text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2018 The Bitcoin Core developers
  // Distributed under the MIT software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include <txmempool.h>
  
  #include <consensus/consensus.h>
  #include <consensus/tx_verify.h>
  #include <consensus/validation.h>
  #include <validation.h>
  #include <policy/policy.h>
  #include <policy/fees.h>
  #include <reverse_iterator.h>
  #include <streams.h>
  #include <timedata.h>
  #include <util/system.h>
  #include <util/moneystr.h>
  #include <util/time.h>
  #include <chainparams.h> // removeForBlock paklist transition
  #include <pegins.h>
  
  CTxMemPoolEntry::CTxMemPoolEntry(const CTransactionRef& _tx, const CAmount& _nFee,
                                   int64_t _nTime, unsigned int _entryHeight,
                                   bool _spendsCoinbase, int64_t _sigOpsCost, LockPoints lp, std::set<std::pair<uint256, COutPoint>>& _setPeginsSpent)
      : tx(_tx), nFee(_nFee), nTxWeight(GetTransactionWeight(*tx)), nUsageSize(RecursiveDynamicUsage(tx)), nTime(_nTime), entryHeight(_entryHeight),
      spendsCoinbase(_spendsCoinbase), sigOpCost(_sigOpsCost), lockPoints(lp),
      setPeginsSpent(_setPeginsSpent)
  {
      nCountWithDescendants = 1;
      nSizeWithDescendants = GetTxSize();
      nModFeesWithDescendants = nFee;
  
      feeDelta = 0;
  
      nCountWithAncestors = 1;
      nSizeWithAncestors = GetTxSize();
      nModFeesWithAncestors = nFee;
      nSigOpCostWithAncestors = sigOpCost;
  }
  
  void CTxMemPoolEntry::UpdateFeeDelta(int64_t newFeeDelta)
  {
      nModFeesWithDescendants += newFeeDelta - feeDelta;
      nModFeesWithAncestors += newFeeDelta - feeDelta;
      feeDelta = newFeeDelta;
  }
  
  void CTxMemPoolEntry::UpdateLockPoints(const LockPoints& lp)
  {
      lockPoints = lp;
  }
  
  size_t CTxMemPoolEntry::GetTxSize() const
  {
      return GetVirtualTransactionSize(nTxWeight, sigOpCost);
  }
  
  // Update the given tx for any in-mempool descendants.
  // Assumes that setMemPoolChildren is correct for the given tx and all
  // descendants.
  void CTxMemPool::UpdateForDescendants(txiter updateIt, cacheMap &cachedDescendants, const std::set<uint256> &setExclude)
  {
      setEntries stageEntries, setAllDescendants;
      stageEntries = GetMemPoolChildren(updateIt);
  
      while (!stageEntries.empty()) {
          const txiter cit = *stageEntries.begin();
          setAllDescendants.insert(cit);
          stageEntries.erase(cit);
          const setEntries &setChildren = GetMemPoolChildren(cit);
          for (txiter childEntry : setChildren) {
              cacheMap::iterator cacheIt = cachedDescendants.find(childEntry);
              if (cacheIt != cachedDescendants.end()) {
                  // We've already calculated this one, just add the entries for this set
                  // but don't traverse again.
                  for (txiter cacheEntry : cacheIt->second) {
                      setAllDescendants.insert(cacheEntry);
                  }
              } else if (!setAllDescendants.count(childEntry)) {
                  // Schedule for later processing
                  stageEntries.insert(childEntry);
              }
          }
      }
      // setAllDescendants now contains all in-mempool descendants of updateIt.
      // Update and add to cached descendant map
      int64_t modifySize = 0;
      CAmount modifyFee = 0;
      int64_t modifyCount = 0;
      for (txiter cit : setAllDescendants) {
          if (!setExclude.count(cit->GetTx().GetHash())) {
              modifySize += cit->GetTxSize();
              modifyFee += cit->GetModifiedFee();
              modifyCount++;
              cachedDescendants[updateIt].insert(cit);
              // Update ancestor state for each descendant
              mapTx.modify(cit, update_ancestor_state(updateIt->GetTxSize(), updateIt->GetModifiedFee(), 1, updateIt->GetSigOpCost()));
          }
      }
      mapTx.modify(updateIt, update_descendant_state(modifySize, modifyFee, modifyCount));
  }
  
  // vHashesToUpdate is the set of transaction hashes from a disconnected block
  // which has been re-added to the mempool.
  // for each entry, look for descendants that are outside vHashesToUpdate, and
  // add fee/size information for such descendants to the parent.
  // for each such descendant, also update the ancestor state to include the parent.
  void CTxMemPool::UpdateTransactionsFromBlock(const std::vector<uint256> &vHashesToUpdate)
  {
      LOCK(cs);
      // For each entry in vHashesToUpdate, store the set of in-mempool, but not
      // in-vHashesToUpdate transactions, so that we don't have to recalculate
      // descendants when we come across a previously seen entry.
      cacheMap mapMemPoolDescendantsToUpdate;
  
      // Use a set for lookups into vHashesToUpdate (these entries are already
      // accounted for in the state of their ancestors)
      std::set<uint256> setAlreadyIncluded(vHashesToUpdate.begin(), vHashesToUpdate.end());
  
      // Iterate in reverse, so that whenever we are looking at a transaction
      // we are sure that all in-mempool descendants have already been processed.
      // This maximizes the benefit of the descendant cache and guarantees that
      // setMemPoolChildren will be updated, an assumption made in
      // UpdateForDescendants.
      for (const uint256 &hash : reverse_iterate(vHashesToUpdate)) {
          // we cache the in-mempool children to avoid duplicate updates
          setEntries setChildren;
          // calculate children from mapNextTx
          txiter it = mapTx.find(hash);
          if (it == mapTx.end()) {
              continue;
          }
          auto iter = mapNextTx.lower_bound(COutPoint(hash, 0));
          // First calculate the children, and update setMemPoolChildren to
          // include them, and update their setMemPoolParents to include this tx.
          for (; iter != mapNextTx.end() && iter->first->hash == hash; ++iter) {
              const uint256 &childHash = iter->second->GetHash();
              txiter childIter = mapTx.find(childHash);
              assert(childIter != mapTx.end());
              // We can skip updating entries we've encountered before or that
              // are in the block (which are already accounted for).
              if (setChildren.insert(childIter).second && !setAlreadyIncluded.count(childHash)) {
                  UpdateChild(it, childIter, true);
                  UpdateParent(childIter, it, true);
              }
          }
          UpdateForDescendants(it, mapMemPoolDescendantsToUpdate, setAlreadyIncluded);
      }
  }
  
