Bug 737075 - unmark gray strongly held observers implemented in JS. r=bsmedberg, smaug

content/base/src/nsCCUncollectableMarker.cpp

@@ -62,6 +62,7 @@
 #include "nsFrameLoader.h"
 #include "nsGenericElement.h"
 #include "xpcpublic.h"
+#include "nsObserverService.h"
 
 static bool sInited = 0;
 PRUint32 nsCCUncollectableMarker::sGeneration = 0;
@@ -373,6 +374,10 @@ nsCCUncollectableMarker::Observe(nsISupports* aSubject, const char* aTopic,
   if (cleanupJS) {
     nsContentUtils::UnmarkGrayJSListenersInCCGenerationDocuments(sGeneration);
     MarkMessageManagers();
+
+    nsCOMPtr<nsIObserverService> obs = mozilla::services::GetObserverService();
+    static_cast<nsObserverService *>(obs.get())->UnmarkGrayStrongObservers();
+
     previousWasJSCleanup = true;
   } else if (previousWasJSCleanup) {
     previousWasJSCleanup = false;

xpcom/ds/Makefile.in

@@ -101,6 +101,7 @@ EXPORTS		= \
 		nsIByteBuffer.h \
 		nsIUnicharBuffer.h \
 		nsMathUtils.h \
+		nsObserverList.h \
 		nsObserverService.h \
 		nsStaticNameTable.h \
 		nsStaticAtom.h \

xpcom/ds/nsObserverList.cpp

@@ -40,6 +40,7 @@
 #include "nsAutoPtr.h"
 #include "nsCOMArray.h"
 #include "nsISimpleEnumerator.h"
+#include "xpcpublic.h"
 
 nsresult
 nsObserverList::AddObserver(nsIObserver* anObserver, bool ownsWeak)
@@ -131,6 +132,16 @@ nsObserverList::NotifyObservers(nsISupports *aSubject,
     }
 }
 
+void
+nsObserverList::UnmarkGrayStrongObservers()
+{
+    for (PRUint32 i = 0; i < mObservers.Length(); ++i) {
+        if (!mObservers[i].isWeakRef) {
+            xpc_TryUnmarkWrappedGrayObject(mObservers[i].asObserver());
+        }
+    }
+}
+
 NS_IMPL_ISUPPORTS1(nsObserverEnumerator, nsISimpleEnumerator)
 
 nsObserverEnumerator::nsObserverEnumerator(nsObserverList* aObserverList)

xpcom/ds/nsObserverList.h

@@ -91,6 +91,10 @@ public:
   // The array is filled in last-added-first order.
   void FillObserverArray(nsCOMArray<nsIObserver> &aArray);
 
+  // Unmark any strongly held observers implemented in JS so the cycle
+  // collector will not traverse them.
+  void UnmarkGrayStrongObservers();
+
 private:
   nsTArray<ObserverRef> mObservers;
 };

xpcom/ds/nsObserverService.cpp

@@ -190,3 +190,21 @@ NS_IMETHODIMP nsObserverService::NotifyObservers(nsISupports *aSubject,
     return NS_OK;
 }
 
+static PLDHashOperator
+UnmarkGrayObserverEntry(nsObserverList* aObserverList, void* aClosure)
+{
+    if (aObserverList) {
+        aObserverList->UnmarkGrayStrongObservers();
+    }
+    return PL_DHASH_NEXT;
+}
+
+NS_IMETHODIMP
+nsObserverService::UnmarkGrayStrongObservers()
+{
+    NS_ENSURE_VALIDCALL
+
+    mObserverTopicTable.EnumerateEntries(UnmarkGrayObserverEntry, nsnull);
+
+    return NS_OK;
+}

xpcom/ds/nsObserverService.h

@@ -62,6 +62,10 @@ public:
   static nsresult
   Create(nsISupports* outer, const nsIID& aIID, void* *aInstancePtr);
 
+  // Unmark any strongly held observers implemented in JS so the cycle
+  // collector will not traverse them.
+  NS_IMETHOD UnmarkGrayStrongObservers();
+
 private:
   ~nsObserverService(void);