--- /dev/null
+/* -*- 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 */