Sweep compartments when no objects live in them (bug 639270, r=gregor).

js/src/jsapi.cpp

@@ -1333,7 +1333,7 @@ JS_TransplantObject(JSContext *cx, JSObject *origobj, JSObject *target)
     // types of security wrappers based on whether the new compartment
     // is same origin with them.
     Value targetv = ObjectValue(*obj);
-    WrapperVector &vector = cx->runtime->compartments;
+    CompartmentVector &vector = cx->runtime->compartments;
     AutoValueVector toTransplant(cx);
     if (!toTransplant.reserve(vector.length()))
         return NULL;
@@ -1427,7 +1427,7 @@ js_TransplantObjectWithWrapper(JSContext *cx,
     // and not |origwrapper|. They need to be updated to point at the new
     // location object.
     Value targetv = ObjectValue(*targetobj);
-    WrapperVector &vector = cx->runtime->compartments;
+    CompartmentVector &vector = cx->runtime->compartments;
     AutoValueVector toTransplant(cx);
     if (!toTransplant.reserve(vector.length()))
         return NULL;
@@ -3081,6 +3081,23 @@ JS_NewGlobalObject(JSContext *cx, JSClass *clasp)
     return obj;
 }
 
+class AutoHoldCompartment {
+  public:
+    explicit AutoHoldCompartment(JSCompartment *compartment JS_GUARD_OBJECT_NOTIFIER_PARAM)
+      : holdp(&compartment->hold)
+    {
+        JS_GUARD_OBJECT_NOTIFIER_INIT;
+        *holdp = true;
+    }
+
+    ~AutoHoldCompartment() {
+        *holdp = false;
+    }
+  private:
+    bool *holdp;
+    JS_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
 JS_PUBLIC_API(JSObject *)
 JS_NewCompartmentAndGlobalObject(JSContext *cx, JSClass *clasp, JSPrincipals *principals)
 {
@@ -3089,6 +3106,8 @@ JS_NewCompartmentAndGlobalObject(JSContext *cx, JSClass *clasp, JSPrincipals *pr
     if (!compartment)
         return NULL;
 
+    AutoHoldCompartment hold(compartment);
+
     JSCompartment *saved = cx->compartment;
     cx->compartment = compartment;
     JSObject *obj = JS_NewGlobalObject(cx, clasp);

js/src/jscntxt.h

@@ -988,7 +988,7 @@ typedef void
 
 namespace js {
 
-typedef js::Vector<JSCompartment *, 0, js::SystemAllocPolicy> WrapperVector;
+typedef js::Vector<JSCompartment *, 0, js::SystemAllocPolicy> CompartmentVector;
 
 }
 
@@ -1000,7 +1000,7 @@ struct JSRuntime {
 #endif
 
     /* List of compartments (protected by the GC lock). */
-    js::WrapperVector compartments;
+    js::CompartmentVector compartments;
 
     /* Runtime state, synchronized by the stateChange/gcLock condvar/lock. */
     JSRuntimeState      state;

js/src/jscompartment.cpp

@@ -66,6 +66,7 @@ JSCompartment::JSCompartment(JSRuntime *rt)
     gcBytes(0),
     gcTriggerBytes(0),
     gcLastBytes(0),
+    hold(false),
     data(NULL),
     active(false),
 #ifdef JS_METHODJIT
@@ -82,8 +83,7 @@ JSCompartment::JSCompartment(JSRuntime *rt)
 #if ENABLE_YARR_JIT
     regExpAllocator(NULL),
 #endif
-    mathCache(NULL),
-    marked(false)
+    mathCache(NULL)
 {
     JS_INIT_CLIST(&scripts);
 
