Simple BlinkGC heap compaction.

third_party/WebKit/Source/platform/heap/ThreadState.h

 /*
  * 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 266 matching lines @@
   void preGC();
   void postGC(BlinkGC::GCType);
   void preSweep();
   void completeSweep();
   void postSweep();
   // makeConsistentForMutator() drops marks from marked objects and rebuild
   // free lists. This is called after taking a snapshot and before resuming
   // the executions of mutators.
   void makeConsistentForMutator();
 
+  void compact();
+
   // Support for disallowing allocation. Mainly used for sanity
   // checks asserts.
   bool isAllocationAllowed() const {
     return !isAtSafePoint() && !m_noAllocationCount;
   }
   void enterNoAllocationScope() { m_noAllocationCount++; }
   void leaveNoAllocationScope() { m_noAllocationCount--; }
   bool isWrapperTracingForbidden() { return isMixinInConstruction(); }
   bool isGCForbidden() const {
     return m_gcForbiddenCount || isMixinInConstruction();
@@ skipping 18 matching lines @@
     MainThreadGCForbiddenScope()
         : m_threadState(ThreadState::mainThreadState()) {
       m_threadState->enterGCForbiddenScope();
     }
     ~MainThreadGCForbiddenScope() { m_threadState->leaveGCForbiddenScope(); }
 
    private:
     ThreadState* const m_threadState;
   };
 
+  class GCForbiddenScope final {
+    STACK_ALLOCATED();
+
+   public:
+    explicit GCForbiddenScope(ThreadState* threadState)
+        : m_threadState(threadState) {
+      m_threadState->enterGCForbiddenScope();
+    }
+    ~GCForbiddenScope() { m_threadState->leaveGCForbiddenScope(); }
+
+   private:
+    ThreadState* const m_threadState;
+  };
+
   void flushHeapDoesNotContainCacheIfNeeded();
 
   // Safepoint related functionality.
   //
   // When a thread attempts to perform GC it needs to stop all other threads
   // that use the heap or at least guarantee that they will not touch any
   // heap allocated object until GC is complete.
   //
   // We say that a thread is at a safepoint if this thread is guaranteed to
   // not touch any heap allocated object or any heap related functionality until
@@ skipping 219 matching lines @@
 
   void resetHeapCounters();
   void increaseAllocatedObjectSize(size_t);
   void decreaseAllocatedObjectSize(size_t);
   void increaseMarkedObjectSize(size_t);
 
   void callThreadShutdownHooks();
 
   v8::Isolate* isolate() const { return m_isolate; }
 
+  BlinkGC::StackState stackState() const { return m_stackState; }
+
   void collectGarbage(BlinkGC::StackState, BlinkGC::GCType, BlinkGC::GCReason);
   void collectGarbageForTerminatingThread();
   void collectAllGarbage();
 
+  static const char* gcReasonString(BlinkGC::GCReason);
+
  private:
   enum SnapshotType { HeapSnapshot, FreelistSnapshot };
 
   explicit ThreadState(BlinkGC::ThreadHeapMode);
   ~ThreadState();
 
   NO_SANITIZE_ADDRESS void copyStackUntilSafePointScope();
   void clearSafePointScopeMarker() {
     m_safePointStackCopy.clear();
     m_safePointScopeMarker = nullptr;
@@ skipping 174 matching lines @@
 class ThreadStateFor<AnyThread> {
   STATIC_ONLY(ThreadStateFor);
 
  public:
   static ThreadState* state() { return ThreadState::current(); }
 };
 
 }  // namespace blink
 
 #endif  // ThreadState_h