LCOV - code coverage report
Current view: directory - objdir/dist/include/mozilla/net - ChannelEventQueue.h (source / functions) Found Hit Coverage
Test: app.info Lines: 38 0 0.0 %
Date: 2012-06-02 Functions: 14 0 0.0 %

       1                 : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
       2                 :  * vim: set sw=2 ts=8 et tw=80 :
       3                 :  */
       4                 : /* ***** BEGIN LICENSE BLOCK *****
       5                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       6                 :  *
       7                 :  * The contents of this file are subject to the Mozilla Public License Version
       8                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       9                 :  * the License. You may obtain a copy of the License at:
      10                 :  * http://www.mozilla.org/MPL/
      11                 :  *
      12                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      13                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      14                 :  * for the specific language governing rights and limitations under the
      15                 :  * License.
      16                 :  *
      17                 :  * The Original Code is Mozilla Code.
      18                 :  *
      19                 :  * The Initial Developer of the Original Code is
      20                 :  *   The Mozilla Foundation
      21                 :  * Portions created by the Initial Developer are Copyright (C) 2010
      22                 :  * the Initial Developer. All Rights Reserved.
      23                 :  *
      24                 :  * Contributor(s):
      25                 :  *   Josh Matthews <josh@joshmatthews.net> (initial developer)
      26                 :  *   Jason Duell <jduell.mcbugs@gmail.com>
      27                 :  *
      28                 :  * Alternatively, the contents of this file may be used under the terms of
      29                 :  * either the GNU General Public License Version 2 or later (the "GPL"), or
      30                 :  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      31                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      32                 :  * of those above. If you wish to allow use of your version of this file only
      33                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      34                 :  * use your version of this file under the terms of the MPL, indicate your
      35                 :  * decision by deleting the provisions above and replace them with the notice
      36                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      37                 :  * the provisions above, a recipient may use your version of this file under
      38                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      39                 :  *
      40                 :  * ***** END LICENSE BLOCK ***** */
      41                 : 
      42                 : #ifndef mozilla_net_ChannelEventQueue_h
      43                 : #define mozilla_net_ChannelEventQueue_h
      44                 : 
      45                 : #include <nsTArray.h>
      46                 : #include <nsAutoPtr.h>
      47                 : 
      48                 : class nsISupports;
      49                 : 
      50                 : namespace mozilla {
      51                 : namespace net {
      52                 : 
      53                 : class ChannelEvent
      54                 : {
      55                 :  public:
      56               0 :   ChannelEvent() { MOZ_COUNT_CTOR(ChannelEvent); }
      57               0 :   virtual ~ChannelEvent() { MOZ_COUNT_DTOR(ChannelEvent); }
      58                 :   virtual void Run() = 0;
      59                 : };
      60                 : 
      61                 : // Workaround for Necko re-entrancy dangers. We buffer IPDL messages in a
      62                 : // queue if still dispatching previous one(s) to listeners/observers.
      63                 : // Otherwise synchronous XMLHttpRequests and/or other code that spins the
      64                 : // event loop (ex: IPDL rpc) could cause listener->OnDataAvailable (for
      65                 : // instance) to be dispatched and called before mListener->OnStartRequest has
      66                 : // completed.
      67                 : 
      68                 : class AutoEventEnqueuerBase;
      69                 : 
      70                 : class ChannelEventQueue
      71                 : {
      72                 :  public:
      73               0 :   ChannelEventQueue(nsISupports *owner)
      74                 :     : mForced(false)
      75                 :     , mSuspended(false)
      76                 :     , mFlushing(false)
      77               0 :     , mOwner(owner) {}
      78                 : 
      79               0 :   ~ChannelEventQueue() {}
      80                 : 
      81                 :   // Checks to determine if an IPDL-generated channel event can be processed
      82                 :   // immediately, or needs to be queued using Enqueue().
      83                 :   inline bool ShouldEnqueue();
      84                 : 
      85                 :   // Puts IPDL-generated channel event into queue, to be run later
      86                 :   // automatically when EndForcedQueueing and/or Resume is called.
      87                 :   inline void Enqueue(ChannelEvent* callback);
      88                 : 
      89                 :   // After StartForcedQueueing is called, ShouldEnqueue() will return true and
      90                 :   // no events will be run/flushed until EndForcedQueueing is called.
      91                 :   // - Note: queueing may still be required after EndForcedQueueing() (if the
      92                 :   //   queue is suspended, etc):  always call ShouldEnqueue() to determine
      93                 :   //   whether queueing is needed.
