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
  27  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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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.
  55    */
  56   attribute nsIThreadObserver observer;
  57
  58   /**
  59    * This method causes any events currently enqueued on the thread to be
  60    * suppressed until PopEventQueue is called.  Additionally, any new events
  61    * dispatched to the thread will only be processed if they are accepted by
  62    * the given filter.  If the filter is null, then new events are accepted.
  63    * Calls to PushEventQueue may be nested and must each be paired with a call
  64    * to PopEventQueue in order to restore the original state of the thread.
  65    *
  66    * @param filter
  67    *   The thread event filter to apply to dispatched events, or null to accept
  68    *   all dispatched events.
  69    */
  70   void pushEventQueue(in nsIThreadEventFilter filter);
  71
  72   /**
  73    * Revert a call to PushEventQueue.  When an event queue is popped, any
  74    * events remaining in the queue are appended to the elder queue.
  75    */
  76   void popEventQueue();
  77 };
  78
  79 /**
  80  * This interface provides the observer with hooks to implement a layered
  81  * event queue.  For example, it is possible to overlay processing events
  82  * for a GUI toolkit on top of the events for a thread:
  83  *
  84  *   var NativeQueue;
  85  *   Observer = {
  86  *     onDispatchedEvent(thread) {
  87  *       NativeQueue.signal();
  88  *     }
  89  *     onProcessNextEvent(thread, mayWait, recursionDepth) {
  90  *       if (NativeQueue.hasNextEvent())
  91  *         NativeQueue.processNextEvent();
  92  *       while (mayWait && !thread.hasPendingEvent()) {
  93  *         NativeQueue.wait();
  94  *         NativeQueue.processNextEvent();
  95  *       }
  96  *     }
  97  *   };
  98  *
  99  * NOTE: The implementation of this interface must be threadsafe.
 100  *
 101  * NOTE: It is valid to change the thread's observer during a call to an
 102  *       observer method.
 103  */
 104 [scriptable, uuid(81D0B509-F198-4417-8020-08EB4271491F)]
 105 interface nsIThreadObserver : nsISupports
 106 {
 107   /**
 108    * This method is called after an event has been dispatched to the thread.
 109    * This method may be called from any thread.
 110    *
 111    * @param thread
 112    *   The thread where the event is being dispatched.
 113    */
 114   void onDispatchedEvent(in nsIThreadInternal thread);
 115
 116   /**
 117    * This method is called (from nsIThread::ProcessNextEvent) before an event
 118    * is processed.  This method is only called on the target thread.
 119    *
 120    * @param thread
 121    *   The thread being asked to process another event.
 122    * @param mayWait
 123    *   Indicates whether or not the method is allowed to block the calling
 124    *   thread.  For example, this parameter is false during thread shutdown.
 125    * @param recursionDepth
 126    *   Indicates the number of calls to ProcessNextEvent on the call stack in
 127    *   addition to the current call.
 128    */
 129   void onProcessNextEvent(in nsIThreadInternal thread, in boolean mayWait,
 130                           in unsigned long recursionDepth);
 131
 132   /**
 133    * This method is called (from nsIThread::ProcessNextEvent) after an event
 134    * is processed.  This method is only called on the target thread.
 135    *
 136    * @param thread
 137    *   The thread that processed another event.
 138    * @param recursionDepth
 139    *   Indicates the number of calls to ProcessNextEvent on the call stack in
 140    *   addition to the current call.
 141    */
 142   void afterProcessNextEvent(in nsIThreadInternal thread,
 143                              in unsigned long recursionDepth);
 144 };
 145
 146 /**
 147  * Interface passed to the nsIThreadInternal::PushEventQueue method.
 148  */
 149 [scriptable, uuid(a0605c0b-17f5-4681-b8cd-a1cd75d42559)]
 150 interface nsIThreadEventFilter : nsISupports
 151 {
 152   /**
 153    * This method is called to determine whether or not an event may be accepted
 154    * by a "nested" event queue (see nsIThreadInternal::PushEventQueue).
 155    *
 156    * @param event
 157    *   The event being dispatched.
 158    *
 159    * WARNING: This method must not make any calls on the thread object.
 160    */
 161   [notxpcom] boolean acceptEvent(in nsIRunnable event);
 162 };