@@ -447,35 +447,23 @@ ScriptPoolDestroyed(JSContext *cx, mjit::JITScript *jit,
 
 /*
  * This method marks pointers that cross compartment boundaries. It should be
- * called only by per-compartment GCs, since full GCs naturally follow pointers
+ * called only for per-compartment GCs, since full GCs naturally follow pointers
  * across compartments.
  */
 void
-JSCompartment::markCrossCompartment(JSTracer *trc)
+JSCompartment::markCrossCompartmentWrappers(JSTracer *trc)
 {
+    JS_ASSERT(trc->context->runtime->gcCurrentCompartment);
+
     for (WrapperMap::Enum e(crossCompartmentWrappers); !e.empty(); e.popFront())
         MarkValue(trc, e.front().key, "cross-compartment wrapper");
 }
 
-void
-JSCompartment::mark(JSTracer *trc)
-{
-    if (IS_GC_MARKING_TRACER(trc)) {
-        JSRuntime *rt = trc->context->runtime;
-
-        if (rt->gcCurrentCompartment && rt->gcCurrentCompartment != this)
-            return;
-
-        if (marked)
-            return;
-        marked = true;
-    }
-}
-
 void
 JSCompartment::sweep(JSContext *cx, uint32 releaseInterval)
 {
     chunk = NULL;
+
     /* Remove dead wrappers from the table. */
     for (WrapperMap::Enum e(crossCompartmentWrappers); !e.empty(); e.popFront()) {
         JS_ASSERT_IF(IsAboutToBeFinalized(cx, e.front().key.toGCThing()) &&

js/src/jscompartment.h

@@ -381,6 +381,8 @@ struct JS_FRIEND_API(JSCompartment) {
     size_t                       gcTriggerBytes;
     size_t                       gcLastBytes;
 
+    bool                         hold;
+
 #ifdef JS_GCMETER
     js::gc::JSGCArenaStats       compartmentStats[js::gc::FINALIZE_LIMIT];
 #endif
@@ -451,10 +453,7 @@ struct JS_FRIEND_API(JSCompartment) {
     bool init();
 
     /* Mark cross-compartment wrappers. */
-    void markCrossCompartment(JSTracer *trc);
-
-    /* Mark this compartment's local roots. */
-    void mark(JSTracer *trc);
+    void markCrossCompartmentWrappers(JSTracer *trc);
 
     bool wrap(JSContext *cx, js::Value *vp);
     bool wrap(JSContext *cx, JSString **strp);
@@ -481,8 +480,6 @@ struct JS_FRIEND_API(JSCompartment) {
 
     js::MathCache *allocMathCache(JSContext *cx);
 
-    bool                         marked;
-    
     typedef js::HashMap<jsbytecode*,
                         size_t,
                         js::DefaultHasher<jsbytecode*>,
@@ -496,9 +493,6 @@ struct JS_FRIEND_API(JSCompartment) {
         return mathCache ? mathCache : allocMathCache(cx);
     }
 
-    bool isMarked() { return marked; }
-    void clearMark() { marked = false; }
-
     size_t backEdgeCount(jsbytecode *pc) const;
     size_t incBackEdgeCount(jsbytecode *pc);
 };

js/src/jsgc.cpp

@@ -1633,9 +1633,6 @@ MarkContext(JSTracer *trc, JSContext *acx)
         js_TraceSharpMap(trc, &acx->sharpObjectMap);
 
     MarkValue(trc, acx->iterValue, "iterValue");
-
-    if (acx->compartment)
-        acx->compartment->mark(trc);
 }
 
 JS_REQUIRES_STACK void
@@ -1724,8 +1721,6 @@ MarkRuntime(JSTracer *trc)
     while (JSContext *acx = js_ContextIterator(rt, JS_TRUE, &iter))
         MarkContext(trc, acx);
 
-    rt->atomsCompartment->mark(trc);
-
 #ifdef JS_TRACER
     for (JSCompartment **c = rt->compartments.begin(); c != rt->compartments.end(); ++c)
         (*c)->traceMonitor.mark(trc);
@@ -2187,13 +2182,8 @@ SweepCompartments(JSContext *cx, JSGCInvocationKind gckind)
     while (read < end) {
         JSCompartment *compartment = *read++;
 
