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/* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef nsBaseAppShell_h__
#define nsBaseAppShell_h__
#include "mozilla/Atomics.h"
#include "nsIAppShell.h"
#include "nsIThreadInternal.h"
#include "nsIObserver.h"
#include "nsIRunnable.h"
#include "nsCOMPtr.h"
#include "nsTArray.h"
#include "prinrval.h"
* A singleton that manages the UI thread's event queue. Subclass this class
* to enable platform-specific event queue support.
class nsBaseAppShell : public nsIAppShell,
public nsIThreadObserver,
public nsIObserver {
* Called by subclasses. Reset the internal timezone when the user's system
* timezone changes.
static void OnSystemTimezoneChange();
virtual ~nsBaseAppShell();
* This method is called by subclasses when the app shell singleton is
* instantiated.
nsresult Init();
* Called by subclasses from a native event. See ScheduleNativeEventCallback.
void NativeEventCallback();
* Make a decision as to whether or not NativeEventCallback will
* trigger gecko event processing when there are pending gecko
* events.
virtual void DoProcessMoreGeckoEvents();
* Implemented by subclasses. Invoke NativeEventCallback from a native
* event. This method may be called on any thread.
virtual void ScheduleNativeEventCallback() = 0;
* Implemented by subclasses. Process the next native event. Only wait for
* the next native event if mayWait is true. This method is only called on
* the main application thread.
* @param mayWait
* If "true", then this method may wait if necessary for the next available
* native event. DispatchNativeEvent may be called to unblock a call to
* ProcessNextNativeEvent that is waiting.
* @return
* This method returns "true" if a native event was processed.
virtual bool ProcessNextNativeEvent(bool mayWait) = 0;
int32_t mSuspendNativeCount;
uint32_t mEventloopNestingLevel;
bool DoProcessNextNativeEvent(bool mayWait);
bool DispatchDummyEvent(nsIThread* target);
void IncrementEventloopNestingLevel();
void DecrementEventloopNestingLevel();
nsCOMPtr<nsIRunnable> mDummyEvent;
* mBlockedWait points back to a slot that controls the wait loop in
* an outer OnProcessNextEvent invocation. Nested calls always set
* it to false to unblock an outer loop, since all events may
* have been consumed by the inner event loop(s).
bool* mBlockedWait;
mozilla::Atomic<bool> mNativeEventPending;
PRIntervalTime mGeckoTaskBurstStartTime;
PRIntervalTime mLastNativeEventTime;
enum EventloopNestingState {
eEventloopNone, // top level thread execution
eEventloopXPCOM, // innermost native event loop is ProcessNextNativeEvent
eEventloopOther // innermost native event loop is a native library/plugin
// etc
EventloopNestingState mEventloopNestingState;
bool mRunning;
bool mExiting;
* mBlockNativeEvent blocks the appshell from processing native events.
* It is set to true while a nested native event loop (eEventloopOther)
* is processing gecko events in NativeEventCallback(), thus queuing up
* native events until we return to that loop (bug 420148).
* We force mBlockNativeEvent to false in case handling one of the gecko
* events spins up a nested XPCOM event loop (eg. modal window) which would
* otherwise lead to a "deadlock" where native events aren't processed at all.
bool mBlockNativeEvent;
* Tracks whether we have processed any gecko events in NativeEventCallback so
* that we can avoid erroneously entering a blocking loop waiting for gecko
* events to show up during OnProcessNextEvent. This is required because on
* OS X ProcessGeckoEvents may be invoked inside the context of
* ProcessNextNativeEvent and may result in NativeEventCallback being invoked
* and in turn invoking NS_ProcessPendingEvents. Because
* ProcessNextNativeEvent may be invoked prior to the NS_HasPendingEvents
* waiting loop, this is the only way to make the loop aware that events may
* have been processed.
* This variable is set to false in OnProcessNextEvent prior to the first
* call to DoProcessNextNativeEvent. It is set to true by
* NativeEventCallback after calling NS_ProcessPendingEvents.
bool mProcessedGeckoEvents;
#endif // nsBaseAppShell_h__