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127 lines
3.2 KiB
C++
127 lines
3.2 KiB
C++
// Copyright 2013 The Flutter Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "flutter/fml/concurrent_message_loop.h"
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#include <algorithm>
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#include "flutter/fml/thread.h"
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#include "flutter/fml/trace_event.h"
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namespace fml {
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std::shared_ptr<ConcurrentMessageLoop> ConcurrentMessageLoop::Create(
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size_t worker_count) {
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return std::shared_ptr<ConcurrentMessageLoop>{
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new ConcurrentMessageLoop(worker_count)};
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}
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ConcurrentMessageLoop::ConcurrentMessageLoop(size_t worker_count)
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: worker_count_(std::max<size_t>(worker_count, 1ul)) {
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for (size_t i = 0; i < worker_count_; ++i) {
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workers_.emplace_back([i, this]() {
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fml::Thread::SetCurrentThreadName(
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std::string{"io.flutter.worker." + std::to_string(i + 1)});
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WorkerMain();
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});
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}
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}
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ConcurrentMessageLoop::~ConcurrentMessageLoop() {
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Terminate();
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for (auto& worker : workers_) {
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worker.join();
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}
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}
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size_t ConcurrentMessageLoop::GetWorkerCount() const {
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return worker_count_;
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}
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std::shared_ptr<ConcurrentTaskRunner> ConcurrentMessageLoop::GetTaskRunner() {
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return std::make_shared<ConcurrentTaskRunner>(weak_from_this());
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}
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void ConcurrentMessageLoop::PostTask(const fml::closure& task) {
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if (!task) {
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return;
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}
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std::unique_lock lock(tasks_mutex_);
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// Don't just drop tasks on the floor in case of shutdown.
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if (shutdown_) {
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FML_DLOG(WARNING)
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<< "Tried to post a task to shutdown concurrent message "
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"loop. The task will be executed on the callers thread.";
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lock.unlock();
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task();
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return;
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}
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tasks_.push(task);
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// Unlock the mutex before notifying the condition variable because that mutex
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// has to be acquired on the other thread anyway. Waiting in this scope till
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// it is acquired there is a pessimization.
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lock.unlock();
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tasks_condition_.notify_one();
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}
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void ConcurrentMessageLoop::WorkerMain() {
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while (true) {
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std::unique_lock lock(tasks_mutex_);
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tasks_condition_.wait(lock,
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[&]() { return tasks_.size() > 0 || shutdown_; });
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if (tasks_.size() == 0) {
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// This can only be caused by shutdown.
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FML_DCHECK(shutdown_);
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break;
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}
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auto task = tasks_.front();
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tasks_.pop();
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// Don't hold onto the mutex while the task is being executed as it could
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// itself try to post another tasks to this message loop.
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lock.unlock();
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TRACE_EVENT0("flutter", "ConcurrentWorkerWake");
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// Execute the one tasks we woke up for.
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task();
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}
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}
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void ConcurrentMessageLoop::Terminate() {
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std::scoped_lock lock(tasks_mutex_);
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shutdown_ = true;
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tasks_condition_.notify_all();
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}
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ConcurrentTaskRunner::ConcurrentTaskRunner(
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std::weak_ptr<ConcurrentMessageLoop> weak_loop)
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: weak_loop_(std::move(weak_loop)) {}
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ConcurrentTaskRunner::~ConcurrentTaskRunner() = default;
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void ConcurrentTaskRunner::PostTask(const fml::closure& task) {
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if (!task) {
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return;
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}
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if (auto loop = weak_loop_.lock()) {
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loop->PostTask(task);
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return;
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}
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FML_DLOG(WARNING)
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<< "Tried to post to a concurrent message loop that has already died. "
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"Executing the task on the callers thread.";
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task();
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}
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} // namespace fml
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