnect == pindexMostWork ? pblock : NULL)) {
                  if (state.IsInvalid()) {
                      // The block violates a consensus rule.
                      if (!state.CorruptionPossible())
                          InvalidChainFound(vpindexToConnect.back());
                      state = CValidationState();
                      fInvalidFound = true;
                      fContinue = false;
                      break;
                  } else {
                      // A system error occurred (disk space, database error, ...).
                      return false;
                  }
              } else {
                  PruneBlockIndexCandidates();
                  if (!pindexOldTip || chainActive.Tip()->nChainWork > pindexOldTip->nChainWork) {
                      // We're in a better position than we were. Return temporarily to release the lock.
                      fContinue = false;
                      break;
                  }
              }
          }
      }
  
      if (fBlocksDisconnected) {
          mempool.removeForReorg(pcoinsTip, chainActive.Tip()->nHeight + 1, STANDARD_LOCKTIME_VERIFY_FLAGS);
          LimitMempoolSize(mempool, GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
      }
      mempool.check(pcoinsTip);
  
      // Callbacks/notifications for a new best chain.
      if (fInvalidFound)
          CheckForkWarningConditionsOnNewFork(vpindexToConnect.back());
      else
          CheckForkWarningConditions();
  
      return true;
  }
  
  static void NotifyHeaderTip() {
      bool fNotify = false;
      bool fInitialBlockDownload = false;
      static CBlockIndex* pindexHeaderOld = NULL;
      CBlockIndex* pindexHeader = NULL;
      {
          LOCK(cs_main);
          pindexHeader = pindexBestHeader;
  
          if (pindexHeader != pindexHeaderOld) {
              fNotify = true;
              fInitialBlockDownload = IsInitialBlockDownload();
              pindexHeaderOld = pindexHeader;
          }
      }
      // Send block tip changed notifications without cs_main
      if (fNotify) {
          uiInterface.NotifyHeaderTip(fInitialBlockDownload, pindexHeader);
          GetMainSignals().NotifyHeaderTip(pindexHeader, fInitialBlockDownload);
      }
  }
  
  /**
   * Make the best chain active, in multiple steps. The result is either failure
   * or an activated best chain. pblock is either NULL or a pointer to a block
   * that is already loaded (to avoid loading it again from disk).
   */
  bool ActivateBestChain(CValidationState &state, const CChainParams& chainparams, const CBlock *pblock) {
      CBlockIndex *pindexMostWork = NULL;
      CBlockIndex *pindexNewTip = NULL;
      do {
          boost::this_thread::interruption_point();
          if (ShutdownRequested())
              break;
  
          const CBlockIndex *pindexFork;
          bool fInitialDownload;
          {
              LOCK(cs_main);
              CBlockIndex *pindexOldTip = chainActive.Tip();
              if (pindexMostWork == NULL) {
                  pindexMostWork = FindMostWorkChain();
              }
  
              // Whether we have anything to do at all.
              if (pindexMostWork == NULL || pindexMostWork == chainActive.Tip())
                  return true;
  
              bool fInvalidFound = false;
              if (!ActivateBestChainStep(state, chainparams, pindexMostWork, pblock && pblock->GetHash() == pindexMostWork->GetBlockHash() ? pblock : NULL, fInvalidFound))
                  return false;
  
              if (fInvalidFound) {
                  // Wipe cache, we may need another branch now.
                  pindexMostWork = NULL;
              }
              pindexNewTip = chainActive.Tip();
              pindexFork = chainActive.FindFork(pindexOldTip);
              fInitialDownload = IsInitialBlockDownload();
          }
          // When we reach this point, we switched to a new tip (stored in pindexNewTip).
  
          // Notifications/callbacks that can run without cs_main
  
          // Notify external listeners about the new tip.
          GetMainSignals().UpdatedBlockTip(pindexNewTip, pindexFork, fInitialDownload);
  
          // Always notify the UI if a new block tip was connected
          if (pindexFork != pindexNewTip) {
              uiInterface.NotifyBlockTip(fInitialDownload, pindexNewTip);
          }
      } while (pindexNewTip != pindexMostWork);
      CheckBlockIndex(chainparams.GetConsensus());
  
      // Write changes periodically to disk, after relay.
      if (!FlushStateToDisk(state, FLUSH_STATE_PERIODIC)) {
          return false;
      }
  
      return true;
  }
  
  bool InvalidateBlock(CValidationState& state, const Consensus::Params& consensusParams, CBlockIndex *pindex)
  {
      AssertLockHeld(cs_main);
  
      // Mark the block itself as invalid.
      pindex->nStatus |= BLOCK_FAILED_VALID;
      setDirtyBlockIndex.insert(pindex);
      setBlockIndexCandidates.erase(pindex);
  
      while (chainActive.Contains(pindex)) {
          CBlockIndex *pindexWalk = chainActive.Tip();
          pindexWalk->nStatus |= BLOCK_FAILED_CHILD;
          setDirtyBlockIndex.insert(pindexWalk);
          setBlockIndexCandidates.erase(pindexWalk);
          // ActivateBestChain considers blocks already in chainActive
          // unconditionally valid already, so force disconnect away from it.
          if (!DisconnectTip(state, consensusParams)) {
              mempool.removeForReorg(pcoinsTip, chainActive.Tip()->nHeight + 1, STANDARD_LOCKTIME_VERIFY_FLAGS);
              return false;
          }
      }
  
      LimitMempoolSize(mempool, GetArg("-maxmempool", DEFAULT_MAX_MEMPOOL_SIZE) * 1000000, GetArg("-mempoolexpiry", DEFAULT_MEMPOOL_EXPIRY) * 60 * 60);
  
      // The resulting new best tip may not be in setBlockIndexCandidates anymore, so
      // add it again.
      BlockMap::iterator it = mapBlockIndex.begin();
      while (it != mapBlockIndex.end()) {
          if (it->second->IsValid(BLOCK_VALID_TRANSACTIONS) && it->second->nChainTx && !setBlockIndexCandidates.value_comp()(it->second, chainActive.Tip())) {
              setBlockIndexCandidates.insert(it->second);
          }
          it++;
      }
  
      InvalidChainFound(pindex);
      mempool.removeForReorg(pcoinsTip, chainActive.Tip()->nHeight + 1, STANDARD_LOCKTIME_VERIFY_FLAGS);
      uiInterface.NotifyBlockTip(IsInitialBlockDownload(), pindex->pprev);
      return true;
  }
  
  bool ReconsiderBlock(CValidationState& state, CBlockIndex *pindex) {
      AssertLockHeld(cs_main);
  
      int nHeight = pindex->nHeight;
  
      // Remove the invalidity flag from this block and all its descendants.
      BlockMap::iterator it = mapBlockIndex.begin();
      while (it != mapBlockIndex.end()) {
          if (!it->second->IsValid() && it->second->GetAncestor(nHeight) == pindex) {
              it->second->nStatus &= ~BLOCK_FAILED_MASK;
              setDirtyBlockIndex.insert(it->second);
              if (it->second->IsValid(BLOCK_VALID_TRANSACTIONS) && it->second->nChainTx && setBlockIndexCandidates.value_comp()(chainActive.Tip(), it->second)) {
                  setBlockIndexCandidates.insert(it->second);
              }
              if (it->second == pindexBestInvalid) {
                  // Reset invalid block marker if it was pointing to one of those.
                  pindexBestInvalid = NULL;
              }
          }
          it++;
      }
  
      // Remove the invalidity flag from all ancestors too.
      while (pindex != NULL) {
          if (pindex->nStatus & BLOCK_FAILED_MASK) {
              pindex->nStatus &= ~BLOCK_FAILED_MASK;
              setDirtyBlockIndex.insert(pindex);
          }
          pindex = pindex->pprev;
      }
      return true;
  }
  
  CBlockIndex* AddToBlockIndex(const CBlockHeader& block)
  {
      // Check for duplicate
      uint256 hash = block.GetHash();
      BlockMap::iterator it = mapBlockIndex.find(hash);
      if (it != mapBlockIndex.end())
          return it->second;
  
      // Construct new block index object
      CBlockIndex* pindexNew = new CBlockIndex(block);
      assert(pindexNew);
      // We assign the sequence id to blocks only when the full data is available,
      // to avoid miners withholding blocks but broadcasting headers, to get a
      // competitive advantage.
      pindexNew->nSequenceId = 0;
      BlockMap::iterator mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
      pindexNew->phashBlock = &((*mi).first);
      BlockMap::iterator miPrev = mapBlockIndex.find(block.hashPrevBlock);
      if (miPrev != mapBlockIndex.end())
      {
          pindexNew->pprev = (*miPrev).second;
          pindexNew->nHeight = pindexNew->pprev->nHeight + 1;
          pindexNew->BuildSkip();
      }
      pindexNew->nChainWork = (pindexNew->pprev ? pindexNew->pprev->nChainWork : 0) + GetBlockProof(*pindexNew);
      pindexNew->RaiseValidity(BLOCK_VALID_TREE);
      if (pindexBestHeader == NULL || pindexBestHeader->nChainWork < pindexNew->nChainWork)
          pindexBestHeader = pindexNew;
  
      setDirtyBlockIndex.insert(pindexNew);
  
      return pindexNew;
  }
  
  /** Mark a block as having its data received and checked (up to BLOCK_VALID_TRANSACTIONS). */
  bool ReceivedBlockTransactions(const CBlock &block, CValidationState& state, CBlockIndex *pindexNew, const CDiskBlockPos& pos)
  {
      pindexNew->nTx = block.vtx.size();
      pindexNew->nChainTx = 0;
      pindexNew->nFile = pos.nFile;
      pindexNew->nDataPos = pos.nPos;
      pindexNew->nUndoPos = 0;
      pindexNew->nStatus |= BLOCK_HAVE_DATA;
      pindexNew->RaiseValidity(BLOCK_VALID_TRANSACTIONS);
      setDirtyBlockIndex.insert(pindexNew);
  
      if (pindexNew->pprev == NULL || pindexNew->pprev->nChainTx) {
          // If pindexNew is the genesis block or all parents are BLOCK_VALID_TRANSACTIONS.
          deque<CBlockIndex*> queue;
          queue.push_back(pindexNew);
  
