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// Copyright Epic Games, Inc. All Rights Reserved.
#include <zencore/workthreadpool.h>
#include <zencore/blockingqueue.h>
#include <zencore/logging.h>
#include <zencore/string.h>
#include <zencore/testing.h>
#include <zencore/thread.h>
#include <zencore/trace.h>
#include <thread>
#include <vector>
#define ZEN_USE_WINDOWS_THREADPOOL 1
#if ZEN_PLATFORM_WINDOWS && ZEN_USE_WINDOWS_THREADPOOL
# include <zencore/windows.h>
#endif
namespace zen {
namespace detail {
struct LambdaWork : IWork
{
LambdaWork(auto Work) : WorkFunction(Work) {}
virtual void Execute() override { WorkFunction(); }
std::function<void()> WorkFunction;
};
} // namespace detail
//////////////////////////////////////////////////////////////////////////
#if ZEN_USE_WINDOWS_THREADPOOL && ZEN_PLATFORM_WINDOWS
namespace {
thread_local bool t_IsThreadNamed{false};
}
struct WorkerThreadPool::Impl
{
PTP_POOL m_ThreadPool = nullptr;
PTP_CLEANUP_GROUP m_CleanupGroup = nullptr;
TP_CALLBACK_ENVIRON m_CallbackEnvironment;
PTP_WORK m_Work = nullptr;
std::string m_WorkerThreadBaseName;
std::atomic<int> m_WorkerThreadCounter{0};
RwLock m_QueueLock;
std::deque<Ref<IWork>> m_WorkQueue;
Impl(int InThreadCount, std::string_view WorkerThreadBaseName) : m_WorkerThreadBaseName(WorkerThreadBaseName)
{
// Thread pool setup
m_ThreadPool = CreateThreadpool(NULL);
SetThreadpoolThreadMinimum(m_ThreadPool, InThreadCount);
SetThreadpoolThreadMaximum(m_ThreadPool, InThreadCount * 2);
InitializeThreadpoolEnvironment(&m_CallbackEnvironment);
m_CleanupGroup = CreateThreadpoolCleanupGroup();
SetThreadpoolCallbackPool(&m_CallbackEnvironment, m_ThreadPool);
SetThreadpoolCallbackCleanupGroup(&m_CallbackEnvironment, m_CleanupGroup, NULL);
m_Work = CreateThreadpoolWork(&WorkCallback, this, &m_CallbackEnvironment);
}
~Impl()
{
WaitForThreadpoolWorkCallbacks(m_Work, /* CancelPendingCallbacks */ TRUE);
CloseThreadpoolWork(m_Work);
}
void ScheduleWork(Ref<IWork> Work)
{
m_QueueLock.WithExclusiveLock([&] { m_WorkQueue.push_back(std::move(Work)); });
SubmitThreadpoolWork(m_Work);
}
[[nodiscard]] size_t PendingWorkItemCount() const { return 0; }
static VOID CALLBACK WorkCallback(_Inout_ PTP_CALLBACK_INSTANCE Instance, _Inout_opt_ PVOID Context, _Inout_ PTP_WORK Work)
{
ZEN_UNUSED(Instance, Work);
Impl* ThisPtr = reinterpret_cast<Impl*>(Context);
ThisPtr->DoWork();
}
void DoWork()
{
if (!t_IsThreadNamed)
{
t_IsThreadNamed = true;
const int ThreadIndex = ++m_WorkerThreadCounter;
zen::ExtendableStringBuilder<128> ThreadName;
ThreadName << m_WorkerThreadBaseName << "_" << ThreadIndex;
SetCurrentThreadName(ThreadName);
}
Ref<IWork> WorkFromQueue;
{
RwLock::ExclusiveLockScope _{m_QueueLock};
WorkFromQueue = std::move(m_WorkQueue.front());
m_WorkQueue.pop_front();
}
WorkFromQueue->Execute();
}
};
#else
struct WorkerThreadPool::ThreadStartInfo
{
int ThreadNumber;
zen::Latch* Latch;
};
struct WorkerThreadPool::Impl
{
void WorkerThreadFunction(ThreadStartInfo Info);
std::string m_WorkerThreadBaseName;
std::vector<std::thread> m_WorkerThreads;
BlockingQueue<Ref<IWork>> m_WorkQueue;
Impl(int InThreadCount, std::string_view WorkerThreadBaseName) : m_WorkerThreadBaseName(WorkerThreadBaseName)
{
trace::ThreadGroupBegin(m_WorkerThreadBaseName.c_str());
zen::Latch WorkerLatch{InThreadCount};
for (int i = 0; i < InThreadCount; ++i)
{
m_WorkerThreads.emplace_back(&Impl::WorkerThreadFunction, this, ThreadStartInfo{i + 1, &WorkerLatch});
}
WorkerLatch.Wait();
trace::ThreadGroupEnd();
}
~Impl()
{
m_WorkQueue.CompleteAdding();
for (std::thread& Thread : m_WorkerThreads)
{
Thread.join();
}
m_WorkerThreads.clear();
}
void ScheduleWork(Ref<IWork> Work) { m_WorkQueue.Enqueue(std::move(Work)); }
[[nodiscard]] size_t PendingWorkItemCount() const { return m_WorkQueue.Size(); }
};
void
WorkerThreadPool::Impl::WorkerThreadFunction(ThreadStartInfo Info)
{
SetCurrentThreadName(fmt::format("{}_{}", m_WorkerThreadBaseName, Info.ThreadNumber));
Info.Latch->CountDown();
do
{
Ref<IWork> Work;
if (m_WorkQueue.WaitAndDequeue(Work))
{
try
{
Work->Execute();
}
catch (std::exception& e)
{
Work->m_Exception = std::current_exception();
ZEN_WARN("Caught exception in worker thread: {}", e.what());
}
}
else
{
return;
}
} while (true);
}
#endif
//////////////////////////////////////////////////////////////////////////
WorkerThreadPool::WorkerThreadPool(int InThreadCount) : WorkerThreadPool(InThreadCount, "workerthread")
{
}
WorkerThreadPool::WorkerThreadPool(int InThreadCount, std::string_view WorkerThreadBaseName)
{
m_Impl = std::make_unique<Impl>(InThreadCount, WorkerThreadBaseName);
}
WorkerThreadPool::~WorkerThreadPool()
{
m_Impl.reset();
}
void
WorkerThreadPool::ScheduleWork(Ref<IWork> Work)
{
m_Impl->ScheduleWork(std::move(Work));
}
void
WorkerThreadPool::ScheduleWork(std::function<void()>&& Work)
{
ScheduleWork(Ref<IWork>(new detail::LambdaWork(Work)));
}
[[nodiscard]] size_t
WorkerThreadPool::PendingWorkItemCount() const
{
return m_Impl->PendingWorkItemCount();
}
//////////////////////////////////////////////////////////////////////////
#if ZEN_WITH_TESTS
void
workthreadpool_forcelink()
{
}
using namespace std::literals;
TEST_CASE("threadpool.basic")
{
WorkerThreadPool Threadpool{1};
auto Future42 = Threadpool.EnqueueTask(std::packaged_task<int()>{[] { return 42; }});
auto Future99 = Threadpool.EnqueueTask(std::packaged_task<int()>{[] { return 99; }});
auto FutureThrow = Threadpool.EnqueueTask(std::packaged_task<void()>{[] { throw std::runtime_error("meep!"); }});
CHECK_EQ(Future42.get(), 42);
CHECK_EQ(Future99.get(), 99);
CHECK_THROWS(FutureThrow.get());
}
#endif
} // namespace zen
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