      94                 :   inline void StartForcedQueueing();
      95                 :   inline void EndForcedQueueing();
      96                 : 
      97                 :   // Suspend/resume event queue.  ShouldEnqueue() will return true and no events
      98                 :   // will be run/flushed until resume is called.  These should be called when
      99                 :   // the channel owning the event queue is suspended/resumed.
     100                 :   // - Note: these suspend/resume functions are NOT meant to be called
     101                 :   //   recursively: call them only at initial suspend, and actual resume).
     102                 :   // - Note: Resume flushes the queue and invokes any pending callbacks
     103                 :   //   immediately--caller must arrange any needed asynchronicity vis a vis
     104                 :   //   the channel's own Resume() method.
     105                 :   inline void Suspend();
     106                 :   inline void Resume();
     107                 : 
     108                 :  private:
     109                 :   inline void MaybeFlushQueue();
     110                 :   void FlushQueue();
     111                 : 
     112                 :   nsTArray<nsAutoPtr<ChannelEvent> > mEventQueue;
     113                 : 
     114                 :   bool mForced;
     115                 :   bool mSuspended;
     116                 :   bool mFlushing;
     117                 : 
     118                 :   // Keep ptr to avoid refcount cycle: only grab ref during flushing.
     119                 :   nsISupports *mOwner;
     120                 : 
     121                 :   friend class AutoEventEnqueuer;
     122                 : };
     123                 : 
     124                 : inline bool
     125               0 : ChannelEventQueue::ShouldEnqueue()
     126                 : {
     127               0 :   bool answer =  mForced || mSuspended || mFlushing;
     128                 : 
     129               0 :   NS_ABORT_IF_FALSE(answer == true || mEventQueue.IsEmpty(),
     130                 :                     "Should always enqueue if ChannelEventQueue not empty");
     131                 : 
     132               0 :   return answer;
     133                 : }
     134                 : 
     135                 : inline void
     136               0 : ChannelEventQueue::Enqueue(ChannelEvent* callback)
     137                 : {
     138               0 :   mEventQueue.AppendElement(callback);
     139               0 : }
     140                 : 
     141                 : inline void
     142               0 : ChannelEventQueue::StartForcedQueueing()
     143                 : {
     144               0 :   mForced = true;
     145               0 : }
     146                 : 
     147                 : inline void
     148               0 : ChannelEventQueue::EndForcedQueueing()
     149                 : {
     150               0 :   mForced = false;
     151               0 :   MaybeFlushQueue();
     152               0 : }
     153                 : 
     154                 : inline void
     155               0 : ChannelEventQueue::Suspend()
     156                 : {
     157               0 :   NS_ABORT_IF_FALSE(!mSuspended,
     158                 :                     "ChannelEventQueue::Suspend called recursively");
     159                 : 
     160               0 :   mSuspended = true;
     161               0 : }
     162                 : 
     163                 : inline void
     164               0 : ChannelEventQueue::Resume()
     165                 : {
     166               0 :   NS_ABORT_IF_FALSE(mSuspended,
     167                 :                     "ChannelEventQueue::Resume called when not suspended!");
     168                 : 
     169               0 :   mSuspended = false;
     170               0 :   MaybeFlushQueue();
     171               0 : }
     172                 : 
     173                 : inline void
     174               0 : ChannelEventQueue::MaybeFlushQueue()
     175                 : {
     176                 :   // Don't flush if forced queuing on, we're already being flushed, or
     177                 :   // suspended, or there's nothing to flush
     178               0 :   if (!mForced && !mFlushing && !mSuspended && !mEventQueue.IsEmpty())
     179               0 :     FlushQueue();
     180               0 : }
     181                 : 
     182                 : // Ensures that ShouldEnqueue() will be true during its lifetime (letting
     183                 : // caller know incoming IPDL msgs should be queued). Flushes the queue when it
     184                 : // goes out of scope.
     185                 : class AutoEventEnqueuer
     186                 : {
     187                 :  public:
     188               0 :   AutoEventEnqueuer(ChannelEventQueue &queue) : mEventQueue(queue) {
     189               0 :     mEventQueue.StartForcedQueueing();
     190               0 :   }
     191               0 :   ~AutoEventEnqueuer() {
     192               0 :     mEventQueue.EndForcedQueueing();
     193               0 :   }
     194                 :  private:
     195                 :   ChannelEventQueue &mEventQueue;
     196                 : };
     197                 : 
     198                 : }
     199                 : }
     200                 : 
     201                 : #endif

Generated by: LCOV version 1.7