devpoll.cpp

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

#include "precompiled.hpp"
#include "devpoll.hpp"
#if defined ZMQ_IOTHREAD_POLLER_USE_DEVPOLL

#include <sys/devpoll.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <limits.h>
#include <algorithm>

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

zmq::devpoll_t::devpoll_t (const zmq::thread_ctx_t &ctx_) :
    worker_poller_base_t (ctx_)
{
    devpoll_fd = open ("/dev/poll", O_RDWR);
    errno_assert (devpoll_fd != -1);
}

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

    close (devpoll_fd);
}

void zmq::devpoll_t::devpoll_ctl (fd_t fd_, short events_)
{
    struct pollfd pfd = {fd_, events_, 0};
    ssize_t rc = write (devpoll_fd, &pfd, sizeof pfd);
    zmq_assert (rc == sizeof pfd);
}

zmq::devpoll_t::handle_t zmq::devpoll_t::add_fd (fd_t fd_,
                                                 i_poll_events *reactor_)
{
    check_thread ();
    //  If the file descriptor table is too small expand it.
    fd_table_t::size_type sz = fd_table.size ();
    if (sz <= (fd_table_t::size_type) fd_) {
        fd_table.resize (fd_ + 1);
        while (sz != (fd_table_t::size_type) (fd_ + 1)) {
            fd_table[sz].valid = false;
            ++sz;
        }
    }

    zmq_assert (!fd_table[fd_].valid);

    fd_table[fd_].events = 0;
    fd_table[fd_].reactor = reactor_;
    fd_table[fd_].valid = true;
    fd_table[fd_].accepted = false;

    devpoll_ctl (fd_, 0);
    pending_list.push_back (fd_);

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

    return fd_;
}

void zmq::devpoll_t::rm_fd (handle_t handle_)
{
    check_thread ();
    zmq_assert (fd_table[handle_].valid);

    devpoll_ctl (handle_, POLLREMOVE);
    fd_table[handle_].valid = false;

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

void zmq::devpoll_t::set_pollin (handle_t handle_)
{
    check_thread ();
    devpoll_ctl (handle_, POLLREMOVE);
    fd_table[handle_].events |= POLLIN;
    devpoll_ctl (handle_, fd_table[handle_].events);
}

void zmq::devpoll_t::reset_pollin (handle_t handle_)
{
    check_thread ();
    devpoll_ctl (handle_, POLLREMOVE);
    fd_table[handle_].events &= ~((short) POLLIN);
    devpoll_ctl (handle_, fd_table[handle_].events);
}

void zmq::devpoll_t::set_pollout (handle_t handle_)
{
    check_thread ();
    devpoll_ctl (handle_, POLLREMOVE);
    fd_table[handle_].events |= POLLOUT;
    devpoll_ctl (handle_, fd_table[handle_].events);
}

void zmq::devpoll_t::reset_pollout (handle_t handle_)
{
    check_thread ();
    devpoll_ctl (handle_, POLLREMOVE);
    fd_table[handle_].events &= ~((short) POLLOUT);
    devpoll_ctl (handle_, fd_table[handle_].events);
}

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

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

void zmq::devpoll_t::loop ()
{
    while (true) {
        struct pollfd ev_buf[max_io_events];
        struct dvpoll poll_req;

        for (pending_list_t::size_type i = 0; i < pending_list.size (); i++)
            fd_table[pending_list[i]].accepted = true;
        pending_list.clear ();

        //  Execute any due timers.
        int timeout = (int) execute_timers ();

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

            // TODO sleep for timeout
            continue;
        }

        //  Wait for events.
        //  On Solaris, we can retrieve no more then (OPEN_MAX - 1) events.
        poll_req.dp_fds = &ev_buf[0];
#if defined ZMQ_HAVE_SOLARIS
        poll_req.dp_nfds = std::min ((int) max_io_events, OPEN_MAX - 1);
#else
        poll_req.dp_nfds = max_io_events;
#endif
        poll_req.dp_timeout = timeout ? timeout : -1;
        int n = ioctl (devpoll_fd, DP_POLL, &poll_req);
        if (n == -1 && errno == EINTR)
            continue;
        errno_assert (n != -1);

        for (int i = 0; i < n; i++) {
            fd_entry_t *fd_ptr = &fd_table[ev_buf[i].fd];
            if (!fd_ptr->valid || !fd_ptr->accepted)
                continue;
            if (ev_buf[i].revents & (POLLERR | POLLHUP))
                fd_ptr->reactor->in_event ();
            if (!fd_ptr->valid || !fd_ptr->accepted)
                continue;
            if (ev_buf[i].revents & POLLOUT)
                fd_ptr->reactor->out_event ();
            if (!fd_ptr->valid || !fd_ptr->accepted)
                continue;
            if (ev_buf[i].revents & POLLIN)
                fd_ptr->reactor->in_event ();
        }
    }
}

#endif