Mojo: More plumbing required to transfer handles over MessagePipes.

mojo/system/local_message_pipe_endpoint.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_LOCAL_MESSAGE_PIPE_ENDPOINT_H_
 #define MOJO_SYSTEM_LOCAL_MESSAGE_PIPE_ENDPOINT_H_
 
 #include <deque>
+#include <vector>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "mojo/public/system/core.h"
 #include "mojo/public/system/system_export.h"
 #include "mojo/system/message_pipe_endpoint.h"
 #include "mojo/system/waiter_list.h"
 
 namespace mojo {
 namespace system {
 
 class MOJO_SYSTEM_EXPORT LocalMessagePipeEndpoint : public MessagePipeEndpoint {
  public:
   LocalMessagePipeEndpoint();
   virtual ~LocalMessagePipeEndpoint();
 
   // |MessagePipeEndpoint| implementation:
   virtual void Close() OVERRIDE;
   virtual bool OnPeerClose() OVERRIDE;
-  virtual MojoResult EnqueueMessage(
+  virtual MojoResult CanEnqueueMessage(
+      const MessageInTransit* message,
+      const std::vector<Dispatcher*>* dispatchers) OVERRIDE;
+  virtual void EnqueueMessage(
       MessageInTransit* message,
-      const std::vector<Dispatcher*>* dispatchers) OVERRIDE;
+      std::vector<scoped_refptr<Dispatcher> >* dispatchers) OVERRIDE;
 
   // There's a dispatcher for |LocalMessagePipeEndpoint|s, so we have to
   // implement/override these:
   virtual void CancelAllWaiters() OVERRIDE;
   virtual MojoResult ReadMessage(
       void* bytes, uint32_t* num_bytes,
       uint32_t max_num_dispatchers,
       std::vector<scoped_refptr<Dispatcher> >* dispatchers,
       MojoReadMessageFlags flags) OVERRIDE;
   virtual MojoResult AddWaiter(Waiter* waiter,
                                MojoWaitFlags flags,
                                MojoResult wake_result) OVERRIDE;
   virtual void RemoveWaiter(Waiter* waiter) OVERRIDE;
 
  private:
+  struct MessageQueueEntry {
+    MessageQueueEntry();
+    // Provide an explicit copy constructor, so that we can use this directly in
+    // a (C++03) STL container. However, we only allow the case where |other| is
+    // empty. (We don't provide a nontrivial constructor, because it wouldn't be
+    // useful with these constraints. This will change with C++11.)
+    MessageQueueEntry(const MessageQueueEntry& other);
+    ~MessageQueueEntry();
+
+    MessageInTransit* message;
+    std::vector<scoped_refptr<Dispatcher> > dispatchers;
+
+   private:
+    // We don't need assignment, however.
+    DISALLOW_ASSIGN(MessageQueueEntry);
+  };
+
   MojoWaitFlags SatisfiedFlags();
   MojoWaitFlags SatisfiableFlags();
 
   bool is_open_;
   bool is_peer_open_;
 
-  std::deque<MessageInTransit*> message_queue_;
+  std::deque<MessageQueueEntry> message_queue_;
   WaiterList waiter_list_;
 
   DISALLOW_COPY_AND_ASSIGN(LocalMessagePipeEndpoint);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_LOCAL_MESSAGE_PIPE_ENDPOINT_H_