          // Recursively process any descendant blocks that now may be eligible to be connected.
          while (!queue.empty()) {
              CBlockIndex *pindex = queue.front();
              queue.pop_front();
              pindex->nChainTx = (pindex->pprev ? pindex->pprev->nChainTx : 0) + pindex->nTx;
              {
                  LOCK(cs_nBlockSequenceId);
                  pindex->nSequenceId = nBlockSequenceId++;
              }
              if (chainActive.Tip() == NULL || !setBlockIndexCandidates.value_comp()(pindex, chainActive.Tip())) {
                  setBlockIndexCandidates.insert(pindex);
              }
              std::pair<std::multimap<CBlockIndex*, CBlockIndex*>::iterator, std::multimap<CBlockIndex*, CBlockIndex*>::iterator> range = mapBlocksUnlinked.equal_range(pindex);
              while (range.first != range.second) {
                  std::multimap<CBlockIndex*, CBlockIndex*>::iterator it = range.first;
                  queue.push_back(it->second);
                  range.first++;
                  mapBlocksUnlinked.erase(it);
              }
          }
      } else {
          if (pindexNew->pprev && pindexNew->pprev->IsValid(BLOCK_VALID_TREE)) {
              mapBlocksUnlinked.insert(std::make_pair(pindexNew->pprev, pindexNew));
          }
      }
  
      return true;
  }
  
  bool FindBlockPos(CValidationState &state, CDiskBlockPos &pos, unsigned int nAddSize, unsigned int nHeight, uint64_t nTime, bool fKnown = false)
  {
      LOCK(cs_LastBlockFile);
  
      unsigned int nFile = fKnown ? pos.nFile : nLastBlockFile;
      if (vinfoBlockFile.size() <= nFile) {
          vinfoBlockFile.resize(nFile + 1);
      }
  
      if (!fKnown) {
          while (vinfoBlockFile[nFile].nSize + nAddSize >= MAX_BLOCKFILE_SIZE) {
              nFile++;
              if (vinfoBlockFile.size() <= nFile) {
                  vinfoBlockFile.resize(nFile + 1);
              }
          }
          pos.nFile = nFile;
          pos.nPos = vinfoBlockFile[nFile].nSize;
      }
  
      if ((int)nFile != nLastBlockFile) {
          if (!fKnown) {
              LogPrintf("Leaving block file %i: %s\n", nLastBlockFile, vinfoBlockFile[nLastBlockFile].ToString());
          }
          FlushBlockFile(!fKnown);
          nLastBlockFile = nFile;
      }
  
      vinfoBlockFile[nFile].AddBlock(nHeight, nTime);
      if (fKnown)
          vinfoBlockFile[nFile].nSize = std::max(pos.nPos + nAddSize, vinfoBlockFile[nFile].nSize);
      else
          vinfoBlockFile[nFile].nSize += nAddSize;
  
      if (!fKnown) {
          unsigned int nOldChunks = (pos.nPos + BLOCKFILE_CHUNK_SIZE - 1) / BLOCKFILE_CHUNK_SIZE;
          unsigned int nNewChunks = (vinfoBlockFile[nFile].nSize + BLOCKFILE_CHUNK_SIZE - 1) / BLOCKFILE_CHUNK_SIZE;
          if (nNewChunks > nOldChunks) {
              if (fPruneMode)
                  fCheckForPruning = true;
              if (CheckDiskSpace(nNewChunks * BLOCKFILE_CHUNK_SIZE - pos.nPos)) {
                  FILE *file = OpenBlockFile(pos);
                  if (file) {
                      LogPrintf("Pre-allocating up to position 0x%x in blk%05u.dat\n", nNewChunks * BLOCKFILE_CHUNK_SIZE, pos.nFile);
                      AllocateFileRange(file, pos.nPos, nNewChunks * BLOCKFILE_CHUNK_SIZE - pos.nPos);
                      fclose(file);
                  }
              }
              else
                  return state.Error("out of disk space");
          }
      }
  
      setDirtyFileInfo.insert(nFile);
      return true;
  }
  
  bool FindUndoPos(CValidationState &state, int nFile, CDiskBlockPos &pos, unsigned int nAddSize)
  {
      pos.nFile = nFile;
  
      LOCK(cs_LastBlockFile);
  
      unsigned int nNewSize;
      pos.nPos = vinfoBlockFile[nFile].nUndoSize;
      nNewSize = vinfoBlockFile[nFile].nUndoSize += nAddSize;
      setDirtyFileInfo.insert(nFile);
  
      unsigned int nOldChunks = (pos.nPos + UNDOFILE_CHUNK_SIZE - 1) / UNDOFILE_CHUNK_SIZE;
      unsigned int nNewChunks = (nNewSize + UNDOFILE_CHUNK_SIZE - 1) / UNDOFILE_CHUNK_SIZE;
      if (nNewChunks > nOldChunks) {
          if (fPruneMode)
              fCheckForPruning = true;
          if (CheckDiskSpace(nNewChunks * UNDOFILE_CHUNK_SIZE - pos.nPos)) {
              FILE *file = OpenUndoFile(pos);
              if (file) {
                  LogPrintf("Pre-allocating up to position 0x%x in rev%05u.dat\n", nNewChunks * UNDOFILE_CHUNK_SIZE, pos.nFile);
                  AllocateFileRange(file, pos.nPos, nNewChunks * UNDOFILE_CHUNK_SIZE - pos.nPos);
                  fclose(file);
              }
          }
          else
              return state.Error("out of disk space");
      }
  
      return true;
  }
  
  bool CheckBlockHeader(const CBlockHeader& block, CValidationState& state, bool fCheckPOW)
  {
      // Check proof of work matches claimed amount
      if (fCheckPOW && !CheckProofOfWork(block.GetPOWHash(), block.nBits, Params().GetConsensus()))
          return state.DoS(50, error("CheckBlockHeader(): proof of work failed"),
                           REJECT_INVALID, "high-hash");
  
      // Check timestamp
      if (block.GetBlockTime() > GetAdjustedTime() + 2 * 60 * 60)
          return state.Invalid(error("CheckBlockHeader(): block timestamp too far in the future"),
                               REJECT_INVALID, "time-too-new");
  
      return true;
  }
  
  bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bool fCheckMerkleRoot)
  {
      // These are checks that are independent of context.
  
      if (block.fChecked)
          return true;
  
      // Check that the header is valid (particularly PoW).  This is mostly
      // redundant with the call in AcceptBlockHeader.
      if (!CheckBlockHeader(block, state, fCheckPOW))
          return false;
  
      // Check the merkle root.
      if (fCheckMerkleRoot) {
          bool mutated;
          uint256 hashMerkleRoot2 = BlockMerkleRoot(block, &mutated);
          if (block.hashMerkleRoot != hashMerkleRoot2)
              return state.DoS(100, error("CheckBlock(): hashMerkleRoot mismatch"),
                               REJECT_INVALID, "bad-txnmrklroot", true);
  
          // Check for merkle tree malleability (CVE-2012-2459): repeating sequences
          // of transactions in a block without affecting the merkle root of a block,
          // while still invalidating it.
          if (mutated)
              return state.DoS(100, error("CheckBlock(): duplicate transaction"),
                               REJECT_INVALID, "bad-txns-duplicate", true);
      }
  
      // All potential-corruption validation must be done before we do any
      // transaction validation, as otherwise we may mark the header as invalid
      // because we receive the wrong transactions for it.
  
      // Size limits (relaxed)
      if (block.vtx.empty() || block.vtx.size() > MaxBlockSize(true) || ::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION) > MaxBlockSize(true))
          return state.DoS(100, error("%s: size limits failed", __func__),
                           REJECT_INVALID, "bad-blk-length");
  
      // First transaction must be coinbase, the rest must not be
      if (block.vtx.empty() || !block.vtx[0].IsCoinBase())
          return state.DoS(100, error("CheckBlock(): first tx is not coinbase"),
                           REJECT_INVALID, "bad-cb-missing");
      for (unsigned int i = 1; i < block.vtx.size(); i++)
          if (block.vtx[i].IsCoinBase())
              return state.DoS(100, error("CheckBlock(): more than one coinbase"),
                               REJECT_INVALID, "bad-cb-multiple");
  
  
      if(sporkManager.IsSporkActive(SPORK_3_INSTANTSEND_BLOCK_FILTERING)) {
          // We should never accept block which conflicts with completed transaction lock,
          // that's why this is in CheckBlock unlike coinbase payee/amount.
          // Require other nodes to comply, send them some data in case they are missing it.
          BOOST_FOREACH(const CTransaction& tx, block.vtx) {
              // skip coinbase, it has no inputs
              if (tx.IsCoinBase()) continue;
              // LOOK FOR TRANSACTION LOCK IN OUR MAP OF OUTPOINTS
              BOOST_FOREACH(const CTxIn& txin, tx.vin) {
                  uint256 hashLocked;
                  if(instantsend.GetLockedOutPointTxHash(txin.prevout, hashLocked) && hashLocked != tx.GetHash()) {
                      // The node which relayed this will have to swtich later,
                      // relaying instantsend data won't help it.
                      LOCK(cs_main);
                      mapRejectedBlocks.insert(make_pair(block.GetHash(), GetTime()));
                      return state.DoS(0, error("CheckBlock(NRG): transaction %s conflicts with transaction lock %s",
                                                  tx.GetHash().ToString(), hashLocked.ToString()),
                                       REJECT_INVALID, "conflict-tx-lock");
                  }
              }
          }
      } else {
          LogPrintf("CheckBlock(NRG): spork is off, skipping transaction locking checks\n");
      }
  
