mailbox.hpp

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/*
    Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file

    This file is part of libzmq, the ZeroMQ core engine in C++.

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

    As a special exception, the Contributors give you permission to link
    this library with independent modules to produce an executable,
    regardless of the license terms of these independent modules, and to
    copy and distribute the resulting executable under terms of your choice,
    provided that you also meet, for each linked independent module, the
    terms and conditions of the license of that module. An independent
    module is a module which is not derived from or based on this library.
    If you modify this library, you must extend this exception to your
    version of the library.

    libzmq 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_MAILBOX_HPP_INCLUDED__
#define __ZMQ_MAILBOX_HPP_INCLUDED__

#include <stddef.h>

#include "platform.hpp"
#include "signaler.hpp"
#include "fd.hpp"
#include "config.hpp"
#include "command.hpp"
#include "ypipe.hpp"
#include "mutex.hpp"
#include "i_mailbox.hpp"

namespace zmq
{

    class mailbox_t : public i_mailbox
    {
    public:

        mailbox_t ();
        ~mailbox_t ();

        fd_t get_fd () const;
        void send (const command_t &cmd_);
        int recv (command_t *cmd_, int timeout_);

#ifdef HAVE_FORK
        // close the file descriptors in the signaller. This is used in a forked
        // child process to close the file descriptors so that they do not interfere
        // with the context in the parent process.
        void forked () { signaler.forked (); }
#endif

    private:

        //  The pipe to store actual commands.
        typedef ypipe_t <command_t, command_pipe_granularity> cpipe_t;
        cpipe_t cpipe;

        //  Signaler to pass signals from writer thread to reader thread.
        signaler_t signaler;

        //  There's only one thread receiving from the mailbox, but there
        //  is arbitrary number of threads sending. Given that ypipe requires
        //  synchronised access on both of its endpoints, we have to synchronise
        //  the sending side.
        mutex_t sync;

        //  True if the underlying pipe is active, ie. when we are allowed to
        //  read commands from it.
        bool active;

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

}

#endif