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| 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 | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef BASE_RUN_LOOP_H_ | |
| 6 #define BASE_RUN_LOOP_H_ | |
| 7 | |
| 8 #include "base/base_export.h" | |
| 9 #include "base/callback.h" | |
| 10 #include "base/memory/weak_ptr.h" | |
| 11 #include "base/message_loop/message_loop.h" | |
| 12 | |
| 13 namespace base { | |
| 14 #if defined(OS_ANDROID) | |
| 15 class MessagePumpForUI; | |
| 16 #endif | |
| 17 | |
| 18 #if defined(OS_WIN) | |
| 19 class MessagePumpDispatcher; | |
| 20 #endif | |
| 21 | |
| 22 #if defined(OS_IOS) | |
| 23 class MessagePumpUIApplication; | |
| 24 #endif | |
| 25 | |
| 26 // Helper class to Run a nested MessageLoop. Please do not use nested | |
| 27 // MessageLoops in production code! If you must, use this class instead of | |
| 28 // calling MessageLoop::Run/Quit directly. RunLoop::Run can only be called once | |
| 29 // per RunLoop lifetime. Create a RunLoop on the stack and call Run/Quit to run | |
| 30 // a nested MessageLoop. | |
| 31 class BASE_EXPORT RunLoop { | |
| 32 public: | |
| 33 RunLoop(); | |
| 34 #if defined(OS_WIN) | |
| 35 explicit RunLoop(MessagePumpDispatcher* dispatcher); | |
| 36 #endif | |
| 37 ~RunLoop(); | |
| 38 | |
| 39 // Run the current MessageLoop. This blocks until Quit is called. Before | |
| 40 // calling Run, be sure to grab an AsWeakPtr or the QuitClosure in order to | |
| 41 // stop the MessageLoop asynchronously. MessageLoop::Quit and QuitNow will | |
| 42 // also trigger a return from Run, but those are deprecated. | |
| 43 void Run(); | |
| 44 | |
| 45 // Run the current MessageLoop until it doesn't find any tasks or messages in | |
| 46 // the queue (it goes idle). WARNING: This may never return! Only use this | |
| 47 // when repeating tasks such as animated web pages have been shut down. | |
| 48 void RunUntilIdle(); | |
| 49 | |
| 50 bool running() const { return running_; } | |
| 51 | |
| 52 // Quit an earlier call to Run(). There can be other nested RunLoops servicing | |
| 53 // the same task queue (MessageLoop); Quitting one RunLoop has no bearing on | |
| 54 // the others. Quit can be called before, during or after Run. If called | |
| 55 // before Run, Run will return immediately when called. Calling Quit after the | |
| 56 // RunLoop has already finished running has no effect. | |
| 57 // | |
| 58 // WARNING: You must NEVER assume that a call to Quit will terminate the | |
| 59 // targetted message loop. If a nested message loop continues running, the | |
| 60 // target may NEVER terminate. It is very easy to livelock (run forever) in | |
| 61 // such a case. | |
| 62 void Quit(); | |
| 63 | |
| 64 // Convenience method to get a closure that safely calls Quit (has no effect | |
| 65 // if the RunLoop instance is gone). | |
| 66 // | |
| 67 // Example: | |
| 68 // RunLoop run_loop; | |
| 69 // PostTask(run_loop.QuitClosure()); | |
| 70 // run_loop.Run(); | |
| 71 base::Closure QuitClosure(); | |
| 72 | |
| 73 private: | |
| 74 friend class MessageLoop; | |
| 75 #if defined(OS_ANDROID) | |
| 76 // Android doesn't support the blocking MessageLoop::Run, so it calls | |
| 77 // BeforeRun and AfterRun directly. | |
| 78 friend class base::MessagePumpForUI; | |
| 79 #endif | |
| 80 | |
| 81 #if defined(OS_IOS) | |
| 82 // iOS doesn't support the blocking MessageLoop::Run, so it calls | |
| 83 // BeforeRun directly. | |
| 84 friend class base::MessagePumpUIApplication; | |
| 85 #endif | |
| 86 | |
| 87 // Return false to abort the Run. | |
| 88 bool BeforeRun(); | |
| 89 void AfterRun(); | |
| 90 | |
| 91 MessageLoop* loop_; | |
| 92 | |
| 93 // Parent RunLoop or NULL if this is the top-most RunLoop. | |
| 94 RunLoop* previous_run_loop_; | |
| 95 | |
| 96 #if defined(OS_WIN) | |
| 97 MessagePumpDispatcher* dispatcher_; | |
| 98 #endif | |
| 99 | |
| 100 // Used to count how many nested Run() invocations are on the stack. | |
| 101 int run_depth_; | |
| 102 | |
| 103 bool run_called_; | |
| 104 bool quit_called_; | |
| 105 bool running_; | |
| 106 | |
| 107 // Used to record that QuitWhenIdle() was called on the MessageLoop, meaning | |
| 108 // that we should quit Run once it becomes idle. | |
| 109 bool quit_when_idle_received_; | |
| 110 | |
| 111 // WeakPtrFactory for QuitClosure safety. | |
| 112 base::WeakPtrFactory<RunLoop> weak_factory_; | |
| 113 | |
| 114 DISALLOW_COPY_AND_ASSIGN(RunLoop); | |
| 115 }; | |
| 116 | |
| 117 } // namespace base | |
| 118 | |
| 119 #endif // BASE_RUN_LOOP_H_ | |
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