Oilpan: Implement a GC to take a heap snapshot

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 831 matching lines @@
 }
 
 void ThreadState::makeConsistentForGC()
 {
     ASSERT(isInGC());
     TRACE_EVENT0("blink_gc", "ThreadState::makeConsistentForGC");
     for (int i = 0; i < NumberOfHeaps; ++i)
         m_heaps[i]->makeConsistentForGC();
 }
 
+void ThreadState::makeConsistentForMutator()
+{
+    ASSERT(isInGC());
+    for (int i = 0; i < NumberOfHeaps; ++i)
+        m_heaps[i]->makeConsistentForMutator();
+}
+
 void ThreadState::preGC()
 {
     ASSERT(!isInGC());
     setGCState(GCRunning);
     makeConsistentForGC();
     prepareRegionTree();
     flushHeapDoesNotContainCacheIfNeeded();
     clearHeapAges();
 }
 
@@ skipping 12 matching lines @@
         bool disabledByDefaultGCTracingEnabled;
         TRACE_EVENT_CATEGORY_GROUP_ENABLED(TRACE_DISABLED_BY_DEFAULT("blink_gc"), &disabledByDefaultGCTracingEnabled);
 
         snapshot();
         if (disabledByDefaultGCTracingEnabled)
             collectAndReportMarkSweepStats();
         incrementMarkedObjectsAge();
     }
 #endif
 
-    setGCState(gcType == GCWithSweep ? EagerSweepScheduled : LazySweepScheduled);
     for (int i = 0; i < NumberOfHeaps; i++)
         m_heaps[i]->prepareForSweep();
+
+    if (gcType == GCWithSweep) {
+        setGCState(EagerSweepScheduled);
+    } else if (gcType == GCWithoutSweep) {
+        setGCState(LazySweepScheduled);
+    } else {
+        takeSnapshot();
+
+        // This unmarks all marked objects and marks all unmarked objects dead.
+        makeConsistentForMutator();
+
+        // Force setting NoGCScheduled to circumvent checkThread()
+        // in setGCState().
+        m_gcState = NoGCScheduled;
+    }
 }
 
 void ThreadState::preSweep()
 {
     checkThread();
     if (gcState() != EagerSweepScheduled && gcState() != LazySweepScheduled)
         return;
 
     {
         if (isMainThread())
@@ skipping 362 matching lines @@
         m_vectorBackingHeapIndex = heapIndexOfVectorHeapLeastRecentlyExpanded(Vector1HeapIndex, Vector4HeapIndex);
 }
 
 void ThreadState::promptlyFreed(size_t gcInfoIndex)
 {
     size_t entryIndex = gcInfoIndex & likelyToBePromptlyFreedArrayMask;
     // See the comment in vectorBackingHeap() for why this is +3.
     m_likelyToBePromptlyFreed[entryIndex] += 3;
 }
 
+void ThreadState::takeSnapshot()
+{
+    ASSERT(isInGC());
+    // TODO(ssid): Implement this.
+}
+
 #if ENABLE(GC_PROFILING)
 const GCInfo* ThreadState::findGCInfoFromAllThreads(Address address)
 {
     bool needLockForIteration = !ThreadState::current()->isInGC();
     if (needLockForIteration)
         threadAttachMutex().lock();
 
     for (ThreadState* state : attachedThreads()) {
         if (const GCInfo* gcInfo = state->findGCInfo(address)) {
             if (needLockForIteration)
@@ skipping 70 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