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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #ifndef BASE_RUN_LOOP_H_ | 5 #ifndef BASE_RUN_LOOP_H_ |
6 #define BASE_RUN_LOOP_H_ | 6 #define BASE_RUN_LOOP_H_ |
7 | 7 |
8 #include "base/base_export.h" | 8 #include "base/base_export.h" |
9 #include "base/callback.h" | 9 #include "base/callback.h" |
10 #include "base/macros.h" | 10 #include "base/macros.h" |
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22 class MessagePumpUIApplication; | 22 class MessagePumpUIApplication; |
23 #endif | 23 #endif |
24 | 24 |
25 // Helper class to Run a nested MessageLoop. Please do not use nested | 25 // Helper class to Run a nested MessageLoop. Please do not use nested |
26 // MessageLoops in production code! If you must, use this class instead of | 26 // MessageLoops in production code! If you must, use this class instead of |
27 // calling MessageLoop::Run/Quit directly. RunLoop::Run can only be called once | 27 // calling MessageLoop::Run/Quit directly. RunLoop::Run can only be called once |
28 // per RunLoop lifetime. Create a RunLoop on the stack and call Run/Quit to run | 28 // per RunLoop lifetime. Create a RunLoop on the stack and call Run/Quit to run |
29 // a nested MessageLoop. | 29 // a nested MessageLoop. |
30 class BASE_EXPORT RunLoop { | 30 class BASE_EXPORT RunLoop { |
31 public: | 31 public: |
| 32 class Delegate {}; |
| 33 |
32 RunLoop(); | 34 RunLoop(); |
33 ~RunLoop(); | 35 ~RunLoop(); |
34 | 36 |
35 // Run the current MessageLoop. This blocks until Quit is called. Before | 37 // Run the current MessageLoop. This blocks until Quit is called. Before |
36 // calling Run, be sure to grab the QuitClosure in order to stop the | 38 // calling Run, be sure to grab the QuitClosure in order to stop the |
37 // MessageLoop asynchronously. MessageLoop::QuitWhenIdle and QuitNow will also | 39 // MessageLoop asynchronously. MessageLoop::QuitWhenIdle and QuitNow will also |
38 // trigger a return from Run, but those are deprecated. | 40 // trigger a return from Run, but those are deprecated. |
39 void Run(); | 41 void Run(); |
40 | 42 |
41 // Run the current MessageLoop until it doesn't find any tasks or messages in | 43 // Run the current MessageLoop until it doesn't find any tasks or messages in |
42 // the queue (it goes idle). WARNING: This may never return! Only use this | 44 // the queue (it goes idle). WARNING: This may never return! Only use this |
43 // when repeating tasks such as animated web pages have been shut down. | 45 // when repeating tasks such as animated web pages have been shut down. |
44 void RunUntilIdle(); | 46 void RunUntilIdle(); |
45 | 47 |
46 bool running() const { return running_; } | 48 bool running() const { |
| 49 DCHECK(thread_checker_.CalledOnValidThread()); |
| 50 return running_; |
| 51 } |
47 | 52 |
48 // Quit() quits an earlier call to Run() immediately. QuitWhenIdle() quits an | 53 // Quit() quits an earlier call to Run() immediately. QuitWhenIdle() quits an |
49 // earlier call to Run() when there aren't any tasks or messages in the queue. | 54 // earlier call to Run() when there aren't any tasks or messages in the queue. |
50 // | 55 // |
51 // There can be other nested RunLoops servicing the same task queue | 56 // There can be other nested RunLoops servicing the same task queue |
52 // (MessageLoop); Quitting one RunLoop has no bearing on the others. Quit() | 57 // (MessageLoop); Quitting one RunLoop has no bearing on the others. Quit() |
53 // and QuitWhenIdle() can be called before, during or after Run(). If called | 58 // and QuitWhenIdle() can be called before, during or after Run(). If called |
54 // before Run(), Run() will return immediately when called. Calling Quit() or | 59 // before Run(), Run() will return immediately when called. Calling Quit() or |
55 // QuitWhenIdle() after the RunLoop has already finished running has no | 60 // QuitWhenIdle() after the RunLoop has already finished running has no |
56 // effect. | 61 // effect. |
57 // | 62 // |
58 // WARNING: You must NEVER assume that a call to Quit() or QuitWhenIdle() will | 63 // WARNING: You must NEVER assume that a call to Quit() or QuitWhenIdle() will |
59 // terminate the targetted message loop. If a nested message loop continues | 64 // terminate the targetted message loop. If a nested message loop continues |
60 // running, the target may NEVER terminate. It is very easy to livelock (run | 65 // running, the target may NEVER terminate. It is very easy to livelock (run |
61 // forever) in such a case. | 66 // forever) in such a case. |
