msg_queue.h

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/* -*- c++ -*- */
/*
 * Copyright 2009 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3, or (at your option)
 * any later version.
 * 
 * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */
#ifndef INCLUDED_MSG_QUEUE_H
#define INCLUDED_MSG_QUEUE_H

#include <gruel/thread.h>
#include <gruel/pmt.h>
#include <deque>

namespace gruel {

  class msg_queue;
  typedef boost::shared_ptr<msg_queue> msg_queue_sptr;

  msg_queue_sptr make_msg_queue(unsigned int limit=0);

  /*!
   * \brief thread-safe message queue
   */
  class msg_queue {

    gruel::mutex              d_mutex;
    gruel::condition_variable d_not_empty;
    gruel::condition_variable d_not_full;
    unsigned int              d_limit;    // max # of messages in queue.  0 -> unbounded

    std::deque<pmt::pmt_t>    d_msgs;

  public:
    msg_queue(unsigned int limit);
    ~msg_queue();

    /*!
     * \brief Insert message at tail of queue.
     * \param msg message
     *
     * Block if queue if full.
     */
    void insert_tail(pmt::pmt_t msg);

    /*!
     * \brief Delete message from head of queue and return it.
     * Block if no message is available.
     */
    pmt::pmt_t delete_head();
    
    /*!
     * \brief If there's a message in the q, delete it and return it.
     * If no message is available, return pmt_t().
     */
    pmt::pmt_t delete_head_nowait();
    
    //! Delete all messages from the queue
    void flush();

    //! is the queue empty?
    bool empty_p() const { return d_msgs.empty(); }
  
    //! is the queue full?
    bool full_p() const { return d_limit != 0 && count() >= d_limit; }
  
    //! return number of messages in queue
    unsigned int count() const { return d_msgs.size(); }

    //! return limit on number of message in queue.  0 -> unbounded
    unsigned int limit() const { return d_limit; }
  };

} /* namespace gruel */

#endif /* INCLUDED_MSG_QUEUE_H */