116 lines
3.7 KiB
C++
116 lines
3.7 KiB
C++
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_RUN_LOOP_H_
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#define BASE_RUN_LOOP_H_
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#include "base/base_export.h"
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#include "base/callback.h"
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#include "base/macros.h"
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#include "base/memory/weak_ptr.h"
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#include "base/message_loop/message_loop.h"
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#include "build/build_config.h"
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namespace base {
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#if defined(OS_ANDROID)
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class MessagePumpForUI;
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#endif
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#if defined(OS_IOS)
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class MessagePumpUIApplication;
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#endif
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// Helper class to Run a nested MessageLoop. Please do not use nested
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// MessageLoops in production code! If you must, use this class instead of
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// calling MessageLoop::Run/Quit directly. RunLoop::Run can only be called once
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// per RunLoop lifetime. Create a RunLoop on the stack and call Run/Quit to run
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// a nested MessageLoop.
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class BASE_EXPORT RunLoop {
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public:
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RunLoop();
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~RunLoop();
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// Run the current MessageLoop. This blocks until Quit is called. Before
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// calling Run, be sure to grab the QuitClosure in order to stop the
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// MessageLoop asynchronously. MessageLoop::QuitWhenIdle and QuitNow will also
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// trigger a return from Run, but those are deprecated.
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void Run();
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// Run the current MessageLoop until it doesn't find any tasks or messages in
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// the queue (it goes idle). WARNING: This may never return! Only use this
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// when repeating tasks such as animated web pages have been shut down.
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void RunUntilIdle();
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bool running() const { return running_; }
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// Quit() quits an earlier call to Run() immediately. QuitWhenIdle() quits an
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// earlier call to Run() when there aren't any tasks or messages in the queue.
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//
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// There can be other nested RunLoops servicing the same task queue
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// (MessageLoop); Quitting one RunLoop has no bearing on the others. Quit()
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// and QuitWhenIdle() can be called before, during or after Run(). If called
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// before Run(), Run() will return immediately when called. Calling Quit() or
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// QuitWhenIdle() after the RunLoop has already finished running has no
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// effect.
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//
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// WARNING: You must NEVER assume that a call to Quit() or QuitWhenIdle() will
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// terminate the targetted message loop. If a nested message loop continues
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// running, the target may NEVER terminate. It is very easy to livelock (run
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// forever) in such a case.
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void Quit();
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void QuitWhenIdle();
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// Convenience methods to get a closure that safely calls Quit() or
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// QuitWhenIdle() (has no effect if the RunLoop instance is gone).
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//
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// Example:
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// RunLoop run_loop;
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// PostTask(run_loop.QuitClosure());
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// run_loop.Run();
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base::Closure QuitClosure();
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base::Closure QuitWhenIdleClosure();
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private:
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friend class MessageLoop;
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#if defined(OS_ANDROID)
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// Android doesn't support the blocking MessageLoop::Run, so it calls
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// BeforeRun and AfterRun directly.
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friend class base::MessagePumpForUI;
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#endif
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#if defined(OS_IOS)
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// iOS doesn't support the blocking MessageLoop::Run, so it calls
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// BeforeRun directly.
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friend class base::MessagePumpUIApplication;
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#endif
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// Return false to abort the Run.
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bool BeforeRun();
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void AfterRun();
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MessageLoop* loop_;
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// Parent RunLoop or NULL if this is the top-most RunLoop.
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RunLoop* previous_run_loop_;
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// Used to count how many nested Run() invocations are on the stack.
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int run_depth_;
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bool run_called_;
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bool quit_called_;
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bool running_;
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// Used to record that QuitWhenIdle() was called on the MessageLoop, meaning
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// that we should quit Run once it becomes idle.
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bool quit_when_idle_received_;
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// WeakPtrFactory for QuitClosure safety.
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base::WeakPtrFactory<RunLoop> weak_factory_;
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DISALLOW_COPY_AND_ASSIGN(RunLoop);
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};
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} // namespace base
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#endif // BASE_RUN_LOOP_H_
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