Refactor content/common/message_router to ipc/message_router

BUG=586366

Review URL: https://codereview.chromium.org/1710973002

Cr-Commit-Position: refs/heads/master@{#376326}

4 files changed, 130 insertions, 0 deletions

diff --git a/ipc/BUILD.gn b/ipc/BUILD.gn
index 2451d6f..c3d3bb4 100644
--- a/ipc/BUILD.gn
+++ b/ipc/BUILD.gn
@@ -91,6 +91,8 @@ component("ipc") {
     "message_filter.h",
     "message_filter_router.cc",
     "message_filter_router.h",
+    "message_router.cc",
+    "message_router.h",
     "param_traits_log_macros.h",
     "param_traits_macros.h",
     "param_traits_read_macros.h",
diff --git a/ipc/ipc.gypi b/ipc/ipc.gypi
index 6b7cf93..da570d2 100644
--- a/ipc/ipc.gypi
+++ b/ipc/ipc.gypi
@@ -96,6 +96,8 @@
           'message_filter.h',
           'message_filter_router.cc',
           'message_filter_router.h',
+          'message_router.cc',
+          'message_router.h',
           'param_traits_log_macros.h',
           'param_traits_macros.h',
           'param_traits_read_macros.h',
diff --git a/ipc/message_router.cc b/ipc/message_router.cc
new file mode 100644
index 0000000..aaf4a1f
--- /dev/null
+++ b/ipc/message_router.cc
@@ -0,0 +1,55 @@
+// Copyright (c) 2011 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.
+
+#include "ipc/message_router.h"
+
+#include "ipc/ipc_message.h"
+
+namespace IPC {
+
+MessageRouter::MessageRouter() {}
+
+MessageRouter::~MessageRouter() {}
+
+bool MessageRouter::OnControlMessageReceived(const IPC::Message& msg) {
+  NOTREACHED()
+      << "should override in subclass if you care about control messages";
+  return false;
+}
+
+bool MessageRouter::Send(IPC::Message* msg) {
+  NOTREACHED()
+      << "should override in subclass if you care about sending messages";
+  return false;
+}
+
+bool MessageRouter::AddRoute(int32_t routing_id, IPC::Listener* listener) {
+  if (routes_.Lookup(routing_id)) {
+    DLOG(ERROR) << "duplicate routing ID";
+    return false;
+  }
+  routes_.AddWithID(listener, routing_id);
+  return true;
+}
+
+void MessageRouter::RemoveRoute(int32_t routing_id) {
+  routes_.Remove(routing_id);
+}
+
+bool MessageRouter::OnMessageReceived(const IPC::Message& msg) {
+  if (msg.routing_id() == MSG_ROUTING_CONTROL)
+    return OnControlMessageReceived(msg);
+
+  return RouteMessage(msg);
+}
+
+bool MessageRouter::RouteMessage(const IPC::Message& msg) {
+  IPC::Listener* listener = routes_.Lookup(msg.routing_id());
+  if (!listener)
+    return false;
+
+  return listener->OnMessageReceived(msg);
+}
+
+}  // namespace IPC
diff --git a/ipc/message_router.h b/ipc/message_router.h
new file mode 100644
index 0000000..db4bc27
--- /dev/null
+++ b/ipc/message_router.h
@@ -0,0 +1,71 @@
+// Copyright (c) 2012 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_MESSAGE_ROUTER_H_
+#define IPC_MESSAGE_ROUTER_H_
+
+#include <stdint.h>
+
+#include "base/id_map.h"
+#include "base/macros.h"
+#include "ipc/ipc_export.h"
+#include "ipc/ipc_listener.h"
+#include "ipc/ipc_sender.h"
+
+// The MessageRouter handles all incoming messages sent to it by routing them
+// to the correct listener.  Routing is based on the Message's routing ID.
+// Since routing IDs are typically assigned asynchronously by the browser
+// process, the MessageRouter has the notion of pending IDs for listeners that
+// have not yet been assigned a routing ID.
+//
+// When a message arrives, the routing ID is used to index the set of routes to
+// find a listener.  If a listener is found, then the message is passed to it.
+// Otherwise, the message is ignored if its routing ID is not equal to
+// MSG_ROUTING_CONTROL.
+//
+// The MessageRouter supports the IPC::Sender interface for outgoing messages,
+// but does not define a meaningful implementation of it.  The subclass of
+// MessageRouter is intended to provide that if appropriate.
+//
+// The MessageRouter can be used as a concrete class provided its Send method
+// is not called and it does not receive any control messages.
+
+namespace IPC {
+
+class IPC_EXPORT MessageRouter : public Listener, public Sender {
+ public:
+  MessageRouter();
+  ~MessageRouter() override;
+
+  // Implemented by subclasses to handle control messages
+  virtual bool OnControlMessageReceived(const Message& msg);
+
+  // Listener implementation:
+  bool OnMessageReceived(const Message& msg) override;
+
+  // Like OnMessageReceived, except it only handles routed messages.  Returns
+  // true if the message was dispatched, or false if there was no listener for
+  // that route id.
+  virtual bool RouteMessage(const Message& msg);
+
+  // Sender implementation:
+  bool Send(Message* msg) override;
+
+  // Called to add a listener for a particular message routing ID.
+  // Returns true if succeeded.
+  bool AddRoute(int32_t routing_id, Listener* listener);
+
+  // Called to remove a listener for a particular message routing ID.
+  void RemoveRoute(int32_t routing_id);
+
+ private:
+  // A list of all listeners with assigned routing IDs.
+  IDMap<Listener> routes_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessageRouter);
+};
+
+}  // namespace IPC
+
+#endif  // IPC_MESSAGE_ROUTER_H_