pgm_sender.cpp

/*
    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/>.
*/

#include "platform.hpp"

#if defined ZMQ_HAVE_OPENPGM

#ifdef ZMQ_HAVE_WINDOWS
#include "windows.hpp"
#endif

#include <stdlib.h>

#include "io_thread.hpp"
#include "pgm_sender.hpp"
#include "session_base.hpp"
#include "err.hpp"
#include "wire.hpp"
#include "stdint.hpp"

zmq::pgm_sender_t::pgm_sender_t (io_thread_t *parent_,
      const options_t &options_) :
    io_object_t (parent_),
    has_tx_timer (false),
    has_rx_timer (false),
    session (NULL),
    encoder (0),
    more_flag (false),
    pgm_socket (false, options_),
    options (options_),
    out_buffer (NULL),
    out_buffer_size (0),
    write_size (0)
{
    int rc = msg.init ();
    errno_assert (rc == 0);
}

int zmq::pgm_sender_t::init (bool udp_encapsulation_, const char *network_)
{
    int rc = pgm_socket.init (udp_encapsulation_, network_);
    if (rc != 0)
        return rc;

    out_buffer_size = pgm_socket.get_max_tsdu_size ();
    out_buffer = (unsigned char*) malloc (out_buffer_size);
    alloc_assert (out_buffer);

    return rc;
}

void zmq::pgm_sender_t::plug (io_thread_t *io_thread_, session_base_t *session_)
{
    //  Allocate 2 fds for PGM socket.
    fd_t downlink_socket_fd = retired_fd;
    fd_t uplink_socket_fd = retired_fd;
    fd_t rdata_notify_fd = retired_fd;
    fd_t pending_notify_fd = retired_fd;

    session = session_;

    //  Fill fds from PGM transport and add them to the poller.
    pgm_socket.get_sender_fds (&downlink_socket_fd, &uplink_socket_fd,
        &rdata_notify_fd, &pending_notify_fd);

    handle = add_fd (downlink_socket_fd);
    uplink_handle = add_fd (uplink_socket_fd);
    rdata_notify_handle = add_fd (rdata_notify_fd);
    pending_notify_handle = add_fd (pending_notify_fd);

    //  Set POLLIN. We wont never want to stop polling for uplink = we never
    //  want to stop processing NAKs.
    set_pollin (uplink_handle);
    set_pollin (rdata_notify_handle);
    set_pollin (pending_notify_handle);

    //  Set POLLOUT for downlink_socket_handle.
    set_pollout (handle);
}

void zmq::pgm_sender_t::unplug ()
{
    if (has_rx_timer) {
        cancel_timer (rx_timer_id);
        has_rx_timer = false;
    }

    if (has_tx_timer) {
        cancel_timer (tx_timer_id);
        has_tx_timer = false;
    }

    rm_fd (handle);
    rm_fd (uplink_handle);
    rm_fd (rdata_notify_handle);
    rm_fd (pending_notify_handle);
    session = NULL;
}

void zmq::pgm_sender_t::terminate ()
{
    unplug ();
    delete this;
}

void zmq::pgm_sender_t::restart_output ()
{
    set_pollout (handle);
    out_event ();
}

void zmq::pgm_sender_t::restart_input ()
{
    zmq_assert (false);
}

zmq::pgm_sender_t::~pgm_sender_t ()
{
    int rc = msg.close ();
    errno_assert (rc == 0);

    if (out_buffer) {
        free (out_buffer);
        out_buffer = NULL;
    }
}

void zmq::pgm_sender_t::in_event ()
{
    if (has_rx_timer) {
        cancel_timer (rx_timer_id);
        has_rx_timer = false;
    }

    //  In-event on sender side means NAK or SPMR receiving from some peer.
    pgm_socket.process_upstream ();
    if (errno == ENOMEM || errno == EBUSY) {
        const long timeout = pgm_socket.get_rx_timeout ();
        add_timer (timeout, rx_timer_id);
        has_rx_timer = true;
    }
}

void zmq::pgm_sender_t::out_event ()
{
    //  POLLOUT event from send socket. If write buffer is empty,
    //  try to read new data from the encoder.
    if (write_size == 0) {

        //  First two bytes (sizeof uint16_t) are used to store message
        //  offset in following steps. Note that by passing our buffer to
        //  the get data function we prevent it from returning its own buffer.
        unsigned char *bf = out_buffer + sizeof (uint16_t);
        size_t bfsz = out_buffer_size - sizeof (uint16_t);
        uint16_t offset = 0xffff;

        size_t bytes = encoder.encode (&bf, bfsz);
        while (bytes < bfsz) {
            if (!more_flag && offset == 0xffff)
                offset = static_cast <uint16_t> (bytes);
            int rc = session->pull_msg (&msg);
            if (rc == -1)
                break;
            more_flag = msg.flags () & msg_t::more;
            encoder.load_msg (&msg);
            bf = out_buffer + sizeof (uint16_t) + bytes;
            bytes += encoder.encode (&bf, bfsz - bytes);
        }

        //  If there are no data to write stop polling for output.
        if (bytes == 0) {
            reset_pollout (handle);
            return;
        }

        write_size = sizeof (uint16_t) + bytes;

        //  Put offset information in the buffer.
        put_uint16 (out_buffer, offset);
    }

    if (has_tx_timer) {
        cancel_timer (tx_timer_id);
        set_pollout (handle);
        has_tx_timer = false;
    }

    //  Send the data.
    size_t nbytes = pgm_socket.send (out_buffer, write_size);

    //  We can write either all data or 0 which means rate limit reached.
    if (nbytes == write_size)
        write_size = 0;
    else {
        zmq_assert (nbytes == 0);

        if (errno == ENOMEM) {
            // Stop polling handle and wait for tx timeout
            const long timeout = pgm_socket.get_tx_timeout ();
            add_timer (timeout, tx_timer_id);
            reset_pollout (handle);
            has_tx_timer = true;
        }
        else
            errno_assert (errno == EBUSY);
    }
}

void zmq::pgm_sender_t::timer_event (int token)
{
    //  Timer cancels on return by poller_base.
    if (token == rx_timer_id) {
        has_rx_timer = false;
        in_event ();
    }
    else
    if (token == tx_timer_id) {
        // Restart polling handle and retry sending
        has_tx_timer = false;
        set_pollout (handle);
        out_event ();
    }
    else
        zmq_assert (false);
}

#endif