epoll.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"

#ifdef ZMQ_HAVE_LINUX

#include <sys/epoll.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <algorithm>

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

zmq::epoll_t::epoll_t () :
    stopping (false)
{
    epoll_fd = epoll_create (1);
    errno_assert (epoll_fd != -1);
}

zmq::epoll_t::~epoll_t ()
{
    //  Wait till the worker thread exits.
    worker.stop ();

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

    close (epoll_fd);
    for (retired_t::iterator it = retired.begin (); it != retired.end (); it ++)
        delete *it;
}

zmq::handle_t zmq::epoll_t::add_fd (fd_t fd_, i_poll_events *events_)
{
    poll_entry_t *pe = new poll_entry_t;
    zmq_assert (pe != NULL);

    //  The memset is not actually needed. It's here to prevent debugging
    //  tools to complain about using uninitialised memory.
    memset (pe, 0, sizeof (poll_entry_t));

    pe->fd = fd_;
    pe->ev.events = 0;
    pe->ev.data.ptr = pe;
    pe->events = events_;

    int rc = epoll_ctl (epoll_fd, EPOLL_CTL_ADD, fd_, &pe->ev);
    errno_assert (rc != -1);

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

    handle_t handle;
    handle.ptr = pe;
    return handle;
}

void zmq::epoll_t::rm_fd (handle_t handle_)
{
    poll_entry_t *pe = (poll_entry_t*) handle_.ptr;
    int rc = epoll_ctl (epoll_fd, EPOLL_CTL_DEL, pe->fd, &pe->ev);
    errno_assert (rc != -1);
    pe->fd = retired_fd;
    retired.push_back (pe);

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

void zmq::epoll_t::set_pollin (handle_t handle_)
{
    poll_entry_t *pe = (poll_entry_t*) handle_.ptr;
    pe->ev.events |= EPOLLIN;
    int rc = epoll_ctl (epoll_fd, EPOLL_CTL_MOD, pe->fd, &pe->ev);
    errno_assert (rc != -1);
}

void zmq::epoll_t::reset_pollin (handle_t handle_)
{
    poll_entry_t *pe = (poll_entry_t*) handle_.ptr;
    pe->ev.events &= ~((short) EPOLLIN);
    int rc = epoll_ctl (epoll_fd, EPOLL_CTL_MOD, pe->fd, &pe->ev);
    errno_assert (rc != -1);
}

void zmq::epoll_t::set_pollout (handle_t handle_)
{
    poll_entry_t *pe = (poll_entry_t*) handle_.ptr;
    pe->ev.events |= EPOLLOUT;
    int rc = epoll_ctl (epoll_fd, EPOLL_CTL_MOD, pe->fd, &pe->ev);
    errno_assert (rc != -1);
}

void zmq::epoll_t::reset_pollout (handle_t handle_)
{
    poll_entry_t *pe = (poll_entry_t*) handle_.ptr;
    pe->ev.events &= ~((short) EPOLLOUT);
    int rc = epoll_ctl (epoll_fd, EPOLL_CTL_MOD, pe->fd, &pe->ev);
    errno_assert (rc != -1);
}

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

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

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

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

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

void zmq::epoll_t::loop ()
{
    epoll_event ev_buf [max_io_events];

    while (!stopping) {

        //  Wait for events.
        int n;
        while (true) {
            n = epoll_wait (epoll_fd, &ev_buf [0], max_io_events,
                timers.empty () ? -1 : max_timer_period);
            if (!(n == -1 && errno == EINTR)) {
                errno_assert (n != -1);
                break;
            }
        }

        //  Handle timer.
        if (!n) {

            //  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 (int i = 0; i < n; i ++) {
            poll_entry_t *pe = ((poll_entry_t*) ev_buf [i].data.ptr);

            if (pe->fd == retired_fd)
                continue;
            if (ev_buf [i].events & (EPOLLERR | EPOLLHUP))
                pe->events->in_event ();
            if (pe->fd == retired_fd)
               continue;
            if (ev_buf [i].events & EPOLLOUT)
                pe->events->out_event ();
            if (pe->fd == retired_fd)
                continue;
            if (ev_buf [i].events & EPOLLIN)
                pe->events->in_event ();
        }

        //  Destroy retired event sources.
        for (retired_t::iterator it = retired.begin (); it != retired.end ();
              it ++)
            delete *it;
        retired.clear ();
    }
}

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

#endif