  bool CTxMemPool::CalculateMemPoolAncestors(const CTxMemPoolEntry &entry, setEntries &setAncestors, uint64_t limitAncestorCount, uint64_t limitAncestorSize, uint64_t limitDescendantCount, uint64_t limitDescendantSize, std::string &errString, bool fSearchForParents /* = true */) const
  {
      setEntries parentHashes;
      const CTransaction &tx = entry.GetTx();
  
      if (fSearchForParents) {
          // Get parents of this transaction that are in the mempool
          // GetMemPoolParents() is only valid for entries in the mempool, so we
          // iterate mapTx to find parents.
          for (unsigned int i = 0; i < tx.vin.size(); i++) {
              boost::optional<txiter> piter = GetIter(tx.vin[i].prevout.hash);
              if (piter) {
                  parentHashes.insert(*piter);
                  if (parentHashes.size() + 1 > limitAncestorCount) {
                      errString = strprintf("too many unconfirmed parents [limit: %u]", limitAncestorCount);
                      return false;
                  }
              }
          }
      } else {
          // If we're not searching for parents, we require this to be an
          // entry in the mempool already.
          txiter it = mapTx.iterator_to(entry);
          parentHashes = GetMemPoolParents(it);
      }
  
      size_t totalSizeWithAncestors = entry.GetTxSize();
  
      while (!parentHashes.empty()) {
          txiter stageit = *parentHashes.begin();
  
          setAncestors.insert(stageit);
          parentHashes.erase(stageit);
          totalSizeWithAncestors += stageit->GetTxSize();
  
          if (stageit->GetSizeWithDescendants() + entry.GetTxSize() > limitDescendantSize) {
              errString = strprintf("exceeds descendant size limit for tx %s [limit: %u]", stageit->GetTx().GetHash().ToString(), limitDescendantSize);
              return false;
          } else if (stageit->GetCountWithDescendants() + 1 > limitDescendantCount) {
              errString = strprintf("too many descendants for tx %s [limit: %u]", stageit->GetTx().GetHash().ToString(), limitDescendantCount);
              return false;
          } else if (totalSizeWithAncestors > limitAncestorSize) {
              errString = strprintf("exceeds ancestor size limit [limit: %u]", limitAncestorSize);
              return false;
          }
  
          const setEntries & setMemPoolParents = GetMemPoolParents(stageit);
          for (txiter phash : setMemPoolParents) {
              // If this is a new ancestor, add it.
              if (setAncestors.count(phash) == 0) {
                  parentHashes.insert(phash);
              }
              if (parentHashes.size() + setAncestors.size() + 1 > limitAncestorCount) {
                  errString = strprintf("too many unconfirmed ancestors [limit: %u]", limitAncestorCount);
                  return false;
              }
          }
      }
  
      return true;
  }
  
  void CTxMemPool::UpdateAncestorsOf(bool add, txiter it, setEntries &setAncestors)
  {
      setEntries parentIters = GetMemPoolParents(it);
      // add or remove this tx as a child of each parent
      for (txiter piter : parentIters) {
          UpdateChild(piter, it, add);
      }
      const int64_t updateCount = (add ? 1 : -1);
      const int64_t updateSize = updateCount * it->GetTxSize();
      const CAmount updateFee = updateCount * it->GetModifiedFee();
      for (txiter ancestorIt : setAncestors) {
          mapTx.modify(ancestorIt, update_descendant_state(updateSize, updateFee, updateCount));
      }
  }
  
  void CTxMemPool::UpdateEntryForAncestors(txiter it, const setEntries &setAncestors)
  {
      int64_t updateCount = setAncestors.size();
      int64_t updateSize = 0;
      CAmount updateFee = 0;
      int64_t updateSigOpsCost = 0;
      for (txiter ancestorIt : setAncestors) {
          updateSize += ancestorIt->GetTxSize();
          updateFee += ancestorIt->GetModifiedFee();
          updateSigOpsCost += ancestorIt->GetSigOpCost();
      }
      mapTx.modify(it, update_ancestor_state(updateSize, updateFee, updateCount, updateSigOpsCost));
  }
  
  void CTxMemPool::UpdateChildrenForRemoval(txiter it)
  {
      const setEntries &setMemPoolChildren = GetMemPoolChildren(it);
      for (txiter updateIt : setMemPoolChildren) {
          UpdateParent(updateIt, it, false);
      }
  }
  
  void CTxMemPool::UpdateForRemoveFromMempool(const setEntries &entriesToRemove, bool updateDescendants)
  {
      // For each entry, walk back all ancestors and decrement size associated with this
      // transaction
      const uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
      if (updateDescendants) {
          // updateDescendants should be true whenever we're not recursively
          // removing a tx and all its descendants, eg when a transaction is
          // confirmed in a block.
          // Here we only update statistics and not data in mapLinks (which
          // we need to preserve until we're finished with all operations that
          // need to traverse the mempool).
          for (txiter removeIt : entriesToRemove) {
              setEntries setDescendants;
              CalculateDescendants(removeIt, setDescendants);
              setDescendants.erase(removeIt); // don't update state for self
              int64_t modifySize = -((int64_t)removeIt->GetTxSize());
              CAmount modifyFee = -removeIt->GetModifiedFee();
              int modifySigOps = -removeIt->GetSigOpCost();
              for (txiter dit : setDescendants) {
                  mapTx.modify(dit, update_ancestor_state(modifySize, modifyFee, -1, modifySigOps));
              }
          }
      }
      for (txiter removeIt : entriesToRemove) {
          setEntries setAncestors;
          const CTxMemPoolEntry &entry = *removeIt;
          std::string dummy;
          // Since this is a tx that is already in the mempool, we can call CMPA
          // with fSearchForParents = false.  If the mempool is in a consistent
          // state, then using true or false should both be correct, though false
          // should be a bit faster.
          // However, if we happen to be in the middle of processing a reorg, then
          // the mempool can be in an inconsistent state.  In this case, the set
          // of ancestors reachable via mapLinks will be the same as the set of
          // ancestors whose packages include this transaction, because when we
          // add a new transaction to the mempool in addUnchecked(), we assume it
          // has no children, and in the case of a reorg where that assumption is
          // false, the in-mempool children aren't linked to the in-block tx's
          // until UpdateTransactionsFromBlock() is called.
          // So if we're being called during a reorg, ie before
          // UpdateTransactionsFromBlock() has been called, then mapLinks[] will
          // differ from the set of mempool parents we'd calculate by searching,
          // and it's important that we use the mapLinks[] notion of ancestor
          // transactions as the set of things to update for removal.
          CalculateMemPoolAncestors(entry, setAncestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
          // Note that UpdateAncestorsOf severs the child links that point to
          // removeIt in the entries for the parents of removeIt.
          UpdateAncestorsOf(false, removeIt, setAncestors);
      }
      // After updating all the ancestor sizes, we can now sever the link between each
      // transaction being removed and any mempool children (ie, update setMemPoolParents
      // for each direct child of a transaction being removed).
      for (txiter removeIt : entriesToRemove) {
          UpdateChildrenForRemoval(removeIt);
      }
  }
  
