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// Copyright (c) 2011-2012 The Bitcoin 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)
{
printf("LOCKCONTENTION: %s\n", pszName);
printf("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);
}
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)
{
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)
{
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 */
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