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cuberite-2a/src/DeadlockDetect.cpp

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// DeadlockDetect.cpp
// Declares the cDeadlockDetect class that tries to detect deadlocks and aborts the server when it detects one
#include "Globals.h"
#include "DeadlockDetect.h"
#include "Root.h"
#include "World.h"
#include <cstdlib>
/** Number of milliseconds per cycle */
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const int CYCLE_MILLISECONDS = 100;
cDeadlockDetect::cDeadlockDetect(void) :
Super("Deadlock Detector"),
m_IntervalSec(1000)
{
}
cDeadlockDetect::~cDeadlockDetect()
{
// Check that all tracked CSs have been removed, report any remaining:
cCSLock lock(m_CS);
if (!m_TrackedCriticalSections.empty())
{
LOGWARNING("DeadlockDetect: Some CS objects (%u) haven't been removed from tracking", static_cast<unsigned>(m_TrackedCriticalSections.size()));
for (const auto & tcs: m_TrackedCriticalSections)
{
LOGWARNING(" CS %p / %s",
static_cast<void *>(tcs.first),
tcs.second.c_str()
);
}
}
}
void cDeadlockDetect::Start(int a_IntervalSec)
{
m_IntervalSec = a_IntervalSec;
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// Read the initial world data:
cRoot::Get()->ForEachWorld([=](cWorld & a_World)
{
SetWorldAge(a_World.GetName(), a_World.GetWorldAge());
return false;
});
Super::Start();
}
void cDeadlockDetect::TrackCriticalSection(cCriticalSection & a_CS, const AString & a_Name)
{
cCSLock lock(m_CS);
m_TrackedCriticalSections.emplace_back(&a_CS, a_Name);
}
void cDeadlockDetect::UntrackCriticalSection(cCriticalSection & a_CS)
{
cCSLock lock(m_CS);
for (auto itr = m_TrackedCriticalSections.begin(), end = m_TrackedCriticalSections.end(); itr != end; ++itr)
{
if (itr->first == &a_CS)
{
m_TrackedCriticalSections.erase(itr);
return;
}
}
}
void cDeadlockDetect::Execute(void)
{
// Loop until the signal to terminate:
while (!m_ShouldTerminate)
{
// Check the world ages:
cRoot::Get()->ForEachWorld([=](cWorld & a_World)
{
CheckWorldAge(a_World.GetName(), a_World.GetWorldAge());
return false;
});
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std::this_thread::sleep_for(std::chrono::milliseconds(CYCLE_MILLISECONDS));
} // while (should run)
}
void cDeadlockDetect::SetWorldAge(const AString & a_WorldName, const cTickTimeLong a_Age)
{
m_WorldAges[a_WorldName].m_Age = a_Age;
m_WorldAges[a_WorldName].m_NumCyclesSame = 0;
}
void cDeadlockDetect::CheckWorldAge(const AString & a_WorldName, const cTickTimeLong a_Age)
{
WorldAges::iterator itr = m_WorldAges.find(a_WorldName);
if (itr == m_WorldAges.end())
{
SetWorldAge(a_WorldName, a_Age);
return;
}
cDeadlockDetect::sWorldAge & WorldAge = itr->second;
if (WorldAge.m_Age == a_Age)
{
WorldAge.m_NumCyclesSame += 1;
if (WorldAge.m_NumCyclesSame > (m_IntervalSec * 1000) / CYCLE_MILLISECONDS)
{
DeadlockDetected(a_WorldName, a_Age);
}
}
else
{
WorldAge.m_Age = a_Age;
WorldAge.m_NumCyclesSame = 0;
}
}
void cDeadlockDetect::DeadlockDetected(const AString & a_WorldName, const cTickTimeLong a_WorldAge)
{
LOGERROR("Deadlock detected: world %s has been stuck at age %lld. Aborting the server.",
a_WorldName.c_str(), static_cast<long long>(a_WorldAge.count())
);
ListTrackedCSs();
ASSERT(!"Deadlock detected");
std::abort();
}
void cDeadlockDetect::ListTrackedCSs(void)
{
cCSLock lock(m_CS);
for (const auto & cs: m_TrackedCriticalSections)
{
LOG("CS at %p, %s: RecursionCount = %d, ThreadIDHash = %04llx",
static_cast<void *>(cs.first), cs.second.c_str(),
cs.first->m_RecursionCount, static_cast<UInt64>(std::hash<std::thread::id>()(cs.first->m_OwningThreadID))
);
}
}