1 /* -*- Mode: c++; tab-width: 2; indent-tabs-mode: nil; -*- */
2 /* This Source Code Form is subject to the terms of the Mozilla Public
3 * License, v. 2.0. If a copy of the MPL was not distributed with this
4 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6 #ifndef nsBaseAppShell_h__
7 #define nsBaseAppShell_h__
9 #include "mozilla/Atomics.h"
10 #include "nsIAppShell.h"
11 #include "nsIThreadInternal.h"
12 #include "nsIObserver.h"
13 #include "nsIRunnable.h"
19 * A singleton that manages the UI thread's event queue. Subclass this class
20 * to enable platform-specific event queue support.
22 class nsBaseAppShell
: public nsIAppShell
,
23 public nsIThreadObserver
,
26 NS_DECL_THREADSAFE_ISUPPORTS
29 NS_DECL_NSITHREADOBSERVER
35 * Called by subclasses. Reset the internal timezone when the user's system
38 static void OnSystemTimezoneChange();
41 virtual ~nsBaseAppShell();
44 * This method is called by subclasses when the app shell singleton is
50 * Called by subclasses from a native event. See ScheduleNativeEventCallback.
52 void NativeEventCallback();
55 * Make a decision as to whether or not NativeEventCallback will
56 * trigger gecko event processing when there are pending gecko
59 virtual void DoProcessMoreGeckoEvents();
62 * Implemented by subclasses. Invoke NativeEventCallback from a native
63 * event. This method may be called on any thread.
65 virtual void ScheduleNativeEventCallback() = 0;
68 * Implemented by subclasses. Process the next native event. Only wait for
69 * the next native event if mayWait is true. This method is only called on
70 * the main application thread.
73 * If "true", then this method may wait if necessary for the next available
74 * native event. DispatchNativeEvent may be called to unblock a call to
75 * ProcessNextNativeEvent that is waiting.
77 * This method returns "true" if a native event was processed.
79 virtual bool ProcessNextNativeEvent(bool mayWait
) = 0;
81 int32_t mSuspendNativeCount
;
82 uint32_t mEventloopNestingLevel
;
85 bool DoProcessNextNativeEvent(bool mayWait
);
87 bool DispatchDummyEvent(nsIThread
* target
);
89 void IncrementEventloopNestingLevel();
90 void DecrementEventloopNestingLevel();
92 nsCOMPtr
<nsIRunnable
> mDummyEvent
;
94 * mBlockedWait points back to a slot that controls the wait loop in
95 * an outer OnProcessNextEvent invocation. Nested calls always set
96 * it to false to unblock an outer loop, since all events may
97 * have been consumed by the inner event loop(s).
101 mozilla::Atomic
<bool> mNativeEventPending
;
102 PRIntervalTime mStarvationDelay
;
103 PRIntervalTime mSwitchTime
;
104 PRIntervalTime mLastNativeEventTime
;
105 enum EventloopNestingState
{
106 eEventloopNone
, // top level thread execution
107 eEventloopXPCOM
, // innermost native event loop is ProcessNextNativeEvent
108 eEventloopOther
// innermost native event loop is a native library/plugin
111 EventloopNestingState mEventloopNestingState
;
115 * mBlockNativeEvent blocks the appshell from processing native events.
116 * It is set to true while a nested native event loop (eEventloopOther)
117 * is processing gecko events in NativeEventCallback(), thus queuing up
118 * native events until we return to that loop (bug 420148).
119 * We force mBlockNativeEvent to false in case handling one of the gecko
120 * events spins up a nested XPCOM event loop (eg. modal window) which would
121 * otherwise lead to a "deadlock" where native events aren't processed at all.
123 bool mBlockNativeEvent
;
125 * Tracks whether we have processed any gecko events in NativeEventCallback so
126 * that we can avoid erroneously entering a blocking loop waiting for gecko
127 * events to show up during OnProcessNextEvent. This is required because on
128 * OS X ProcessGeckoEvents may be invoked inside the context of
129 * ProcessNextNativeEvent and may result in NativeEventCallback being invoked
130 * and in turn invoking NS_ProcessPendingEvents. Because
131 * ProcessNextNativeEvent may be invoked prior to the NS_HasPendingEvents
132 * waiting loop, this is the only way to make the loop aware that events may
133 * have been processed.
135 * This variable is set to false in OnProcessNextEvent prior to the first
136 * call to DoProcessNextNativeEvent. It is set to true by
137 * NativeEventCallback after calling NS_ProcessPendingEvents.
139 bool mProcessedGeckoEvents
;
142 #endif // nsBaseAppShell_h__