      // Check transactions
      BOOST_FOREACH(const CTransaction& tx, block.vtx)
          if (!CheckTransaction(tx, state))
              return error("CheckBlock(): CheckTransaction of %s failed with %s",
                  tx.GetHash().ToString(),
                  FormatStateMessage(state));
  
      unsigned int nSigOps = 0;
      BOOST_FOREACH(const CTransaction& tx, block.vtx)
      {
          nSigOps += GetLegacySigOpCount(tx);
      }
      // sigops limits (relaxed)
      if (nSigOps > MaxBlockSigOps(true))
          return state.DoS(100, error("CheckBlock(): out-of-bounds SigOpCount"),
                           REJECT_INVALID, "bad-blk-sigops");
  
      if (fCheckPOW && fCheckMerkleRoot)
          block.fChecked = true;
  
      return true;
  }
  
  static bool CheckIndexAgainstCheckpoint(const CBlockIndex* pindexPrev, CValidationState& state, const CChainParams& chainparams, const uint256& hash)
  {
      if (*pindexPrev->phashBlock == chainparams.GetConsensus().hashGenesisBlock)
          return true;
  
      int nHeight = pindexPrev->nHeight+1;
      // Don't accept any forks from the main chain prior to last checkpoint
      CBlockIndex* pcheckpoint = Checkpoints::GetLastCheckpoint(chainparams.Checkpoints());
      if (pcheckpoint && nHeight < pcheckpoint->nHeight)
          return state.DoS(100, error("%s: forked chain older than last checkpoint (height %d)", __func__, nHeight));
  
      return true;
  }
  
  bool ContextualCheckBlockHeader(const CBlockHeader& block, CValidationState& state, CBlockIndex * const pindexPrev)
  {
      const Consensus::Params& consensusParams = Params().GetConsensus();
      uint32_t const nHeight = static_cast<uint32_t>(pindexPrev->nHeight) + 1;
  
      // height check
      if (block.nHeight != nHeight)
      {
          return state.DoS(100, error("%s: block height is invalid", __func__),
                              REJECT_INVALID, "bad-blk-height");
      }
  
      // Check proof of work
      if (block.nBits != GetNextWorkRequired(pindexPrev, &block, consensusParams))
      {
          return state.DoS(100, error("%s : incorrect proof of work at %d", __func__, nHeight),
                              REJECT_INVALID, "bad-diffbits");
      }
  
      // Check timestamp against prev
      if (block.GetBlockTime() <= pindexPrev->GetMedianTimePast())
          return state.Invalid(error("%s: block's timestamp is too early", __func__),
                               REJECT_INVALID, "time-too-old");
  
      // Reject block.nVersion=1 blocks when 95% (75% on testnet) of the network has upgraded:
      if (block.nVersion < 2 && IsSuperMajority(2, pindexPrev, consensusParams.nMajorityRejectBlockOutdated, consensusParams))
          return state.Invalid(error("%s: rejected nVersion=1 block", __func__),
                               REJECT_OBSOLETE, "bad-version");
  
      // Reject block.nVersion=2 blocks when 95% (75% on testnet) of the network has upgraded:
      if (block.nVersion < 3 && IsSuperMajority(3, pindexPrev, consensusParams.nMajorityRejectBlockOutdated, consensusParams))
          return state.Invalid(error("%s: rejected nVersion=2 block", __func__),
                               REJECT_OBSOLETE, "bad-version");
  
      // Reject block.nVersion=3 blocks when 95% (75% on testnet) of the network has upgraded:
      if (block.nVersion < 4 && IsSuperMajority(4, pindexPrev, consensusParams.nMajorityRejectBlockOutdated, consensusParams))
          return state.Invalid(error("%s : rejected nVersion=3 block", __func__),
                               REJECT_OBSOLETE, "bad-version");
  
      return true;
  }
  
  bool ContextualCheckBlock(const CBlock& block, CValidationState& state, CBlockIndex * const pindexPrev)
  {
      const int nHeight = pindexPrev == NULL ? 0 : pindexPrev->nHeight + 1;
      const Consensus::Params& consensusParams = Params().GetConsensus();
  
      // Start enforcing BIP113 (Median Time Past) using versionbits logic.
      int nLockTimeFlags = 0;
      if (VersionBitsState(pindexPrev, consensusParams, Consensus::DEPLOYMENT_CSV, versionbitscache) == THRESHOLD_ACTIVE) {
          nLockTimeFlags |= LOCKTIME_MEDIAN_TIME_PAST;
      }
  
      int64_t nLockTimeCutoff = (nLockTimeFlags & LOCKTIME_MEDIAN_TIME_PAST)
                                ? pindexPrev->GetMedianTimePast()
                                : block.GetBlockTime();
  
      bool fDIP0001Active_context = (VersionBitsState(pindexPrev, consensusParams, Consensus::DEPLOYMENT_DIP0001, versionbitscache) == THRESHOLD_ACTIVE);
  
      // Size limits
      unsigned int nMaxBlockSize = MaxBlockSize(fDIP0001Active_context);
      if (block.vtx.empty() || block.vtx.size() > nMaxBlockSize || ::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION) > nMaxBlockSize)
          return state.DoS(100, error("%s: size limits failed", __func__),
                           REJECT_INVALID, "bad-blk-length");
  
      // Check that all transactions are finalized and not over-sized
      // Also count sigops
      unsigned int nSigOps = 0;
      BOOST_FOREACH(const CTransaction& tx, block.vtx) {
          if (!IsFinalTx(tx, nHeight, nLockTimeCutoff)) {
              return state.DoS(10, error("%s: contains a non-final transaction", __func__), REJECT_INVALID, "bad-txns-nonfinal");
          }
          if (fDIP0001Active_context && ::GetSerializeSize(tx, SER_NETWORK, PROTOCOL_VERSION) > MAX_STANDARD_TX_SIZE) {
              return state.DoS(100, error("%s: contains an over-sized transaction", __func__), REJECT_INVALID, "bad-txns-oversized");
          }
          nSigOps += GetLegacySigOpCount(tx);
      }
  
      // Check sigops
      if (nSigOps > MaxBlockSigOps(fDIP0001Active_context))
          return state.DoS(100, error("%s: out-of-bounds SigOpCount", __func__),
                           REJECT_INVALID, "bad-blk-sigops");
  
      // Enforce block.nVersion=2 rule that the coinbase starts with serialized block height
      // if 750 of the last 1,000 blocks are version 2 or greater (51/100 if testnet):
      if (block.nVersion >= 2 && IsSuperMajority(2, pindexPrev, consensusParams.nMajorityEnforceBlockUpgrade, consensusParams))
      {
          CScript expect = CScript() << nHeight;
          if (block.vtx[0].vin[0].scriptSig.size() < expect.size() ||
              !std::equal(expect.begin(), expect.end(), block.vtx[0].vin[0].scriptSig.begin())) {
              return state.DoS(100, error("%s: block height mismatch in coinbase", __func__), REJECT_INVALID, "bad-cb-height");
          }
      }
  
      return true;
  }
  
  static bool AcceptBlockHeader(const CBlockHeader& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex)
  {
      AssertLockHeld(cs_main);
  
      // Check for duplicate
      uint256 hash = block.GetHash();
      BlockMap::iterator miSelf = mapBlockIndex.find(hash);
      CBlockIndex *pindex = NULL;
  
      // TODO : ENABLE BLOCK CACHE IN SPECIFIC CASES
      if (hash != chainparams.GetConsensus().hashGenesisBlock) {
  
          if (miSelf != mapBlockIndex.end()) {
              // Block header is already known.
              pindex = miSelf->second;
              if (ppindex)
                  *ppindex = pindex;
              if (pindex->nStatus & BLOCK_FAILED_MASK)
                  return state.Invalid(error("%s: block is marked invalid", __func__), 0, "duplicate");
              return true;
          }
  
          // Get prev block index
          CBlockIndex* pindexPrev = NULL;
          BlockMap::iterator mi = mapBlockIndex.find(block.hashPrevBlock);
          if (mi == mapBlockIndex.end())
              return state.DoS(10, error("%s: prev block not found", __func__), 0, "bad-prevblk");
          pindexPrev = (*mi).second;
          if (pindexPrev->nStatus & BLOCK_FAILED_MASK)
              return state.DoS(100, error("%s: prev block invalid", __func__), REJECT_INVALID, "bad-prevblk");
          if (block.nHeight != (pindexPrev->nHeight + 1))
              return state.DoS(100, error("%s: invalid block height", __func__), REJECT_INVALID, "bad-blk-height");
  
          assert(pindexPrev);
          if (fCheckpointsEnabled && !CheckIndexAgainstCheckpoint(pindexPrev, state, chainparams, hash))
              return error("%s: CheckIndexAgainstCheckpoint(): %s", __func__, state.GetRejectReason().c_str());
  
          if (!CheckBlockHeader(block, state))
              return false;
  
          if (!ContextualCheckBlockHeader(block, state, pindexPrev))
              return false;
      }
      if (pindex == NULL)
          pindex = AddToBlockIndex(block);
  
      if (ppindex)
          *ppindex = pindex;
  
      CheckBlockIndex(chainparams.GetConsensus());
  
