content/browser/startup_task_runner.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_
   6 #define CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_
   7
   8 #include <list>
   9
  10 #include "base/callback.h"
  11 #include "base/single_thread_task_runner.h"
  12
  13 #include "build/build_config.h"
  14
  15 #include "content/public/browser/browser_main_runner.h"
  16
  17 namespace content {
  18
  19 // A startup task is a void function returning the status on completion.
  20 // a status of > 0 indicates a failure, and that no further startup tasks should
  21 // be run.
  22 typedef base::Callback<int(void)> StartupTask;
  23
  24 // This class runs startup tasks. The tasks are either run immediately inline,
  25 // or are queued one at a time on the UI thread's message loop. If the events
  26 // are queued, UI events that are received during startup will be acted upon
  27 // between startup tasks. The motivation for this is that, on targets where the
  28 // UI is already started, it allows us to keep the UI responsive during startup.
  29 //
  30 // Note that this differs from a SingleThreadedTaskRunner in that there may be
  31 // no opportunity to handle UI events between the tasks of a
  32 // SingleThreadedTaskRunner.
  33
  34 class CONTENT_EXPORT StartupTaskRunner {
  35
  36  public:
  37   // Constructor: Note that |startup_complete_callback| is optional. If it is
  38   // not null it will be called once all the startup tasks have run.
  39   StartupTaskRunner(base::Callback<void(int)> startup_complete_callback,
  40                     scoped_refptr<base::SingleThreadTaskRunner> proxy);
  41
  42   ~StartupTaskRunner();
  43
  44   // Add a task to the queue of startup tasks to be run.
  45   void AddTask(StartupTask& callback);
  46
  47   // Start running the tasks asynchronously.
  48   void StartRunningTasksAsync();
  49
  50   // Run all tasks, or all remaining tasks, synchronously
  51   void RunAllTasksNow();
  52
  53  private:
  54   friend class base::RefCounted<StartupTaskRunner>;
  55
  56   std::list<StartupTask> task_list_;
  57   void WrappedTask();
  58
  59   base::Callback<void(int)> startup_complete_callback_;
  60   scoped_refptr<base::SingleThreadTaskRunner> proxy_;
  61
  62   DISALLOW_COPY_AND_ASSIGN(StartupTaskRunner);
  63 };
  64
  65 }  // namespace content
  66 #endif  // CONTENT_BROWSER_STARTUP_TASK_RUNNER_H_