62 void Quit(); | 67 void Quit(); |
63 void QuitWhenIdle(); | 68 void QuitWhenIdle(); |
64 | 69 |
65 // Convenience methods to get a closure that safely calls Quit() or | 70 // Convenience methods to get a closure that safely calls Quit() or |
66 // QuitWhenIdle() (has no effect if the RunLoop instance is gone). | 71 // QuitWhenIdle() (has no effect if the RunLoop instance is gone). |
67 // | 72 // |
68 // Example: | 73 // Example: |
69 // RunLoop run_loop; | 74 // RunLoop run_loop; |
70 // PostTask(run_loop.QuitClosure()); | 75 // PostTask(run_loop.QuitClosure()); |
71 // run_loop.Run(); | 76 // run_loop.Run(); |
72 base::Closure QuitClosure(); | 77 base::Closure QuitClosure(); |
73 base::Closure QuitWhenIdleClosure(); | 78 base::Closure QuitWhenIdleClosure(); |
74 | 79 |
| 80 // Returns true if there is an active RunLoop on this thread. |
| 81 static bool IsRunningOnCurrentThread(); |
| 82 |
| 83 // Returns true if there is an active RunLoop on this thread and it's nested |
| 84 // within another active RunLoop. |
| 85 static bool IsNestedOnCurrentThread(); |
| 86 |
| 87 // A NestingObserver is notified when a nested run loop begins. The observers |
| 88 // are notified before the current thread's RunLoop::Delegate::Run() is |
| 89 // invoked and nested work begins. |
| 90 class BASE_EXPORT NestingObserver { |
| 91 public: |
| 92 virtual void OnBeginNestedMessageLoop() = 0; |
| 93 |
| 94 protected: |
| 95 virtual ~NestingObserver() = default; |
| 96 }; |
| 97 |
| 98 static void AddNestingObserverOnCurrentThread(NestingObserver* observer); |
| 99 static void RemoveNestingObserverOnCurrentThread(NestingObserver* observer); |
| 100 |
| 101 // Returns true if nesting is allowed on this thread. |
| 102 static bool IsNestingAllowedOnCurrentThread(); |
| 103 |
| 104 // Disallow nesting. After this is called, running a nested RunLoop or calling |
| 105 // Add/RemoveNestingObserverOnCurrentThread() on this thread will crash. |
| 106 static void DisallowNestingOnCurrentThread(); |
| 107 |
75 private: | 108 private: |
76 friend class MessageLoop; | 109 friend class MessageLoop; |
77 #if defined(OS_ANDROID) | 110 #if defined(OS_ANDROID) |
78 // Android doesn't support the blocking MessageLoop::Run, so it calls | 111 // Android doesn't support the blocking MessageLoop::Run, so it calls |
79 // BeforeRun and AfterRun directly. | 112 // BeforeRun and AfterRun directly. |
80 friend class base::MessagePumpForUI; | 113 friend class base::MessagePumpForUI; |
81 #endif | 114 #endif |
82 | 115 |
83 #if defined(OS_IOS) | 116 #if defined(OS_IOS) |
84 // iOS doesn't support the blocking MessageLoop::Run, so it calls | 117 // iOS doesn't support the blocking MessageLoop::Run, so it calls |
85 // BeforeRun directly. | 118 // BeforeRun directly. |
86 friend class base::MessagePumpUIApplication; | 119 friend class base::MessagePumpUIApplication; |
87 #endif | 120 #endif |
88 | 121 |
89 // Return false to abort the Run. | 122 // Return false to abort the Run. |
90 bool BeforeRun(); | 123 bool BeforeRun(); |
91 void AfterRun(); | 124 void AfterRun(); |
92 | 125 |
93 MessageLoop* loop_; | 126 MessageLoop* loop_; |
94 | 127 |
95 // Parent RunLoop or NULL if this is the top-most RunLoop. | 128 bool run_called_ = false; |
96 RunLoop* previous_run_loop_; | 129 bool quit_called_ = false; |
97 | 130 bool running_ = false; |
98 // Used to count how many nested Run() invocations are on the stack. | |
99 int run_depth_; | |
100 | |
101 bool run_called_; | |
102 bool quit_called_; | |
103 bool running_; | |
104 | 131 |
105 // Used to record that QuitWhenIdle() was called on the MessageLoop, meaning | 132 // Used to record that QuitWhenIdle() was called on the MessageLoop, meaning |
106 // that we should quit Run once it becomes idle. | 133 // that we should quit Run once it becomes idle. |
107 bool quit_when_idle_received_; | 134 bool quit_when_idle_received_ = false; |
108 | 135 |
| 136 // RunLoop's non-static methods are affine to thread it's running on. |
109 base::ThreadChecker thread_checker_; | 137 base::ThreadChecker thread_checker_; |
110 | 138 |
111 // WeakPtrFactory for QuitClosure safety. | 139 // WeakPtrFactory for QuitClosure safety. |
112 base::WeakPtrFactory<RunLoop> weak_factory_; | 140 base::WeakPtrFactory<RunLoop> weak_factory_; |
113 | 141 |
114 DISALLOW_COPY_AND_ASSIGN(RunLoop); | 142 DISALLOW_COPY_AND_ASSIGN(RunLoop); |
115 }; | 143 }; |
116 | 144 |
117 } // namespace base | 145 } // namespace base |
118 | 146 |
119 #endif // BASE_RUN_LOOP_H_ | 147 #endif // BASE_RUN_LOOP_H_ |
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