  void CTxMemPoolEntry::UpdateDescendantState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount)
  {
      nSizeWithDescendants += modifySize;
      assert(int64_t(nSizeWithDescendants) > 0);
      nModFeesWithDescendants += modifyFee;
      nCountWithDescendants += modifyCount;
      assert(int64_t(nCountWithDescendants) > 0);
  }
  
  void CTxMemPoolEntry::UpdateAncestorState(int64_t modifySize, CAmount modifyFee, int64_t modifyCount, int64_t modifySigOps)
  {
      nSizeWithAncestors += modifySize;
      assert(int64_t(nSizeWithAncestors) > 0);
      nModFeesWithAncestors += modifyFee;
      nCountWithAncestors += modifyCount;
      assert(int64_t(nCountWithAncestors) > 0);
      nSigOpCostWithAncestors += modifySigOps;
      assert(int(nSigOpCostWithAncestors) >= 0);
  }
  
  CTxMemPool::CTxMemPool(CBlockPolicyEstimator* estimator) :
      nTransactionsUpdated(0), minerPolicyEstimator(estimator)
  {
      _clear(); //lock free clear
  
      // Sanity checks off by default for performance, because otherwise
      // accepting transactions becomes O(N^2) where N is the number
      // of transactions in the pool
      nCheckFrequency = 0;
  }
  
  bool CTxMemPool::isSpent(const COutPoint& outpoint) const
  {
      LOCK(cs);
      return mapNextTx.count(outpoint);
  }
  
  unsigned int CTxMemPool::GetTransactionsUpdated() const
  {
      LOCK(cs);
      return nTransactionsUpdated;
  }
  
  void CTxMemPool::AddTransactionsUpdated(unsigned int n)
  {
      LOCK(cs);
      nTransactionsUpdated += n;
  }
  
  void CTxMemPool::addUnchecked(const CTxMemPoolEntry &entry, setEntries &setAncestors, bool validFeeEstimate)
  {
      NotifyEntryAdded(entry.GetSharedTx());
      // Add to memory pool without checking anything.
      // Used by AcceptToMemoryPool(), which DOES do
      // all the appropriate checks.
      indexed_transaction_set::iterator newit = mapTx.insert(entry).first;
      mapLinks.insert(make_pair(newit, TxLinks()));
  
      // Update transaction for any feeDelta created by PrioritiseTransaction
      // TODO: refactor so that the fee delta is calculated before inserting
      // into mapTx.
      CAmount delta{0};
      ApplyDelta(entry.GetTx().GetHash(), delta);
      if (delta) {
              mapTx.modify(newit, update_fee_delta(delta));
      }
  
      // Update cachedInnerUsage to include contained transaction's usage.
      // (When we update the entry for in-mempool parents, memory usage will be
      // further updated.)
      cachedInnerUsage += entry.DynamicMemoryUsage();
  
      const CTransaction& tx = newit->GetTx();
      std::set<uint256> setParentTransactions;
      for (unsigned int i = 0; i < tx.vin.size(); i++) {
          mapNextTx.insert(std::make_pair(&tx.vin[i].prevout, &tx));
          setParentTransactions.insert(tx.vin[i].prevout.hash);
      }
      // Don't bother worrying about child transactions of this one.
      // Normal case of a new transaction arriving is that there can't be any
      // children, because such children would be orphans.
      // An exception to that is if a transaction enters that used to be in a block.
      // In that case, our disconnect block logic will call UpdateTransactionsFromBlock
      // to clean up the mess we're leaving here.
  
      // Update ancestors with information about this tx
      for (const auto& pit : GetIterSet(setParentTransactions)) {
              UpdateParent(newit, pit, true);
      }
      UpdateAncestorsOf(true, newit, setAncestors);
      UpdateEntryForAncestors(newit, setAncestors);
  
      nTransactionsUpdated++;
      totalTxSize += entry.GetTxSize();
      if (minerPolicyEstimator) {minerPolicyEstimator->processTransaction(entry, validFeeEstimate);}
  
      vTxHashes.emplace_back(tx.GetWitnessHash(), newit);
      newit->vTxHashesIdx = vTxHashes.size() - 1;
  }
  
  void CTxMemPool::removeUnchecked(txiter it, MemPoolRemovalReason reason)
  {
      NotifyEntryRemoved(it->GetSharedTx(), reason);
      const uint256 hash = it->GetTx().GetHash();
      for (const CTxIn& txin : it->GetTx().vin)
          mapNextTx.erase(txin.prevout);
  
      if (vTxHashes.size() > 1) {
          vTxHashes[it->vTxHashesIdx] = std::move(vTxHashes.back());
          vTxHashes[it->vTxHashesIdx].second->vTxHashesIdx = it->vTxHashesIdx;
          vTxHashes.pop_back();
          if (vTxHashes.size() * 2 < vTxHashes.capacity())
              vTxHashes.shrink_to_fit();
      } else
          vTxHashes.clear();
  
      totalTxSize -= it->GetTxSize();
      cachedInnerUsage -= it->DynamicMemoryUsage();
      cachedInnerUsage -= memusage::DynamicUsage(mapLinks[it].parents) + memusage::DynamicUsage(mapLinks[it].children);
      mapLinks.erase(it);
      mapTx.erase(it);
      nTransactionsUpdated++;
      if (minerPolicyEstimator) {minerPolicyEstimator->removeTx(hash, false);}
  }
  
