ChannelMojo: Handle errors in pending message processing.

ipc/mojo/ipc_channel_mojo_readers.h

 // Copyright 2014 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 IPC_MOJO_IPC_CHANNEL_MOJO_READERS_H_
 #define IPC_MOJO_IPC_CHANNEL_MOJO_READERS_H_
 
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "ipc/mojo/ipc_message_pipe_reader.h"
 #include "mojo/public/cpp/system/core.h"
 
 namespace mojo {
 namespace embedder {
 struct ChannelInfo;
 }
 }
 
 namespace IPC {
 
 class ChannelMojo;
 class Message;
 
 namespace internal {
 
 // A MessagePipeReader implementation for IPC::Message communication.
-class MessageReader : public MessagePipeReader {
+class IPC_MOJO_EXPORT MessageReader : public MessagePipeReader {
  public:
   MessageReader(mojo::ScopedMessagePipeHandle pipe, ChannelMojo* owner);
 
   bool Send(scoped_ptr<Message> message);
 
   // MessagePipeReader implementation
   virtual void OnMessageReceived() OVERRIDE;
   virtual void OnPipeClosed() OVERRIDE;
   virtual void OnPipeError(MojoResult error) OVERRIDE;
 
  private:
+  // Be virtual for testing.
+  virtual MojoResult WriteMessageToPipe(

[yzshen1, 2014/09/15 17:26:07]

Is it possible to do it in a different way? For example, forcefully close the
handle to trigger a write error? I am a little afraid making it virtual is more
expensive than before, and this is on the performance critical path. What do you
think?

[Hajime Morrita, 2014/09/15 18:16:53]

Sounds good. I made change and things got much simpler.
Thanks for the suggestion!

+      const void* bytes,
+      uint32_t num_bytes,
+      const MojoHandle* handles,
+      uint32_t num_handles,
+      MojoWriteMessageFlags flags);
+
   ChannelMojo* owner_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageReader);
 };
 
 // MessagePipeReader implementation for control messages.
 // Actual message handling is implemented by sublcasses.
 class ControlReader : public MessagePipeReader {
  public:
   ControlReader(mojo::ScopedMessagePipeHandle pipe, ChannelMojo* owner);
@@ skipping 42 matching lines @@
  private:
   MojoResult RespondHelloRequest(MojoHandle message_channel);
 
   DISALLOW_COPY_AND_ASSIGN(ClientControlReader);
 };
 
 }  // namespace internal
 }  // namespace IPC
 
 #endif  // IPC_MOJO_IPC_CHANNEL_MOJO_READERS_H_