Bug 1380397 - Use PersistentRooted to implement XPCJSObjectHolder r=mccr8

js/xpconnect/src/XPCConvert.cpp

@@ -729,13 +729,13 @@ XPCConvert::JSData2Native(void* d, HandleValue s,
 }
 
 static inline bool
-CreateHolderIfNeeded(HandleObject obj, MutableHandleValue d,
+CreateHolderIfNeeded(JSContext* cx, HandleObject obj, MutableHandleValue d,
                      nsIXPConnectJSObjectHolder** dest)
 {
     if (dest) {
         if (!obj)
             return false;
-        RefPtr<XPCJSObjectHolder> objHolder = new XPCJSObjectHolder(obj);
+        RefPtr<XPCJSObjectHolder> objHolder = new XPCJSObjectHolder(cx, obj);
         objHolder.forget(dest);
     }
 
@@ -796,7 +796,7 @@ XPCConvert::NativeInterface2JSObject(MutableHandleValue d,
     if (flat) {
         if (allowNativeWrapper && !JS_WrapObject(cx, &flat))
             return false;
-        return CreateHolderIfNeeded(flat, d, dest);
+        return CreateHolderIfNeeded(cx, flat, d, dest);
     }
 
     if (iid->Equals(NS_GET_IID(nsISupports))) {
@@ -808,7 +808,7 @@ XPCConvert::NativeInterface2JSObject(MutableHandleValue d,
             flat = promise->PromiseObj();
             if (!JS_WrapObject(cx, &flat))
                 return false;
-            return CreateHolderIfNeeded(flat, d, dest);
+            return CreateHolderIfNeeded(cx, flat, d, dest);
         }
     }
 
@@ -867,7 +867,7 @@ XPCConvert::NativeInterface2JSObject(MutableHandleValue d,
         } else {
             if (!flat)
                 return false;
-            RefPtr<XPCJSObjectHolder> objHolder = new XPCJSObjectHolder(flat);
+            RefPtr<XPCJSObjectHolder> objHolder = new XPCJSObjectHolder(cx, flat);
             objHolder.forget(dest);
         }
     }

js/xpconnect/src/XPCInlines.h

@@ -25,12 +25,6 @@ XPCJSRuntime::AddWrappedJSRoot(nsXPCWrappedJS* wrappedJS)
     wrappedJS->AddToRootSet(&mWrappedJSRoots);
 }
 
-inline void
-XPCJSRuntime::AddObjectHolderRoot(XPCJSObjectHolder* holder)
-{
-    holder->AddToRootSet(&mObjectHolderRoots);
-}
-
 /***************************************************************************/
 
 inline bool

js/xpconnect/src/XPCJSRuntime.cpp

@@ -629,12 +629,6 @@ void XPCJSRuntime::TraceNativeBlackRoots(JSTracer* trc)
             roots->TraceJSAll(trc);
     }
 
-    // XPCJSObjectHolders don't participate in cycle collection, so always
-    // trace them here.
-    XPCRootSetElem* e;
-    for (e = mObjectHolderRoots; e; e = e->GetNextRoot())
-        static_cast<XPCJSObjectHolder*>(e)->TraceJS(trc);
-
     JSContext* cx = XPCJSContext::Get()->Context();
     dom::TraceBlackJS(trc, JS_GetGCParameter(cx, JSGC_NUMBER),
                       nsXPConnect::XPConnect()->IsShuttingDown());
@@ -2807,7 +2801,6 @@ XPCJSRuntime::XPCJSRuntime(JSContext* aCx)
    mDoingFinalization(false),
    mVariantRoots(nullptr),
    mWrappedJSRoots(nullptr),
-   mObjectHolderRoots(nullptr),
    mAsyncSnowWhiteFreer(new AsyncFreeSnowWhite())
 {
     MOZ_COUNT_CTOR_INHERITED(XPCJSRuntime, CycleCollectedJSRuntime);

js/xpconnect/src/XPCWrappedNative.cpp

@@ -2238,20 +2238,8 @@ XPCJSObjectHolder::GetJSObject()
     return mJSObj;
 }
 
-XPCJSObjectHolder::XPCJSObjectHolder(JSObject* obj)
-    : mJSObj(obj)
+XPCJSObjectHolder::XPCJSObjectHolder(JSContext* cx, JSObject* obj)
+  : mJSObj(cx, obj)
 {
     MOZ_ASSERT(obj);
-    XPCJSRuntime::Get()->AddObjectHolderRoot(this);
-}
-
-XPCJSObjectHolder::~XPCJSObjectHolder()
-{
-    RemoveFromRootSet();
-}
-
-void
-XPCJSObjectHolder::TraceJS(JSTracer* trc)
-{
-    JS::TraceEdge(trc, &mJSObj, "XPCJSObjectHolder::mJSObj");
 }

js/xpconnect/src/xpcprivate.h

@@ -619,7 +619,6 @@ public:
 
     inline void AddVariantRoot(XPCTraceableVariant* variant);
     inline void AddWrappedJSRoot(nsXPCWrappedJS* wrappedJS);
-    inline void AddObjectHolderRoot(XPCJSObjectHolder* holder);
 
     void DebugDump(int16_t depth);
 
@@ -664,7 +663,6 @@ private:
     bool mDoingFinalization;
     XPCRootSetElem* mVariantRoots;
     XPCRootSetElem* mWrappedJSRoots;
-    XPCRootSetElem* mObjectHolderRoots;
     nsTArray<xpcGCCallback> extraGCCallbacks;
     JS::GCSliceCallback mPrevGCSliceCallback;
     JS::DoCycleCollectionCallback mPrevDoCycleCollectionCallback;
@@ -2049,8 +2047,7 @@ private:
 
 /***************************************************************************/
 
-class XPCJSObjectHolder final : public nsIXPConnectJSObjectHolder,
-                                public XPCRootSetElem
+class XPCJSObjectHolder final : public nsIXPConnectJSObjectHolder
 {
 public:
     // all the interface method declarations...
@@ -2060,16 +2057,13 @@ public:
     // non-interface implementation
 
 public:
-    void TraceJS(JSTracer* trc);
-
-    explicit XPCJSObjectHolder(JSObject* obj);
+    XPCJSObjectHolder(JSContext* cx, JSObject* obj);
 
 private:
-    virtual ~XPCJSObjectHolder();
-
+    virtual ~XPCJSObjectHolder() {}
     XPCJSObjectHolder() = delete;
 
-    JS::Heap<JSObject*> mJSObj;
+    JS::PersistentRooted<JSObject*> mJSObj;
 };
 
 /***************************************************************************