Bug 414747: Make BroadcastListener use nsWeakRef rather than strong references, just in case. r/sr=jst b3a=mconnor

content/xul/document/src/nsXULDocument.cpp

@@ -181,7 +181,7 @@ struct BroadcasterMapEntry : public PLDHashEntryHdr {
 };
 
 struct BroadcastListener {
-    nsCOMPtr<nsIDOMElement> mListener; // [OWNING], and traversed
+    nsWeakPtr mListener;
     nsCOMPtr<nsIAtom> mAttribute;
 };
 
@@ -323,34 +323,12 @@ TraverseObservers(nsIURI* aKey, nsIObserver* aData, void* aContext)
     return PL_DHASH_NEXT;
 }
 
-static PLDHashOperator PR_CALLBACK
-TraverseBroadcasters(PLDHashTable* aTable, PLDHashEntryHdr* aEntry,
-                     PRUint32 aNumber, void* aContext)
-{
-    BroadcasterMapEntry* entry =
-        static_cast<BroadcasterMapEntry*>(aEntry);
-    nsCycleCollectionTraversalCallback *cb =
-        static_cast<nsCycleCollectionTraversalCallback*>(aContext);
-
-    for (PRInt32 i = entry->mListeners.Count() - 1; i >= 0; --i) {
-        BroadcastListener *listener =
-            (BroadcastListener *)entry->mListeners[i];
-
-        cb->NoteXPCOMChild(listener->mListener);
-    }
-
-    return PL_DHASH_NEXT;
-}
-
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(nsXULDocument, nsXMLDocument)
     // XXX tmp->mForwardReferences?
     // XXX tmp->mContextStack?
 
     tmp->mElementMap.Enumerate(TraverseElement, &cb);
 
-    if (tmp->mBroadcasterMap)
-        PL_DHashTableEnumerate(tmp->mBroadcasterMap, TraverseBroadcasters, &cb);
-
     // An element will only have a template builder as long as it's in the
     // document, so we'll traverse the table here instead of from the element.
     if (tmp->mTemplateBuilderTable)
@@ -795,13 +773,13 @@ nsXULDocument::AddBroadcastListenerFor(nsIDOMElement* aBroadcaster,
     BroadcasterMapEntry* entry =
         static_cast<BroadcasterMapEntry*>
                    (PL_DHashTableOperate(mBroadcasterMap, aBroadcaster,
-                                         PL_DHASH_LOOKUP));
+                                            PL_DHASH_LOOKUP));
 
     if (PL_DHASH_ENTRY_IS_FREE(entry)) {
         entry =
             static_cast<BroadcasterMapEntry*>
                        (PL_DHashTableOperate(mBroadcasterMap, aBroadcaster,
-                                             PL_DHASH_ADD));
+                                                PL_DHASH_ADD));
 
         if (! entry)
             return NS_ERROR_OUT_OF_MEMORY;
@@ -820,7 +798,9 @@ nsXULDocument::AddBroadcastListenerFor(nsIDOMElement* aBroadcaster,
     for (PRInt32 i = entry->mListeners.Count() - 1; i >= 0; --i) {
         bl = static_cast<BroadcastListener*>(entry->mListeners[i]);
 
-        if ((bl->mListener == aListener) && (bl->mAttribute == attr))
+        nsCOMPtr<nsIDOMElement> blListener = do_QueryReferent(bl->mListener);
+
+        if ((blListener == aListener) && (bl->mAttribute == attr))
             return NS_OK;
     }
 
@@ -828,7 +808,7 @@ nsXULDocument::AddBroadcastListenerFor(nsIDOMElement* aBroadcaster,
     if (! bl)
         return NS_ERROR_OUT_OF_MEMORY;
 
-    bl->mListener  = aListener;
+    bl->mListener  = do_GetWeakReference(aListener);
     bl->mAttribute = attr;
 
     entry->mListeners.AppendElement(bl);
@@ -850,7 +830,7 @@ nsXULDocument::RemoveBroadcastListenerFor(nsIDOMElement* aBroadcaster,
     BroadcasterMapEntry* entry =
         static_cast<BroadcasterMapEntry*>
                    (PL_DHashTableOperate(mBroadcasterMap, aBroadcaster,
-                                         PL_DHASH_LOOKUP));
+                                            PL_DHASH_LOOKUP));
 
     if (PL_DHASH_ENTRY_IS_BUSY(entry)) {
         nsCOMPtr<nsIAtom> attr = do_GetAtom(aAttr);
@@ -858,7 +838,9 @@ nsXULDocument::RemoveBroadcastListenerFor(nsIDOMElement* aBroadcaster,
             BroadcastListener* bl =
                 static_cast<BroadcastListener*>(entry->mListeners[i]);
 
-            if ((bl->mListener == aListener) && (bl->mAttribute == attr)) {
+            nsCOMPtr<nsIDOMElement> blListener = do_QueryReferent(bl->mListener);
+
+            if ((blListener == aListener) && (bl->mAttribute == attr)) {
                 entry->mListeners.RemoveElementAt(i);
                 delete bl;
 
@@ -967,7 +949,7 @@ nsXULDocument::AttributeChanged(nsIDocument* aDocument,
         BroadcasterMapEntry* entry =
             static_cast<BroadcasterMapEntry*>
                        (PL_DHashTableOperate(mBroadcasterMap, domele.get(),
-                                             PL_DHASH_LOOKUP));
+                                                PL_DHASH_LOOKUP));
 
         if (PL_DHASH_ENTRY_IS_BUSY(entry)) {
             // We've got listeners: push the value.
@@ -983,8 +965,10 @@ nsXULDocument::AttributeChanged(nsIDocument* aDocument,
                 if ((bl->mAttribute == aAttribute) ||
                     (bl->mAttribute == nsGkAtoms::_asterix)) {
                     nsCOMPtr<nsIContent> listener
-                        = do_QueryInterface(bl->mListener);
-                    listenerArray.AppendObject(listener);
+                        = do_QueryReferent(bl->mListener);
+                    if (listener) {
+                      listenerArray.AppendObject(listener);
+                    }
                 }
             }