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 // Copyright (c) 2009 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 CHROME_COMMON_CHILD_PROCESS_HOST_H_

 #define CHROME_COMMON_CHILD_PROCESS_HOST_H_

 #include "build/build_config.h"

 #include <list>

 #include "base/basictypes.h"

 #include "base/scoped_ptr.h"

 #include "base/waitable_event_watcher.h"

 #include "chrome/common/child_process_info.h"

 #include "chrome/common/ipc_channel.h"

 namespace mozilla {

 namespace ipc {

 class FileDescriptor;

 }

 }

 class NotificationType;

 // Plugins/workers and other child processes that live on the IO thread should

 // derive from this class.

 class ChildProcessHost :

                          public IPC::Message::Sender,

                          public ChildProcessInfo,

                          public base::WaitableEventWatcher::Delegate,

                          public IPC::Channel::Listener {

  public:

   virtual ~ChildProcessHost();

   // ResourceDispatcherHost::Receiver implementation:

   virtual bool Send(IPC::Message* msg);

   // The Iterator class allows iteration through either all child processes, or

   // ones of a specific type, depending on which constructor is used.  Note that

   // this should be done from the IO thread and that the iterator should not be

   // kept around as it may be invalidated on subsequent event processing in the

   // event loop.

   class Iterator {

    public:

     Iterator();

     Iterator(ProcessType type);

     ChildProcessHost* operator->() { return *iterator_; }

     ChildProcessHost* operator*() { return *iterator_; }

     ChildProcessHost* operator++();

     bool Done();

    private:

     bool all_;

     ProcessType type_;

     std::list<ChildProcessHost*>::iterator iterator_;

   };

  protected:

   explicit ChildProcessHost(ProcessType type);

   // Derived classes return true if it's ok to shut down the child process.

   virtual bool CanShutdown() = 0;

   // Creates the IPC channel.  Returns true iff it succeeded.

   bool CreateChannel();

   bool CreateChannel(mozilla::ipc::FileDescriptor& aFileDescriptor);

   // Once the subclass gets a handle to the process, it needs to tell

   // ChildProcessHost using this function.

   void SetHandle(base::ProcessHandle handle);

   // Notifies us that an instance has been created on this child process.

   void InstanceCreated();

   // IPC::Channel::Listener implementation:

   virtual void OnMessageReceived(const IPC::Message& msg) { }

   virtual void OnChannelConnected(int32_t peer_pid) { }

   virtual void OnChannelError() { }

   bool opening_channel() { return opening_channel_; }

   const std::wstring& channel_id() { return channel_id_; }

   base::WaitableEvent* GetProcessEvent() { return process_event_.get(); }

   const IPC::Channel& channel() const { return *channel_; }

   IPC::Channel* channelp() const { return channel_.get(); }

  private:

   // Sends the given notification to the notification service on the UI thread.

   void Notify(NotificationType type);

  protected:

   // WaitableEventWatcher::Delegate implementation:

   virtual void OnWaitableEventSignaled(base::WaitableEvent *event);

  private:

   // By using an internal class as the IPC::Channel::Listener, we can intercept

   // OnMessageReceived/OnChannelConnected and do our own processing before

   // calling the subclass' implementation.

   class ListenerHook : public IPC::Channel::Listener {

    public:

     ListenerHook(ChildProcessHost* host);

     virtual void OnMessageReceived(const IPC::Message& msg);

     virtual void OnChannelConnected(int32_t peer_pid);

     virtual void OnChannelError();

     virtual void GetQueuedMessages(std::queue<IPC::Message>& queue);

    private:

     ChildProcessHost* host_;

   };

   ListenerHook listener_;

   // True while we're waiting the channel to be opened.

   bool opening_channel_;

   // The IPC::Channel.

   scoped_ptr<IPC::Channel> channel_;

   // IPC Channel's id.

   std::wstring channel_id_;

   // Used to watch the child process handle.

   base::WaitableEventWatcher watcher_;

   scoped_ptr<base::WaitableEvent> process_event_;

 };

 #endif  // CHROME_COMMON_CHILD_PROCESS_HOST_H_