xpcom/threads/nsIThreadInternal.idl

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   3 /* ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is Mozilla code.
  17  *
  18  * The Initial Developer of the Original Code is Google Inc.
  19  * Portions created by the Initial Developer are Copyright (C) 2006
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *  Darin Fisher <darin@meer.net>
  24  *
  25  * Alternatively, the contents of this file may be used under the terms of
  26  * either the GNU General Public License Version 2 or later (the "GPL"), or
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  36  *
  37  * ***** END LICENSE BLOCK ***** */
  38
  39 #include "nsIThread.idl"
  40
  41 interface nsIThreadObserver;
  42 interface nsIThreadEventFilter;
  43
  44 /**
  45  * The XPCOM thread object implements this interface, which allows a consumer
  46  * to observe dispatch activity on the thread.
  47  */
  48 [scriptable, uuid(f89b5063-b06d-42f8-bf23-4dfcf2d80d6a)]
  49 interface nsIThreadInternal : nsIThread
  50 {
  51   /**
  52    * Get/set the current thread observer (may be null).  This attribute may be
  53    * read from any thread, but must only be set on the thread corresponding to
  54    * this thread object.  The observer will be released on the thread
  55    * corresponding to this thread object after all other events have been
  56    * processed during a call to Shutdown.
  57    */
  58   attribute nsIThreadObserver observer;
  59
  60   /**
  61    * This method causes any events currently enqueued on the thread to be
  62    * suppressed until PopEventQueue is called.  Additionally, any new events
  63    * dispatched to the thread will only be processed if they are accepted by
  64    * the given filter.  If the filter is null, then new events are accepted.
  65    * Calls to PushEventQueue may be nested and must each be paired with a call
  66    * to PopEventQueue in order to restore the original state of the thread.
  67    *
  68    * @param filter
  69    *   The thread event filter to apply to dispatched events, or null to accept
  70    *   all dispatched events.
  71    */
  72   void pushEventQueue(in nsIThreadEventFilter filter);
  73
  74   /**
  75    * Revert a call to PushEventQueue.  When an event queue is popped, any
  76    * events remaining in the queue are appended to the elder queue.
  77    */
  78   void popEventQueue();
  79 };
  80
  81 /**
  82  * This interface provides the observer with hooks to implement a layered
  83  * event queue.  For example, it is possible to overlay processing events
  84  * for a GUI toolkit on top of the events for a thread:
  85  *
  86  *   var NativeQueue;
  87  *   Observer = {
  88  *     onDispatchedEvent(thread) {
  89  *       NativeQueue.signal();
  90  *     }
  91  *     onProcessNextEvent(thread, mayWait, recursionDepth) {
  92  *       if (NativeQueue.hasNextEvent())
  93  *         NativeQueue.processNextEvent();
  94  *       while (mayWait && !thread.hasPendingEvent()) {
  95  *         NativeQueue.wait();
  96  *         NativeQueue.processNextEvent();
  97  *       }
  98  *     }
  99  *   };
 100  *
 101  * NOTE: The implementation of this interface must be threadsafe.
 102  *
 103  * NOTE: It is valid to change the thread's observer during a call to an
 104  *       observer method.
 105  */
 106 [scriptable, uuid(81D0B509-F198-4417-8020-08EB4271491F)]
 107 interface nsIThreadObserver : nsISupports
 108 {
 109   /**
 110    * This method is called after an event has been dispatched to the thread.
 111    * This method may be called from any thread.
 112    *
 113    * @param thread
 114    *   The thread where the event is being dispatched.
 115    */
 116   void onDispatchedEvent(in nsIThreadInternal thread);
 117
 118   /**
 119    * This method is called (from nsIThread::ProcessNextEvent) before an event
 120    * is processed.  This method is only called on the target thread.
 121    *
 122    * @param thread
 123    *   The thread being asked to process another event.
 124    * @param mayWait
 125    *   Indicates whether or not the method is allowed to block the calling
 126    *   thread.  For example, this parameter is false during thread shutdown.
 127    * @param recursionDepth
 128    *   Indicates the number of calls to ProcessNextEvent on the call stack in
 129    *   addition to the current call.
 130    */
 131   void onProcessNextEvent(in nsIThreadInternal thread, in boolean mayWait,
 132                           in unsigned long recursionDepth);
 133
 134   /**
 135    * This method is called (from nsIThread::ProcessNextEvent) after an event
 136    * is processed.  This method is only called on the target thread.
 137    *
 138    * @param thread
 139    *   The thread that processed another event.
 140    * @param recursionDepth
 141    *   Indicates the number of calls to ProcessNextEvent on the call stack in
 142    *   addition to the current call.
 143    */
 144   void afterProcessNextEvent(in nsIThreadInternal thread,
 145                              in unsigned long recursionDepth);
 146 };
 147
 148 /**
 149  * Interface passed to the nsIThreadInternal::PushEventQueue method.
 150  */
 151 [scriptable, uuid(a0605c0b-17f5-4681-b8cd-a1cd75d42559)]
 152 interface nsIThreadEventFilter : nsISupports
 153 {
 154   /**
 155    * This method is called to determine whether or not an event may be accepted
 156    * by a "nested" event queue (see nsIThreadInternal::PushEventQueue).
 157    *
 158    * @param event
 159    *   The event being dispatched.
 160    *
 161    * WARNING: This method must not make any calls on the thread object.
 162    */
 163   [notxpcom] boolean acceptEvent(in nsIRunnable event);
 164 };