Oilpan: Implement a GC to take a heap snapshot

Source/platform/heap/HeapTest.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 504 matching lines @@
                     SafePointScope scope(ThreadState::NoHeapPointersOnStack);
                     Platform::current()->yieldCurrentThread();
                 }
 
                 if (gcCount < gcPerThread) {
                     Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
                     gcCount++;
                     atomicIncrement(&m_gcCount);
                 }
 
+                // Taking snapshot shouldn't have any bad side effect.
+                Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::TakeSnapshot, Heap::ForcedGC);
                 Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
                 EXPECT_EQ(wrapper->value(), 0x0bbac0de);
                 EXPECT_EQ((*globalPersistent)->value(), 0x0ed0cabb);
             }
             SafePointScope scope(ThreadState::NoHeapPointersOnStack);
             Platform::current()->yieldCurrentThread();
         }
         ThreadState::detach();
         atomicDecrement(&m_threadsToFinish);
     }
@@ skipping 24 matching lines @@
                     SafePointScope scope(ThreadState::NoHeapPointersOnStack);
                     Platform::current()->yieldCurrentThread();
                 }
 
                 if (gcCount < gcPerThread) {
                     Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
                     gcCount++;
                     atomicIncrement(&m_gcCount);
                 }
 
+                // Taking snapshot shouldn't have any bad side effect.
+                Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::TakeSnapshot, Heap::ForcedGC);
                 Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
                 EXPECT_TRUE(weakMap->isEmpty());
                 EXPECT_TRUE(weakMap2.isEmpty());
             }
             SafePointScope scope(ThreadState::NoHeapPointersOnStack);
             Platform::current()->yieldCurrentThread();
         }
         ThreadState::detach();
         atomicDecrement(&m_threadsToFinish);
     }
@@ skipping 3050 matching lines @@
         objectAddresses.append(objectAddress);
         endAddresses.append(objectAddress + sizeof(SimpleObject) - 1);
     }
     LargeHeapObject* largeObject = LargeHeapObject::create();
     largeObjectAddress = reinterpret_cast<Address>(largeObject);
     largeObjectEndAddress = largeObjectAddress + sizeof(LargeHeapObject) - 1;
 
     // This is a low-level test where we call checkAndMarkPointer. This method
     // causes the object start bitmap to be computed which requires the heap
     // to be in a consistent state (e.g. the free allocation area must be put
-    // into a free list header). However when we call makeConsistentForSweeping it
+    // into a free list header). However when we call makeConsistentForGC it
     // also clears out the freelists so we have to rebuild those before trying
     // to allocate anything again. We do this by forcing a GC after doing the
     // checkAndMarkPointer tests.
     {
         TestGCScope scope(ThreadState::HeapPointersOnStack);
         EXPECT_TRUE(scope.allThreadsParked()); // Fail the test if we could not park all threads.
         Heap::flushHeapDoesNotContainCache();
         for (size_t i = 0; i < objectAddresses.size(); i++) {
             EXPECT_TRUE(Heap::checkAndMarkPointer(&visitor, objectAddresses[i]));
             EXPECT_TRUE(Heap::checkAndMarkPointer(&visitor, endAddresses[i]));
@@ skipping 2461 matching lines @@
 {
     Persistent<ClassWithMember> object = ClassWithMember::create();
     EXPECT_EQ(0, object->traceCount());
     TestMixinAllocatingObject* mixin = TestMixinAllocatingObject::create(object.get());
     EXPECT_TRUE(mixin);
     EXPECT_GT(object->traceCount(), 0);
     EXPECT_GT(mixin->traceCount(), 0);
 }
 
 } // namespace blink