text: // Copyright (c) 2011-2012 The EvolveChain developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  #include "sync.h"
  
  #include "util.h"
  
  #include <boost/foreach.hpp>
  
  #ifdef DEBUG_LOCKCONTENTION
  void PrintLockContention(const char* pszName, const char* pszFile, int nLine)
  {
      LogPrintf("LOCKCONTENTION: %s\n", pszName);
      LogPrintf("Locker: %s:%d\n", pszFile, nLine);
  }
  #endif /* DEBUG_LOCKCONTENTION */
  
  #ifdef DEBUG_LOCKORDER
  //
  // Early deadlock detection.
  // Problem being solved:
  //    Thread 1 locks  A, then B, then C
  //    Thread 2 locks  D, then C, then A
  //     --> may result in deadlock between the two threads, depending on when they run.
  // Solution implemented here:
  // Keep track of pairs of locks: (A before B), (A before C), etc.
  // Complain if any thread tries to lock in a different order.
  //
  
  struct CLockLocation
  {
      CLockLocation(const char* pszName, const char* pszFile, int nLine)
      {
          mutexName = pszName;
          sourceFile = pszFile;
          sourceLine = nLine;
      }
  
      std::string ToString() const
      {
          return mutexName+"  "+sourceFile+":"+itostr(sourceLine);
      }
  
      std::string MutexName() const { return mutexName; }
  
  private:
      std::string mutexName;
      std::string sourceFile;
      int sourceLine;
  };
  
  typedef std::vector< std::pair<void*, CLockLocation> > LockStack;
  
  static boost::mutex dd_mutex;
  static std::map<std::pair<void*, void*>, LockStack> lockorders;
  static boost::thread_specific_ptr<LockStack> lockstack;
  
  
  static void potential_deadlock_detected(const std::pair<void*, void*>& mismatch, const LockStack& s1, const LockStack& s2)
  {
      LogPrintf("POTENTIAL DEADLOCK DETECTED\n");
      LogPrintf("Previous lock order was:\n");
      BOOST_FOREACH(const PAIRTYPE(void*, CLockLocation)& i, s2)
      {
          if (i.first == mismatch.first) LogPrintf(" (1)");
          if (i.first == mismatch.second) LogPrintf(" (2)");
          LogPrintf(" %s\n", i.second.ToString());
      }
      LogPrintf("Current lock order is:\n");
      BOOST_FOREACH(const PAIRTYPE(void*, CLockLocation)& i, s1)
      {
          if (i.first == mismatch.first) LogPrintf(" (1)");
          if (i.first == mismatch.second) LogPrintf(" (2)");
          LogPrintf(" %s\n", i.second.ToString());
      }
  }
  
  static void push_lock(void* c, const CLockLocation& locklocation, bool fTry)
  {
      if (lockstack.get() == NULL)
          lockstack.reset(new LockStack);
  
      LogPrint("lock", "Locking: %s\n", locklocation.ToString());
      dd_mutex.lock();
  
      (*lockstack).push_back(std::make_pair(c, locklocation));
  
      if (!fTry) {
          BOOST_FOREACH(const PAIRTYPE(void*, CLockLocation)& i, (*lockstack)) {
              if (i.first == c) break;
  
              std::pair<void*, void*> p1 = std::make_pair(i.first, c);
              if (lockorders.count(p1))
                  continue;
              lockorders[p1] = (*lockstack);
  
              std::pair<void*, void*> p2 = std::make_pair(c, i.first);
              if (lockorders.count(p2))
              {
                  potential_deadlock_detected(p1, lockorders[p2], lockorders[p1]);
                  break;
              }
          }
      }
      dd_mutex.unlock();
  }
  
  static void pop_lock()
  {
      if (fDebug)
      {
          const CLockLocation& locklocation = (*lockstack).rbegin()->second;
          LogPrint("lock", "Unlocked: %s\n", locklocation.ToString());
      }
      dd_mutex.lock();
      (*lockstack).pop_back();
      dd_mutex.unlock();
  }
  
  void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry)
  {
      push_lock(cs, CLockLocation(pszName, pszFile, nLine), fTry);
  }
  
  void LeaveCritical()
  {
      pop_lock();
  }
  
  std::string LocksHeld()
  {
      std::string result;
      BOOST_FOREACH(const PAIRTYPE(void*, CLockLocation)&i, *lockstack)
          result += i.second.ToString() + std::string("\n");
      return result;
  }
  
  void AssertLockHeldInternal(const char *pszName, const char* pszFile, int nLine, void *cs)
  {
      BOOST_FOREACH(const PAIRTYPE(void*, CLockLocation)&i, *lockstack)
          if (i.first == cs) return;
      fprintf(stderr, "Assertion failed: lock %s not held in %s:%i; locks held:\n%s",
              pszName, pszFile, nLine, LocksHeld().c_str());
      abort();
  }
  
  #endif /* DEBUG_LOCKORDER */
  