--- /dev/null
+//===-- llvm/Support/ThreadPool.h - A ThreadPool implementation -*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a crude C++11 based thread pool.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_THREAD_POOL_H
+#define LLVM_SUPPORT_THREAD_POOL_H
+
+#include "llvm/Support/thread.h"
+
+#include <condition_variable>
+#include <functional>
+#include <future>
+#include <memory>
+#include <mutex>
+#include <queue>
+#include <utility>
+
+namespace llvm {
+
+/// A ThreadPool for asynchronous parallel execution on a defined number of
+/// threads.
+///
+/// The pool keeps a vector of threads alive, waiting on a condition variable
+/// for some work to become available.
+class ThreadPool {
+public:
+#ifndef _MSC_VER
+ using VoidTy = void;
+#else
+ // MSVC 2013 has a bug and can't use std::packaged_task<void()>;
+ // We force it to use bool(bool) instead.
+ using VoidTy = bool;
+#endif
+ using TaskTy = std::function<VoidTy(VoidTy)>;
+ using PackagedTaskTy = std::packaged_task<VoidTy(VoidTy)>;
+
+ /// Construct a pool with the number of core available on the system (or
+ /// whatever the value returned by std::thread::hardware_concurrency() is).
+ ThreadPool();
+
+ /// Construct a pool of \p ThreadCount threads
+ ThreadPool(unsigned ThreadCount);
+
+ /// Blocking destructor: the pool will wait for all the threads to complete.
+ ~ThreadPool();
+
+ /// Asynchronous submission of a task to the pool. The returned future can be
+ /// used to wait for the task to finish and is *non-blocking* on destruction.
+ template <typename Function, typename... Args>
+ inline std::shared_future<VoidTy> async(Function &&F, Args &&... ArgList) {
+ auto Task =
+ std::bind(std::forward<Function>(F), std::forward<Args...>(ArgList...));
+#ifndef _MSC_VER
+ return asyncImpl(std::move(Task));
+#else
+ return asyncImpl([Task] (VoidTy) -> VoidTy { Task(); return VoidTy(); });
+#endif
+ }
+
+ /// Asynchronous submission of a task to the pool. The returned future can be
+ /// used to wait for the task to finish and is *non-blocking* on destruction.
+ template <typename Function>
+ inline std::shared_future<VoidTy> async(Function &&F) {
+#ifndef _MSC_VER
+ return asyncImpl(std::forward<Function>(F));
+#else
+ return asyncImpl([F] (VoidTy) -> VoidTy { F(); return VoidTy(); });
+#endif
+ }
+
+ /// Blocking wait for all the threads to complete and the queue to be empty.
+ /// It is an error to try to add new tasks while blocking on this call.
+ void wait();
+
+private:
+ /// Asynchronous submission of a task to the pool. The returned future can be
+ /// used to wait for the task to finish and is *non-blocking* on destruction.
+ std::shared_future<VoidTy> asyncImpl(TaskTy F);
+
+ /// Threads in flight
+ std::vector<llvm::thread> Threads;
+
+ /// Tasks waiting for execution in the pool.
+ std::queue<PackagedTaskTy> Tasks;
+
+ /// Locking and signaling for accessing the Tasks queue.
+ std::mutex QueueLock;
+ std::condition_variable QueueCondition;
+
+ /// Locking and signaling for job completion
+ std::mutex CompletionLock;
+ std::condition_variable CompletionCondition;
+
+ /// Keep track of the number of thread actually busy
+ std::atomic<unsigned> ActiveThreads;
+
+#if LLVM_ENABLE_THREADS // avoids warning for unused variable
+ /// Signal for the destruction of the pool, asking thread to exit.
