mojo/system/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_MESSAGE_PIPE_ENDPOINT_H_
   6 #define MOJO_SYSTEM_MESSAGE_PIPE_ENDPOINT_H_
   7
   8 #include <stdint.h>
   9
  10 #include <vector>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "mojo/public/c/system/message_pipe.h"
  16 #include "mojo/public/c/system/types.h"
  17 #include "mojo/system/dispatcher.h"
  18 #include "mojo/system/message_in_transit.h"
  19 #include "mojo/system/system_impl_export.h"
  20
  21 namespace mojo {
  22 namespace system {
  23
  24 class Channel;
  25 class Waiter;
  26
  27 // This is an interface to one of the ends of a message pipe, and is used by
  28 // |MessagePipe|. Its most important role is to provide a sink for messages
  29 // (i.e., a place where messages can be sent). It has a secondary role: When the
  30 // endpoint is local (i.e., in the current process), there'll be a dispatcher
  31 // corresponding to the endpoint. In that case, the implementation of
  32 // |MessagePipeEndpoint| also implements the functionality required by the
  33 // dispatcher, e.g., to read messages and to wait. Implementations of this class
  34 // are not thread-safe; instances are protected by |MesssagePipe|'s lock.
  35 class MOJO_SYSTEM_IMPL_EXPORT MessagePipeEndpoint {
  36  public:
  37   virtual ~MessagePipeEndpoint() {}
  38
  39   enum Type {
  40     kTypeLocal,
  41     kTypeProxy
  42   };
  43   virtual Type GetType() const = 0;
  44
  45   // All implementations must implement these.
  46   // Returns false if the endpoint should be closed and destroyed, else true.
  47   virtual bool OnPeerClose() = 0;
  48   // Implements |MessagePipe::EnqueueMessage()|. The major differences are that:
  49   //  a) Dispatchers have been vetted and cloned/attached to the message.
  50   //  b) At this point, we cannot report failure (if, e.g., a channel is torn
  51   //     down at this point, we should silently swallow the message).
  52   virtual void EnqueueMessage(scoped_ptr<MessageInTransit> message) = 0;
  53
  54   // Implementations must override these if they represent a local endpoint,
  55   // i.e., one for which there's a |MessagePipeDispatcher| (and thus a handle).
  56   // An implementation for a proxy endpoint (for which there's no dispatcher)
  57   // needs not override these methods, since they should never be called.
  58   //
  59   // These methods implement the methods of the same name in |MessagePipe|,
  60   // though |MessagePipe|'s implementation may have to do a little more if the
  61   // operation involves both endpoints.
  62   virtual void Close();
  63   virtual void CancelAllWaiters();
  64   virtual MojoResult ReadMessage(void* bytes,
  65                                  uint32_t* num_bytes,
  66                                  DispatcherVector* dispatchers,
  67                                  uint32_t* num_dispatchers,
  68                                  MojoReadMessageFlags flags);
  69   virtual MojoResult AddWaiter(Waiter* waiter,
  70                                MojoWaitFlags flags,
  71                                MojoResult wake_result);
  72   virtual void RemoveWaiter(Waiter* waiter);
  73
  74   // Implementations must override these if they represent a proxy endpoint. An
  75   // implementation for a local endpoint needs not override these methods, since
  76   // they should never be called.
  77   virtual void Attach(scoped_refptr<Channel> channel,
  78                       MessageInTransit::EndpointId local_id);
  79   // Returns false if the endpoint should be closed and destroyed, else true.
  80   virtual bool Run(MessageInTransit::EndpointId remote_id);
  81   virtual void OnRemove();
  82
  83  protected:
  84   MessagePipeEndpoint() {}
  85
  86  private:
  87   DISALLOW_COPY_AND_ASSIGN(MessagePipeEndpoint);
  88 };
  89
  90 }  // namespace system
  91 }  // namespace mojo
  92
  93 #endif  // MOJO_SYSTEM_MESSAGE_PIPE_ENDPOINT_H_