Oilpan: fix computation of ThreadState::m_collectionRate.

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 875 matching lines @@
     }
 }
 
 void ThreadState::preGC()
 {
     ASSERT(!isInGC());
     setGCState(GCRunning);
     makeConsistentForSweeping();
     prepareRegionTree();
     flushHeapDoesNotContainCacheIfNeeded();
+    if (isMainThread())
+        m_allocatedObjectSizeBeforeSweeping = Heap::allocatedObjectSize() + Heap::markedObjectSize();

[haraken, 2015/01/13 11:56:48]

Shall we rename it to m_objectSizeBeforeGC?

[sof, 2015/01/13 12:11:53]

Done.

 }
 
 void ThreadState::postGC(GCType gcType)
 {
     ASSERT(isInGC());
     setGCState(gcType == GCWithSweep ? EagerSweepScheduled : LazySweepScheduled);
     for (int i = 0; i < NumberOfHeaps; i++)
         m_heaps[i]->prepareForSweep();
 }
 
@@ skipping 124 matching lines @@
     }
 }
 
 void ThreadState::postGCProcessing()
 {
     checkThread();
     if (gcState() != EagerSweepScheduled && gcState() != LazySweepScheduled)
         return;
 
     m_didV8GCAfterLastGC = false;
-    if (isMainThread())
-        m_allocatedObjectSizeBeforeSweeping = Heap::allocatedObjectSize();

[haraken, 2015/01/13 11:56:48]

Before this CL, m_allocatedObjectSizeBeforeSweeping was 0 in most cases
probably?

[sof, 2015/01/13 12:11:53]

Yes; m_collectionRate then mapping to +Inf.

[haraken, 2015/01/13 12:23:08]

oh...

Also let's add a zero-division check to the calculation of m_collectionRate.

[sof, 2015/01/13 12:35:57]

Asserted on m_collectionRate's range.

 
 #if ENABLE(GC_PROFILE_HEAP)
     // We snapshot the heap prior to sweeping to get numbers for both resources
     // that have been allocated since the last GC and for resources that are
     // going to be freed.
     bool gcTracingEnabled;
     TRACE_EVENT_CATEGORY_GROUP_ENABLED("blink_gc", &gcTracingEnabled);
     if (gcTracingEnabled)
         snapshot();
 #endif
@@ skipping 110 matching lines @@
             return gcInfo;
         }
     }
     if (needLockForIteration)
         threadAttachMutex().unlock();
     return nullptr;
 }
 #endif
 
 } // namespace blink