Oilpan: support eager finalization/sweeping.

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 894 matching lines @@
 #endif
 
 #if ENABLE(OILPAN)
     if (gcState() == EagerSweepScheduled) {
         // Eager sweeping should happen only in testing.
         setGCState(Sweeping);
         completeSweep();
     } else {
         // The default behavior is lazy sweeping.
         setGCState(Sweeping);
+        eagerSweep();
         scheduleIdleLazySweep();
     }
 #else
     // FIXME: For now, we disable lazy sweeping in non-oilpan builds
     // to avoid unacceptable behavior regressions on trunk.
     setGCState(Sweeping);
     completeSweep();
 #endif
 
 #if ENABLE(GC_PROFILING)
     snapshotFreeListIfNecessary();
 #endif
 }
 
+void ThreadState::eagerSweep()
+{
+    // Some objects need to be finalized promptly and cannot be handled
+    // by lazy sweeping. Keep those in a designated heap and sweep it
+    // eagerly.
+    ASSERT(isSweepingInProgress());
+    ASSERT(!sweepForbidden());

[haraken, 2015/05/19 23:23:37]

I think this should be:

  if (sweepForbidden())
    return;

See the comment in completeSweep() when sweepForbidden() can become true.

[sof, 2015/05/20 09:43:01]

Done + xref'ed the comment.

+
+    ThreadState::SweepForbiddenScope scope(this);
+    {
+        if (isMainThread())
+            ScriptForbiddenScope::enter();
+
+        TRACE_EVENT0("blink_gc", "ThreadState::eagerSweep");
+        double timeStamp = WTF::currentTimeMS();

[haraken, 2015/05/19 23:23:37]

Remove this (see below).

[sof, 2015/05/20 09:43:01]

Removed.

+
+        m_heaps[EagerSweepHeapIndex]->completeSweep();
+
+        Platform::current()->histogramCustomCounts("BlinkGC.EagerSweep", WTF::currentTimeMS() - timeStamp, 0, 10 * 1000, 50);

[haraken, 2015/05/19 23:23:37]

This UMA doesn't exist (and wouldn't be worth adding). So remove this.

+
+        if (isMainThread())
+            ScriptForbiddenScope::exit();
+    }
+}
+
 void ThreadState::completeSweep()
 {
     // If we are not in a sweeping phase, there is nothing to do here.
     if (!isSweepingInProgress())
         return;
 
     // completeSweep() can be called recursively if finalizers can allocate
     // memory and the allocation triggers completeSweep(). This check prevents
     // the sweeping from being executed recursively.
     if (sweepForbidden())
@@ skipping 369 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