gecko-dev/ipc/glue/MessageLink.h

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=4 et :
 */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef ipc_glue_MessageLink_h
#define ipc_glue_MessageLink_h 1

#include "base/basictypes.h"
#include "base/message_loop.h"

#include "mozilla/WeakPtr.h"
#include "mozilla/ipc/Transport.h"

namespace mozilla {
namespace ipc {

class MessageChannel;

struct HasResultCodes {
  enum Result {
    MsgProcessed,
    MsgDropped,
    MsgNotKnown,
    MsgNotAllowed,
    MsgPayloadError,
    MsgProcessingError,
    MsgRouteError,
    MsgValueError
  };
};

enum Side : uint8_t { ParentSide, ChildSide, UnknownSide };

class MessageLink {
 public:
  typedef IPC::Message Message;

  explicit MessageLink(MessageChannel* aChan);
  virtual ~MessageLink();

  // n.b.: These methods all require that the channel monitor is
  // held when they are invoked.
  virtual void EchoMessage(Message* msg) = 0;
  virtual void SendMessage(Message* msg) = 0;
  virtual void SendClose() = 0;

  virtual bool Unsound_IsClosed() const = 0;
  virtual uint32_t Unsound_NumQueuedMessages() const = 0;

 protected:
  MessageChannel* mChan;
};

class ProcessLink : public MessageLink, public Transport::Listener {
  void OnCloseChannel();
  void OnChannelOpened();
  void OnTakeConnectedChannel();
  void OnEchoMessage(Message* msg);

  void AssertIOThread() const {
    MOZ_ASSERT(mIOLoop == MessageLoop::current(), "not on I/O thread!");
  }

 public:
  explicit ProcessLink(MessageChannel* chan);
  virtual ~ProcessLink();

  // The ProcessLink will register itself as the IPC::Channel::Listener on the
  // transport passed here. If the transport already has a listener registered
  // then a listener chain will be established (the ProcessLink listener
  // methods will be called first and may call some methods on the original
  // listener as well). Once the channel is closed (either via normal shutdown
  // or a pipe error) the chain will be destroyed and the original listener
  // will again be registered.
  void Open(Transport* aTransport, MessageLoop* aIOLoop, Side aSide);

  // Run on the I/O thread, only when using inter-process link.
  // These methods acquire the monitor and forward to the
  // similarly named methods in AsyncChannel below
  // (OnMessageReceivedFromLink(), etc)
  virtual void OnMessageReceived(Message&& msg) override;
  virtual void OnChannelConnected(int32_t peer_pid) override;
  virtual void OnChannelError() override;

  virtual void EchoMessage(Message* msg) override;
  virtual void SendMessage(Message* msg) override;
  virtual void SendClose() override;

  virtual bool Unsound_IsClosed() const override;
  virtual uint32_t Unsound_NumQueuedMessages() const override;

 protected:
  void OnChannelConnectError();

 protected:
  Transport* mTransport;
  MessageLoop* mIOLoop;                    // thread where IO happens
  Transport::Listener* mExistingListener;  // channel's previous listener
};

class ThreadLink : public MessageLink {
 public:
  ThreadLink(MessageChannel* aChan, MessageChannel* aTargetChan);
  virtual ~ThreadLink();

  virtual void EchoMessage(Message* msg) override;
  virtual void SendMessage(Message* msg) override;
  virtual void SendClose() override;

  virtual bool Unsound_IsClosed() const override;
  virtual uint32_t Unsound_NumQueuedMessages() const override;

 protected:
  MessageChannel* mTargetChan;
};

}  // namespace ipc
}  // namespace mozilla

#endif  // ifndef ipc_glue_MessageLink_h