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1 // Copyright 2016 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 #include "base/task_scheduler/task_tracker.h" | |
6 | |
7 #include "base/callback.h" | |
8 #include "base/debug/task_annotator.h" | |
9 | |
10 namespace base { | |
11 namespace internal { | |
12 | |
13 namespace { | |
14 const char kQueueFunctionName[] = "base::PostTask"; | |
15 } // namespace | |
16 | |
17 TaskTracker::TaskTracker() = default; | |
18 TaskTracker::~TaskTracker() = default; | |
19 | |
20 void TaskTracker::Shutdown() { | |
21 AutoSchedulerLock auto_lock(lock_); | |
22 | |
23 DCHECK(!shutdown_completed_ && !shutdown_cv_) | |
24 << "TaskTracker::Shutdown() should only be invoked once."; | |
25 | |
26 shutdown_cv_ = lock_.CreateConditionVariable(); | |
27 | |
28 // Wait until the number of tasks blocking shutdown is zero. | |
29 while (num_tasks_blocking_shutdown_ != 0) | |
30 shutdown_cv_->Wait(); | |
31 | |
32 shutdown_cv_.reset(); | |
33 shutdown_completed_ = true; | |
34 } | |
35 | |
36 void TaskTracker::PostTask( | |
37 const Callback<void(scoped_ptr<Task>)>& post_task_callback, | |
38 scoped_ptr<Task> task) { | |
39 DCHECK(!post_task_callback.is_null()); | |
40 DCHECK(task); | |
41 | |
42 if (!BeforePostTask(task->traits.shutdown_behavior())) | |
43 return; | |
44 | |
45 debug::TaskAnnotator task_annotator; | |
46 task_annotator.DidQueueTask(kQueueFunctionName, *task.get()); | |
47 | |
48 post_task_callback.Run(std::move(task)); | |
49 } | |
50 | |
51 void TaskTracker::RunTask(const Task* task) { | |
52 DCHECK(task); | |
53 | |
54 const TaskShutdownBehavior shutdown_behavior = | |
55 task->traits.shutdown_behavior(); | |
56 if (!BeforeRunTask(shutdown_behavior)) | |
57 return; | |
58 | |
59 debug::TaskAnnotator task_annotator; | |
60 task_annotator.RunTask(kQueueFunctionName, *task); | |
61 | |
62 AfterRunTask(shutdown_behavior); | |
63 } | |
64 | |
65 bool TaskTracker::IsShuttingDownForTesting() const { | |
66 AutoSchedulerLock auto_lock(lock_); | |
67 return shutdown_cv_.get() != nullptr; | |
68 } | |
69 | |
70 bool TaskTracker::BeforePostTask(TaskShutdownBehavior shutdown_behavior) { | |
71 AutoSchedulerLock auto_lock(lock_); | |
72 | |
73 if (shutdown_completed_) | |
74 return false; | |
75 | |
76 if (shutdown_behavior == TaskShutdownBehavior::BLOCK_SHUTDOWN) { | |
77 // BLOCK_SHUTDOWN tasks block shutdown between the moment they are posted | |
78 // and the moment they complete their execution. | |
79 ++num_tasks_blocking_shutdown_; | |
80 | |
81 // TODO(fdoray): Add a UMA histogram with the number of BLOCK_SHUTDOWN tasks | |
robliao
2016/03/17 23:34:21
Should we go ahead and do this now?
fdoray
2016/03/18 20:35:39
Done.
| |
82 // posted during shutdown. | |
83 | |
84 return true; | |
85 } | |
86 | |
87 return !shutdown_cv_; | |
88 } | |
89 | |
90 bool TaskTracker::BeforeRunTask(TaskShutdownBehavior shutdown_behavior) { | |
91 AutoSchedulerLock auto_lock(lock_); | |
92 | |
93 if (shutdown_completed_) { | |
94 // A BLOCK_SHUTDOWN task posted after shutdown has completed is an ordering | |
95 // bug. This DCHECK aims to catch those early. | |
96 DCHECK_NE(TaskShutdownBehavior::BLOCK_SHUTDOWN, shutdown_behavior); | |
97 return false; | |
98 } | |
99 | |
100 switch (shutdown_behavior) { | |
101 case TaskShutdownBehavior::BLOCK_SHUTDOWN: | |
102 return true; | |
103 | |
104 case TaskShutdownBehavior::SKIP_ON_SHUTDOWN: | |
105 if (shutdown_cv_) | |
106 return false; | |
107 | |
108 // SKIP_ON_SHUTDOWN tasks block shutdown while they are running. | |
109 ++num_tasks_blocking_shutdown_; | |
110 return true; | |
111 | |
112 case TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN: | |
113 return !shutdown_cv_; | |
114 } | |
115 | |
116 NOTREACHED(); | |
117 return false; | |
118 } | |
119 | |
120 void TaskTracker::AfterRunTask(TaskShutdownBehavior shutdown_behavior) { | |
121 if (shutdown_behavior == TaskShutdownBehavior::BLOCK_SHUTDOWN || | |
122 shutdown_behavior == TaskShutdownBehavior::SKIP_ON_SHUTDOWN) { | |
123 AutoSchedulerLock auto_lock(lock_); | |
124 DCHECK_GT(num_tasks_blocking_shutdown_, 0U); | |
125 --num_tasks_blocking_shutdown_; | |
126 if (num_tasks_blocking_shutdown_ == 0 && shutdown_cv_) | |
127 shutdown_cv_->Signal(); | |
128 } | |
129 } | |
130 | |
131 } // namespace internal | |
132 } // namespace base | |
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