Oilpan: A precise GC should be prioritized than an idle GC

Source/platform/heap/ThreadState.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 632 matching lines @@
         return false;
 #if ENABLE(IDLE_GC)
     return judgeGCThreshold(1024 * 1024, 1.5);
 #else
     return false;
 #endif
 }
 
 bool ThreadState::shouldSchedulePreciseGC()
 {
-    if (gcState() != NoGCScheduled)
-        return false;

[Yuta Kitamura, 2015/08/18 03:06:28]

Let me confirm my understanding of this removal.

* If an idle GC is already scheduled, it's fine to override it
  with a precise GC.
* Sweeping is never scheduled at this point.

Correct?

[haraken, 2015/08/18 03:45:23]

Yes, that is the intention of this CL.
Yes. scheduleGCIfNeeded() should not be called while the lazy sweeping is going
on. Even if it's called for some reason, scheduleGCIfNeeded() returns
immediately if isSweepingInProgress() is true (See line 704).

 #if ENABLE(IDLE_GC)
     return false;

[haraken, 2015/08/18 02:39:53]

yutak@: After landing this change, you just need to change this line to
judgeGCThreshold(1024 * 1024, xxx) to schedule a precise GC with a threshold
xxx.

 #else
     return judgeGCThreshold(1024 * 1024, 1.5);
 #endif
 }
 
 bool ThreadState::shouldSchedulePageNavigationGC(float estimatedRemovalRatio)
 {
     return judgeGCThreshold(1024 * 1024, 1.5);
 }
 
@@ skipping 918 matching lines @@
         json->beginArray(it->key.ascii().data());
         for (size_t age = 0; age <= maxHeapObjectAge; ++age)
             json->pushInteger(it->value.ages[age]);
         json->endArray();
     }
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), statsName, this, json.release());
 }
 #endif
 
 } // namespace blink