concurrent_message_loop.h

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef FLUTTER_FML_CONCURRENT_MESSAGE_LOOP_H_
#define FLUTTER_FML_CONCURRENT_MESSAGE_LOOP_H_
 
#include <condition_variable>
#include <map>
#include <queue>
#include <thread>
 
#include "flutter/fml/closure.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/task_runner.h"
 
namespace fml {
 
class ConcurrentTaskRunner;
 
class ConcurrentMessageLoop
    : public std::enable_shared_from_this<ConcurrentMessageLoop> {
 public:
  static std::shared_ptr<ConcurrentMessageLoop> Create(
      size_t worker_count = std::thread::hardware_concurrency());
 
  virtual ~ConcurrentMessageLoop();
 
  size_t GetWorkerCount() const;
 
  std::shared_ptr<ConcurrentTaskRunner> GetTaskRunner();
 
  void Terminate();
 
  void PostTaskToAllWorkers(const fml::closure& task);
 
  bool RunsTasksOnCurrentThread();
 
 protected:
  explicit ConcurrentMessageLoop(size_t worker_count);
  virtual void ExecuteTask(const fml::closure& task);
 
 private:
  friend ConcurrentTaskRunner;
 
  size_t worker_count_ = 0;
  std::vector<std::thread> workers_;
  std::mutex tasks_mutex_;
  std::condition_variable tasks_condition_;
  std::queue<fml::closure> tasks_;
  std::vector<std::thread::id> worker_thread_ids_;
  std::map<std::thread::id, std::vector<fml::closure>> thread_tasks_;
  bool shutdown_ = false;
 
  void WorkerMain();
 
  void PostTask(const fml::closure& task);
 
  bool HasThreadTasksLocked() const;
 
  std::vector<fml::closure> GetThreadTasksLocked();
 
  FML_DISALLOW_COPY_AND_ASSIGN(ConcurrentMessageLoop);
};
 
class ConcurrentTaskRunner : public BasicTaskRunner {
 public:
  explicit ConcurrentTaskRunner(std::weak_ptr<ConcurrentMessageLoop> weak_loop);
 
  virtual ~ConcurrentTaskRunner();
 
  void PostTask(const fml::closure& task) override;
 
 private:
  friend ConcurrentMessageLoop;
 
  std::weak_ptr<ConcurrentMessageLoop> weak_loop_;
 
  FML_DISALLOW_COPY_AND_ASSIGN(ConcurrentTaskRunner);
};
 
}  // namespace fml
 
#endif  // FLUTTER_FML_CONCURRENT_MESSAGE_LOOP_H_