Separates ipc code from common (http://crbug.com/16829)

ipc/ipc_sync_message.h

+// Copyright (c) 2006-2008 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_IPC_SYNC_MESSAGE_H__
+#define IPC_IPC_SYNC_MESSAGE_H__
+
+#if defined(OS_WIN)
+#include <windows.h>
+#endif
+#include <string>
+#include "base/basictypes.h"
+#include "ipc/ipc_message.h"
+
+namespace base {
+class WaitableEvent;
+}
+
+namespace IPC {
+
+class MessageReplyDeserializer;
+
+class SyncMessage : public Message {
+ public:
+  SyncMessage(int32 routing_id, uint16 type, PriorityValue priority,
+              MessageReplyDeserializer* deserializer);
+
+  // Call this to get a deserializer for the output parameters.
+  // Note that this can only be called once, and the caller is responsible
+  // for deleting the deserializer when they're done.
+  MessageReplyDeserializer* GetReplyDeserializer();
+
+  // If this message can cause the receiver to block while waiting for user
+  // input (i.e. by calling MessageBox), then the caller needs to pump window
+  // messages and dispatch asynchronous messages while waiting for the reply.
+  // If this event is passed in, then window messages will start being pumped
+  // when it's set.  Note that this behavior will continue even if the event is
+  // later reset.  The event must be valid until after the Send call returns.
+  void set_pump_messages_event(base::WaitableEvent* event) {
+    pump_messages_event_ = event;
+    if (event) {
+      header()->flags |= PUMPING_MSGS_BIT;
+    } else {
+      header()->flags &= ~PUMPING_MSGS_BIT;
+    }
+  }
+
+  // Call this if you always want to pump messages.  You can call this method
+  // or set_pump_messages_event but not both.
+  void EnableMessagePumping();
+
+  base::WaitableEvent* pump_messages_event() const {
+    return pump_messages_event_;
+  }
+
+  // Returns true if the message is a reply to the given request id.
+  static bool IsMessageReplyTo(const Message& msg, int request_id);
+
+  // Given a reply message, returns an iterator to the beginning of the data
+  // (i.e. skips over the synchronous specific data).
+  static void* GetDataIterator(const Message* msg);
+
+  // Given a synchronous message (or its reply), returns its id.
+  static int GetMessageId(const Message& msg);
+
+  // Generates a reply message to the given message.
+  static Message* GenerateReply(const Message* msg);
+
+ private:
+  struct SyncHeader {
+    // unique ID (unique per sender)
+    int message_id;
+  };
+
+  static bool ReadSyncHeader(const Message& msg, SyncHeader* header);
+  static bool WriteSyncHeader(Message* msg, const SyncHeader& header);
+
+  MessageReplyDeserializer* deserializer_;
+  base::WaitableEvent* pump_messages_event_;
+
+  static uint32 next_id_;  // for generation of unique ids
+};
+
+// Used to deserialize parameters from a reply to a synchronous message
+class MessageReplyDeserializer {
+ public:
+  bool SerializeOutputParameters(const Message& msg);
+ private:
+  // Derived classes need to implement this, using the given iterator (which
+  // is skipped past the header for synchronous messages).
+  virtual bool SerializeOutputParameters(const Message& msg, void* iter) = 0;
+};
+
+}  // namespace IPC
+
+#endif  // IPC_IPC_SYNC_MESSAGE_H__