forwarder2: Make the Forwarder instances operate on a single thread.

tools/android/forwarder2/forwarders_manager.h

 // Copyright 2013 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 TOOLS_ANDROID_FORWARDER2_FORWARDERS_MANAGER_H_
 #define TOOLS_ANDROID_FORWARDER2_FORWARDERS_MANAGER_H_
 
-#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
+#include "base/threading/thread.h"
 #include "tools/android/forwarder2/pipe_notifier.h"
 
-namespace base {
-
-class SingleThreadTaskRunner;
-
-}  // namespace base
-
 namespace forwarder2 {
 
 class Forwarder;
 class Socket;
 
-// Creates and manages lifetime of a set of Forwarder instances. This class
-// ensures in particular that the forwarder instances are deleted on their
-// construction thread no matter which thread ~ForwardersManager() is called on.
+// Creates, owns and notifies Forwarder instances on its own internal thread.
 class ForwardersManager {
  public:
-  // Can be called on any thread.
   ForwardersManager();
+
+  // Must be called on the thread the constructor was called on.
   ~ForwardersManager();
 
-  // Note that the (unique) thread that this method is called on must outlive
-  // the ForwardersManager instance. This is needed since the Forwarder
-  // instances are deleted on the thread they were constructed on.
+  // Can be called on any thread.
   void CreateAndStartNewForwarder(scoped_ptr<Socket> socket1,
                                   scoped_ptr<Socket> socket2);
 
  private:
-  // Ref-counted thread-safe delegate that can (by definition) outlive its outer
-  // ForwarderManager instance. This is needed since the forwarder instances are
-  // destroyed on a thread other than the one ~ForwardersManager() is called on.
-  // The forwarder instances can also call OnForwarderError() below at any time
-  // on their construction thread (which is the same as their destruction
-  // thread). This means that a WeakPtr to ForwardersManager can't be used
-  // instead of ref-counting since checking the validity of the WeakPtr on a
-  // thread other than the one ~ForwardersManager() is called on would be racy.
-  class Delegate : public base::RefCountedThreadSafe<Delegate> {
-   public:
-    Delegate();
+  void CreateNewForwarderOnInternalThread(scoped_ptr<Socket> socket1,
+                                          scoped_ptr<Socket> socket2);
 
-    void Clear();
+  void WaitForEventsOnInternalThreadSoon();
+  void WaitForEventsOnInternalThread();
 
-    void CreateAndStartNewForwarder(scoped_ptr<Socket> socket1,
-                                    scoped_ptr<Socket> socket2);
-
-   private:
-    friend class base::RefCountedThreadSafe<Delegate>;
-
-    virtual ~Delegate();
-
-    void OnForwarderError(scoped_ptr<Forwarder> forwarder);
-
-    void ClearOnForwarderConstructorThread();
-
-    scoped_refptr<base::SingleThreadTaskRunner> forwarders_constructor_runner_;
-    PipeNotifier deletion_notifier_;
-    ScopedVector<Forwarder> forwarders_;
-  };
-
-  const scoped_refptr<Delegate> delegate_;
+  ScopedVector<Forwarder> forwarders_;
+  PipeNotifier deletion_notifier_;
+  PipeNotifier wakeup_notifier_;
+  base::Thread thread_;
 };
 
 }  // namespace forwarder2
 
 #endif  // TOOLS_ANDROID_FORWARDER2_FORWARDERS_MANAGER_H_