  // Calculates descendants of entry that are not already in setDescendants, and adds to
  // setDescendants. Assumes entryit is already a tx in the mempool and setMemPoolChildren
  // is correct for tx and all descendants.
  // Also assumes that if an entry is in setDescendants already, then all
  // in-mempool descendants of it are already in setDescendants as well, so that we
  // can save time by not iterating over those entries.
  void CTxMemPool::CalculateDescendants(txiter entryit, setEntries& setDescendants) const
  {
      setEntries stage;
      if (setDescendants.count(entryit) == 0) {
          stage.insert(entryit);
      }
      // Traverse down the children of entry, only adding children that are not
      // accounted for in setDescendants already (because those children have either
      // already been walked, or will be walked in this iteration).
      while (!stage.empty()) {
          txiter it = *stage.begin();
          setDescendants.insert(it);
          stage.erase(it);
  
          const setEntries &setChildren = GetMemPoolChildren(it);
          for (txiter childiter : setChildren) {
              if (!setDescendants.count(childiter)) {
                  stage.insert(childiter);
              }
          }
      }
  }
  
  void CTxMemPool::removeRecursive(const CTransaction &origTx, MemPoolRemovalReason reason)
  {
      // Remove transaction from memory pool
      {
          LOCK(cs);
          setEntries txToRemove;
          txiter origit = mapTx.find(origTx.GetHash());
          if (origit != mapTx.end()) {
              txToRemove.insert(origit);
          } else {
              // When recursively removing but origTx isn't in the mempool
              // be sure to remove any children that are in the pool. This can
              // happen during chain re-orgs if origTx isn't re-accepted into
              // the mempool for any reason.
              for (unsigned int i = 0; i < origTx.vout.size(); i++) {
                  auto it = mapNextTx.find(COutPoint(origTx.GetHash(), i));
                  if (it == mapNextTx.end())
                      continue;
                  txiter nextit = mapTx.find(it->second->GetHash());
                  assert(nextit != mapTx.end());
                  txToRemove.insert(nextit);
              }
          }
          setEntries setAllRemoves;
          for (txiter it : txToRemove) {
              CalculateDescendants(it, setAllRemoves);
          }
  
          RemoveStaged(setAllRemoves, false, reason);
      }
  }
  
  void CTxMemPool::removeForReorg(const CCoinsViewCache *pcoins, unsigned int nMemPoolHeight, int flags)
  {
      // Remove transactions spending a coinbase which are now immature and no-longer-final transactions
      LOCK(cs);
      setEntries txToRemove;
      for (indexed_transaction_set::const_iterator it = mapTx.begin(); it != mapTx.end(); it++) {
          const CTransaction& tx = it->GetTx();
          LockPoints lp = it->GetLockPoints();
          bool validLP =  TestLockPointValidity(&lp);
          if (!CheckFinalTx(tx, flags) || !CheckSequenceLocks(*this, tx, flags, &lp, validLP)) {
              // Note if CheckSequenceLocks fails the LockPoints may still be invalid
              // So it's critical that we remove the tx and not depend on the LockPoints.
              txToRemove.insert(it);
          } else if (it->GetSpendsCoinbase()) {
              for (const CTxIn& txin : tx.vin) {
                  indexed_transaction_set::const_iterator it2 = mapTx.find(txin.prevout.hash);
                  if (it2 != mapTx.end())
                      continue;
                  const Coin &coin = pcoins->AccessCoin(txin.prevout);
                  if (nCheckFrequency != 0) assert(!coin.IsSpent());
                  if (coin.IsSpent() || (coin.IsCoinBase() && ((signed long)nMemPoolHeight) - coin.nHeight < COINBASE_MATURITY)) {
                      txToRemove.insert(it);
                      break;
                  }
              }
          }
          if (!validLP) {
              mapTx.modify(it, update_lock_points(lp));
          }
  
          // On re-org, remove *all* peg-in and PAK-based peg-outs due to possible
          // invalidity from dynafed transitions
          // TODO: Only boot out now-invalid transactions. Re-orgs are very rare in
          // federated systems but can occasionally happen due to consensus algorithm.
  
          // Little hack to quickly check if any outputs are PAK ones
          // by sending in empty(reject) list.
          if (!IsPAKValidTx(tx, CPAKList(), Params().ParentGenesisBlockHash(), Params().GetConsensus().pegged_asset)) {
              txToRemove.insert(it);
              continue;
          }
          for (const auto& input : tx.vin) {
              if (input.m_is_pegin) {
                  txToRemove.insert(it);
                  break;
              }
          }
      }
      setEntries setAllRemoves;
      for (txiter it : txToRemove) {
          CalculateDescendants(it, setAllRemoves);
      }
      RemoveStaged(setAllRemoves, false, MemPoolRemovalReason::REORG);
  }
  
  void CTxMemPool::removeConflicts(const CTransaction &tx)
  {
      // Remove transactions which depend on inputs of tx, recursively
      AssertLockHeld(cs);
      for (const CTxIn &txin : tx.vin) {
          auto it = mapNextTx.find(txin.prevout);
          if (it != mapNextTx.end()) {
              const CTransaction &txConflict = *it->second;
              if (txConflict != tx)
              {
                  ClearPrioritisation(txConflict.GetHash());
                  removeRecursive(txConflict, MemPoolRemovalReason::CONFLICT);
              }
          }
      }
  }
  
  /**
   * Called when a block is connected. Removes from mempool and updates the miner fee estimator.
   */
  void CTxMemPool::removeForBlock(const std::vector<CTransactionRef>& vtx, unsigned int nBlockHeight, const CBlockIndex* p_block_index_new)
  {
      LOCK(cs);
      std::vector<const CTxMemPoolEntry*> entries;
      for (const auto& tx : vtx)
      {
          uint256 hash = tx->GetHash();
  
          indexed_transaction_set::iterator i = mapTx.find(hash);
          if (i != mapTx.end())
              entries.push_back(&*i);
      }
      // Before the txs in the new block have been removed from the mempool, update policy estimates
      if (minerPolicyEstimator) {minerPolicyEstimator->processBlock(nBlockHeight, entries);}
      for (const auto& tx : vtx)
      {
          txiter it = mapTx.find(tx->GetHash());
          if (it != mapTx.end()) {
              setEntries stage;
              stage.insert(it);
              RemoveStaged(stage, true, MemPoolRemovalReason::BLOCK);
          }
          removeConflicts(*tx);
          ClearPrioritisation(tx->GetHash());
      }
  
