/*
    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    0MQ 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef __ZMQ_SIGNALER_HPP_INCLUDED__
#define __ZMQ_SIGNALER_HPP_INCLUDED__

#ifdef HAVE_FORK
#include <unistd.h>
#endif

#include "fd.hpp"

namespace zmq
{

    //  This is a cross-platform equivalent to signal_fd. However, as opposed
    //  to signal_fd there can be at most one signal in the signaler at any
    //  given moment. Attempt to send a signal before receiving the previous
    //  one will result in undefined behaviour.

    class signaler_t
    {
    public:

        signaler_t ();
        ~signaler_t ();

        fd_t get_fd ();
        void send ();
        int wait (int timeout_);
        void recv ();

#ifdef HAVE_FORK
        // close the file descriptors in a forked child process so that they
        // do not interfere with the context in the parent process.
        void forked();
#endif

    private:

        //  Creates a pair of filedescriptors that will be used
        //  to pass the signals.
        static int make_fdpair (fd_t *r_, fd_t *w_);

        //  Underlying write & read file descriptor
        //  Will be -1 if we exceeded number of available handles
        fd_t w;
        fd_t r;

        //  Disable copying of signaler_t object.
        signaler_t (const signaler_t&);
        const signaler_t &operator = (const signaler_t&);

#ifdef HAVE_FORK
        // the process that created this context. Used to detect forking.
        pid_t pid;
        // idempotent close of file descriptors that is safe to use by destructor
        // and forked().
        void close_internal();
#endif
    };
}

#endif