      // Notify external listeners about accepted block header
      GetMainSignals().AcceptedBlockHeader(pindex);
  
      return true;
  }
  
  // Exposed wrapper for AcceptBlockHeader
  bool ProcessNewBlockHeaders(const std::vector<CBlockHeader>& headers, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex)
  {
      {
          LOCK(cs_main);
          for (const CBlockHeader& header : headers) {
              if (!AcceptBlockHeader(header, state, chainparams, ppindex)) {
                  return false;
              }
          }
      }
      NotifyHeaderTip();
      return true;
  }
  
  /** Store block on disk. If dbp is non-NULL, the file is known to already reside on disk */
  static bool AcceptBlock(const CBlock& block, CValidationState& state, const CChainParams& chainparams, CBlockIndex** ppindex, bool fRequested, const CDiskBlockPos* dbp, bool* fNewBlock)
  {
      if (fNewBlock) *fNewBlock = false;
      AssertLockHeld(cs_main);
  
      CBlockIndex *pindexDummy = NULL;
      CBlockIndex *&pindex = ppindex ? *ppindex : pindexDummy;
  
      if (!AcceptBlockHeader(block, state, chainparams, &pindex))
          return false;
  
      // Try to process all requested blocks that we don't have, but only
      // process an unrequested block if it's new and has enough work to
      // advance our tip, and isn't too many blocks ahead.
      bool fAlreadyHave = pindex->nStatus & BLOCK_HAVE_DATA;
      bool fHasMoreWork = (chainActive.Tip() ? pindex->nChainWork > chainActive.Tip()->nChainWork : true);
      // Blocks that are too out-of-order needlessly limit the effectiveness of
      // pruning, because pruning will not delete block files that contain any
      // blocks which are too close in height to the tip.  Apply this test
      // regardless of whether pruning is enabled; it should generally be safe to
      // not process unrequested blocks.
      bool fTooFarAhead = (pindex->nHeight > int(chainActive.Height() + MIN_BLOCKS_TO_KEEP));
  
      // TODO: Decouple this function from the block download logic by removing fRequested
      // This requires some new chain datastructure to efficiently look up if a
      // block is in a chain leading to a candidate for best tip, despite not
      // being such a candidate itself.
  
      // TODO: deal better with return value and error conditions for duplicate
      // and unrequested blocks.
      if (fAlreadyHave) return true;
      if (!fRequested) {  // If we didn't ask for it:
          if (pindex->nTx != 0) return true;  // This is a previously-processed block that was pruned
          if (!fHasMoreWork) return true;     // Don't process less-work chains
          if (fTooFarAhead) return true;      // Block height is too high
      }
      if (fNewBlock) *fNewBlock = true;
  
      if ((!CheckBlock(block, state)) || !ContextualCheckBlock(block, state, pindex->pprev)) {
          if (state.IsInvalid() && !state.CorruptionPossible()) {
              pindex->nStatus |= BLOCK_FAILED_VALID;
              setDirtyBlockIndex.insert(pindex);
          }
          return false;
      }
  
      int nHeight = pindex->nHeight;
  
      // Write block to history file
      try {
          unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
          CDiskBlockPos blockPos;
          if (dbp != NULL)
              blockPos = *dbp;
          if (!FindBlockPos(state, blockPos, nBlockSize+8, nHeight, block.GetBlockTime(), dbp != NULL))
              return error("AcceptBlock(): FindBlockPos failed");
          if (dbp == NULL)
              if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart()))
                  AbortNode(state, "Failed to write block");
          if (!ReceivedBlockTransactions(block, state, pindex, blockPos))
              return error("AcceptBlock(): ReceivedBlockTransactions failed");
      } catch (const std::runtime_error& e) {
          return AbortNode(state, std::string("System error: ") + e.what());
      }
  
      if (fCheckForPruning)
          FlushStateToDisk(state, FLUSH_STATE_NONE); // we just allocated more disk space for block files
  
      return true;
  }
  
  static bool IsSuperMajority(int minVersion, const CBlockIndex* pstart, unsigned nRequired, const Consensus::Params& consensusParams)
  {
      unsigned int nFound = 0;
      for (int i = 0; i < consensusParams.nMajorityWindow && nFound < nRequired && pstart != NULL; i++)
      {
          if (pstart->nVersion >= minVersion)
              ++nFound;
          pstart = pstart->pprev;
      }
      return (nFound >= nRequired);
  }
  
  
  bool ProcessNewBlock(const CChainParams& chainparams, const CBlock* pblock, bool fForceProcessing, const CDiskBlockPos* dbp, bool *fNewBlock)
  {
      {
          LOCK(cs_main);
  
          // Store to disk
          CBlockIndex *pindex = NULL;
          if (fNewBlock) *fNewBlock = false;
          CValidationState state;
          bool ret = AcceptBlock(*pblock, state, chainparams, &pindex, fForceProcessing, dbp, fNewBlock);
          CheckBlockIndex(chainparams.GetConsensus());
          if (!ret) {
              GetMainSignals().BlockChecked(*pblock, state);
              return error("%s: AcceptBlock FAILED", __func__);
          }
      }
  
      NotifyHeaderTip();
  
      CValidationState state; // Only used to report errors, not invalidity - ignore it
      if (!ActivateBestChain(state, chainparams, pblock))
          return error("%s: ActivateBestChain failed", __func__);
  
      LogPrintf("%s : ACCEPTED\n", __func__);
      return true;
  }
  
  bool TestBlockValidity(CValidationState& state, const CChainParams& chainparams, const CBlock& block, CBlockIndex* pindexPrev, bool fCheckPOW, bool fCheckMerkleRoot)
  {
      AssertLockHeld(cs_main);
      assert(pindexPrev && pindexPrev == chainActive.Tip());
      if (fCheckpointsEnabled && !CheckIndexAgainstCheckpoint(pindexPrev, state, chainparams, block.GetHash()))
          return error("%s: CheckIndexAgainstCheckpoint(): %s", __func__, state.GetRejectReason().c_str());
  
      CCoinsViewCache viewNew(pcoinsTip);
      CBlockIndex indexDummy(block);
      indexDummy.pprev = pindexPrev;
      indexDummy.nHeight = pindexPrev->nHeight + 1;
  
      // NOTE: CheckBlockHeader is called by CheckBlock
      if (!ContextualCheckBlockHeader(block, state, pindexPrev))
          return false;
      if (!CheckBlock(block, state, fCheckPOW, fCheckMerkleRoot))
          return false;
      if (!ContextualCheckBlock(block, state, pindexPrev))
          return false;
      if (!ConnectBlock(block, state, &indexDummy, viewNew, true))
          return false;
      assert(state.IsValid());
  
      return true;
  }
  
  /**
   * BLOCK PRUNING CODE
   */
  
  /* Calculate the amount of disk space the block & undo files currently use */
  uint64_t CalculateCurrentUsage()
  {
      uint64_t retval = 0;
      BOOST_FOREACH(const CBlockFileInfo &file, vinfoBlockFile) {
          retval += file.nSize + file.nUndoSize;
      }
      return retval;
  }
  
  /* Prune a block file (modify associated database entries)*/
  void PruneOneBlockFile(const int fileNumber)
  {
      for (BlockMap::iterator it = mapBlockIndex.begin(); it != mapBlockIndex.end(); ++it) {
          CBlockIndex* pindex = it->second;
          if (pindex->nFile == fileNumber) {
              pindex->nStatus &= ~BLOCK_HAVE_DATA;
              pindex->nStatus &= ~BLOCK_HAVE_UNDO;
              pindex->nFile = 0;
              pindex->nDataPos = 0;
              pindex->nUndoPos = 0;
              setDirtyBlockIndex.insert(pindex);
  
              // Prune from mapBlocksUnlinked -- any block we prune would have
              // to be downloaded again in order to consider its chain, at which
              // point it would be considered as a candidate for
              // mapBlocksUnlinked or setBlockIndexCandidates.
              std::pair<std::multimap<CBlockIndex*, CBlockIndex*>::iterator, std::multimap<CBlockIndex*, CBlockIndex*>::iterator> range = mapBlocksUnlinked.equal_range(pindex->pprev);
              while (range.first != range.second) {
                  std::multimap<CBlockIndex *, CBlockIndex *>::iterator it = range.first;
                  range.first++;
                  if (it->second == pindex) {
                      mapBlocksUnlinked.erase(it);
                  }
              }
          }
      }
  
      vinfoBlockFile[fileNumber].SetNull();
      setDirtyFileInfo.insert(fileNumber);
  }
  
  
  void UnlinkPrunedFiles(std::set<int>& setFilesToPrune)
  {
      for (set<int>::iterator it = setFilesToPrune.begin(); it != setFilesToPrune.end(); ++it) {
          CDiskBlockPos pos(*it, 0);
          boost::filesystem::remove(GetBlockPosFilename(pos, "blk"));
          boost::filesystem::remove(GetBlockPosFilename(pos, "rev"));
          LogPrintf("Prune: %s deleted blk/rev (%05u)\n", __func__, *it);
      }
  }
  
  /* Calculate the block/rev files that should be deleted to remain under target*/
  void FindFilesToPrune(std::set<int>& setFilesToPrune, uint64_t nPruneAfterHeight)
  {
      LOCK2(cs_main, cs_LastBlockFile);
      if (chainActive.Tip() == NULL || nPruneTarget == 0) {
          return;
      }
      if ((uint64_t)chainActive.Tip()->nHeight <= nPruneAfterHeight) {
          return;
      }
  
      unsigned int nLastBlockWeCanPrune = chainActive.Tip()->nHeight - MIN_BLOCKS_TO_KEEP;
      uint64_t nCurrentUsage = CalculateCurrentUsage();
      // We don't check to prune until after we've allocated new space for files
      // So we should leave a buffer under our target to account for another allocation
      // before the next pruning.
      uint64_t nBuffer = BLOCKFILE_CHUNK_SIZE + UNDOFILE_CHUNK_SIZE;
      uint64_t nBytesToPrune;
      int count=0;
  
      if (nCurrentUsage + nBuffer >= nPruneTarget) {
          for (int fileNumber = 0; fileNumber < nLastBlockFile; fileNumber++) {
              nBytesToPrune = vinfoBlockFile[fileNumber].nSize + vinfoBlockFile[fileNumber].nUndoSize;
  
              if (vinfoBlockFile[fileNumber].nSize == 0)
                  continue;
  
              if (nCurrentUsage + nBuffer < nPruneTarget)  // are we below our target?
                  break;
  
