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authorZeno Albisser <zeno.albisser@digia.com>2013-08-15 21:46:11 +0200
committerZeno Albisser <zeno.albisser@digia.com>2013-08-15 21:46:11 +0200
commit679147eead574d186ebf3069647b4c23e8ccace6 (patch)
treefc247a0ac8ff119f7c8550879ebb6d3dd8d1ff69 /chromium/base/run_loop.h
downloadqtwebengine-chromium-679147eead574d186ebf3069647b4c23e8ccace6.tar.gz
Initial import.
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+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_RUN_LOOP_H_
+#define BASE_RUN_LOOP_H_
+
+#include "base/base_export.h"
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "base/message_loop/message_loop.h"
+
+class WebEngineContext;
+
+namespace base {
+#if defined(OS_ANDROID)
+class MessagePumpForUI;
+#endif
+
+#if defined(OS_IOS)
+class MessagePumpUIApplication;
+#endif
+
+// Helper class to Run a nested MessageLoop. Please do not use nested
+// MessageLoops in production code! If you must, use this class instead of
+// calling MessageLoop::Run/Quit directly. RunLoop::Run can only be called once
+// per RunLoop lifetime. Create a RunLoop on the stack and call Run/Quit to run
+// a nested MessageLoop.
+class BASE_EXPORT RunLoop {
+ public:
+ RunLoop();
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
+ explicit RunLoop(MessageLoop::Dispatcher* dispatcher);
+#endif
+ ~RunLoop();
+
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
+ void set_dispatcher(MessageLoop::Dispatcher* dispatcher) {
+ dispatcher_ = dispatcher;
+ }
+#endif
+
+ // Run the current MessageLoop. This blocks until Quit is called. Before
+ // calling Run, be sure to grab an AsWeakPtr or the QuitClosure in order to
+ // stop the MessageLoop asynchronously. MessageLoop::Quit and QuitNow will
+ // also trigger a return from Run, but those are deprecated.
+ void Run();
+
+ // Run the current MessageLoop until it doesn't find any tasks or messages in
+ // the queue (it goes idle). WARNING: This may never return! Only use this
+ // when repeating tasks such as animated web pages have been shut down.
+ void RunUntilIdle();
+
+ bool running() const { return running_; }
+
+ // Quit an earlier call to Run(). There can be other nested RunLoops servicing
+ // the same task queue (MessageLoop); Quitting one RunLoop has no bearing on
+ // the others. Quit can be called before, during or after Run. If called
+ // before Run, Run will return immediately when called. Calling Quit after the
+ // RunLoop has already finished running has no effect.
+ //
+ // WARNING: You must NEVER assume that a call to Quit will terminate the
+ // targetted message loop. If a nested message loop continues running, the
+ // target may NEVER terminate. It is very easy to livelock (run forever) in
+ // such a case.
+ void Quit();
+
+ // Convenience method to get a closure that safely calls Quit (has no effect
+ // if the RunLoop instance is gone).
+ //
+ // Example:
+ // RunLoop run_loop;
+ // PostTask(run_loop.QuitClosure());
+ // run_loop.Run();
+ base::Closure QuitClosure();
+
+ private:
+ friend class MessageLoop;
+ friend class ::WebEngineContext;
+#if defined(OS_ANDROID)
+ // Android doesn't support the blocking MessageLoop::Run, so it calls
+ // BeforeRun and AfterRun directly.
+ friend class base::MessagePumpForUI;
+#endif
+
+#if defined(OS_IOS)
+ // iOS doesn't support the blocking MessageLoop::Run, so it calls
+ // BeforeRun directly.
+ friend class base::MessagePumpUIApplication;
+#endif
+
+ // Return false to abort the Run.
+ bool BeforeRun();
+ void AfterRun();
+
+ MessageLoop* loop_;
+
+ // WeakPtrFactory for QuitClosure safety.
+ base::WeakPtrFactory<RunLoop> weak_factory_;
+
+ // Parent RunLoop or NULL if this is the top-most RunLoop.
+ RunLoop* previous_run_loop_;
+
+#if !defined(OS_MACOSX) && !defined(OS_ANDROID)
+ MessageLoop::Dispatcher* dispatcher_;
+#endif
+
+ // Used to count how many nested Run() invocations are on the stack.
+ int run_depth_;
+
+ bool run_called_;
+ bool quit_called_;
+ bool running_;
+
+ // Used to record that QuitWhenIdle() was called on the MessageLoop, meaning
+ // that we should quit Run once it becomes idle.
+ bool quit_when_idle_received_;
+
+ DISALLOW_COPY_AND_ASSIGN(RunLoop);
+};
+
+} // namespace base
+
+#endif // BASE_RUN_LOOP_H_