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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+// Copyright (c) 2008 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_MESSAGE_PUMP_GLIB_H_
+#define BASE_MESSAGE_PUMP_GLIB_H_
+
+#include "base/message_pump.h"
+#include "base/observer_list.h"
+#include "base/time.h"
+#include "mozilla/UniquePtr.h"
+#include "mozilla/Atomics.h"
+
+typedef union _GdkEvent GdkEvent;
+typedef struct _GMainContext GMainContext;
+typedef struct _GPollFD GPollFD;
+typedef struct _GSource GSource;
+
+namespace base {
+
+// This class implements a MessagePump needed for TYPE_UI MessageLoops on
+// OS_LINUX platforms using GLib.
+class MessagePumpForUI : public MessagePump {
+ public:
+ // Observer is notified prior to a GdkEvent event being dispatched. As
+ // Observers are notified of every change, they have to be FAST!
+ class Observer {
+ public:
+ virtual ~Observer() {}
+
+ // This method is called before processing a message.
+ virtual void WillProcessEvent(GdkEvent* event) = 0;
+
+ // This method is called after processing a message.
+ virtual void DidProcessEvent(GdkEvent* event) = 0;
+ };
+
+ // Dispatcher is used during a nested invocation of Run to dispatch events.
+ // If Run is invoked with a non-NULL Dispatcher, MessageLoop does not
+ // dispatch events (or invoke gtk_main_do_event), rather every event is
+ // passed to Dispatcher's Dispatch method for dispatch. It is up to the
+ // Dispatcher to dispatch, or not, the event.
+ //
+ // The nested loop is exited by either posting a quit, or returning false
+ // from Dispatch.
+ class Dispatcher {
+ public:
+ virtual ~Dispatcher() {}
+ // Dispatches the event. If true is returned processing continues as
+ // normal. If false is returned, the nested loop exits immediately.
+ virtual bool Dispatch(GdkEvent* event) = 0;
+ };
+
+ MessagePumpForUI();
+ virtual ~MessagePumpForUI();
+
+ // Like MessagePump::Run, but GdkEvent objects are routed through dispatcher.
+ virtual void RunWithDispatcher(Delegate* delegate, Dispatcher* dispatcher);
+
+ virtual void Run(Delegate* delegate) { RunWithDispatcher(delegate, NULL); }
+ virtual void Quit();
+ virtual void ScheduleWork();
+ virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time);
+
+ // Internal methods used for processing the pump callbacks. They are
+ // public for simplicity but should not be used directly. HandlePrepare
+ // is called during the prepare step of glib, and returns a timeout that
+ // will be passed to the poll. HandleCheck is called after the poll
+ // has completed, and returns whether or not HandleDispatch should be called.
+ // HandleDispatch is called if HandleCheck returned true.
+ int HandlePrepare();
+ bool HandleCheck();
+ void HandleDispatch();
+
+ // Adds an Observer, which will start receiving notifications immediately.
+ void AddObserver(Observer* observer);
+
+ // Removes an Observer. It is safe to call this method while an Observer is
+ // receiving a notification callback.
+ void RemoveObserver(Observer* observer);
+
+ private:
+ // We may make recursive calls to Run, so we save state that needs to be
+ // separate between them in this structure type.
+ struct RunState {
+ Delegate* delegate;
+ Dispatcher* dispatcher;
+
+ // Used to flag that the current Run() invocation should return ASAP.
+ bool should_quit;
+
+ // Used to count how many Run() invocations are on the stack.
+ int run_depth;
+
+ // This keeps the state of whether the pump got signaled that there was new
+ // work to be done. Since we eat the message on the wake up pipe as soon as
+ // we get it, we keep that state here to stay consistent.
+ bool has_work;
+ };
+
+ // Invoked from EventDispatcher. Notifies all observers we're about to
+ // process an event.
+ void WillProcessEvent(GdkEvent* event);
+
+ // Invoked from EventDispatcher. Notifies all observers we processed an
+ // event.
+ void DidProcessEvent(GdkEvent* event);
+
+ // Callback prior to gdk dispatching an event.
+ static void EventDispatcher(GdkEvent* event, void* data);
+
+ RunState* state_;
+
+ // This is a GLib structure that we can add event sources to. We use the
+ // default GLib context, which is the one to which all GTK events are
+ // dispatched.
+ GMainContext* context_;
+
+ // This is the time when we need to do delayed work.
+ TimeTicks delayed_work_time_;
+
+ // The work source. It is shared by all calls to Run and destroyed when
+ // the message pump is destroyed.
+ GSource* work_source_;
+
+ // We use a wakeup pipe to make sure we'll get out of the glib polling phase
+ // when another thread has scheduled us to do some work. There is a glib
+ // mechanism g_main_context_wakeup, but this won't guarantee that our event's
+ // Dispatch() will be called.
+ int wakeup_pipe_read_;
+ int wakeup_pipe_write_;
+ // Use an autoptr to avoid needing the definition of GPollFD in the header.
+ mozilla::UniquePtr<GPollFD> wakeup_gpollfd_;
+
+ mozilla::Atomic<bool> pipe_full_;
+
+ // List of observers.
+ ObserverList<Observer> observers_;
+
+ DISALLOW_COPY_AND_ASSIGN(MessagePumpForUI);
+};
+
+} // namespace base
+
+#endif // BASE_MESSAGE_PUMP_GLIB_H_