              // don't prune files that could have a block within MIN_BLOCKS_TO_KEEP of the main chain's tip but keep scanning
              if (vinfoBlockFile[fileNumber].nHeightLast > nLastBlockWeCanPrune)
                  continue;
  
              PruneOneBlockFile(fileNumber);
              // Queue up the files for removal
              setFilesToPrune.insert(fileNumber);
              nCurrentUsage -= nBytesToPrune;
              count++;
          }
      }
  
      LogPrint("prune", "Prune: target=%dMiB actual=%dMiB diff=%dMiB max_prune_height=%d removed %d blk/rev pairs\n",
             nPruneTarget/1024/1024, nCurrentUsage/1024/1024,
             ((int64_t)nPruneTarget - (int64_t)nCurrentUsage)/1024/1024,
             nLastBlockWeCanPrune, count);
  }
  
  bool CheckDiskSpace(uint64_t nAdditionalBytes)
  {
      uint64_t nFreeBytesAvailable = boost::filesystem::space(GetDataDir()).available;
  
      // Check for nMinDiskSpace bytes (currently 50MB)
      if (nFreeBytesAvailable < nMinDiskSpace + nAdditionalBytes)
          return AbortNode("Disk space is low!", _("Error: Disk space is low!"));
  
      return true;
  }
  
  FILE* OpenDiskFile(const CDiskBlockPos &pos, const char *prefix, bool fReadOnly)
  {
      if (pos.IsNull())
          return NULL;
      boost::filesystem::path path = GetBlockPosFilename(pos, prefix);
      boost::filesystem::create_directories(path.parent_path());
      FILE* file = fopen(path.string().c_str(), "rb+");
      if (!file && !fReadOnly)
          file = fopen(path.string().c_str(), "wb+");
      if (!file) {
          LogPrintf("Unable to open file %s\n", path.string());
          return NULL;
      }
      if (pos.nPos) {
          if (fseek(file, pos.nPos, SEEK_SET)) {
              LogPrintf("Unable to seek to position %u of %s\n", pos.nPos, path.string());
              fclose(file);
              return NULL;
          }
      }
      return file;
  }
  
  FILE* OpenBlockFile(const CDiskBlockPos &pos, bool fReadOnly) {
      return OpenDiskFile(pos, "blk", fReadOnly);
  }
  
  FILE* OpenUndoFile(const CDiskBlockPos &pos, bool fReadOnly) {
      return OpenDiskFile(pos, "rev", fReadOnly);
  }
  
  boost::filesystem::path GetBlockPosFilename(const CDiskBlockPos &pos, const char *prefix)
  {
      return GetDataDir() / "blocks" / strprintf("%s%05u.dat", prefix, pos.nFile);
  }
  
  CBlockIndex * InsertBlockIndex(uint256 hash)
  {
      if (hash.IsNull())
          return NULL;
  
      // Return existing
      BlockMap::iterator mi = mapBlockIndex.find(hash);
      if (mi != mapBlockIndex.end())
          return (*mi).second;
  
      // Create new
      CBlockIndex* pindexNew = new CBlockIndex();
      if (!pindexNew)
          throw runtime_error("InsertBlockIndex(): new CBlockIndex failed");
      mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
      pindexNew->phashBlock = &((*mi).first);
  
      return pindexNew;
  }
  
  bool static LoadBlockIndexDB()
  {
      const CChainParams& chainparams = Params();
      if (!pblocktree->LoadBlockIndexGuts())
          return false;
  
      boost::this_thread::interruption_point();
  
      // Calculate nChainWork
      vector<pair<int, CBlockIndex*> > vSortedByHeight;
      vSortedByHeight.reserve(mapBlockIndex.size());
      BOOST_FOREACH(const PAIRTYPE(uint256, CBlockIndex*)& item, mapBlockIndex)
      {
          CBlockIndex* pindex = item.second;
          vSortedByHeight.push_back(make_pair(pindex->nHeight, pindex));
      }
      sort(vSortedByHeight.begin(), vSortedByHeight.end());
      BOOST_FOREACH(const PAIRTYPE(int, CBlockIndex*)& item, vSortedByHeight)
      {
          CBlockIndex* pindex = item.second;
          pindex->nChainWork = (pindex->pprev ? pindex->pprev->nChainWork : 0) + GetBlockProof(*pindex);
          // We can link the chain of blocks for which we've received transactions at some point.
          // Pruned nodes may have deleted the block.
          if (pindex->nTx > 0) {
              if (pindex->pprev) {
                  if (pindex->pprev->nChainTx) {
                      pindex->nChainTx = pindex->pprev->nChainTx + pindex->nTx;
                  } else {
                      pindex->nChainTx = 0;
                      mapBlocksUnlinked.insert(std::make_pair(pindex->pprev, pindex));
                  }
              } else {
                  pindex->nChainTx = pindex->nTx;
              }
          }
          if (pindex->IsValid(BLOCK_VALID_TRANSACTIONS) && (pindex->nChainTx || pindex->pprev == NULL))
              setBlockIndexCandidates.insert(pindex);
          if (pindex->nStatus & BLOCK_FAILED_MASK && (!pindexBestInvalid || pindex->nChainWork > pindexBestInvalid->nChainWork))
              pindexBestInvalid = pindex;
          if (pindex->pprev)
              pindex->BuildSkip();
          if (pindex->IsValid(BLOCK_VALID_TREE) && (pindexBestHeader == NULL || CBlockIndexWorkComparator()(pindexBestHeader, pindex)))
              pindexBestHeader = pindex;
      }
  
      // Load block file info
      pblocktree->ReadLastBlockFile(nLastBlockFile);
      vinfoBlockFile.resize(nLastBlockFile + 1);
      LogPrintf("%s: last block file = %i\n", __func__, nLastBlockFile);
      for (int nFile = 0; nFile <= nLastBlockFile; nFile++) {
          pblocktree->ReadBlockFileInfo(nFile, vinfoBlockFile[nFile]);
      }
      LogPrintf("%s: last block file info: %s\n", __func__, vinfoBlockFile[nLastBlockFile].ToString());
      for (int nFile = nLastBlockFile + 1; true; nFile++) {
          CBlockFileInfo info;
          if (pblocktree->ReadBlockFileInfo(nFile, info)) {
              vinfoBlockFile.push_back(info);
          } else {
              break;
          }
      }
  
      // Check presence of blk files
      LogPrintf("Checking all blk files are present...\n");
      set<int> setBlkDataFiles;
      BOOST_FOREACH(const PAIRTYPE(uint256, CBlockIndex*)& item, mapBlockIndex)
      {
          CBlockIndex* pindex = item.second;
          if (pindex->nStatus & BLOCK_HAVE_DATA) {
              setBlkDataFiles.insert(pindex->nFile);
          }
      }
      for (std::set<int>::iterator it = setBlkDataFiles.begin(); it != setBlkDataFiles.end(); it++)
      {
          CDiskBlockPos pos(*it, 0);
          if (CAutoFile(OpenBlockFile(pos, true), SER_DISK, CLIENT_VERSION).IsNull()) {
              return false;
          }
      }
  
      // Check whether we have ever pruned block & undo files
      pblocktree->ReadFlag("prunedblockfiles", fHavePruned);
      if (fHavePruned)
          LogPrintf("LoadBlockIndexDB(): Block files have previously been pruned\n");
  
      // Check whether we need to continue reindexing
      bool fReindexing = false;
      pblocktree->ReadReindexing(fReindexing);
      fReindex |= fReindexing;
  
      // Check whether we have a transaction index
      pblocktree->ReadFlag("txindex", fTxIndex);
      LogPrintf("%s: transaction index %s\n", __func__, fTxIndex ? "enabled" : "disabled");
  
      // Check whether we have an address index
      pblocktree->ReadFlag("addressindex", fAddressIndex);
      LogPrintf("%s: address index %s\n", __func__, fAddressIndex ? "enabled" : "disabled");
  
      // Check whether we have a timestamp index
      pblocktree->ReadFlag("timestampindex", fTimestampIndex);
      LogPrintf("%s: timestamp index %s\n", __func__, fTimestampIndex ? "enabled" : "disabled");
  
      // Check whether we have a spent index
      pblocktree->ReadFlag("spentindex", fSpentIndex);
      LogPrintf("%s: spent index %s\n", __func__, fSpentIndex ? "enabled" : "disabled");
  
      // Load pointer to end of best chain
      BlockMap::iterator it = mapBlockIndex.find(pcoinsTip->GetBestBlock());
      if (it == mapBlockIndex.end())
          return true;
      chainActive.SetTip(it->second);
  
      PruneBlockIndexCandidates();
  
      LogPrintf("%s: hashBestChain=%s height=%d date=%s progress=%f\n", __func__,
          chainActive.Tip()->GetBlockHash().ToString(), chainActive.Height(),
          DateTimeStrFormat("%Y-%m-%d %H:%M:%S", chainActive.Tip()->GetBlockTime()),
          Checkpoints::GuessVerificationProgress(chainparams.Checkpoints(), chainActive.Tip()));
  
      return true;
  }
  
  CVerifyDB::CVerifyDB()
  {
      uiInterface.ShowProgress(_("Verifying blocks..."), 0);
  }
  