+ bool EnableFlag;
+#endif
+};
+}
+
+#endif // LLVM_SUPPORT_THREAD_POOL_H
#else // !LLVM_ENABLE_THREADS
+#include <utility>
+
namespace llvm {
struct thread {
StringRef.cpp
SystemUtils.cpp
TargetParser.cpp
+ ThreadPool.cpp
Timer.cpp
ToolOutputFile.cpp
Triple.cpp
--- /dev/null
+//==-- llvm/Support/ThreadPool.cpp - A ThreadPool implementation -*- C++ -*-==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a crude C++11 based thread pool.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/ThreadPool.h"
+
+#include "llvm/Config/llvm-config.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+#if LLVM_ENABLE_THREADS
+
+// Default to std::thread::hardware_concurrency
+ThreadPool::ThreadPool() : ThreadPool(std::thread::hardware_concurrency()) {}
+
+ThreadPool::ThreadPool(unsigned ThreadCount)
+ : ActiveThreads(0), EnableFlag(true) {
+ // Create ThreadCount threads that will loop forever, wait on QueueCondition
+ // for tasks to be queued or the Pool to be destroyed.
+ Threads.reserve(ThreadCount);
+ for (unsigned ThreadID = 0; ThreadID < ThreadCount; ++ThreadID) {
+ Threads.emplace_back([&] {
+ while (true) {
+ PackagedTaskTy Task;
+ {
+ std::unique_lock<std::mutex> LockGuard(QueueLock);
+ // Wait for tasks to be pushed in the queue
+ QueueCondition.wait(LockGuard,
+ [&] { return !EnableFlag || !Tasks.empty(); });
+ // Exit condition
+ if (!EnableFlag && Tasks.empty())
+ return;
+ // Yeah, we have a task, grab it and release the lock on the queue
+
+ // We first need to signal that we are active before popping the queue
+ // in order for wait() to properly detect that even if the queue is
+ // empty, there is still a task in flight.
+ {
+ ++ActiveThreads;
+ std::unique_lock<std::mutex> LockGuard(CompletionLock);
+ }
+ Task = std::move(Tasks.front());
+ Tasks.pop();
+ }
+ // Run the task we just grabbed
+#ifndef _MSC_VER
+ Task();
+#else
+ Task(/* unused */ false);
+#endif
+
+ {
+ // Adjust `ActiveThreads`, in case someone waits on ThreadPool::wait()
+ std::unique_lock<std::mutex> LockGuard(CompletionLock);
+ --ActiveThreads;
+ }
+
+ // Notify task completion, in case someone waits on ThreadPool::wait()
+ CompletionCondition.notify_all();
+ }
+ });
+ }
+}
+
+void ThreadPool::wait() {
+ // Wait for all threads to complete and the queue to be empty
+ std::unique_lock<std::mutex> LockGuard(CompletionLock);
+ CompletionCondition.wait(LockGuard,
+ [&] { return Tasks.empty() && !ActiveThreads; });
+}
+
+std::shared_future<ThreadPool::VoidTy> ThreadPool::asyncImpl(TaskTy Task) {
+ /// Wrap the Task in a packaged_task to return a future object.
+ PackagedTaskTy PackagedTask(std::move(Task));
+ auto Future = PackagedTask.get_future();
+ {
+ // Lock the queue and push the new task
+ std::unique_lock<std::mutex> LockGuard(QueueLock);
+
+ // Don't allow enqueueing after disabling the pool
+ assert(EnableFlag && "Queuing a thread during ThreadPool destruction");
+
+ Tasks.push(std::move(PackagedTask));
+ }
+ QueueCondition.notify_one();
+ return Future.share();
+}
+
+// The destructor joins all threads, waiting for completion.
