epoll.cpp

/* SPDX-License-Identifier: MPL-2.0 */

#include "precompiled.hpp"
#if defined ZMQ_IOTHREAD_POLLER_USE_EPOLL
#include "epoll.hpp"

#if !defined ZMQ_HAVE_WINDOWS
#include <unistd.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <algorithm>
#include <new>

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

#ifdef ZMQ_HAVE_WINDOWS
const zmq::epoll_t::epoll_fd_t zmq::epoll_t::epoll_retired_fd =
  INVALID_HANDLE_VALUE;
#endif

zmq::epoll_t::epoll_t (const zmq::thread_ctx_t &ctx_) :
    worker_poller_base_t (ctx_)
{
#ifdef ZMQ_IOTHREAD_POLLER_USE_EPOLL_CLOEXEC
    //  Setting this option result in sane behaviour when exec() functions
    //  are used. Old sockets are closed and don't block TCP ports, avoid
    //  leaks, etc.
    _epoll_fd = epoll_create1 (EPOLL_CLOEXEC);
#else
    _epoll_fd = epoll_create (1);
#endif
    errno_assert (_epoll_fd != epoll_retired_fd);
}

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

#ifdef ZMQ_HAVE_WINDOWS
    epoll_close (_epoll_fd);
#else
    close (_epoll_fd);
#endif
    for (retired_t::iterator it = _retired.begin (), end = _retired.end ();
         it != end; ++it) {
        LIBZMQ_DELETE (*it);
    }
}

zmq::epoll_t::handle_t zmq::epoll_t::add_fd (fd_t fd_, i_poll_events *events_)
{
    check_thread ();
    poll_entry_t *pe = new (std::nothrow) poll_entry_t;
    alloc_assert (pe);

    //  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_;

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

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

    return pe;
}

void zmq::epoll_t::rm_fd (handle_t handle_)
{
    check_thread ();
    poll_entry_t *pe = static_cast<poll_entry_t *> (handle_);
    const 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.
    adjust_load (-1);
}

void zmq::epoll_t::set_pollin (handle_t handle_)
{
    check_thread ();
    poll_entry_t *pe = static_cast<poll_entry_t *> (handle_);
    pe->ev.events |= EPOLLIN;
    const 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_)
{
    check_thread ();
    poll_entry_t *pe = static_cast<poll_entry_t *> (handle_);
    pe->ev.events &= ~(static_cast<uint32_t> (EPOLLIN));
    const 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_)
{
    check_thread ();
    poll_entry_t *pe = static_cast<poll_entry_t *> (handle_);
    pe->ev.events |= EPOLLOUT;
    const 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_)
{
    check_thread ();
    poll_entry_t *pe = static_cast<poll_entry_t *> (handle_);
    pe->ev.events &= ~(static_cast<uint32_t> (EPOLLOUT));
    const int rc = epoll_ctl (_epoll_fd, EPOLL_CTL_MOD, pe->fd, &pe->ev);
    errno_assert (rc != -1);
}

void zmq::epoll_t::stop ()
{
    check_thread ();
}

int zmq::epoll_t::max_fds ()
{
    return -1;
}

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

    while (true) {
        //  Execute any due timers.
        const int timeout = static_cast<int> (execute_timers ());

        if (get_load () == 0) {
            if (timeout == 0)
                break;

            // TODO sleep for timeout
            continue;
        }

        //  Wait for events.
        const int n = epoll_wait (_epoll_fd, &ev_buf[0], max_io_events,
                                  timeout ? timeout : -1);
        if (n == -1) {
            errno_assert (errno == EINTR);
            continue;
        }

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

            if (NULL == pe)
                continue;
            if (NULL == pe->events)
                continue;
            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 (), end = _retired.end ();
             it != end; ++it) {
            LIBZMQ_DELETE (*it);
        }
        _retired.clear ();
    }
}

#endif