Flush code faster when doing emergency GCs.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index f3830dd18bdc55bd04423728947b82f7d521085a..3eb3e1b5ea144cc3a0bb3bb9f1cbe60ffc50b024 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -736,6 +736,9 @@ class Heap {
   static const int kReduceMemoryFootprintMask = 1;
   static const int kAbortIncrementalMarkingMask = 2;
 
+  // We do up to 7 GCs when there is a low memory notification.
+  static const int kMaxEmergencyGCs = 7;
+
   // Making the heap iterable requires us to abort incremental marking.
   static const int kMakeHeapIterableMask = kAbortIncrementalMarkingMask;
 
@@ -747,7 +750,8 @@ class Heap {
       const GCCallbackFlags gc_callback_flags = kNoGCCallbackFlags);
 
   // Last hope GC, should try to squeeze as much as possible.
-  void CollectAllAvailableGarbage(const char* gc_reason = NULL);
+  void CollectAllAvailableGarbage(const char* gc_reason = NULL,
+                                  int maxGCs = kMaxEmergencyGCs);
 
   // Check whether the heap is currently iterable.
   bool IsHeapIterable();
@@ -985,6 +989,9 @@ class Heap {
 
   inline bool IsInGCPostProcessing() { return gc_post_processing_depth_ > 0; }
 
+  bool flush_eagerly() { return flush_eagerly_; }
+  void set_flush_eagerly(bool to) { flush_eagerly_ = to; }
+
 #ifdef DEBUG
   void set_allocation_timeout(int timeout) { allocation_timeout_ = timeout; }
 
@@ -1551,6 +1558,9 @@ class Heap {
   int allocation_timeout_;
 #endif  // DEBUG
 
+  // For emergency memory-freeing GCs.
+  bool flush_eagerly_;
+
   // Limit that triggers a global GC on the next (normally caused) GC.  This
   // is checked when we have already decided to do a GC to help determine
   // which collector to invoke, before expanding a paged space in the old
@@ -2129,6 +2139,17 @@ class HeapStats {
 };
 
 
+class FlushEagerly {
+ public:
+  explicit inline FlushEagerly(Heap* heap);
+  inline ~FlushEagerly();
+
+ private:
+  Heap* heap_;
+  bool old_state_;
+};
+
+
 class AlwaysAllocateScope {
  public:
   explicit inline AlwaysAllocateScope(Isolate* isolate);