blob: 2805f479e6b2db963b457bfeff78c7f424af8e6c [file] [log] [blame]
// Copyright (c) 2013 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 <vector>
#include "base/base_export.h"
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/sequenced_task_runner.h"
#include "base/synchronization/lock.h"
#include "base/threading/platform_thread.h"
#include "base/time/time.h"
namespace base {
// A DeferredSequencedTaskRunner is a subclass of SequencedTaskRunner that
// queues up all requests until the first call to Start() is issued.
// DeferredSequencedTaskRunner may be created in two ways:
// . with an explicit SequencedTaskRunner that the events are flushed to
// . without a SequencedTaskRunner. In this configuration the
// SequencedTaskRunner is supplied in StartWithTaskRunner().
class BASE_EXPORT DeferredSequencedTaskRunner : public SequencedTaskRunner {
explicit DeferredSequencedTaskRunner(
scoped_refptr<SequencedTaskRunner> target_runner);
// Use this constructor when you don't have the target SequencedTaskRunner.
// When using this call StartWithTaskRunner().
// TaskRunner implementation
bool PostDelayedTask(const Location& from_here,
OnceClosure task,
TimeDelta delay) override;
bool RunsTasksInCurrentSequence() const override;
// SequencedTaskRunner implementation
bool PostNonNestableDelayedTask(const Location& from_here,
OnceClosure task,
TimeDelta delay) override;
// Start the execution - posts all queued tasks to the target executor. The
// deferred tasks are posted with their initial delay, meaning that the task
// execution delay is actually measured from Start.
// Fails when called a second time.
void Start();
// Same as Start(), but must be used with the no-arg constructor.
void StartWithTaskRunner(
scoped_refptr<SequencedTaskRunner> target_task_runner);
struct DeferredTask {
DeferredTask(DeferredTask&& other);
DeferredTask& operator=(DeferredTask&& other);
Location posted_from;
OnceClosure task;
// The delay this task was initially posted with.
TimeDelta delay;
bool is_non_nestable;
~DeferredSequencedTaskRunner() override;
// Both variants of Start() call into this.
void StartImpl();
// Creates a |Task| object and adds it to |deferred_tasks_queue_|.
void QueueDeferredTask(const Location& from_here,
OnceClosure task,
TimeDelta delay,
bool is_non_nestable);
// // Protects |started_| and |deferred_tasks_queue_|.
mutable Lock lock_;
const PlatformThreadId created_thread_id_;
bool started_ = false;
scoped_refptr<SequencedTaskRunner> target_task_runner_;
std::vector<DeferredTask> deferred_tasks_queue_;
} // namespace base