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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
#include "common.h"
#include "eventpipebuffermanager.h"
#include "eventpipeeventinstance.h"
#include "sampleprofiler.h"
#include "hosting.h"
#include "threadsuspend.h"
#ifdef FEATURE_PERFTRACING
Volatile<BOOL> SampleProfiler::s_profilingEnabled = false;
Thread* SampleProfiler::s_pSamplingThread = NULL;
const WCHAR* SampleProfiler::s_providerName = W("Microsoft-DotNETCore-SampleProfiler");
EventPipeProvider* SampleProfiler::s_pEventPipeProvider = NULL;
EventPipeEvent* SampleProfiler::s_pThreadTimeEvent = NULL;
BYTE* SampleProfiler::s_pPayloadExternal = NULL;
BYTE* SampleProfiler::s_pPayloadManaged = NULL;
CLREventStatic SampleProfiler::s_threadShutdownEvent;
long SampleProfiler::s_samplingRateInNs = 1000000; // 1ms
void SampleProfiler::Enable()
{
CONTRACTL
{
THROWS;
GC_TRIGGERS;
MODE_ANY;
PRECONDITION(s_pSamplingThread == NULL);
// Synchronization of multiple callers occurs in EventPipe::Enable.
PRECONDITION(EventPipe::GetLock()->OwnedByCurrentThread());
}
CONTRACTL_END;
if(s_pEventPipeProvider == NULL)
{
s_pEventPipeProvider = EventPipe::CreateProvider(SL(s_providerName));
s_pThreadTimeEvent = s_pEventPipeProvider->AddEvent(
0, /* eventID */
0, /* keywords */
0, /* eventVersion */
EventPipeEventLevel::Informational,
false /* NeedStack */);
}
if(s_pPayloadExternal == NULL)
{
s_pPayloadExternal = new BYTE[sizeof(unsigned int)];
*((unsigned int *)s_pPayloadExternal) = static_cast<unsigned int>(SampleProfilerSampleType::External);
s_pPayloadManaged = new BYTE[sizeof(unsigned int)];
*((unsigned int *)s_pPayloadManaged) = static_cast<unsigned int>(SampleProfilerSampleType::Managed);
}
s_profilingEnabled = true;
s_pSamplingThread = SetupUnstartedThread();
if(s_pSamplingThread->CreateNewThread(0, ThreadProc, NULL))
{
// Start the sampling thread.
s_pSamplingThread->SetBackground(TRUE);
s_pSamplingThread->StartThread();
}
else
{
_ASSERT(!"Unable to create sample profiler thread.");
}
}
void SampleProfiler::Disable()
{
CONTRACTL
{
THROWS;
GC_TRIGGERS;
MODE_ANY;
// Synchronization of multiple callers occurs in EventPipe::Disable.
PRECONDITION(EventPipe::GetLock()->OwnedByCurrentThread());
}
CONTRACTL_END;
// Bail early if profiling is not enabled.
if(!s_profilingEnabled)
{
return;
}
// Reset the event before shutdown.
s_threadShutdownEvent.Reset();
// The sampling thread will watch this value and exit
// when profiling is disabled.
s_profilingEnabled = false;
// Wait for the sampling thread to clean itself up.
s_threadShutdownEvent.Wait(0, FALSE /* bAlertable */);
}
void SampleProfiler::SetSamplingRate(long nanoseconds)
{
LIMITED_METHOD_CONTRACT;
s_samplingRateInNs = nanoseconds;
}
DWORD WINAPI SampleProfiler::ThreadProc(void *args)
{
CONTRACTL
{
NOTHROW;
GC_TRIGGERS;
MODE_PREEMPTIVE;
PRECONDITION(s_pSamplingThread != NULL);
}
CONTRACTL_END;
// Complete thread initialization and start the profiling loop.
if(s_pSamplingThread->HasStarted())
{
// Switch to pre-emptive mode so that this thread doesn't starve the GC.
GCX_PREEMP();
while(s_profilingEnabled)
{
// Check to see if we can suspend managed execution.
if(ThreadSuspend::SysIsSuspendInProgress() || (ThreadSuspend::GetSuspensionThread() != 0))
{
// Skip the current sample.
PAL_nanosleep(s_samplingRateInNs);
continue;
}
// Actually suspend managed execution.
ThreadSuspend::SuspendEE(ThreadSuspend::SUSPEND_REASON::SUSPEND_OTHER);
// Walk all managed threads and capture stacks.
WalkManagedThreads();
// Resume managed execution.
ThreadSuspend::RestartEE(FALSE /* bFinishedGC */, TRUE /* SuspendSucceeded */);
// Wait until it's time to sample again.
PAL_nanosleep(s_samplingRateInNs);
}
}
// Destroy the sampling thread when it is done running.
DestroyThread(s_pSamplingThread);
s_pSamplingThread = NULL;
// Signal Disable() that the thread has been destroyed.
s_threadShutdownEvent.Set();
return S_OK;
}
// The thread store lock must already be held by the thread before this function
// is called. ThreadSuspend::SuspendEE acquires the thread store lock.
void SampleProfiler::WalkManagedThreads()
{
CONTRACTL
{
NOTHROW;
GC_TRIGGERS;
MODE_PREEMPTIVE;
}
CONTRACTL_END;
Thread *pTargetThread = NULL;
// Iterate over all managed threads.
// Assumes that the ThreadStoreLock is held because we've suspended all threads.
while ((pTargetThread = ThreadStore::GetThreadList(pTargetThread)) != NULL)
{
StackContents stackContents;
// Walk the stack and write it out as an event.
if(EventPipe::WalkManagedStackForThread(pTargetThread, stackContents) && !stackContents.IsEmpty())
{
// Set the payload. If the GC mode on suspension > 0, then the thread was in cooperative mode.
// Even though there are some cases where this is not managed code, we assume it is managed code here.
// If the GC mode on suspension == 0 then the thread was in preemptive mode, which we qualify as external here.
BYTE *pPayload = s_pPayloadExternal;
if(pTargetThread->GetGCModeOnSuspension())
{
pPayload = s_pPayloadManaged;
}
// Write the sample.
EventPipe::WriteSampleProfileEvent(s_pSamplingThread, s_pThreadTimeEvent, pTargetThread, stackContents, pPayload, c_payloadSize);
}
// Reset the GC mode.
pTargetThread->ClearGCModeOnSuspension();
}
}
#endif // FEATURE_PERFTRACING
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