  CVerifyDB::~CVerifyDB()
  {
      uiInterface.ShowProgress("", 100);
  }
  
  bool CVerifyDB::VerifyDB(const CChainParams& chainparams, CCoinsView *coinsview, int nCheckLevel, int nCheckDepth)
  {
      LOCK(cs_main);
      if (chainActive.Tip() == NULL || chainActive.Tip()->pprev == NULL)
          return true;
  
      // Verify blocks in the best chain
      if (nCheckDepth <= 0)
          nCheckDepth = 1000000000; // suffices until the year 19000
      if (nCheckDepth > chainActive.Height())
          nCheckDepth = chainActive.Height();
      nCheckLevel = std::max(0, std::min(4, nCheckLevel));
      LogPrintf("Verifying last %i blocks at level %i\n", nCheckDepth, nCheckLevel);
      CCoinsViewCache coins(coinsview);
      CBlockIndex* pindexState = chainActive.Tip();
      CBlockIndex* pindexFailure = NULL;
      int nGoodTransactions = 0;
      CValidationState state;
      for (CBlockIndex* pindex = chainActive.Tip(); pindex && pindex->pprev; pindex = pindex->pprev)
      {
          boost::this_thread::interruption_point();
          uiInterface.ShowProgress(_("Verifying blocks..."), std::max(1, std::min(99, (int)(((double)(chainActive.Height() - pindex->nHeight)) / (double)nCheckDepth * (nCheckLevel >= 4 ? 50 : 100)))));
          if (pindex->nHeight < chainActive.Height()-nCheckDepth)
              break;
          CBlock block;
          // check level 0: read from disk
          if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
              return error("VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
          // check level 1: verify block validity
          if (nCheckLevel >= 1 && !CheckBlock(block, state))
              return error("VerifyDB(): *** found bad block at %d, hash=%s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
          // check level 2: verify undo validity
          if (nCheckLevel >= 2 && pindex) {
              CBlockUndo undo;
              CDiskBlockPos pos = pindex->GetUndoPos();
              if (!pos.IsNull()) {
                  if (!UndoReadFromDisk(undo, pos, pindex->pprev->GetBlockHash()))
                      return error("VerifyDB(): *** found bad undo data at %d, hash=%s\n", pindex->nHeight, pindex->GetBlockHash().ToString());
              }
          }
          // check level 3: check for inconsistencies during memory-only disconnect of tip blocks
          if (nCheckLevel >= 3 && pindex == pindexState && (coins.DynamicMemoryUsage() + pcoinsTip->DynamicMemoryUsage()) <= nCoinCacheUsage) {
              bool fClean = true;
              if (!DisconnectBlock(block, state, pindex, coins, &fClean))
                  return error("VerifyDB(): *** irrecoverable inconsistency in block data at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
              pindexState = pindex->pprev;
              if (!fClean) {
                  nGoodTransactions = 0;
                  pindexFailure = pindex;
              } else
                  nGoodTransactions += block.vtx.size();
          }
          if (ShutdownRequested())
              return true;
      }
      if (pindexFailure)
          return error("VerifyDB(): *** coin database inconsistencies found (last %i blocks, %i good transactions before that)\n", chainActive.Height() - pindexFailure->nHeight + 1, nGoodTransactions);
  
      // check level 4: try reconnecting blocks
      if (nCheckLevel >= 4) {
          CBlockIndex *pindex = pindexState;
          while (pindex != chainActive.Tip()) {
              boost::this_thread::interruption_point();
              uiInterface.ShowProgress(_("Verifying blocks..."), std::max(1, std::min(99, 100 - (int)(((double)(chainActive.Height() - pindex->nHeight)) / (double)nCheckDepth * 50))));
              pindex = chainActive.Next(pindex);
              CBlock block;
              if (!ReadBlockFromDisk(block, pindex, chainparams.GetConsensus()))
                  return error("VerifyDB(): *** ReadBlockFromDisk failed at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
              if (!ConnectBlock(block, state, pindex, coins))
                  return error("VerifyDB(): *** found unconnectable block at %d, hash=%s", pindex->nHeight, pindex->GetBlockHash().ToString());
          }
      }
  
      LogPrintf("No coin database inconsistencies in last %i blocks (%i transactions)\n", chainActive.Height() - pindexState->nHeight, nGoodTransactions);
  
      return true;
  }
  
  // May NOT be used after any connections are up as much
  // of the peer-processing logic assumes a consistent
  // block index state
  void UnloadBlockIndex()
  {
      LOCK(cs_main);
      setBlockIndexCandidates.clear();
      chainActive.SetTip(NULL);
      pindexBestInvalid = NULL;
      pindexBestHeader = NULL;
      mempool.clear();
      mapBlocksUnlinked.clear();
      vinfoBlockFile.clear();
      nLastBlockFile = 0;
      nBlockSequenceId = 1;
      setDirtyBlockIndex.clear();
      setDirtyFileInfo.clear();
      versionbitscache.Clear();
      for (int b = 0; b < VERSIONBITS_NUM_BITS; b++) {
          warningcache[b].clear();
      }
  
      BOOST_FOREACH(BlockMap::value_type& entry, mapBlockIndex) {
          delete entry.second;
      }
      mapBlockIndex.clear();
      fHavePruned = false;
  }
  
  bool LoadBlockIndex()
  {
      // Load block index from databases
      if (!fReindex && !LoadBlockIndexDB())
          return false;
      return true;
  }
  
  bool InitBlockIndex(const CChainParams& chainparams)
  {
      LOCK(cs_main);
  
      // Check whether we're already initialized
      if (chainActive.Genesis() != NULL)
          return true;
  
      // Use the provided setting for -txindex in the new database
      fTxIndex = GetBoolArg("-txindex", DEFAULT_TXINDEX);
      pblocktree->WriteFlag("txindex", fTxIndex);
  
      // Use the provided setting for -addressindex in the new database
      fAddressIndex = GetBoolArg("-addressindex", DEFAULT_ADDRESSINDEX);
      pblocktree->WriteFlag("addressindex", fAddressIndex);
  
      // Use the provided setting for -timestampindex in the new database
      fTimestampIndex = GetBoolArg("-timestampindex", DEFAULT_TIMESTAMPINDEX);
      pblocktree->WriteFlag("timestampindex", fTimestampIndex);
  
      fSpentIndex = GetBoolArg("-spentindex", DEFAULT_SPENTINDEX);
      pblocktree->WriteFlag("spentindex", fSpentIndex);
  
      LogPrintf("Initializing databases...\n");
  
      // Only add the genesis block if not reindexing (in which case we reuse the one already on disk)
      if (!fReindex) {
          try {
              CBlock &block = const_cast<CBlock&>(chainparams.GenesisBlock());
              // Start new block file
              unsigned int nBlockSize = ::GetSerializeSize(block, SER_DISK, CLIENT_VERSION);
              CDiskBlockPos blockPos;
              CValidationState state;
              if (!FindBlockPos(state, blockPos, nBlockSize+8, 0, block.GetBlockTime()))
                  return error("%s: FindBlockPos failed", __func__);
              if (!WriteBlockToDisk(block, blockPos, chainparams.MessageStart()))
                  return error("%s: writing genesis block to disk failed", __func__);
              CBlockIndex *pindex = AddToBlockIndex(block);
              if (!ReceivedBlockTransactions(block, state, pindex, blockPos))
                  return error("%s: genesis block not accepted", __func__);
              if (!ActivateBestChain(state, chainparams, &block))
                  return error("%s: genesis block cannot be activated", __func__);
              // Force a chainstate write so that when we VerifyDB in a moment, it doesn't check stale data
              return FlushStateToDisk(state, FLUSH_STATE_ALWAYS);
          } catch (const std::runtime_error& e) {
              return error("%s: failed to initialize block database: %s", __func__, e.what());
          }
      }
  
      return true;
  }
  
  bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskBlockPos *dbp)
  {
      // Map of disk positions for blocks with unknown parent (only used for reindex)
      static std::multimap<uint256, CDiskBlockPos> mapBlocksUnknownParent;
      int64_t nStart = GetTimeMillis();
  
      int nLoaded = 0;
      try {
          unsigned int nMaxBlockSize = MaxBlockSize(true);
          // This takes over fileIn and calls fclose() on it in the CBufferedFile destructor
          CBufferedFile blkdat(fileIn, 2*nMaxBlockSize, nMaxBlockSize+8, SER_DISK, CLIENT_VERSION);
          uint64_t nRewind = blkdat.GetPos();
          while (!blkdat.eof()) {
              boost::this_thread::interruption_point();
  
              blkdat.SetPos(nRewind);
              nRewind++; // start one byte further next time, in case of failure
              blkdat.SetLimit(); // remove former limit
              unsigned int nSize = 0;
              try {
                  // locate a header
                  unsigned char buf[MESSAGE_START_SIZE];
                  blkdat.FindByte(chainparams.MessageStart()[0]);
                  nRewind = blkdat.GetPos()+1;
                  blkdat >> FLATDATA(buf);
                  if (memcmp(buf, chainparams.MessageStart(), MESSAGE_START_SIZE))
                      continue;
                  // read size
                  blkdat >> nSize;
                  if (nSize < 80 || nSize > nMaxBlockSize)
                      continue;
              } catch (const std::exception&) {
                  // no valid block header found; don't complain
                  break;
              }
              try {
                  // read block
                  uint64_t nBlockPos = blkdat.GetPos();
                  if (dbp)
                      dbp->nPos = nBlockPos;
                  blkdat.SetLimit(nBlockPos + nSize);
                  blkdat.SetPos(nBlockPos);
                  CBlock block;
                  blkdat >> block;
                  nRewind = blkdat.GetPos();
  
