OLD | NEW |
---|---|
(Empty) | |
1 // Copyright 2017 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 MEDIA_MIDI_TASK_SERVICE_H_ | |
6 #define MEDIA_MIDI_TASK_SERVICE_H_ | |
7 | |
8 #include "base/callback_forward.h" | |
9 #include "base/macros.h" | |
10 #include "base/memory/ref_counted.h" | |
11 #include "base/single_thread_task_runner.h" | |
12 #include "base/synchronization/lock.h" | |
13 #include "base/threading/thread.h" | |
14 #include "base/time/time.h" | |
15 #include "media/midi/midi_export.h" | |
16 | |
17 namespace midi { | |
18 | |
19 // TaskService manages TaskRunners that can be used in midi and provides | |
20 // functionalities to ensure thread safety. | |
21 class MIDI_EXPORT TaskService final { | |
22 public: | |
23 using RunnerId = size_t; | |
24 using InstanceId = int; | |
25 | |
26 static constexpr RunnerId kDefaultRunnerId = 0; | |
27 | |
28 TaskService(); | |
29 ~TaskService(); | |
30 | |
31 // Issues an InstanceId internally to post tasks via PostBoundTask() and | |
32 // PostDelayedBoundTask() with the InstanceId. Once UnbindInstance() is | |
33 // called, tasks posted via these methods with unbind InstanceId won't be | |
34 // invoked any more. | |
35 // Returns true if call is bound or unbound correctly. Otherwise returns | |
36 // false, that happens when the BindInstance() is called twice without | |
37 // unbinding the previous instance. | |
38 bool BindInstance(); | |
39 bool UnbindInstance(); | |
40 | |
41 // Posts a task to run on a specified TaskRunner. |runner_id| should be | |
42 // kDefaultRunnerId or a positive number. If kDefaultRunnerId is specified | |
43 // the task runs on the thread on which BindInstance() is called. Other number | |
44 // will run the task on a dedicated thread that is bound to the |runner_id|. | |
45 void PostStaticTask(RunnerId runner_id, base::OnceClosure task); | |
46 | |
47 // Posts a task to run on a specified TaskRunner, and ensures that the bound | |
48 // instance should not quit UnbindInstance() while a bound task is running. | |
49 // See PostStaticTask() for |runner_id|. | |
50 void PostBoundTask(RunnerId runner, base::OnceClosure task); | |
51 void PostBoundDelayedTask(RunnerId runner_id, | |
52 base::OnceClosure task, | |
53 base::TimeDelta delay); | |
54 | |
55 private: | |
56 // Returns a SingleThreadTaskRunner reference. Each TaskRunner will be | |
57 // constructed on demand. | |
58 scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner(RunnerId runner_id); | |
59 | |
60 // Helps to run a posted bound task on TaskRunner safely. | |
61 void RunTask(InstanceId instance_id, | |
62 RunnerId runner_id, | |
63 base::OnceClosure task); | |
64 | |
65 // Keeps a TaskRunner for the thread that calls BindInstance() to post reply | |
66 // tasks. | |
67 scoped_refptr<base::SingleThreadTaskRunner> reply_task_runner_; | |
yhirano
2017/06/13 09:30:47
[optional] PostReplyTask is gone, so it may be goo
Takashi Toyoshima
2017/06/13 10:06:46
Done.
| |
68 | |
69 // Holds threads to host SingleThreadTaskRunners. | |
70 std::vector<std::unique_ptr<base::Thread>> threads_; | |
71 | |
72 // Holds lock objects to ensure that tasks run while the instance is bound. | |
73 std::vector<std::unique_ptr<base::Lock>> thread_task_locks_; | |
74 | |
75 // Holds InstanceId for the next bound instance. | |
76 InstanceId next_instance_id_; | |
77 | |
78 // Holds InstanceId for the current bound instance. | |
79 InstanceId bound_instance_id_; | |
80 | |
81 // Protects |next_instance_id_| and |bound_instance_id_|. | |
82 base::Lock instance_lock_; | |
83 | |
84 // Protects all other members. | |
85 base::Lock lock_; | |
86 | |
87 // If multiple locks should be obtained simultaneously, we should acquire them | |
88 // in the order below so to avoid deadklocks. | |
89 // |instance_lock_| -> |lock_| -> |(one of) thread_task_locks_|. | |
90 | |
91 DISALLOW_COPY_AND_ASSIGN(TaskService); | |
92 }; | |
93 | |
94 }; // namespace midi | |
95 | |
96 #endif // MEDIA_MIDI_TASK_SERVICE_H_ | |
OLD | NEW |