Fixing race between CallbackCanceled and CancelCallback in AsyncInvoker.

webrtc/base/asyncinvoker-inl.h

 /*
  *  Copyright 2014 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_BASE_ASYNCINVOKER_INL_H_
 #define WEBRTC_BASE_ASYNCINVOKER_INL_H_
 
 #include "webrtc/base/atomicops.h"
 #include "webrtc/base/bind.h"
 #include "webrtc/base/callback.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/messagehandler.h"
 #include "webrtc/base/sigslot.h"
 #include "webrtc/base/thread.h"
+#include "webrtc/base/thread_annotations.h"
 
 namespace rtc {
 
 class AsyncInvoker;
 
 // Helper class for AsyncInvoker. Runs a task and triggers a callback
 // on the calling thread if necessary.
 class AsyncClosure {
  public:
   explicit AsyncClosure(AsyncInvoker* invoker) : invoker_(invoker) {}
@@ skipping 30 matching lines @@
 
  protected:
   NotifyingAsyncClosureBase(AsyncInvoker* invoker,
                             const Location& callback_posted_from,
                             Thread* calling_thread);
   void TriggerCallback();
   void SetCallback(const Callback0<void>& callback) {
     CritScope cs(&crit_);
     callback_ = callback;
   }
-  bool CallbackCanceled() const { return calling_thread_ == nullptr; }
+  bool CallbackCanceled() const {
+    CritScope cs(&crit_);
+    return calling_thread_ == nullptr;
+  }
 
  private:
   Location callback_posted_from_;
-  Callback0<void> callback_;
   CriticalSection crit_;
-  Thread* calling_thread_;
+  Callback0<void> callback_ GUARDED_BY(crit_);
+  Thread* calling_thread_ GUARDED_BY(crit_);
 
   void CancelCallback();
 };
 
 // Closures that have a non-void return value and require a callback.
 template <class ReturnT, class FunctorT, class HostT>
 class NotifyingAsyncClosure : public NotifyingAsyncClosureBase {
  public:
   NotifyingAsyncClosure(AsyncInvoker* invoker,
                         const Location& callback_posted_from,
@@ skipping 43 matching lines @@
     TriggerCallback();
   }
 
  private:
   FunctorT functor_;
 };
 
 }  // namespace rtc
 
 #endif  // WEBRTC_BASE_ASYNCINVOKER_INL_H_