      // Eject transactions that are invalid for *following* block due to transition
      // We check every epoch_length blocks due to peg-ins expiring an epoch after
      // being changed
      if (p_block_index_new) {
          const CChainParams& chainparams = Params();
          uint32_t epoch_length = chainparams.GetConsensus().dynamic_epoch_length;
          if ((p_block_index_new->nHeight+1) % epoch_length == 0) {
              CPAKList enforced_paklist = GetActivePAKList(p_block_index_new, chainparams.GetConsensus());
              std::vector<CTransactionRef> tx_to_remove;
              for (const auto& entry : mapTx) {
                  const CTransaction& tx = entry.GetTx();
                  if (chainparams.GetEnforcePak() && !IsPAKValidTx(tx, enforced_paklist, chainparams.ParentGenesisBlockHash(), chainparams.GetConsensus().pegged_asset)) {
                      tx_to_remove.push_back(MakeTransactionRef(tx));
                      continue;
                  }
  
                  const auto& fedpegscripts = GetValidFedpegScripts(p_block_index_new, chainparams.GetConsensus(), true /* nextblock_validation */);
                  for (size_t nIn = 0; nIn < tx.vin.size(); nIn++) {
                      const CTxIn& in = tx.vin[nIn];
                      std::string err;
                      if (in.m_is_pegin && (!tx.HasWitness() || !IsValidPeginWitness(tx.witness.vtxinwit[nIn].m_pegin_witness, fedpegscripts, in.prevout, err, true /* check_depth */))) {
                          tx_to_remove.push_back(MakeTransactionRef(tx));
                          break;
                      }
                  }
              }
              for (auto& tx : tx_to_remove) {
                  const uint256 tx_id = tx->GetHash();
                  removeRecursive(*tx, MemPoolRemovalReason::BLOCK);
                  ClearPrioritisation(tx_id);
              }
          }
      }
  
      lastRollingFeeUpdate = GetTime();
      blockSinceLastRollingFeeBump = true;
  }
  
  void CTxMemPool::_clear()
  {
      mapLinks.clear();
      mapTx.clear();
      mapNextTx.clear();
      totalTxSize = 0;
      cachedInnerUsage = 0;
      lastRollingFeeUpdate = GetTime();
      blockSinceLastRollingFeeBump = false;
      rollingMinimumFeeRate = 0;
      ++nTransactionsUpdated;
  }
  
  void CTxMemPool::clear()
  {
      LOCK(cs);
      _clear();
  }
  
  static void CheckInputsAndUpdateCoins(const CTxMemPoolEntry& entry, CCoinsViewCache& mempoolDuplicate, const int64_t spendheight, std::set<std::pair<uint256, COutPoint>>& setGlobalPeginsSpent)
  {
      CTransaction tx = entry.GetTx();
      CValidationState state;
      CAmountMap fee_map;
      std::set<std::pair<uint256, COutPoint> > setPeginsSpent;
      const auto& fedpegscripts = GetValidFedpegScripts(chainActive.Tip(), Params().GetConsensus(), true /* nextblock_validation */);
      bool fCheckResult = tx.IsCoinBase() || Consensus::CheckTxInputs(tx, state, mempoolDuplicate, spendheight, fee_map, setPeginsSpent, NULL, false, true, fedpegscripts);
      assert(fCheckResult);
      UpdateCoins(tx, mempoolDuplicate, 1000000);
  
      // ELEMENTS:
      assert(setPeginsSpent == entry.setPeginsSpent);
      size_t prevPeginsCount = setGlobalPeginsSpent.size();
      setGlobalPeginsSpent.insert(setPeginsSpent.begin(), setPeginsSpent.end());
      assert(setGlobalPeginsSpent.size() == prevPeginsCount + setPeginsSpent.size());
  }
  
  void CTxMemPool::check(const CCoinsViewCache *pcoins) const
  {
      LOCK(cs);
      if (nCheckFrequency == 0)
          return;
  
      if (GetRand(std::numeric_limits<uint32_t>::max()) >= nCheckFrequency)
          return;
  
      LogPrint(BCLog::MEMPOOL, "Checking mempool with %u transactions and %u inputs\n", (unsigned int)mapTx.size(), (unsigned int)mapNextTx.size());
  
      uint64_t checkTotal = 0;
      uint64_t innerUsage = 0;
  
      CCoinsViewCache mempoolDuplicate(const_cast<CCoinsViewCache*>(pcoins));
      const int64_t spendheight = GetSpendHeight(mempoolDuplicate);
  
      std::list<const CTxMemPoolEntry*> waitingOnDependants;
      // ELEMENTS:
      std::set<std::pair<uint256, COutPoint> > setGlobalPeginsSpent;
  
      for (indexed_transaction_set::const_iterator it = mapTx.begin(); it != mapTx.end(); it++) {
          unsigned int i = 0;
          checkTotal += it->GetTxSize();
          innerUsage += it->DynamicMemoryUsage();
          const CTransaction& tx = it->GetTx();
          txlinksMap::const_iterator linksiter = mapLinks.find(it);
          assert(linksiter != mapLinks.end());
          const TxLinks &links = linksiter->second;
          innerUsage += memusage::DynamicUsage(links.parents) + memusage::DynamicUsage(links.children);
          bool fDependsWait = false;
          setEntries setParentCheck;
          for (const CTxIn &txin : tx.vin) {
              // Check that every mempool transaction's inputs refer to available coins, or other mempool tx's.
              indexed_transaction_set::const_iterator it2 = mapTx.find(txin.prevout.hash);
              if (it2 != mapTx.end()) {
                  const CTransaction& tx2 = it2->GetTx();
                  assert(tx2.vout.size() > txin.prevout.n && !tx2.vout[txin.prevout.n].IsNull());
                  fDependsWait = true;
                  setParentCheck.insert(it2);
              } else {
                  // peg-in inputs are not sanity-checked to be valid
                  assert(txin.m_is_pegin || pcoins->HaveCoin(txin.prevout));
              }
              // Check whether its inputs are marked in mapNextTx.
              auto it3 = mapNextTx.find(txin.prevout);
              assert(it3 != mapNextTx.end());
              assert(it3->first == &txin.prevout);
              assert(it3->second == &tx);
              i++;
          }
          assert(setParentCheck == GetMemPoolParents(it));
          // Verify ancestor state is correct.
          setEntries setAncestors;
          uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
          std::string dummy;
          CalculateMemPoolAncestors(*it, setAncestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy);
          uint64_t nCountCheck = setAncestors.size() + 1;
          uint64_t nSizeCheck = it->GetTxSize();
          CAmount nFeesCheck = it->GetModifiedFee();
          int64_t nSigOpCheck = it->GetSigOpCost();
  
