libzmq/src/select.cpp

/*
    Copyright (c) 2007-2009 FastMQ Inc.

    This file is part of 0MQ.

    0MQ is free software; you can redistribute it and/or modify it under
    the terms of the Lesser GNU 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
    Lesser GNU General Public License for more details.

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

#include "platform.hpp"

#include <string.h>
#include <algorithm>

#ifdef ZMQ_HAVE_WINDOWS
#include "winsock2.h"
#elif defined ZMQ_HAVE_HPUX
#include <sys/param.h>
#include <sys/types.h>
#include <sys/time.h>
#elif defined ZMQ_HAVE_OPENVMS
#include <sys/types.h>
#include <sys/time.h>
#else
#include <sys/select.h>
#endif

#include "select.hpp"
#include "err.hpp"
#include "config.hpp"
#include "i_poll_events.hpp"

zmq::select_t::select_t () :
    maxfd (retired_fd),
    retired (false),
    stopping (false)
{
    //  Clear file descriptor sets.
    FD_ZERO (&source_set_in);
    FD_ZERO (&source_set_out);
    FD_ZERO (&source_set_err);
}

zmq::select_t::~select_t ()
{
    worker.stop ();

    //  Make sure there are no fds registered on shutdown.
    zmq_assert (load.get () == 0);
}

zmq::handle_t zmq::select_t::add_fd (fd_t fd_, i_poll_events *events_)
{
    //  Store the file descriptor.
    fd_entry_t entry = {fd_, events_};
    fds.push_back (entry);

    //  Start polling on errors.
    FD_SET (fd_, &source_set_err);

    //  Adjust maxfd if necessary.
    if (fd_ > maxfd)
        maxfd = fd_;

    //  Increase the load metric of the thread.
    load.add (1);

    handle_t handle;
    handle.fd = fd_;
    return handle;
}

void zmq::select_t::rm_fd (handle_t handle_)
{
    //  Get file descriptor.
    fd_t fd = handle_.fd;

    //  Mark the descriptor as retired.
    fd_set_t::iterator it;
    for (it = fds.begin (); it != fds.end (); it ++)
        if (it->fd == fd)
            break;
    zmq_assert (it != fds.end ());
    it->fd = retired_fd;
    retired = true;

    //  Stop polling on the descriptor.
    FD_CLR (fd, &source_set_in);
    FD_CLR (fd, &source_set_out);
    FD_CLR (fd, &source_set_err);

    //  Discard all events generated on this file descriptor.
    FD_CLR (fd, &readfds);
    FD_CLR (fd, &writefds);
    FD_CLR (fd, &exceptfds);

    //  Adjust the maxfd attribute if we have removed the
    //  highest-numbered file descriptor.
    if (fd == maxfd) {
        maxfd = retired_fd;
        for (fd_set_t::iterator it = fds.begin (); it != fds.end (); it ++)
            if (it->fd > maxfd)
                maxfd = it->fd;
    }

    //  Decrease the load metric of the thread.
    load.sub (1);
}

void zmq::select_t::set_pollin (handle_t handle_)
{
    FD_SET (handle_.fd, &source_set_in);
}

void zmq::select_t::reset_pollin (handle_t handle_)
{
    FD_CLR (handle_.fd, &source_set_in);
}

void zmq::select_t::set_pollout (handle_t handle_)
{
    FD_SET (handle_.fd, &source_set_out);
}

void zmq::select_t::reset_pollout (handle_t handle_)
{
    FD_CLR (handle_.fd, &source_set_out);
}

void zmq::select_t::add_timer (i_poll_events *events_)
{
    timers.push_back (events_);
}

void zmq::select_t::cancel_timer (i_poll_events *events_)
{
    timers_t::iterator it = std::find (timers.begin (), timers.end (), events_);
    if (it != timers.end ())
        timers.erase (it);
}

int zmq::select_t::get_load ()
{
    return load.get ();
}

void zmq::select_t::start ()
{
    worker.start (worker_routine, this);
}

void zmq::select_t::stop ()
{
    stopping = true;
}

void zmq::select_t::loop ()
{
    while (!stopping) {

        //  Intialise the pollsets.
        memcpy (&readfds, &source_set_in, sizeof source_set_in);
        memcpy (&writefds, &source_set_out, sizeof source_set_out);
        memcpy (&exceptfds, &source_set_err, sizeof source_set_err);

        //  Compute the timout interval. Select is free to overwrite the
        //  value so we have to compute it each time anew.
        timeval timeout = {max_timer_period / 1000,
            (max_timer_period % 1000) * 1000};

        //  Wait for events.
        int rc = select (maxfd + 1, &readfds, &writefds, &exceptfds,
            timers.empty () ? NULL : &timeout);

#ifdef ZMQ_HAVE_WINDOWS
        wsa_assert (rc != SOCKET_ERROR);
#else
        if (rc == -1 && errno == EINTR)
            continue;
        errno_assert (rc != -1);
#endif

        //  Handle timer.
        if (!rc) {

            //  Use local list of timers as timer handlers may fill new timers
            //  into the original array.
            timers_t t;
            std::swap (timers, t);

            //  Trigger all the timers.
            for (timers_t::iterator it = t.begin (); it != t.end (); it ++)
                (*it)->timer_event ();

            continue;
        }

        for (fd_set_t::size_type i = 0; i < fds.size (); i ++) {
            if (fds [i].fd == retired_fd)
                continue;
            if (FD_ISSET (fds [i].fd, &exceptfds))
                fds [i].events->in_event ();
            if (fds [i].fd == retired_fd)
                continue;
            if (FD_ISSET (fds [i].fd, &writefds))
                fds [i].events->out_event ();
            if (fds [i].fd == retired_fd)
                continue;
            if (FD_ISSET (fds [i].fd, &readfds))
                fds [i].events->in_event ();
        }

        //  Destroy retired event sources.
        if (retired) {
            for (fd_set_t::size_type i = 0; i < fds.size (); i ++) {
                if (fds [i].fd == retired_fd) {
                    fds.erase (fds.begin () + i);
                    i --;
                }
            }
            retired = false;
        }
    }
}

void zmq::select_t::worker_routine (void *arg_)
{
    ((select_t*) arg_)->loop ();
}