/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */

/*

 * Copyright (c) 2010 The Boeing Company

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation;

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 *

 * Author: Tom Goff <thomas.goff@boeing.com>

 */

#ifndef UNIX_FD_READER_H

#define UNIX_FD_READER_H

#include <stdint.h>

#include "ns3/callback.h"

#include "ns3/system-thread.h"

#include "ns3/event-id.h"

namespace ns3 {

/**

 * \brief A class that asynchronously reads from a file descriptor.

 *

 * This class can be used to start a system thread that reads from a

 * given file descriptor and invokes a given callback when data is

 * received.  This class handles thread management automatically but

 * the \p DoRead() method must be implemented by a subclass.

 */

class FdReader : public SimpleRefCount<FdReader>

{

public:

  FdReader();

  virtual ~FdReader();

  /**

   * Start a new read thread.

   *

   * \param fd A valid file descriptor open for reading.

   *

   * \param readCallback A callback to invoke when new data is

   * available.

   */

  void Start (int fd, Callback<void, uint8_t *, ssize_t> readCallback);

  /**

   * Stop the read thread and reset internal state.  This does not

   * close the file descriptor used for reading.

   */

  void Stop (void);

protected:

  /**

   * \internal

   * \brief A structure representing data read.

   */

  struct Data

  {

    Data () : m_buf (0), m_len (0) {}

    Data (uint8_t *buf, ssize_t len) : m_buf (buf), m_len (len) {}

    uint8_t *m_buf;

    ssize_t m_len;

  };

  /**

   * \internal

   * \brief The read implementation.

   *

   * The value of \p m_len returned controls further processing.  The

   * callback function is only invoked when \p m_len is positive; any

   * data read is not processed when \p m_len is negative; reading

   * stops when \p m_len is zero.

   *

   * The management of memory associated with \p m_buf must be

   * compatible with the read callback.

   *

   * \return A structure representing what was read.

   */

  virtual FdReader::Data DoRead (void) = 0;

  /**

   * \internal

   * \brief The file descriptor to read from.

   */

  int m_fd;

private:

  void Run (void);

  void DestroyEvent (void);

  Callback<void, uint8_t *, ssize_t> m_readCallback;

  Ptr<SystemThread> m_readThread;

  int m_evpipe[2];           // pipe used to signal events between threads

  bool m_stop;               // true means the read thread should stop

  EventId m_destroyEvent;

};

} // namespace ns3