Bug 1364547 - Tell Gecko whether a slice is a final slice, r=jonco,mccr8

--HG--
extra : rebase_source : ea028988b3515cdc441af8f7c2c1ba0794482494

dom/base/nsJSEnvironment.cpp

@@ -2211,9 +2211,9 @@ DOMGCSliceCallback(JSContext* aCx, JS::GCProgress aProgress, const JS::GCDescrip
 
     case JS::GC_SLICE_END:
 
-      // The GC has more work to do, so schedule another GC slice.
+      // Schedule another GC slice if the GC has more work to do.
       nsJSContext::KillInterSliceGCTimer();
-      if (!sShuttingDown) {
+      if (!sShuttingDown && !aDesc.isComplete_) {
         CallCreateInstance("@mozilla.org/timer;1", &sInterSliceGCTimer);
         sInterSliceGCTimer->SetTarget(SystemGroup::EventTargetFor(TaskCategory::GarbageCollection));
         sInterSliceGCTimer->InitWithNamedFuncCallback(InterSliceGCTimerFired,

js/public/GCAPI.h

@@ -332,11 +332,12 @@ enum GCProgress {
 
 struct JS_PUBLIC_API(GCDescription) {
     bool isZone_;
+    bool isComplete_;
     JSGCInvocationKind invocationKind_;
     gcreason::Reason reason_;
 
-    GCDescription(bool isZone, JSGCInvocationKind kind, gcreason::Reason reason)
-      : isZone_(isZone), invocationKind_(kind), reason_(reason) {}
+    GCDescription(bool isZone, bool isComplete, JSGCInvocationKind kind, gcreason::Reason reason)
+      : isZone_(isZone), isComplete_(isComplete), invocationKind_(kind), reason_(reason) {}
 
     char16_t* formatSliceMessage(JSContext* cx) const;
     char16_t* formatSummaryMessage(JSContext* cx) const;

js/src/gc/Statistics.cpp

@@ -961,7 +961,7 @@ Statistics::beginSlice(const ZoneGCStats& zoneStats, JSGCInvocationKind gckind,
     bool wasFullGC = zoneStats.isCollectingAllZones();
     if (sliceCallback) {
         JSContext* cx = TlsContext.get();
-        JS::GCDescription desc(!wasFullGC, gckind, reason);
+        JS::GCDescription desc(!wasFullGC, false, gckind, reason);
         if (first)
             (*sliceCallback)(cx, JS::GC_CYCLE_BEGIN, desc);
         (*sliceCallback)(cx, JS::GC_SLICE_BEGIN, desc);
@@ -1011,7 +1011,7 @@ Statistics::endSlice()
         bool wasFullGC = zoneStats.isCollectingAllZones();
         if (sliceCallback) {
             JSContext* cx = TlsContext.get();
-            JS::GCDescription desc(!wasFullGC, gckind, slices_.back().reason);
+            JS::GCDescription desc(!wasFullGC, last, gckind, slices_.back().reason);
             (*sliceCallback)(cx, JS::GC_SLICE_END, desc);
             if (last)
                 (*sliceCallback)(cx, JS::GC_CYCLE_END, desc);