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

ipc/ipc_sync_channel.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_SENDER_H__
+#define IPC_IPC_SYNC_SENDER_H__
+
+#include <string>
+#include <deque>
+
+#include "base/basictypes.h"
+#include "base/lock.h"
+#include "base/ref_counted.h"
+#include "base/waitable_event_watcher.h"
+#include "ipc/ipc_channel_proxy.h"
+
+namespace base {
+class WaitableEvent;
+};
+
+namespace IPC {
+
+class SyncMessage;
+class MessageReplyDeserializer;
+
+// This is similar to IPC::ChannelProxy, with the added feature of supporting
+// sending synchronous messages.
+// Note that care must be taken that the lifetime of the ipc_thread argument
+// is more than this object.  If the message loop goes away while this object
+// is running and it's used to send a message, then it will use the invalid
+// message loop pointer to proxy it to the ipc thread.
+class SyncChannel : public ChannelProxy,
+                    public base::WaitableEventWatcher::Delegate {
+ public:
+  SyncChannel(const std::string& channel_id, Channel::Mode mode,
+              Channel::Listener* listener, MessageFilter* filter,
+              MessageLoop* ipc_message_loop, bool create_pipe_now,
+              base::WaitableEvent* shutdown_event);
+  ~SyncChannel();
+
+  virtual bool Send(Message* message);
+  virtual bool SendWithTimeout(Message* message, int timeout_ms);
+
+  // Whether we allow sending messages with no time-out.
+  void set_sync_messages_with_no_timeout_allowed(bool value) {
+    sync_messages_with_no_timeout_allowed_ = value;
+  }
+
+ protected:
+  class ReceivedSyncMsgQueue;
+  friend class ReceivedSyncMsgQueue;
+
+  // SyncContext holds the per object data for SyncChannel, so that SyncChannel
+  // can be deleted while it's being used in a different thread.  See
+  // ChannelProxy::Context for more information.
+  class SyncContext : public Context,
+                      public base::WaitableEventWatcher::Delegate {
+   public:
+    SyncContext(Channel::Listener* listener,
+                MessageFilter* filter,
+                MessageLoop* ipc_thread,
+                base::WaitableEvent* shutdown_event);
+
+    ~SyncContext();
+
+    // Adds information about an outgoing sync message to the context so that
+    // we know how to deserialize the reply.
+    void Push(IPC::SyncMessage* sync_msg);
+
+    // Cleanly remove the top deserializer (and throw it away).  Returns the
+    // result of the Send call for that message.
+    bool Pop();
+
+    // Returns an event that's set when the send is complete, timed out or the
+    // process shut down.
+    base::WaitableEvent* GetSendDoneEvent();
+
+    // Returns an event that's set when an incoming message that's not the reply
+    // needs to get dispatched (by calling SyncContext::DispatchMessages).
+    base::WaitableEvent* GetDispatchEvent();
+
+    void DispatchMessages();
+
+    // Checks if the given message is blocking the listener thread because of a
+    // synchronous send.  If it is, the thread is unblocked and true is
+    // returned. Otherwise the function returns false.
+    bool TryToUnblockListener(const Message* msg);
+
+    // Called on the IPC thread when a sync send that runs a nested message loop
+    // times out.
+    void OnSendTimeout(int message_id);
+
+    base::WaitableEvent* shutdown_event() { return shutdown_event_; }
+
+   private:
+    // IPC::ChannelProxy methods that we override.
+
+    // Called on the listener thread.
+   virtual void Clear();
+
+    // Called on the IPC thread.
+    virtual void OnMessageReceived(const Message& msg);
+    virtual void OnChannelError();
+    virtual void OnChannelOpened();
+    virtual void OnChannelClosed();
+
+    // Cancels all pending Send calls.
+    void CancelPendingSends();
+
+    // WaitableEventWatcher::Delegate implementation.
+    virtual void OnWaitableEventSignaled(base::WaitableEvent* arg);
+
+    // When sending a synchronous message, this structure contains an object
+    // that knows how to deserialize the response.
+    struct PendingSyncMsg {
+      PendingSyncMsg(int id, IPC::MessageReplyDeserializer* d,
+                     base::WaitableEvent* e) :
+          id(id), deserializer(d), done_event(e), send_result(false) { }
+      int id;
+      IPC::MessageReplyDeserializer* deserializer;
+      base::WaitableEvent* done_event;
+      bool send_result;
+    };
+
+    typedef std::deque<PendingSyncMsg> PendingSyncMessageQueue;
+    PendingSyncMessageQueue deserializers_;
+    Lock deserializers_lock_;
+
+    scoped_refptr<ReceivedSyncMsgQueue> received_sync_msgs_;
+
+    base::WaitableEvent* shutdown_event_;
+    base::WaitableEventWatcher shutdown_watcher_;
+  };
+
+ private:
+  // WaitableEventWatcher::Delegate implementation.
+  virtual void OnWaitableEventSignaled(base::WaitableEvent* arg);
+
+  SyncContext* sync_context() {
+    return reinterpret_cast<SyncContext*>(context());
+  }
+
+  // Both these functions wait for a reply, timeout or process shutdown.  The
+  // latter one also runs a nested message loop in the meantime.
+  void WaitForReply(base::WaitableEvent* pump_messages_event);
+
+  // Runs a nested message loop until a reply arrives, times out, or the process
+  // shuts down.
+  void WaitForReplyWithNestedMessageLoop();
+
+  bool sync_messages_with_no_timeout_allowed_;
+
+  // Used to signal events between the IPC and listener threads.
+  base::WaitableEventWatcher send_done_watcher_;
+  base::WaitableEventWatcher dispatch_watcher_;
+
+  DISALLOW_EVIL_CONSTRUCTORS(SyncChannel);
+};
+
+}  // namespace IPC
+
+#endif  // IPC_IPC_SYNC_SENDER_H__