+ThreadPool::~ThreadPool() {
+ {
+ std::unique_lock<std::mutex> LockGuard(QueueLock);
+ EnableFlag = false;
+ }
+ QueueCondition.notify_all();
+ for (auto &Worker : Threads)
+ Worker.join();
+}
+
+#else // LLVM_ENABLE_THREADS Disabled
+
+ThreadPool::ThreadPool() : ThreadPool(0) {}
+
+// No threads are launched, issue a warning if ThreadCount is not 0
+ThreadPool::ThreadPool(unsigned ThreadCount)
+ : ActiveThreads(0) {
+ if (ThreadCount) {
+ errs() << "Warning: request a ThreadPool with " << ThreadCount
+ << " threads, but LLVM_ENABLE_THREADS has been turned off\n";
+ }
+}
+
+void ThreadPool::wait() {
+ // Sequential implementation running the tasks
+ while (!Tasks.empty()) {
+ auto Task = std::move(Tasks.front());
+ Tasks.pop();
+ Task();
+ }
+}
+
+std::shared_future<ThreadPool::VoidTy> ThreadPool::asyncImpl(TaskTy Task) {
+ // Get a Future with launch::deferred execution using std::async
+ auto Future = std::async(std::launch::deferred, std::move(Task)).share();
+ // Wrap the future so that both ThreadPool::wait() can operate and the
+ // returned future can be sync'ed on.
+ PackagedTaskTy PackagedTask([Future]() { Future.get(); });
+ Tasks.push(std::move(PackagedTask));
+ return Future;
+}
+
+ThreadPool::~ThreadPool() {
+ wait();
+}
+
+#endif
SwapByteOrderTest.cpp
TargetRegistry.cpp
ThreadLocalTest.cpp
+ ThreadPool.cpp
TimeValueTest.cpp
TrailingObjectsTest.cpp
UnicodeTest.cpp
--- /dev/null
+//========- unittests/Support/ThreadPools.cpp - ThreadPools.h tests --========//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/ThreadPool.h"
+
+#include "llvm/ADT/STLExtras.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace std::chrono;
+
+/// Try best to make this thread not progress faster than the main thread
+static void yield() {
+#ifdef LLVM_ENABLE_THREADS
+ std::this_thread::yield();
+#endif
+ std::this_thread::sleep_for(milliseconds(200));
+#ifdef LLVM_ENABLE_THREADS
+ std::this_thread::yield();
+#endif
+}
+
+TEST(ThreadPoolTest, AsyncBarrier) {
+ // test that async & barrier work together properly.
+
+ std::atomic_int checked_in{0};
+
+ ThreadPool Pool;
+ for (size_t i = 0; i < 5; ++i) {
+ Pool.async([&checked_in, i] {
+ yield();
+ ++checked_in;
+ });
+ }
+ ASSERT_EQ(0, checked_in);
+ Pool.wait();
+ ASSERT_EQ(5, checked_in);
+}
+
+TEST(ThreadPoolTest, Async) {
+ ThreadPool Pool;
+ std::atomic_int i{0};
+ // sleep here just to ensure that the not-equal is correct.
+ Pool.async([&i] {
+ yield();
+ ++i;
+ });
+ Pool.async([&i] { ++i; });
+ ASSERT_NE(2, i.load());
+ Pool.wait();
+ ASSERT_EQ(2, i.load());
+}
+
+TEST(ThreadPoolTest, GetFuture) {
+ ThreadPool Pool;
+ std::atomic_int i{0};
+ // sleep here just to ensure that the not-equal is correct.
+ Pool.async([&i] {
+ yield();
+ ++i;
+ });
+ // Force the future using get()
+ Pool.async([&i] { ++i; }).get();
+ ASSERT_NE(2, i.load());
+ Pool.wait();
+ ASSERT_EQ(2, i.load());
+}
+
+TEST(ThreadPoolTest, PoolDestruction) {
+ // Test that we are waiting on destruction
+ std::atomic_int checked_in{0};
+
+ {
+ ThreadPool Pool;
+ for (size_t i = 0; i < 5; ++i) {
+ Pool.async([&checked_in, i] {
+ yield();
+ ++checked_in;
+ });
+ }
+ ASSERT_EQ(0, checked_in);
+ }
+ ASSERT_EQ(5, checked_in);
+}
projects / oota-llvm.git / commitdiff