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-rw-r--r--src/sync.cpp119
1 files changed, 119 insertions, 0 deletions
diff --git a/src/sync.cpp b/src/sync.cpp
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index 0000000000..fd9bcb62bc
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+++ b/src/sync.cpp
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+// Copyright (c) 2011-2012 The Bitcoin developers
+// Distributed under the MIT/X11 software license, see the accompanying
+// file license.txt or http://www.opensource.org/licenses/mit-license.php.
+
+#include "sync.h"
+
+
+
+#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 trys 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);
+ }
+
+private:
+ std::string mutexName;
+ std::string sourceFile;
+ int sourceLine;
+};
+
+typedef std::vector< std::pair<void*, CLockLocation> > LockStack;
+
+static boost::interprocess::interprocess_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)
+{
+ printf("POTENTIAL DEADLOCK DETECTED\n");
+ printf("Previous lock order was:\n");
+ BOOST_FOREACH(const PAIRTYPE(void*, CLockLocation)& i, s2)
+ {
+ if (i.first == mismatch.first) printf(" (1)");
+ if (i.first == mismatch.second) printf(" (2)");
+ printf(" %s\n", i.second.ToString().c_str());
+ }
+ printf("Current lock order is:\n");
+ BOOST_FOREACH(const PAIRTYPE(void*, CLockLocation)& i, s1)
+ {
+ if (i.first == mismatch.first) printf(" (1)");
+ if (i.first == mismatch.second) printf(" (2)");
+ printf(" %s\n", i.second.ToString().c_str());
+ }
+}
+
+static void push_lock(void* c, const CLockLocation& locklocation, bool fTry)
+{
+ bool fOrderOK = true;
+ if (lockstack.get() == NULL)
+ lockstack.reset(new LockStack);
+
+ if (fDebug) printf("Locking: %s\n", locklocation.ToString().c_str());
+ 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;
+ printf("Unlocked: %s\n", locklocation.ToString().c_str());
+ }
+ 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();
+}
+
+#endif /* DEBUG_LOCKORDER */