                  // detect out of order blocks, and store them for later
                  uint256 hash = block.GetHash();
                  if (hash != chainparams.GetConsensus().hashGenesisBlock && mapBlockIndex.find(block.hashPrevBlock) == mapBlockIndex.end()) {
                      LogPrint("reindex", "%s: Out of order block %s, parent %s not known\n", __func__, hash.ToString(),
                              block.hashPrevBlock.ToString());
                      if (dbp)
                          mapBlocksUnknownParent.insert(std::make_pair(block.hashPrevBlock, *dbp));
                      continue;
                  }
  
                  // process in case the block isn't known yet
                  if (mapBlockIndex.count(hash) == 0 || (mapBlockIndex[hash]->nStatus & BLOCK_HAVE_DATA) == 0) {
                      LOCK(cs_main);
                      CValidationState state;
                      if (AcceptBlock(block, state, chainparams, NULL, true, dbp, NULL))
                          nLoaded++;
                      if (state.IsError())
                          break;
                  } else if (hash != chainparams.GetConsensus().hashGenesisBlock && mapBlockIndex[hash]->nHeight % 1000 == 0) {
                      LogPrint("reindex", "Block Import: already had block %s at height %d\n", hash.ToString(), mapBlockIndex[hash]->nHeight);
                  }
  
                  // Activate the genesis block so normal node progress can continue
                  if (hash == chainparams.GetConsensus().hashGenesisBlock) {
                      CValidationState state;
                      if (!ActivateBestChain(state, chainparams)) {
                          break;
                      }
                  }
  
                  NotifyHeaderTip();
  
                  // Recursively process earlier encountered successors of this block
                  deque<uint256> queue;
                  queue.push_back(hash);
                  while (!queue.empty()) {
                      uint256 head = queue.front();
                      queue.pop_front();
                      std::pair<std::multimap<uint256, CDiskBlockPos>::iterator, std::multimap<uint256, CDiskBlockPos>::iterator> range = mapBlocksUnknownParent.equal_range(head);
                      while (range.first != range.second) {
                          std::multimap<uint256, CDiskBlockPos>::iterator it = range.first;
                          if (ReadBlockFromDisk(block, it->second, chainparams.GetConsensus()))
                          {
                              LogPrint("reindex", "%s: Processing out of order child %s of %s\n", __func__, block.GetHash().ToString(),
                                      head.ToString());
                              LOCK(cs_main);
                              CValidationState dummy;
                              if (AcceptBlock(block, dummy, chainparams, NULL, true, &it->second, NULL))
                              {
                                  nLoaded++;
                                  queue.push_back(block.GetHash());
                              }
                          }
                          range.first++;
                          mapBlocksUnknownParent.erase(it);
                          NotifyHeaderTip();
                      }
                  }
              } catch (const std::exception& e) {
                  LogPrintf("%s: Deserialize or I/O error - %s\n", __func__, e.what());
              }
          }
      } catch (const std::runtime_error& e) {
          AbortNode(std::string("System error: ") + e.what());
      }
      if (nLoaded > 0)
          LogPrintf("Loaded %i blocks from external file in %dms\n", nLoaded, GetTimeMillis() - nStart);
      return nLoaded > 0;
  }
  
  void static CheckBlockIndex(const Consensus::Params& consensusParams)
  {
      if (!fCheckBlockIndex) {
          return;
      }
  
      LOCK(cs_main);
  
      // During a reindex, we read the genesis block and call CheckBlockIndex before ActivateBestChain,
      // so we have the genesis block in mapBlockIndex but no active chain.  (A few of the tests when
      // iterating the block tree require that chainActive has been initialized.)
      if (chainActive.Height() < 0) {
          assert(mapBlockIndex.size() <= 1);
          return;
      }
  
      // Build forward-pointing map of the entire block tree.
      std::multimap<CBlockIndex*,CBlockIndex*> forward;
      for (BlockMap::iterator it = mapBlockIndex.begin(); it != mapBlockIndex.end(); it++) {
          forward.insert(std::make_pair(it->second->pprev, it->second));
      }
  
      assert(forward.size() == mapBlockIndex.size());
  
      std::pair<std::multimap<CBlockIndex*,CBlockIndex*>::iterator,std::multimap<CBlockIndex*,CBlockIndex*>::iterator> rangeGenesis = forward.equal_range(NULL);
      CBlockIndex *pindex = rangeGenesis.first->second;
      rangeGenesis.first++;
      assert(rangeGenesis.first == rangeGenesis.second); // There is only one index entry with parent NULL.
  
      // Iterate over the entire block tree, using depth-first search.
      // Along the way, remember whether there are blocks on the path from genesis
      // block being explored which are the first to have certain properties.
      size_t nNodes = 0;
      int nHeight = 0;
      CBlockIndex* pindexFirstInvalid = NULL; // Oldest ancestor of pindex which is invalid.
      CBlockIndex* pindexFirstMissing = NULL; // Oldest ancestor of pindex which does not have BLOCK_HAVE_DATA.
      CBlockIndex* pindexFirstNeverProcessed = NULL; // Oldest ancestor of pindex for which nTx == 0.
      CBlockIndex* pindexFirstNotTreeValid = NULL; // Oldest ancestor of pindex which does not have BLOCK_VALID_TREE (regardless of being valid or not).
      CBlockIndex* pindexFirstNotTransactionsValid = NULL; // Oldest ancestor of pindex which does not have BLOCK_VALID_TRANSACTIONS (regardless of being valid or not).
      CBlockIndex* pindexFirstNotChainValid = NULL; // Oldest ancestor of pindex which does not have BLOCK_VALID_CHAIN (regardless of being valid or not).
      CBlockIndex* pindexFirstNotScriptsValid = NULL; // Oldest ancestor of pindex which does not have BLOCK_VALID_SCRIPTS (regardless of being valid or not).
      while (pindex != NULL) {
          nNodes++;
          if (pindexFirstInvalid == NULL && pindex->nStatus & BLOCK_FAILED_VALID) pindexFirstInvalid = pindex;
          if (pindexFirstMissing == NULL && !(pindex->nStatus & BLOCK_HAVE_DATA)) pindexFirstMissing = pindex;
          if (pindexFirstNeverProcessed == NULL && pindex->nTx == 0) pindexFirstNeverProcessed = pindex;
          if (pindex->pprev != NULL && pindexFirstNotTreeValid == NULL && (pindex->nStatus & BLOCK_VALID_MASK) < BLOCK_VALID_TREE) pindexFirstNotTreeValid = pindex;
          if (pindex->pprev != NULL && pindexFirstNotTransactionsValid == NULL && (pindex->nStatus & BLOCK_VALID_MASK) < BLOCK_VALID_TRANSACTIONS) pindexFirstNotTransactionsValid = pindex;
          if (pindex->pprev != NULL && pindexFirstNotChainValid == NULL && (pindex->nStatus & BLOCK_VALID_MASK) < BLOCK_VALID_CHAIN) pindexFirstNotChainValid = pindex;
          if (pindex->pprev != NULL && pindexFirstNotScriptsValid == NULL && (pindex->nStatus & BLOCK_VALID_MASK) < BLOCK_VALID_SCRIPTS) pindexFirstNotScriptsValid = pindex;
  
