127 lines
2.3 KiB
C++
127 lines
2.3 KiB
C++
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include "WorkerThread.h"
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#include "FaissAssert.h"
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#include <exception>
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namespace faiss {
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namespace {
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// Captures any exceptions thrown by the lambda and returns them via the promise
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void runCallback(std::function<void()>& fn,
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std::promise<bool>& promise) {
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try {
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fn();
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promise.set_value(true);
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} catch (...) {
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promise.set_exception(std::current_exception());
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}
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}
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} // namespace
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WorkerThread::WorkerThread() :
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wantStop_(false) {
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startThread();
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// Make sure that the thread has started before continuing
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add([](){}).get();
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}
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WorkerThread::~WorkerThread() {
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stop();
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waitForThreadExit();
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}
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void
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WorkerThread::startThread() {
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thread_ = std::thread([this](){ threadMain(); });
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}
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void
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WorkerThread::stop() {
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std::lock_guard<std::mutex> guard(mutex_);
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wantStop_ = true;
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monitor_.notify_one();
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}
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std::future<bool>
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WorkerThread::add(std::function<void()> f) {
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std::lock_guard<std::mutex> guard(mutex_);
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if (wantStop_) {
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// The timer thread has been stopped, or we want to stop; we can't
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// schedule anything else
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std::promise<bool> p;
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auto fut = p.get_future();
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// did not execute
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p.set_value(false);
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return fut;
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}
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auto pr = std::promise<bool>();
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auto fut = pr.get_future();
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queue_.emplace_back(std::make_pair(std::move(f), std::move(pr)));
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// Wake up our thread
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monitor_.notify_one();
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return fut;
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}
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void
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WorkerThread::threadMain() {
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threadLoop();
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// Call all pending tasks
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FAISS_ASSERT(wantStop_);
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// flush all pending operations
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for (auto& f : queue_) {
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runCallback(f.first, f.second);
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}
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}
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void
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WorkerThread::threadLoop() {
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while (true) {
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std::pair<std::function<void()>, std::promise<bool>> data;
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{
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std::unique_lock<std::mutex> lock(mutex_);
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while (!wantStop_ && queue_.empty()) {
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monitor_.wait(lock);
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}
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if (wantStop_) {
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return;
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}
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data = std::move(queue_.front());
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queue_.pop_front();
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}
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runCallback(data.first, data.second);
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}
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}
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void
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WorkerThread::waitForThreadExit() {
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try {
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thread_.join();
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} catch (...) {
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}
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}
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} // namespace
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