Fix revokeEvents to reliably revoke them. Bug 284389, r=darin, sr=dbaron,

a=asa

view/src/nsViewManager.cpp

@@ -358,14 +358,6 @@ static void* PR_CALLBACK HandlePLEvent(PLEvent* aEvent)
   NS_ASSERTION(nsnull != aEvent,"Event is null");
   nsViewManagerEvent *event = NS_STATIC_CAST(nsViewManagerEvent*, aEvent);
 
-  // Search for valid view manager before trying to access it.  This
-  // is working around a bug in RevokeEvents.
-  const nsVoidArray *vmArray = nsViewManager::GetViewManagerArray();
-  if (!vmArray || vmArray->IndexOf(event->ViewManager()) == -1) {
-    NS_ERROR("RevokeEvents is buggy.  Fix it!");
-    return nsnull;
-  }
-
   event->HandleEvent();
   return nsnull;
 }

xpcom/threads/nsEventQueue.cpp

@@ -346,13 +346,12 @@ nsEventQueueImpl::ExitMonitor()
 NS_IMETHODIMP
 nsEventQueueImpl::RevokeEvents(void* owner)
 {
-  PL_RevokeEvents(mEventQueue, owner);
-  if (mElderQueue) {
-    nsCOMPtr<nsIEventQueue> elder(do_QueryInterface(mElderQueue));
-    if (elder)
-      elder->RevokeEvents(owner);
-  }
-  return NS_OK;
+  nsCOMPtr<nsIEventQueue> youngest;
+  GetYoungest(getter_AddRefs(youngest));
+  NS_ASSERTION(youngest, "How could we possibly not have a youngest queue?");
+  nsCOMPtr<nsPIEventQueueChain> youngestAsChain(do_QueryInterface(youngest));
+  NS_ASSERTION(youngestAsChain, "RevokeEvents won't work; expect crashes");
+  return youngestAsChain->RevokeEventsInternal(owner);
 }
 
 
@@ -657,3 +656,12 @@ nsEventQueueImpl::GetElder(nsIEventQueue **aQueue)
   return mElderQueue->QueryInterface(NS_GET_IID(nsIEventQueue), (void**)&aQueue);
 }
 
+NS_IMETHODIMP
+nsEventQueueImpl::RevokeEventsInternal(void* aOwner)
+{
+  PL_RevokeEvents(mEventQueue, aOwner);
+  if (mElderQueue) {
+    mElderQueue->RevokeEventsInternal(aOwner);
+  }
+  return NS_OK;
+}

xpcom/threads/nsEventQueue.h

@@ -64,6 +64,7 @@ public:
     NS_IMETHOD GetYounger(nsIEventQueue **aQueue);
     NS_IMETHOD SetElder(nsPIEventQueueChain *aQueue);
     NS_IMETHOD GetElder(nsIEventQueue **aQueue);
+    NS_IMETHOD RevokeEventsInternal(void* aOwner);
 
 private:
     ~nsEventQueueImpl();

xpcom/threads/nsIEventQueue.idl

@@ -95,6 +95,10 @@ interface nsIEventQueue : nsIEventTarget
     void enterMonitor();
     void exitMonitor();
 
+    /**
+     * Revoke events in this event queue and all other event queues
+     * for this thread that have |owner| as the event owner.
+     */
     [noscript] void revokeEvents(in voidPtr owner);
     [noscript] PLEventQueuePtr getPLEventQueue();
 

xpcom/threads/nsPIEventQueueChain.h

@@ -74,8 +74,10 @@ public:
 
     /**
      * Fetch (and addref) the youngest member of the chain which is
-     * still accepting events, or at least still contains events in need
-     * of processing.
+     * still accepting events.  Note that there may be still younger
+     * queues which still contain events in need of processing but
+     * have already stopped accepting new events.
+     *
      * @param *aQueue the youngest such queue. aQueue must not be null.
      *        *aQueue will be returned null, if no such queue is found.
      * @return error indication -- can be NS_OK even if *aQueue is 0
@@ -87,6 +89,13 @@ public:
 
     NS_IMETHOD SetElder(nsPIEventQueueChain *aQueue) = 0;
     NS_IMETHOD GetElder(nsIEventQueue **aQueue) = 0;
+
+    /**
+     * Revoke events for aOwner in this queue and all elder queues.  This
+     * differs in behavior from nsIEventQueue::RevokeEvents in that that
+     * method revokes events in younger queues too.
+     */
+    NS_IMETHOD RevokeEventsInternal(void* aOwner) = 0;
 };
 
 #endif /* nsPIEventQueueChain_h___ */