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

tools/android/forwarder2/forwarder.h

 // Copyright (c) 2012 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_FORWARDER_H_
 #define TOOLS_ANDROID_FORWARDER2_FORWARDER_H_
 
-#include "base/callback.h"
+#include <sys/select.h>
+
 #include "base/memory/scoped_ptr.h"
-#include "base/threading/thread.h"
-#include "tools/android/forwarder2/self_deleter_helper.h"
+#include "base/threading/thread_checker.h"
 
 namespace forwarder2 {
 
-class PipeNotifier;
 class Socket;
 
-// Internal class that wraps a helper thread to forward traffic between
-// |socket1| and |socket2|. After creating a new instance, call its Start()
-// method to launch operations. Thread stops automatically if one of the socket
-// disconnects, but ensures that all buffered writes to the other, still alive,
-// socket, are written first. When this happens, the instance will delete itself
-// automatically.
-// Note that the instance will always be destroyed on the same thread that
-// created it.
+// Internal class that forwards traffic between |socket1| and |socket2|. Note
+// that this class is not thread-safe.
 class Forwarder {
  public:
-  // Callback used on error invoked by the Forwarder to self-delete.
-  typedef base::Callback<void (scoped_ptr<Forwarder>)> ErrorCallback;
-
-  Forwarder(scoped_ptr<Socket> socket1,
-            scoped_ptr<Socket> socket2,
-            PipeNotifier* deletion_notifier,
-            const ErrorCallback& error_callback);
+  Forwarder(scoped_ptr<Socket> socket1, scoped_ptr<Socket> socket2);
 
   ~Forwarder();
 
-  void Start();
+  void RegisterFDs(fd_set* read_fds, fd_set* write_fds, int* max_fd);
+
+  void ProcessEvents(const fd_set& read_fds, const fd_set& write_fds);
+
+  bool IsClosed() const;
+
+  void Shutdown();
 
  private:
-  void ThreadHandler();
+  class BufferedCopier;
 
-  void OnThreadHandlerCompletion(const ErrorCallback& error_callback);
-
-  SelfDeleterHelper<Forwarder> self_deleter_helper_;
-  PipeNotifier* const deletion_notifier_;
-  scoped_ptr<Socket> socket1_;
-  scoped_ptr<Socket> socket2_;
-  base::Thread thread_;
+  base::ThreadChecker thread_checker_;
+  const scoped_ptr<Socket> socket1_;
+  const scoped_ptr<Socket> socket2_;
+  // Copies data from socket1 to socket2.
+  const scoped_ptr<BufferedCopier> buffer1_;
+  // Copies data from socket2 to socket1.
+  const scoped_ptr<BufferedCopier> buffer2_;
 };
 
 }  // namespace forwarder2
 
 #endif  // TOOLS_ANDROID_FORWARDER2_FORWARDER_H_