          for (txiter ancestorIt : setAncestors) {
              nSizeCheck += ancestorIt->GetTxSize();
              nFeesCheck += ancestorIt->GetModifiedFee();
              nSigOpCheck += ancestorIt->GetSigOpCost();
          }
  
          assert(it->GetCountWithAncestors() == nCountCheck);
          assert(it->GetSizeWithAncestors() == nSizeCheck);
          assert(it->GetSigOpCostWithAncestors() == nSigOpCheck);
          assert(it->GetModFeesWithAncestors() == nFeesCheck);
  
          // Check children against mapNextTx
          CTxMemPool::setEntries setChildrenCheck;
          auto iter = mapNextTx.lower_bound(COutPoint(it->GetTx().GetHash(), 0));
          uint64_t child_sizes = 0;
          for (; iter != mapNextTx.end() && iter->first->hash == it->GetTx().GetHash(); ++iter) {
              txiter childit = mapTx.find(iter->second->GetHash());
              assert(childit != mapTx.end()); // mapNextTx points to in-mempool transactions
              if (setChildrenCheck.insert(childit).second) {
                  child_sizes += childit->GetTxSize();
              }
          }
          assert(setChildrenCheck == GetMemPoolChildren(it));
          // Also check to make sure size is greater than sum with immediate children.
          // just a sanity check, not definitive that this calc is correct...
          assert(it->GetSizeWithDescendants() >= child_sizes + it->GetTxSize());
  
          if (fDependsWait)
              waitingOnDependants.push_back(&(*it));
          else {
              CheckInputsAndUpdateCoins(*it, mempoolDuplicate, spendheight, setGlobalPeginsSpent);
          }
      }
      unsigned int stepsSinceLastRemove = 0;
      while (!waitingOnDependants.empty()) {
          const CTxMemPoolEntry* entry = waitingOnDependants.front();
          waitingOnDependants.pop_front();
          if (!mempoolDuplicate.HaveInputs(entry->GetTx())) {
              waitingOnDependants.push_back(entry);
              stepsSinceLastRemove++;
              assert(stepsSinceLastRemove < waitingOnDependants.size());
          } else {
              CheckInputsAndUpdateCoins(*entry, mempoolDuplicate, spendheight, setGlobalPeginsSpent);
              stepsSinceLastRemove = 0;
          }
      }
      for (auto it = mapNextTx.cbegin(); it != mapNextTx.cend(); it++) {
          uint256 hash = it->second->GetHash();
          indexed_transaction_set::const_iterator it2 = mapTx.find(hash);
          const CTransaction& tx = it2->GetTx();
          assert(it2 != mapTx.end());
          assert(&tx == it->second);
      }
  
      //
      // ELEMENTS:
      for (std::set<std::pair<uint256, COutPoint> >::const_iterator it = setGlobalPeginsSpent.begin(); it != setGlobalPeginsSpent.end(); it++) {
          assert(!pcoins->IsPeginSpent(*it));
      }
      // END ELEMENTS
      //
  
      assert(totalTxSize == checkTotal);
      assert(innerUsage == cachedInnerUsage);
  }
  
  bool CTxMemPool::CompareDepthAndScore(const uint256& hasha, const uint256& hashb)
  {
      LOCK(cs);
      indexed_transaction_set::const_iterator i = mapTx.find(hasha);
      if (i == mapTx.end()) return false;
      indexed_transaction_set::const_iterator j = mapTx.find(hashb);
      if (j == mapTx.end()) return true;
      uint64_t counta = i->GetCountWithAncestors();
      uint64_t countb = j->GetCountWithAncestors();
      if (counta == countb) {
          return CompareTxMemPoolEntryByScore()(*i, *j);
      }
      return counta < countb;
  }
  
  namespace {
  class DepthAndScoreComparator
  {
  public:
      bool operator()(const CTxMemPool::indexed_transaction_set::const_iterator& a, const CTxMemPool::indexed_transaction_set::const_iterator& b)
      {
          uint64_t counta = a->GetCountWithAncestors();
          uint64_t countb = b->GetCountWithAncestors();
          if (counta == countb) {
              return CompareTxMemPoolEntryByScore()(*a, *b);
          }
          return counta < countb;
      }
  };
  } // namespace
  
  std::vector<CTxMemPool::indexed_transaction_set::const_iterator> CTxMemPool::GetSortedDepthAndScore() const
  {
      std::vector<indexed_transaction_set::const_iterator> iters;
      AssertLockHeld(cs);
  
      iters.reserve(mapTx.size());
  
      for (indexed_transaction_set::iterator mi = mapTx.begin(); mi != mapTx.end(); ++mi) {
          iters.push_back(mi);
      }
      std::sort(iters.begin(), iters.end(), DepthAndScoreComparator());
      return iters;
  }
  
  void CTxMemPool::queryHashes(std::vector<uint256>& vtxid)
  {
      LOCK(cs);
      auto iters = GetSortedDepthAndScore();
  
      vtxid.clear();
      vtxid.reserve(mapTx.size());
  
      for (auto it : iters) {
          vtxid.push_back(it->GetTx().GetHash());
      }
  }
  
  static TxMempoolInfo GetInfo(CTxMemPool::indexed_transaction_set::const_iterator it) {
      return TxMempoolInfo{it->GetSharedTx(), it->GetTime(), CFeeRate(it->GetFee(), it->GetTxSize()), it->GetModifiedFee() - it->GetFee()};
  }
  
  std::vector<TxMempoolInfo> CTxMemPool::infoAll() const
  {
      LOCK(cs);
      auto iters = GetSortedDepthAndScore();
  
      std::vector<TxMempoolInfo> ret;
      ret.reserve(mapTx.size());
      for (auto it : iters) {
          ret.push_back(GetInfo(it));
      }
  
      return ret;
  }
  
  CTransactionRef CTxMemPool::get(const uint256& hash) const
  {
      LOCK(cs);
      indexed_transaction_set::const_iterator i = mapTx.find(hash);
      if (i == mapTx.end())
          return nullptr;
      return i->GetSharedTx();
  }
  
