Tweak the new context disposal GC heuristic to cleanly separate...

src/heap.cc

Index: src/heap.cc
===================================================================
--- src/heap.cc	(revision 3981)
+++ src/heap.cc	(working copy)
@@ -115,8 +115,11 @@
 
 int Heap::always_allocate_scope_depth_ = 0;
 int Heap::linear_allocation_scope_depth_ = 0;
-bool Heap::context_disposed_pending_ = false;
 
+int Heap::contexts_disposed_ = 0;
+bool Heap::context_disposed_use_deprecated_heuristic_ = true;
+bool Heap::context_disposed_deprecated_pending_ = false;
+
 #ifdef DEBUG
 bool Heap::allocation_allowed_ = true;
 
@@ -371,32 +374,32 @@
 }
 
 
-void Heap::CollectAllGarbageIfContextDisposed(bool notified) {
-  // If the request has ever been the result of an explicit
-  // notification, we ignore non-notified requests. This is a
-  // temporary solution to let the two ways of achieving GC at
-  // context disposal time co-exist.
-  static bool ever_notified = false;
-  if (notified) ever_notified = true;
-  if (ever_notified && !notified) return;
-
+void Heap::CollectAllGarbageIfContextDisposedDeprecated() {
+  if (!context_disposed_use_deprecated_heuristic_) return;
   // If the garbage collector interface is exposed through the global
   // gc() function, we avoid being clever about forcing GCs when
   // contexts are disposed and leave it to the embedder to make
   // informed decisions about when to force a collection.
-  if (!FLAG_expose_gc && (notified || context_disposed_pending_)) {
+  if (!FLAG_expose_gc && context_disposed_deprecated_pending_) {
     HistogramTimerScope scope(&Counters::gc_context);
     CollectAllGarbage(false);
   }
-  context_disposed_pending_ = false;
+  context_disposed_deprecated_pending_ = false;
 }
 
 
 void Heap::NotifyContextDisposed() {
-  context_disposed_pending_ = true;
+  context_disposed_use_deprecated_heuristic_ = false;
+  contexts_disposed_++;
 }
 
 
+void Heap::NotifyContextDisposedDeprecated() {
+  if (!context_disposed_use_deprecated_heuristic_) return;
+  context_disposed_deprecated_pending_ = true;
+}
+
+
 bool Heap::CollectGarbage(int requested_size, AllocationSpace space) {
   // The VM is in the GC state until exiting this function.
   VMState state(GC);
@@ -639,7 +642,9 @@
   Shrink();
 
   Counters::objs_since_last_full.Set(0);
-  context_disposed_pending_ = false;
+
+  contexts_disposed_ = 0;
+  context_disposed_deprecated_pending_ = false;
 }
 
 
@@ -3088,6 +3093,13 @@
   static int number_idle_notifications = 0;
   static int last_gc_count = gc_count_;
 
+  if (!FLAG_expose_gc && (contexts_disposed_ > 0)) {
+    HistogramTimerScope scope(&Counters::gc_context);
+    CollectAllGarbage(false);
+    ASSERT(contexts_disposed_ == 0);
+    return false;
+  }
+
   bool finished = false;
 
   if (last_gc_count == gc_count_) {