          // Begin: actual consistency checks.
          if (pindex->pprev == NULL) {
              // Genesis block checks.
              assert(pindex->GetBlockHash() == consensusParams.hashGenesisBlock); // Genesis block's hash must match.
              assert(pindex == chainActive.Genesis()); // The current active chain's genesis block must be this block.
          }
          if (pindex->nChainTx == 0) assert(pindex->nSequenceId == 0);  // nSequenceId can't be set for blocks that aren't linked
          // VALID_TRANSACTIONS is equivalent to nTx > 0 for all nodes (whether or not pruning has occurred).
          // HAVE_DATA is only equivalent to nTx > 0 (or VALID_TRANSACTIONS) if no pruning has occurred.
          if (!fHavePruned) {
              // If we've never pruned, then HAVE_DATA should be equivalent to nTx > 0
              assert(!(pindex->nStatus & BLOCK_HAVE_DATA) == (pindex->nTx == 0));
              assert(pindexFirstMissing == pindexFirstNeverProcessed);
          } else {
              // If we have pruned, then we can only say that HAVE_DATA implies nTx > 0
              if (pindex->nStatus & BLOCK_HAVE_DATA) assert(pindex->nTx > 0);
          }
          if (pindex->nStatus & BLOCK_HAVE_UNDO) assert(pindex->nStatus & BLOCK_HAVE_DATA);
          assert(((pindex->nStatus & BLOCK_VALID_MASK) >= BLOCK_VALID_TRANSACTIONS) == (pindex->nTx > 0)); // This is pruning-independent.
          // All parents having had data (at some point) is equivalent to all parents being VALID_TRANSACTIONS, which is equivalent to nChainTx being set.
          assert((pindexFirstNeverProcessed != NULL) == (pindex->nChainTx == 0)); // nChainTx != 0 is used to signal that all parent blocks have been processed (but may have been pruned).
          assert((pindexFirstNotTransactionsValid != NULL) == (pindex->nChainTx == 0));
          assert(pindex->nHeight == nHeight); // nHeight must be consistent.
          assert(pindex->pprev == NULL || pindex->nChainWork >= pindex->pprev->nChainWork); // For every block except the genesis block, the chainwork must be larger than the parent's.
          assert(nHeight < 2 || (pindex->pskip && (pindex->pskip->nHeight < nHeight))); // The pskip pointer must point back for all but the first 2 blocks.
          assert(pindexFirstNotTreeValid == NULL); // All mapBlockIndex entries must at least be TREE valid
          if ((pindex->nStatus & BLOCK_VALID_MASK) >= BLOCK_VALID_TREE) assert(pindexFirstNotTreeValid == NULL); // TREE valid implies all parents are TREE valid
          if ((pindex->nStatus & BLOCK_VALID_MASK) >= BLOCK_VALID_CHAIN) assert(pindexFirstNotChainValid == NULL); // CHAIN valid implies all parents are CHAIN valid
          if ((pindex->nStatus & BLOCK_VALID_MASK) >= BLOCK_VALID_SCRIPTS) assert(pindexFirstNotScriptsValid == NULL); // SCRIPTS valid implies all parents are SCRIPTS valid
          if (pindexFirstInvalid == NULL) {
              // Checks for not-invalid blocks.
              assert((pindex->nStatus & BLOCK_FAILED_MASK) == 0); // The failed mask cannot be set for blocks without invalid parents.
          }
          if (!CBlockIndexWorkComparator()(pindex, chainActive.Tip()) && pindexFirstNeverProcessed == NULL) {
              if (pindexFirstInvalid == NULL) {
                  // If this block sorts at least as good as the current tip and
                  // is valid and we have all data for its parents, it must be in
                  // setBlockIndexCandidates.  chainActive.Tip() must also be there
                  // even if some data has been pruned.
                  if (pindexFirstMissing == NULL || pindex == chainActive.Tip()) {
                      assert(setBlockIndexCandidates.count(pindex));
                  }
                  // If some parent is missing, then it could be that this block was in
                  // setBlockIndexCandidates but had to be removed because of the missing data.
                  // In this case it must be in mapBlocksUnlinked -- see test below.
              }
          } else { // If this block sorts worse than the current tip or some ancestor's block has never been seen, it cannot be in setBlockIndexCandidates.
              assert(setBlockIndexCandidates.count(pindex) == 0);
          }
          // Check whether this block is in mapBlocksUnlinked.
          std::pair<std::multimap<CBlockIndex*,CBlockIndex*>::iterator,std::multimap<CBlockIndex*,CBlockIndex*>::iterator> rangeUnlinked = mapBlocksUnlinked.equal_range(pindex->pprev);
          bool foundInUnlinked = false;
          while (rangeUnlinked.first != rangeUnlinked.second) {
              assert(rangeUnlinked.first->first == pindex->pprev);
              if (rangeUnlinked.first->second == pindex) {
                  foundInUnlinked = true;
                  break;
              }
              rangeUnlinked.first++;
          }
          if (pindex->pprev && (pindex->nStatus & BLOCK_HAVE_DATA) && pindexFirstNeverProcessed != NULL && pindexFirstInvalid == NULL) {
              // If this block has block data available, some parent was never received, and has no invalid parents, it must be in mapBlocksUnlinked.
              assert(foundInUnlinked);
          }
          if (!(pindex->nStatus & BLOCK_HAVE_DATA)) assert(!foundInUnlinked); // Can't be in mapBlocksUnlinked if we don't HAVE_DATA
          if (pindexFirstMissing == NULL) assert(!foundInUnlinked); // We aren't missing data for any parent -- cannot be in mapBlocksUnlinked.
          if (pindex->pprev && (pindex->nStatus & BLOCK_HAVE_DATA) && pindexFirstNeverProcessed == NULL && pindexFirstMissing != NULL) {
              // We HAVE_DATA for this block, have received data for all parents at some point, but we're currently missing data for some parent.
              assert(fHavePruned); // We must have pruned.
              // This block may have entered mapBlocksUnlinked if:
              //  - it has a descendant that at some point had more work than the
              //    tip, and
              //  - we tried switching to that descendant but were missing
              //    data for some intermediate block between chainActive and the
              //    tip.
              // So if this block is itself better than chainActive.Tip() and it wasn't in
              // setBlockIndexCandidates, then it must be in mapBlocksUnlinked.
              if (!CBlockIndexWorkComparator()(pindex, chainActive.Tip()) && setBlockIndexCandidates.count(pindex) == 0) {
                  if (pindexFirstInvalid == NULL) {
                      assert(foundInUnlinked);
                  }
              }
          }
          // assert(pindex->GetBlockHash() == pindex->GetBlockHeader().GetHash()); // Perhaps too slow
          // End: actual consistency checks.
  
          // Try descending into the first subnode.
          std::pair<std::multimap<CBlockIndex*,CBlockIndex*>::iterator,std::multimap<CBlockIndex*,CBlockIndex*>::iterator> range = forward.equal_range(pindex);
          if (range.first != range.second) {
              // A subnode was found.
              pindex = range.first->second;
              nHeight++;
              continue;
          }
          // This is a leaf node.
          // Move upwards until we reach a node of which we have not yet visited the last child.
          while (pindex) {
              // We are going to either move to a parent or a sibling of pindex.
              // If pindex was the first with a certain property, unset the corresponding variable.
              if (pindex == pindexFirstInvalid) pindexFirstInvalid = NULL;
              if (pindex == pindexFirstMissing) pindexFirstMissing = NULL;
              if (pindex == pindexFirstNeverProcessed) pindexFirstNeverProcessed = NULL;
              if (pindex == pindexFirstNotTreeValid) pindexFirstNotTreeValid = NULL;
              if (pindex == pindexFirstNotTransactionsValid) pindexFirstNotTransactionsValid = NULL;
              if (pindex == pindexFirstNotChainValid) pindexFirstNotChainValid = NULL;
              if (pindex == pindexFirstNotScriptsValid) pindexFirstNotScriptsValid = NULL;
              // Find our parent.
              CBlockIndex* pindexPar = pindex->pprev;
              // Find which child we just visited.
              std::pair<std::multimap<CBlockIndex*,CBlockIndex*>::iterator,std::multimap<CBlockIndex*,CBlockIndex*>::iterator> rangePar = forward.equal_range(pindexPar);
              while (rangePar.first->second != pindex) {
                  assert(rangePar.first != rangePar.second); // Our parent must have at least the node we're coming from as child.
                  rangePar.first++;
              }
              // Proceed to the next one.
              rangePar.first++;
              if (rangePar.first != rangePar.second) {
                  // Move to the sibling.
                  pindex = rangePar.first->second;
                  break;
              } else {
                  // Move up further.
                  pindex = pindexPar;
                  nHeight--;
                  continue;
              }
          }
      }
  
      // Check that we actually traversed the entire map.
      assert(nNodes == forward.size());
  }
  
  //////////////////////////////////////////////////////////////////////////////
  //
  // CAlert
  //
  
  std::string GetWarnings(const std::string& strFor)
  {
      int nPriority = 0;
      string strStatusBar;
      string strRPC;
      string strGUI;
  
      if (!CLIENT_VERSION_IS_RELEASE) {
          strStatusBar = "This is a pre-release test build - use at your own risk - do not use for mining or merchant applications";
          strGUI = _("This is a pre-release test build - use at your own risk - do not use for mining or merchant applications");
      }
  
      if (GetBoolArg("-testsafemode", DEFAULT_TESTSAFEMODE))
          strStatusBar = strRPC = strGUI = "testsafemode enabled";
  
      // Misc warnings like out of disk space and clock is wrong
      if (strMiscWarning != "")
      {
          nPriority = 1000;
          strStatusBar = strGUI = strMiscWarning;
      }
  
      if (fLargeWorkForkFound)
      {
          nPriority = 2000;
          strStatusBar = strRPC = "Warning: The network does not appear to fully agree! Some miners appear to be experiencing issues.";
          strGUI = _("Warning: The network does not appear to fully agree! Some miners appear to be experiencing issues.");
      }
      else if (fLargeWorkInvalidChainFound)
      {
          nPriority = 2000;
          strStatusBar = strRPC = "Warning: We do not appear to fully agree with our peers! You may need to upgrade, or other nodes may need to upgrade.";
          strGUI = _("Warning: We do not appear to fully agree with our peers! You may need to upgrade, or other nodes may need to upgrade.");
      }
  
      // Alerts
      {
          LOCK(cs_mapAlerts);
          BOOST_FOREACH(PAIRTYPE(const uint256, CAlert)& item, mapAlerts)
          {
              const CAlert& alert = item.second;
              if (alert.AppliesToMe() && alert.nPriority > nPriority)
              {
                  nPriority = alert.nPriority;
                  strStatusBar = strGUI = alert.strStatusBar;
              }
          }
      }
  
      if (strFor == "gui")
          return strGUI;
      else if (strFor == "statusbar")
          return strStatusBar;
      else if (strFor == "rpc")
          return strRPC;
      assert(!"GetWarnings(): invalid parameter");
      return "error";
  }
   std::string CBlockFileInfo::ToString() const {
       return strprintf("CBlockFileInfo(blocks=%u, size=%u, heights=%u...%u, time=%s...%s)", nBlocks, nSize, nHeightFirst, nHeightLast, DateTimeStrFormat("%Y-%m-%d", nTimeFirst), DateTimeStrFormat("%Y-%m-%d", nTimeLast));
   }
  
  ThresholdState VersionBitsTipState(const Consensus::Params& params, Consensus::DeploymentPos pos)
  {
      AssertLockHeld(cs_main);
      return VersionBitsState(chainActive.Tip(), params, pos, versionbitscache);
  }
  
  class CMainCleanup
  {
  public:
      CMainCleanup() {}
      ~CMainCleanup() {
          // block headers
          BlockMap::iterator it1 = mapBlockIndex.begin();
          for (; it1 != mapBlockIndex.end(); it1++)
              delete (*it1).second;
          mapBlockIndex.clear();
      }
  } instance_of_cmaincleanup;
  