-        /*
-         * Unmarked compartments containing marked objects don't get deleted,
-         * except when LAST_CONTEXT GC is performed.
-         */
-        if ((!compartment->isMarked() && compartment->arenaListsAreEmpty()) ||
-            gckind == GC_LAST_CONTEXT)
-        {
+        if (!compartment->hold &&
+            (compartment->arenaListsAreEmpty() || gckind == GC_LAST_CONTEXT)) {
             JS_ASSERT(compartment->freeLists.isEmpty());
             if (callback)
                 (void) callback(cx, compartment, JSCOMPARTMENT_DESTROY);
@@ -2268,7 +2258,6 @@ MarkAndSweepCompartment(JSContext *cx, JSCompartment *comp, JSGCInvocationKind g
     JS_ASSERT(!rt->gcRegenShapes);
     JS_ASSERT(gckind != GC_LAST_CONTEXT);
     JS_ASSERT(comp != rt->atomsCompartment);
-    JS_ASSERT(!comp->isMarked());
     JS_ASSERT(comp->rt->gcMode == JSGC_MODE_COMPARTMENT);
 
     /*
@@ -2284,9 +2273,7 @@ MarkAndSweepCompartment(JSContext *cx, JSCompartment *comp, JSGCInvocationKind g
          r.front()->clearMarkBitmap();
 
     for (JSCompartment **c = rt->compartments.begin(); c != rt->compartments.end(); ++c)
-        (*c)->markCrossCompartment(&gcmarker);
-
-    comp->mark(&gcmarker);
+        (*c)->markCrossCompartmentWrappers(&gcmarker);
 
     MarkRuntime(&gcmarker);
 
@@ -2384,8 +2371,6 @@ MarkAndSweepCompartment(JSContext *cx, JSCompartment *comp, JSGCInvocationKind g
     ExpireGCChunks(rt);
     TIMESTAMP(sweepDestroyEnd);
 
-    comp->clearMark();
-
     if (rt->gcCallback)
         (void) rt->gcCallback(cx, JSGC_FINALIZE_END);
 }
@@ -2523,9 +2508,6 @@ MarkAndSweep(JSContext *cx, JSGCInvocationKind gckind GCTIMER_PARAM)
     ExpireGCChunks(rt);
     TIMESTAMP(sweepDestroyEnd);
 
-    for (JSCompartment **c = rt->compartments.begin(); c != rt->compartments.end(); ++c)
-        (*c)->clearMark();
-
     if (rt->gcCallback)
         (void) rt->gcCallback(cx, JSGC_FINALIZE_END);
 #ifdef DEBUG_srcnotesize
@@ -2736,9 +2718,6 @@ GCUntilDone(JSContext *cx, JSCompartment *comp, JSGCInvocationKind gckind  GCTIM
 
     AutoGCSession gcsession(cx);
 
-    for (JSCompartment **c = rt->compartments.begin(); c != rt->compartments.end(); ++c)
-        JS_ASSERT(!(*c)->isMarked());
-
     /*
      * We should not be depending on cx->compartment in the GC, so set it to
      * NULL to look for violations.

js/src/jsobj.cpp

@@ -6509,11 +6509,6 @@ js_TraceObject(JSTracer *trc, JSObject *obj)
 
     obj->trace(trc);
 
-    if (obj->getClass()->flags & JSCLASS_IS_GLOBAL) {
-        JSCompartment *compartment = obj->getCompartment();
-        compartment->mark(trc);
-    }
-
     /*
      * NB: clasp->mark could mutate something (which would be a bug, but we are
      * defensive), so don't hoist this above calling clasp->mark.

js/src/xpconnect/src/nsXPConnect.cpp

@@ -2561,7 +2561,7 @@ nsXPConnect::CheckForDebugMode(JSRuntime *rt) {
         } adc(cx);
         JSAutoRequest ar(cx);
 
-        js::WrapperVector &vector = rt->compartments;
+        js::CompartmentVector &vector = rt->compartments;
         for (JSCompartment **p = vector.begin(); p != vector.end(); ++p) {
             JSCompartment *comp = *p;
             if (!comp->principals) {