  TxMempoolInfo CTxMemPool::info(const uint256& hash) const
  {
      LOCK(cs);
      indexed_transaction_set::const_iterator i = mapTx.find(hash);
      if (i == mapTx.end())
          return TxMempoolInfo();
      return GetInfo(i);
  }
  
  void CTxMemPool::PrioritiseTransaction(const uint256& hash, const CAmount& nFeeDelta)
  {
      {
          LOCK(cs);
          CAmount &delta = mapDeltas[hash];
          delta += nFeeDelta;
          txiter it = mapTx.find(hash);
          if (it != mapTx.end()) {
              mapTx.modify(it, update_fee_delta(delta));
              // Now update all ancestors' modified fees with descendants
              setEntries setAncestors;
              uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
              std::string dummy;
              CalculateMemPoolAncestors(*it, setAncestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy, false);
              for (txiter ancestorIt : setAncestors) {
                  mapTx.modify(ancestorIt, update_descendant_state(0, nFeeDelta, 0));
              }
              // Now update all descendants' modified fees with ancestors
              setEntries setDescendants;
              CalculateDescendants(it, setDescendants);
              setDescendants.erase(it);
              for (txiter descendantIt : setDescendants) {
                  mapTx.modify(descendantIt, update_ancestor_state(0, nFeeDelta, 0, 0));
              }
              ++nTransactionsUpdated;
          }
      }
      LogPrintf("PrioritiseTransaction: %s feerate += %s\n", hash.ToString(), FormatMoney(nFeeDelta));
  }
  
  void CTxMemPool::ApplyDelta(const uint256 hash, CAmount &nFeeDelta) const
  {
      LOCK(cs);
      std::map<uint256, CAmount>::const_iterator pos = mapDeltas.find(hash);
      if (pos == mapDeltas.end())
          return;
      const CAmount &delta = pos->second;
      nFeeDelta += delta;
  }
  
  void CTxMemPool::ClearPrioritisation(const uint256 hash)
  {
      LOCK(cs);
      mapDeltas.erase(hash);
  }
  
  const CTransaction* CTxMemPool::GetConflictTx(const COutPoint& prevout) const
  {
      const auto it = mapNextTx.find(prevout);
      return it == mapNextTx.end() ? nullptr : it->second;
  }
  
  boost::optional<CTxMemPool::txiter> CTxMemPool::GetIter(const uint256& txid) const
  {
      auto it = mapTx.find(txid);
      if (it != mapTx.end()) return it;
      return boost::optional<txiter>{};
  }
  
  CTxMemPool::setEntries CTxMemPool::GetIterSet(const std::set<uint256>& hashes) const
  {
      CTxMemPool::setEntries ret;
      for (const auto& h : hashes) {
          const auto mi = GetIter(h);
          if (mi) ret.insert(*mi);
      }
      return ret;
  }
  
  bool CTxMemPool::HasNoInputsOf(const CTransaction &tx) const
  {
      for (unsigned int i = 0; i < tx.vin.size(); i++)
          if (exists(tx.vin[i].prevout.hash))
              return false;
      return true;
  }
  
  CCoinsViewMemPool::CCoinsViewMemPool(CCoinsView* baseIn, const CTxMemPool& mempoolIn) : CCoinsViewBacked(baseIn), mempool(mempoolIn) { }
  
  bool CCoinsViewMemPool::GetCoin(const COutPoint &outpoint, Coin &coin) const {
      // If an entry in the mempool exists, always return that one, as it's guaranteed to never
      // conflict with the underlying cache, and it cannot have pruned entries (as it contains full)
      // transactions. First checking the underlying cache risks returning a pruned entry instead.
      CTransactionRef ptx = mempool.get(outpoint.hash);
      if (ptx) {
          if (outpoint.n < ptx->vout.size()) {
              coin = Coin(ptx->vout[outpoint.n], MEMPOOL_HEIGHT, false);
              return true;
          } else {
              return false;
          }
      }
      return base->GetCoin(outpoint, coin);
  }
  
  // ELEMENTS:
  bool CCoinsViewMemPool::IsPeginSpent(const std::pair<uint256, COutPoint> &outpoint) const {
      return base->IsPeginSpent(outpoint);
  }
  
  size_t CTxMemPool::DynamicMemoryUsage() const {
      LOCK(cs);
      // Estimate the overhead of mapTx to be 12 pointers + an allocation, as no exact formula for boost::multi_index_contained is implemented.
      return memusage::MallocUsage(sizeof(CTxMemPoolEntry) + 12 * sizeof(void*)) * mapTx.size() + memusage::DynamicUsage(mapNextTx) + memusage::DynamicUsage(mapDeltas) + memusage::DynamicUsage(mapLinks) + memusage::DynamicUsage(vTxHashes) + cachedInnerUsage;
  }
  
  void CTxMemPool::RemoveStaged(setEntries &stage, bool updateDescendants, MemPoolRemovalReason reason) {
      AssertLockHeld(cs);
      UpdateForRemoveFromMempool(stage, updateDescendants);
      for (txiter it : stage) {
          removeUnchecked(it, reason);
      }
  }
  
  int CTxMemPool::Expire(int64_t time) {
      LOCK(cs);
      indexed_transaction_set::index<entry_time>::type::iterator it = mapTx.get<entry_time>().begin();
      setEntries toremove;
      while (it != mapTx.get<entry_time>().end() && it->GetTime() < time) {
          toremove.insert(mapTx.project<0>(it));
          it++;
      }
      setEntries stage;
      for (txiter removeit : toremove) {
          CalculateDescendants(removeit, stage);
      }
      RemoveStaged(stage, false, MemPoolRemovalReason::EXPIRY);
      return stage.size();
  }
  
  void CTxMemPool::addUnchecked(const CTxMemPoolEntry &entry, bool validFeeEstimate)
  {
      setEntries setAncestors;
      uint64_t nNoLimit = std::numeric_limits<uint64_t>::max();
      std::string dummy;
      CalculateMemPoolAncestors(entry, setAncestors, nNoLimit, nNoLimit, nNoLimit, nNoLimit, dummy);
      return addUnchecked(entry, setAncestors, validFeeEstimate);
  }
  
