Remove SafePointAwareMutexLocker

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SafePoint_h
 #define SafePoint_h
 
 #include "platform/heap/ThreadState.h"
 #include "wtf/ThreadingPrimitives.h"
 
@@ skipping 15 matching lines @@
 
   ~SafePointScope() {
     if (m_state)
       m_state->leaveSafePoint();
   }
 
  private:
   ThreadState* m_state;
 };
 
-// The SafePointAwareMutexLocker is used to enter a safepoint while waiting for
-// a mutex lock. It also ensures that the lock is not held while waiting for a
-// GC to complete in the leaveSafePoint method, by releasing the lock if the
-// leaveSafePoint method cannot complete without blocking, see
-// SafePointBarrier::checkAndPark.
-class SafePointAwareMutexLocker final {
-  STACK_ALLOCATED();
-  WTF_MAKE_NONCOPYABLE(SafePointAwareMutexLocker);
-
- public:
-  explicit SafePointAwareMutexLocker(
-      MutexBase& mutex,
-      BlinkGC::StackState stackState = BlinkGC::HeapPointersOnStack)
-      : m_mutex(mutex), m_locked(false) {
-    ThreadState* state = ThreadState::current();
-    do {
-      bool leaveSafePoint = false;
-      // We cannot enter a safepoint if we are currently sweeping. In that
-      // case we just try to acquire the lock without being at a safepoint.
-      // If another thread tries to do a GC at that time it might time out
-      // due to this thread not being at a safepoint and waiting on the lock.
-      if (!state->sweepForbidden() && !state->isAtSafePoint()) {
-        state->enterSafePoint(stackState, this);
-        leaveSafePoint = true;
-      }
-      m_mutex.lock();
-      m_locked = true;
-      if (leaveSafePoint) {
-        // When leaving the safepoint we might end up release the mutex
-        // if another thread is requesting a GC, see
-        // SafePointBarrier::checkAndPark. This is the case where we
-        // loop around to reacquire the lock.
-        state->leaveSafePoint(this);
-      }
-    } while (!m_locked);
-  }
-
-  ~SafePointAwareMutexLocker() {
-    ASSERT(m_locked);
-    m_mutex.unlock();
-  }
-
- private:
-  friend class SafePointBarrier;
-
-  void reset() {
-    ASSERT(m_locked);
-    m_mutex.unlock();
-    m_locked = false;
-  }
-
-  MutexBase& m_mutex;
-  bool m_locked;
-};
-
 class SafePointBarrier final {
   USING_FAST_MALLOC(SafePointBarrier);
   WTF_MAKE_NONCOPYABLE(SafePointBarrier);
 
  public:
   SafePointBarrier();
   ~SafePointBarrier();
 
   void enterSafePoint(ThreadState*);
-  void leaveSafePoint(ThreadState*, SafePointAwareMutexLocker* = nullptr);
+  void leaveSafePoint();
 
  private:
   void doPark(ThreadState*, intptr_t* stackEnd);
   void doEnterSafePoint(ThreadState*, intptr_t* stackEnd);
   static void enterSafePointAfterPushRegisters(SafePointBarrier* barrier,
                                                ThreadState* state,
                                                intptr_t* stackEnd) {
     barrier->doEnterSafePoint(state, stackEnd);
   }
   Mutex m_mutex;
 };
 
 }  // namespace blink
 
 #endif