mojo/system/proxy_message_pipe_endpoint.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_
   6 #define MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_
   7
   8 #include <stdint.h>
   9
  10 #include "base/compiler_specific.h"
  11 #include "base/macros.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "mojo/system/message_in_transit.h"
  14 #include "mojo/system/message_in_transit_queue.h"
  15 #include "mojo/system/message_pipe_endpoint.h"
  16 #include "mojo/system/system_impl_export.h"
  17
  18 namespace mojo {
  19 namespace system {
  20
  21 class Channel;
  22 class LocalMessagePipeEndpoint;
  23 class MessagePipe;
  24
  25 // A |ProxyMessagePipeEndpoint| connects an end of a |MessagePipe| to a
  26 // |Channel|, over which it transmits and receives data (to/from another
  27 // |ProxyMessagePipeEndpoint|). So a |MessagePipe| with one endpoint local and
  28 // the other endpoint remote consists of a |LocalMessagePipeEndpoint| and a
  29 // |ProxyMessagePipeEndpoint|, with only the local endpoint being accessible via
  30 // a |MessagePipeDispatcher|.
  31 //
  32 // Like any |MessagePipeEndpoint|, a |ProxyMessagePipeEndpoint| is owned by a
  33 // |MessagePipe|.
  34 //  - A |ProxyMessagePipeEndpoint| starts out *detached*, i.e., not associated
  35 //    to any |Channel|. When *attached*, it gets a reference to a |Channel| and
  36 //    is assigned a local ID. A |ProxyMessagePipeEndpoint| must be detached
  37 //    before destruction; this is done inside |Close()|.
  38 //  - When attached, a |ProxyMessagePipeEndpoint| starts out not running. When
  39 //    run, it gets a remote ID.
  40 class MOJO_SYSTEM_IMPL_EXPORT ProxyMessagePipeEndpoint
  41     : public MessagePipeEndpoint {
  42  public:
  43   ProxyMessagePipeEndpoint();
  44   // Constructs a |ProxyMessagePipeEndpoint| that replaces the given
  45   // |LocalMessagePipeEndpoint| (which this constructor will close), taking its
  46   // message queue's contents. This is done when transferring a message pipe
  47   // handle over a remote message pipe.
  48   ProxyMessagePipeEndpoint(
  49       LocalMessagePipeEndpoint* local_message_pipe_endpoint,
  50       bool is_peer_open);
  51   virtual ~ProxyMessagePipeEndpoint();
  52
  53   // |MessagePipeEndpoint| implementation:
  54   virtual Type GetType() const OVERRIDE;
  55   virtual bool OnPeerClose() OVERRIDE;
  56   virtual void EnqueueMessage(scoped_ptr<MessageInTransit> message) OVERRIDE;
  57   virtual void Attach(scoped_refptr<Channel> channel,
  58                       MessageInTransit::EndpointId local_id) OVERRIDE;
  59   virtual bool Run(MessageInTransit::EndpointId remote_id) OVERRIDE;
  60   virtual void OnRemove() OVERRIDE;
  61
  62  private:
  63   void Detach();
  64
  65 #ifdef NDEBUG
  66   void AssertConsistentState() const {}
  67 #else
  68   void AssertConsistentState() const;
  69 #endif
  70
  71   bool is_attached() const {
  72     return !!channel_;
  73   }
  74
  75   bool is_running() const {
  76     return remote_id_ != MessageInTransit::kInvalidEndpointId;
  77   }
  78
  79   // This should only be set if we're attached.
  80   scoped_refptr<Channel> channel_;
  81
  82   // |local_id_| should be set to something other than
  83   // |MessageInTransit::kInvalidEndpointId| when we're attached.
  84   MessageInTransit::EndpointId local_id_;
  85
  86   // |remote_id_| being set to anything other than
  87   // |MessageInTransit::kInvalidEndpointId| indicates that we're "running",
  88   // i.e., actively able to send messages. We should only ever be running if
  89   // we're attached.
  90   MessageInTransit::EndpointId remote_id_;
  91
  92   bool is_peer_open_;
  93
  94   // This queue is only used while we're detached, to store messages while we're
  95   // not ready to send them yet.
  96   MessageInTransitQueue paused_message_queue_;
  97
  98   DISALLOW_COPY_AND_ASSIGN(ProxyMessagePipeEndpoint);
  99 };
 100
 101 }  // namespace system
 102 }  // namespace mojo
 103
 104 #endif  // MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_