blob: c48aeb1e6b1647a5b49d7e91df2b80449f04373b [file] [log] [blame]
// Copyright 2016 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <memory>
#include <utility>
#include <vector>
#include "base/base_export.h"
#include "base/callback.h"
#include "base/macros.h"
#include "base/memory/ptr_util.h"
#include "base/memory/ref_counted.h"
#include "base/synchronization/atomic_flag.h"
#include "base/task_scheduler/scheduler_lock.h"
#include "base/time/default_tick_clock.h"
#include "base/time/tick_clock.h"
namespace base {
class TaskRunner;
namespace internal {
struct Task;
// The DelayedTaskManager forwards tasks to post task callbacks when they become
// ripe for execution. Tasks are not forwarded before Start() is called. This
// class is thread-safe.
class BASE_EXPORT DelayedTaskManager {
// Posts |task| for execution immediately.
using PostTaskNowCallback = OnceCallback<void(Task task)>;
// |tick_clock| can be specified for testing.
DelayedTaskManager(std::unique_ptr<const TickClock> tick_clock =
// Starts the delayed task manager, allowing past and future tasks to be
// forwarded to their callbacks as they become ripe for execution.
// |service_thread_task_runner| posts tasks to the TaskScheduler service
// thread.
void Start(scoped_refptr<TaskRunner> service_thread_task_runner);
// Schedules a call to |post_task_now_callback| with |task| as argument when
// |task| is ripe for execution and Start() has been called.
void AddDelayedTask(Task task, PostTaskNowCallback post_task_now_callback);
// Schedules a call to |post_task_now_callback| with |task| as argument when
// |delay| expires. Start() must have been called before this.
void AddDelayedTaskNow(Task task,
TimeDelta delay,
PostTaskNowCallback post_task_now_callback);
const std::unique_ptr<const TickClock> tick_clock_;
AtomicFlag started_;
// Synchronizes access to all members below before |started_| is set. Once
// |started_| is set:
// - |service_thread_task_runner| doest not change, so it can be read without
// holding the lock.
// - |tasks_added_before_start_| isn't accessed anymore.
SchedulerLock lock_;
scoped_refptr<TaskRunner> service_thread_task_runner_;
std::vector<std::pair<Task, PostTaskNowCallback>> tasks_added_before_start_;
} // namespace internal
} // namespace base