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// Copyright Epic Games, Inc. All Rights Reserved.
#include <zenutil/parallelwork.h>
#include <zencore/callstack.h>
#include <zencore/except.h>
#include <zencore/fmtutils.h>
#include <zencore/logging.h>
#include <typeinfo>
#if ZEN_WITH_TESTS
# include <zencore/testing.h>
#endif // ZEN_WITH_TESTS
namespace zen {
ParallelWork::ParallelWork(std::atomic<bool>& AbortFlag, std::atomic<bool>& PauseFlag)
: m_AbortFlag(AbortFlag)
, m_PauseFlag(PauseFlag)
, m_PendingWork(1)
{
}
ParallelWork::~ParallelWork()
{
try
{
if (!m_DispatchComplete)
{
ZEN_ASSERT(m_PendingWork.Remaining() > 0);
ZEN_WARN(
"ParallelWork disposed without explicit wait for completion, likely caused by an exception, waiting for dispatched threads "
"to complete");
m_PendingWork.CountDown();
m_DispatchComplete = true;
}
const bool WaitSucceeded = m_PendingWork.Wait();
const ptrdiff_t RemainingWork = m_PendingWork.Remaining();
if (!WaitSucceeded)
{
ZEN_ERROR("ParallelWork::~ParallelWork(): waiting for latch failed, pending work count at {}", RemainingWork);
}
if (RemainingWork != 0)
{
void* Frames[8];
uint32_t FrameCount = GetCallstack(2, 8, Frames);
CallstackFrames* Callstack = CreateCallstack(FrameCount, Frames);
auto _ = MakeGuard([Callstack]() { FreeCallstack(Callstack); });
ZEN_WARN("ParallelWork::~ParallelWork(): waited for outstanding work but pending work count is {} instead of 0", RemainingWork);
uint32_t WaitedMs = 0;
while (m_PendingWork.Remaining() > 0 && WaitedMs < 2000)
{
Sleep(50);
WaitedMs += 50;
}
ptrdiff_t RemainingWorkAfterSafetyWait = m_PendingWork.Remaining();
if (RemainingWorkAfterSafetyWait != 0)
{
ZEN_ERROR("ParallelWork::~ParallelWork(): safety wait for {} tasks failed, pending work count at {} after {}\n{}",
RemainingWork,
RemainingWorkAfterSafetyWait,
NiceLatencyNs(WaitedMs * 1000000u),
CallstackToString(Callstack, " "))
}
else
{
ZEN_ERROR("ParallelWork::~ParallelWork(): safety wait for {} tasks completed after {}\n{}",
RemainingWork,
NiceLatencyNs(WaitedMs * 1000000u),
CallstackToString(Callstack, " "));
}
}
}
catch (const std::exception& Ex)
{
ZEN_ERROR("Exception in ParallelWork::~ParallelWork(): {}", Ex.what());
}
}
ParallelWork::ExceptionCallback
ParallelWork::DefaultErrorFunction()
{
return [&](std::exception_ptr Ex, std::atomic<bool>& AbortFlag) {
m_ErrorLock.WithExclusiveLock([&]() { m_Errors.push_back(Ex); });
AbortFlag = true;
};
}
void
ParallelWork::Wait(int32_t UpdateIntervalMS, UpdateCallback&& UpdateCallback)
{
ZEN_ASSERT(!m_DispatchComplete);
ZEN_ASSERT(m_PendingWork.Remaining() > 0);
m_PendingWork.CountDown();
m_DispatchComplete = true;
while (!m_PendingWork.Wait(UpdateIntervalMS))
{
UpdateCallback(m_AbortFlag.load(), m_PauseFlag.load(), m_PendingWork.Remaining());
}
RethrowErrors();
}
void
ParallelWork::Wait()
{
ZEN_ASSERT(!m_DispatchComplete);
ZEN_ASSERT(m_PendingWork.Remaining() > 0);
m_PendingWork.CountDown();
m_DispatchComplete = true;
const bool WaitSucceeded = m_PendingWork.Wait();
const ptrdiff_t RemainingWork = m_PendingWork.Remaining();
if (!WaitSucceeded)
{
ZEN_ERROR("ParallelWork::Wait(): waiting for latch failed, pending work count at {}", RemainingWork);
}
else if (RemainingWork != 0)
{
ZEN_ERROR("ParallelWork::Wait(): pending work count at {} after successful wait for latch", RemainingWork);
}
RethrowErrors();
}
void
ParallelWork::RethrowErrors()
{
if (!m_Errors.empty())
{
if (m_Errors.size() > 1)
{
ZEN_INFO("Multiple exceptions thrown during ParallelWork execution, dropping the following exceptions:");
auto It = m_Errors.begin() + 1;
while (It != m_Errors.end())
{
try
{
std::rethrow_exception(*It);
}
catch (const std::exception& Ex)
{
ZEN_INFO(" {}", Ex.what());
}
It++;
}
}
std::exception_ptr Ex = m_Errors.front();
m_Errors.clear();
std::rethrow_exception(Ex);
}
}
#if ZEN_WITH_TESTS
TEST_CASE("parallellwork.nowork")
{
std::atomic<bool> AbortFlag;
std::atomic<bool> PauseFlag;
ParallelWork Work(AbortFlag, PauseFlag);
Work.Wait();
}
TEST_CASE("parallellwork.basic")
{
WorkerThreadPool WorkerPool(2);
std::atomic<bool> AbortFlag;
std::atomic<bool> PauseFlag;
ParallelWork Work(AbortFlag, PauseFlag);
for (uint32_t I = 0; I < 5; I++)
{
Work.ScheduleWork(WorkerPool, [](std::atomic<bool>& AbortFlag) { CHECK(!AbortFlag); });
}
Work.Wait();
}
TEST_CASE("parallellwork.throws_in_work")
{
WorkerThreadPool WorkerPool(2);
std::atomic<bool> AbortFlag;
std::atomic<bool> PauseFlag;
ParallelWork Work(AbortFlag, PauseFlag);
for (uint32_t I = 0; I < 10; I++)
{
Work.ScheduleWork(WorkerPool, [I](std::atomic<bool>& AbortFlag) {
ZEN_UNUSED(AbortFlag);
if (I > 3)
{
throw std::runtime_error("We throw in async thread");
}
else
{
Sleep(10);
}
});
}
CHECK_THROWS_WITH(Work.Wait(), "We throw in async thread");
}
TEST_CASE("parallellwork.throws_in_dispatch")
{
WorkerThreadPool WorkerPool(2);
std::atomic<uint32_t> ExecutedCount;
try
{
std::atomic<bool> AbortFlag;
std::atomic<bool> PauseFlag;
ParallelWork Work(AbortFlag, PauseFlag);
for (uint32_t I = 0; I < 5; I++)
{
Work.ScheduleWork(WorkerPool, [I, &ExecutedCount](std::atomic<bool>& AbortFlag) {
if (AbortFlag.load())
{
return;
}
ExecutedCount++;
});
if (I == 3)
{
throw std::runtime_error("We throw in dispatcher thread");
}
}
CHECK(false);
}
catch (const std::runtime_error& Ex)
{
CHECK_EQ("We throw in dispatcher thread", std::string(Ex.what()));
CHECK_LE(ExecutedCount.load(), 4);
}
}
void
parallellwork_forcelink()
{
}
#endif // ZEN_WITH_TESTS
} // namespace zen
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