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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_
#define CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_
#include <list>
#include "base/functional/callback.h"
#include "base/task/single_thread_task_runner.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "content/common/content_export.h"
#include "content/public/browser/browser_main_runner.h"
namespace content {
// A startup task is a void function returning the status on completion.
// a status of > 0 indicates a failure, and that no further startup tasks should
// be run.
using StartupTask = base::OnceCallback<int(void)>;
// This class runs startup tasks. The tasks are either run immediately inline,
// or are queued one at a time on the UI thread's message loop. If the events
// are queued, UI events that are received during startup will be acted upon
// between startup tasks. The motivation for this is that, on targets where the
// UI is already started, it allows us to keep the UI responsive during startup.
//
// Note that this differs from a SingleThreadedTaskRunner in that there may be
// no opportunity to handle UI events between the tasks of a
// SingleThreadedTaskRunner.
class CONTENT_EXPORT StartupTaskRunner {
public:
// Constructor: Note that |startup_complete_callback| is optional. If it is
// not null it will be called, once all the startup tasks have run, with the
// result of running tasks and the duration spent blocking the UI thread.
StartupTaskRunner(
base::OnceCallback<void(int, base::TimeDelta, base::TimeDelta)>
startup_complete_callback,
scoped_refptr<base::SingleThreadTaskRunner> proxy);
StartupTaskRunner(const StartupTaskRunner&) = delete;
StartupTaskRunner& operator=(const StartupTaskRunner&) = delete;
~StartupTaskRunner();
// Add a task to the queue of startup tasks to be run.
void AddTask(StartupTask callback);
// Start running the tasks asynchronously.
void StartRunningTasksAsync();
// Run all tasks, or all remaining tasks, synchronously
// `was_posted` means the caller had posted this task to the task_runner
// instead of executing it inline.
void RunAllTasksNow(bool was_posted);
private:
friend class base::RefCounted<StartupTaskRunner>;
std::list<StartupTask> task_list_;
void WrappedTask();
base::OnceCallback<void(int, base::TimeDelta, base::TimeDelta)>
startup_complete_callback_;
scoped_refptr<base::SingleThreadTaskRunner> proxy_;
// The longest of the wall-clock durations of each individual task that was
// posted to the task_runner.
base::TimeDelta longest_duration_of_posted_startup_tasks_;
// The total wall-clock duration of all the tasks that were run as posted
// tasks.
base::TimeDelta total_duration_of_posted_startup_tasks_;
};
} // namespace content
#endif // CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_
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