  void CTxMemPool::UpdateChild(txiter entry, txiter child, bool add)
  {
      setEntries s;
      if (add && mapLinks[entry].children.insert(child).second) {
          cachedInnerUsage += memusage::IncrementalDynamicUsage(s);
      } else if (!add && mapLinks[entry].children.erase(child)) {
          cachedInnerUsage -= memusage::IncrementalDynamicUsage(s);
      }
  }
  
  void CTxMemPool::UpdateParent(txiter entry, txiter parent, bool add)
  {
      setEntries s;
      if (add && mapLinks[entry].parents.insert(parent).second) {
          cachedInnerUsage += memusage::IncrementalDynamicUsage(s);
      } else if (!add && mapLinks[entry].parents.erase(parent)) {
          cachedInnerUsage -= memusage::IncrementalDynamicUsage(s);
      }
  }
  
  const CTxMemPool::setEntries & CTxMemPool::GetMemPoolParents(txiter entry) const
  {
      assert (entry != mapTx.end());
      txlinksMap::const_iterator it = mapLinks.find(entry);
      assert(it != mapLinks.end());
      return it->second.parents;
  }
  
  const CTxMemPool::setEntries & CTxMemPool::GetMemPoolChildren(txiter entry) const
  {
      assert (entry != mapTx.end());
      txlinksMap::const_iterator it = mapLinks.find(entry);
      assert(it != mapLinks.end());
      return it->second.children;
  }
  
  CFeeRate CTxMemPool::GetMinFee(size_t sizelimit) const {
      LOCK(cs);
      if (!blockSinceLastRollingFeeBump || rollingMinimumFeeRate == 0)
          return CFeeRate(llround(rollingMinimumFeeRate));
  
      int64_t time = GetTime();
      if (time > lastRollingFeeUpdate + 10) {
          double halflife = ROLLING_FEE_HALFLIFE;
          if (DynamicMemoryUsage() < sizelimit / 4)
              halflife /= 4;
          else if (DynamicMemoryUsage() < sizelimit / 2)
              halflife /= 2;
  
          rollingMinimumFeeRate = rollingMinimumFeeRate / pow(2.0, (time - lastRollingFeeUpdate) / halflife);
          lastRollingFeeUpdate = time;
  
          if (rollingMinimumFeeRate < (double)incrementalRelayFee.GetFeePerK() / 2) {
              rollingMinimumFeeRate = 0;
              return CFeeRate(0);
          }
      }
      return std::max(CFeeRate(llround(rollingMinimumFeeRate)), incrementalRelayFee);
  }
  
  void CTxMemPool::trackPackageRemoved(const CFeeRate& rate) {
      AssertLockHeld(cs);
      if (rate.GetFeePerK() > rollingMinimumFeeRate) {
          rollingMinimumFeeRate = rate.GetFeePerK();
          blockSinceLastRollingFeeBump = false;
      }
  }
  
  void CTxMemPool::TrimToSize(size_t sizelimit, std::vector<COutPoint>* pvNoSpendsRemaining) {
      LOCK(cs);
  
      unsigned nTxnRemoved = 0;
      CFeeRate maxFeeRateRemoved(0);
      while (!mapTx.empty() && DynamicMemoryUsage() > sizelimit) {
          indexed_transaction_set::index<descendant_score>::type::iterator it = mapTx.get<descendant_score>().begin();
  
          // We set the new mempool min fee to the feerate of the removed set, plus the
          // "minimum reasonable fee rate" (ie some value under which we consider txn
          // to have 0 fee). This way, we don't allow txn to enter mempool with feerate
          // equal to txn which were removed with no block in between.
          CFeeRate removed(it->GetModFeesWithDescendants(), it->GetSizeWithDescendants());
          removed += incrementalRelayFee;
          trackPackageRemoved(removed);
          maxFeeRateRemoved = std::max(maxFeeRateRemoved, removed);
  
          setEntries stage;
          CalculateDescendants(mapTx.project<0>(it), stage);
          nTxnRemoved += stage.size();
  
          std::vector<CTransaction> txn;
          if (pvNoSpendsRemaining) {
              txn.reserve(stage.size());
              for (txiter iter : stage)
                  txn.push_back(iter->GetTx());
          }
          RemoveStaged(stage, false, MemPoolRemovalReason::SIZELIMIT);
          if (pvNoSpendsRemaining) {
              for (const CTransaction& tx : txn) {
                  for (const CTxIn& txin : tx.vin) {
                      if (exists(txin.prevout.hash)) continue;
                      pvNoSpendsRemaining->push_back(txin.prevout);
                  }
              }
          }
      }
  
      if (maxFeeRateRemoved > CFeeRate(0)) {
          LogPrint(BCLog::MEMPOOL, "Removed %u txn, rolling minimum fee bumped to %s\n", nTxnRemoved, maxFeeRateRemoved.ToString());
      }
  }
  
  uint64_t CTxMemPool::CalculateDescendantMaximum(txiter entry) const {
      // find parent with highest descendant count
      std::vector<txiter> candidates;
      setEntries counted;
      candidates.push_back(entry);
      uint64_t maximum = 0;
      while (candidates.size()) {
          txiter candidate = candidates.back();
          candidates.pop_back();
          if (!counted.insert(candidate).second) continue;
          const setEntries& parents = GetMemPoolParents(candidate);
          if (parents.size() == 0) {
              maximum = std::max(maximum, candidate->GetCountWithDescendants());
          } else {
              for (txiter i : parents) {
                  candidates.push_back(i);
              }
          }
      }
      return maximum;
  }
  
  void CTxMemPool::GetTransactionAncestry(const uint256& txid, size_t& ancestors, size_t& descendants) const {
      LOCK(cs);
      auto it = mapTx.find(txid);
      ancestors = descendants = 0;
      if (it != mapTx.end()) {
          ancestors = it->GetCountWithAncestors();
          descendants = CalculateDescendantMaximum(it);
      }
  }
  
  SaltedTxidHasher::SaltedTxidHasher() : k0(GetRand(std::numeric_limits<uint64_t>::max())), k1(GetRand(std::numeric_limits<uint64_t>::max())) {}
  