commit 866fb2ad19180a5e5a50bf649b38ec9bfd010ac6
author Mathieu Chartier <mathieuc@google.com> Mon Sep 10 10:47:49 2012 -0700
committer Mathieu Chartier <mathieuc@google.com> Mon Sep 10 13:44:38 2012 -0700
tree 157ffb8e68a2776cb06e1ba9c5b7798c5074d791
parent 660ed62e187d1d92d1193d4c596838982a2ca138

Better WaitForConcurrentGcToComplete information

WaitForConcurrentGcToComplete now returns which type of Gc we waited on. This enables us to have smarter logic so that we don't run as many redundant Gcs.

Fixes 074-gc-thrash occasionally failing due to sticky mark bits not clearing older weak references.

Change-Id: I7adb84183816e6a2acc11afd7ae650686fe97a7d

src/heap.h

diff --git a/src/heap.h b/src/heap.h
index 912bfb6..8ee7f10 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -51,13 +51,16 @@
 
 typedef std::vector<Space*> Spaces;
 
+// The ordering of the enum matters, it is used to determine which GCs are run first.
 enum GcType {
-  // Full GC
-  kGcTypeFull,
+  // No Gc
+  kGcTypeNone,
   // Sticky mark bits "generational" GC.
   kGcTypeSticky,
   // Partial GC, over only the alloc space.
   kGcTypePartial,
+  // Full GC
+  kGcTypeFull,
   // Number of different Gc types.
   kGcTypeMax,
 };
@@ -162,7 +165,7 @@
 
   // Blocks the caller until the garbage collector becomes idle and returns
   // true if we waited for the GC to complete.
-  bool WaitForConcurrentGcToComplete();
+  GcType WaitForConcurrentGcToComplete();
 
   const Spaces& GetSpaces() {
     return spaces_;
@@ -295,7 +298,9 @@
   void RecordAllocation(AllocSpace* space, const Object* object)
       LOCKS_EXCLUDED(Locks::heap_bitmap_lock_);
 
-  void CollectGarbageInternal(GcType gc_plan, bool clear_soft_references)
+  // Sometimes CollectGarbageInternal decides to run a different Gc than you requested. Returns
+  // which type of Gc was actually ran.
+  GcType CollectGarbageInternal(GcType gc_plan, bool clear_soft_references)
       LOCKS_EXCLUDED(gc_complete_lock_,
                      Locks::heap_bitmap_lock_,
                      Locks::mutator_lock_,
@@ -361,7 +366,10 @@
   UniquePtr<ConditionVariable> gc_complete_cond_ GUARDED_BY(gc_complete_lock_);
 
   // True while the garbage collector is running.
-  volatile bool is_gc_running_ GUARDED_BY(gc_complete_lock_);;
+  volatile bool is_gc_running_ GUARDED_BY(gc_complete_lock_);
+
+  // Last Gc type we ran. Used by WaitForConcurrentGc to know which Gc was waited on.
+  volatile GcType last_gc_type_ GUARDED_BY(gc_complete_lock_);
 
   // Bytes until concurrent GC starts.
   volatile size_t concurrent_start_bytes_;