blob: 245ca88c1ceec7ae0cac297d2b6d86cc065c22e2 [file] [log] [blame]
// Copyright (c) 2012 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 "base/callback.h"
#include "base/compiler_specific.h"
#include "base/containers/circular_deque.h"
#include "base/macros.h"
#include "base/single_thread_task_runner.h"
#include "base/synchronization/lock.h"
#include "base/test/test_pending_task.h"
#include "base/threading/platform_thread.h"
namespace base {
class TimeDelta;
// ATTENTION: Prefer using base::test::TaskEnvironment and a task runner
// obtained from base/task/post_task.h over this class. This class isn't as
// "simple" as it seems specifically because it runs tasks in a surprising order
// (delays aren't respected and nesting doesn't behave as usual). Should you
// prefer to flush all tasks regardless of delays,
// TaskEnvironment::TimeSource::MOCK_TIME and
// TaskEnvironment::FastForwardUntilNoTasksRemain() have you covered.
// TestSimpleTaskRunner is a simple TaskRunner implementation that can
// be used for testing. It implements SingleThreadTaskRunner as that
// interface implements SequencedTaskRunner, which in turn implements
// TaskRunner, so TestSimpleTaskRunner can be passed in to a function
// that accepts any *TaskRunner object.
// TestSimpleTaskRunner has the following properties which make it simple:
// - Tasks are simply stored in a queue in FIFO order, ignoring delay
// and nestability.
// - Tasks aren't guaranteed to be destroyed immediately after
// they're run.
// However, TestSimpleTaskRunner allows for reentrancy, in that it
// handles the running of tasks that in turn call back into itself
// (e.g., to post more tasks).
// Note that, like any TaskRunner, TestSimpleTaskRunner is
// ref-counted.
class TestSimpleTaskRunner : public SingleThreadTaskRunner {
// SingleThreadTaskRunner implementation.
bool PostDelayedTask(const Location& from_here,
OnceClosure task,
TimeDelta delay) override;
bool PostNonNestableDelayedTask(const Location& from_here,
OnceClosure task,
TimeDelta delay) override;
bool RunsTasksInCurrentSequence() const override;
base::circular_deque<TestPendingTask> TakePendingTasks();
size_t NumPendingTasks() const;
bool HasPendingTask() const;
base::TimeDelta NextPendingTaskDelay() const;
base::TimeDelta FinalPendingTaskDelay() const;
// Clears the queue of pending tasks without running them.
void ClearPendingTasks();
// Runs each current pending task in order and clears the queue. Tasks posted
// by the tasks that run within this call do not run within this call. Can
// only be called on the thread that created this TestSimpleTaskRunner.
void RunPendingTasks();
// Runs pending tasks until the queue is empty. Can only be called on the
// thread that created this TestSimpleTaskRunner.
void RunUntilIdle();
~TestSimpleTaskRunner() override;
// Thread on which this was instantiated.
const PlatformThreadRef thread_ref_ = PlatformThread::CurrentRef();
// Synchronizes access to |pending_tasks_|.
mutable Lock lock_;
base::circular_deque<TestPendingTask> pending_tasks_;
} // namespace base