Mojo: Abstract out the endpoints of MessagePipes.

mojo/system/message_pipe.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 MOJO_SYSTEM_MESSAGE_PIPE_H_
 #define MOJO_SYSTEM_MESSAGE_PIPE_H_
 
-#include <deque>
-
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "mojo/public/system/core.h"
 #include "mojo/public/system/system_export.h"
-#include "mojo/system/waiter_list.h"
 
 namespace mojo {
 namespace system {
 
-class MessageInTransit;
+class MessagePipeEndpoint;
 class Waiter;
 
 // |MessagePipe| is the secondary object implementing a message pipe (see the
-// explanatory comment in core_impl.cc), and is jointly owned by the two
-// dispatchers passed in to the constructor. This class is thread-safe.
+// explanatory comment in core_impl.cc). It is typically owned by the
+// dispatcher(s) corresponding to the local endpoints. This class is
+// thread-safe.
 class MOJO_SYSTEM_EXPORT MessagePipe :
     public base::RefCountedThreadSafe<MessagePipe> {
  public:
+  MessagePipe(scoped_ptr<MessagePipeEndpoint> endpoint_0,
+              scoped_ptr<MessagePipeEndpoint> endpoint_1);
+
+  // Convenience constructor that constructs a |MessagePipe| with two new
+  // |LocalMessagePipeEndpoint|s.
   MessagePipe();
 
   // These are called by the dispatcher to implement its methods of
   // corresponding names. In all cases, the port |port| must be open.
   void CancelAllWaiters(unsigned port);
   void Close(unsigned port);
   // Unlike |MessagePipeDispatcher::WriteMessage()|, this does not validate its
   // arguments. |bytes|/|num_bytes| and |handles|/|num_handles| must be valid.
   MojoResult WriteMessage(unsigned port,
                           const void* bytes, uint32_t num_bytes,
                           const MojoHandle* handles, uint32_t num_handles,
                           MojoWriteMessageFlags flags);
   // Unlike |MessagePipeDispatcher::ReadMessage()|, this does not validate its
   // arguments. |bytes|/|num_bytes| and |handles|/|num_handles| must be valid.
   MojoResult ReadMessage(unsigned port,
                          void* bytes, uint32_t* num_bytes,
                          MojoHandle* handles, uint32_t* num_handles,
                          MojoReadMessageFlags flags);
   MojoResult AddWaiter(unsigned port,
                        Waiter* waiter,
                        MojoWaitFlags flags,
                        MojoResult wake_result);
   void RemoveWaiter(unsigned port, Waiter* waiter);
 
  private:
   friend class base::RefCountedThreadSafe<MessagePipe>;
   virtual ~MessagePipe();
 
-  MojoWaitFlags SatisfiedFlagsNoLock(unsigned port);
-  MojoWaitFlags SatisfiableFlagsNoLock(unsigned port);
-
   base::Lock lock_;  // Protects the following members.
-  bool is_open_[2];
-  // These are *incoming* queues for their corresponding ports. It owns its
-  // contents.
-  // TODO(vtl): When possible (with C++11), convert the plain pointers to
-  // scoped_ptr/unique_ptr.
-  std::deque<MessageInTransit*> message_queues_[2];
-  WaiterList waiter_lists_[2];
+  scoped_ptr<MessagePipeEndpoint> endpoints_[2];
 
   DISALLOW_COPY_AND_ASSIGN(MessagePipe);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_MESSAGE_PIPE_H_