Make full GC reduce memory footprint an explicit event in the idle notification handler.

src/heap/gc-idle-time-handler.h

Index: src/heap/gc-idle-time-handler.h
diff --git a/src/heap/gc-idle-time-handler.h b/src/heap/gc-idle-time-handler.h
index f953c87b3b81049345b2f23e15b451eb694c844d..681edaacb7906d91c1b3c89472a9e43ace376b7f 100644
--- a/src/heap/gc-idle-time-handler.h
+++ b/src/heap/gc-idle-time-handler.h
@@ -16,6 +16,7 @@ enum GCIdleTimeActionType {
   DO_INCREMENTAL_MARKING,
   DO_SCAVENGE,
   DO_FULL_GC,
+  DO_FULL_GC_COMPACT,
   DO_FINALIZE_SWEEPING
 };
 
@@ -62,6 +63,14 @@ class GCIdleTimeAction {
     return result;
   }
 
+  static GCIdleTimeAction FullGCCompact() {
+    GCIdleTimeAction result;
+    result.type = DO_FULL_GC_COMPACT;
+    result.parameter = 0;
+    result.additional_work = false;
+    return result;
+  }
+
   static GCIdleTimeAction FinalizeSweeping() {
     GCIdleTimeAction result;
     result.type = DO_FINALIZE_SWEEPING;
@@ -122,6 +131,10 @@ class GCIdleTimeHandler {
   // 16 ms when there is currently no rendering going on.
   static const size_t kMaxScheduledIdleTime = 50;
 
+  // This is the minimum time needed to trigger a full garbage collection which
+  // tries to reduce memory footprint.
+  static const size_t kMinTimeForReduceMemory = 600;

[rmcilroy, 2015/04/10 11:14:35]

I'm guessing you are relying on the 1000ms IdleHandler code here? Once we move
this to be an idle task we should probably change this to allow
DO_FULL_GC_COMPACT for smaller deadlines, but have abortable compaction.

[Hannes Payer (out of office), 2015/04/10 13:06:57]

Yes, exactly.

+
   // We conservatively assume that in the next kTimeUntilNextIdleEvent ms
   // no idle notification happens.
   static const size_t kTimeUntilNextIdleEvent = 100;
@@ -195,6 +208,8 @@ class GCIdleTimeHandler {
                                   size_t size_of_objects,
                                   size_t mark_compact_speed_in_bytes_per_ms);
 
+  static bool ShouldDoReduceMemoryMarkCompact(size_t idle_time_in_ms);
+
   static bool ShouldDoContextDisposalMarkCompact(int context_disposed,
                                                  double contexts_disposal_rate);