view src/os/unix/ngx_recv.c @ 9202:e88cdaa0f1ff

AIO operations now add timers (ticket #2162). Each AIO (thread IO) operation being run is now accompanied with 1-minute timer. This timer prevents unexpected shutdown of the worker process while an AIO operation is running, and logs an alert if the operation is running for too long. This fixes "open socket left" alerts during worker processes shutdown due to pending AIO (or thread IO) operations while corresponding requests have no timers. In particular, such errors were observed while reading cache headers (ticket #2162), and with worker_shutdown_timeout.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 29 Jan 2024 10:31:37 +0300
parents 5119c8150478
children
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


ssize_t
ngx_unix_recv(ngx_connection_t *c, u_char *buf, size_t size)
{
    ssize_t       n;
    ngx_err_t     err;
    ngx_event_t  *rev;

    rev = c->read;

#if (NGX_HAVE_KQUEUE)

    if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {
        ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0,
                       "recv: eof:%d, avail:%d, err:%d",
                       rev->pending_eof, rev->available, rev->kq_errno);

        if (rev->available == 0) {
            if (rev->pending_eof) {
                rev->ready = 0;
                rev->eof = 1;

                if (rev->kq_errno) {
                    rev->error = 1;
                    ngx_set_socket_errno(rev->kq_errno);

                    return ngx_connection_error(c, rev->kq_errno,
                               "kevent() reported about an closed connection");
                }

                return 0;

            } else {
                rev->ready = 0;
                return NGX_AGAIN;
            }
        }
    }

#endif

#if (NGX_HAVE_EPOLLRDHUP)

    if ((ngx_event_flags & NGX_USE_EPOLL_EVENT)
        && ngx_use_epoll_rdhup)
    {
        ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
                       "recv: eof:%d, avail:%d",
                       rev->pending_eof, rev->available);

        if (rev->available == 0 && !rev->pending_eof) {
            rev->ready = 0;
            return NGX_AGAIN;
        }
    }

#endif

    do {
        n = recv(c->fd, buf, size, 0);

        ngx_log_debug3(NGX_LOG_DEBUG_EVENT, c->log, 0,
                       "recv: fd:%d %z of %uz", c->fd, n, size);

        if (n == 0) {
            rev->ready = 0;
            rev->eof = 1;

#if (NGX_HAVE_KQUEUE)

            /*
             * on FreeBSD recv() may return 0 on closed socket
             * even if kqueue reported about available data
             */

            if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {
                rev->available = 0;
            }

#endif

            return 0;
        }

        if (n > 0) {

#if (NGX_HAVE_KQUEUE)

            if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {
                rev->available -= n;

                /*
                 * rev->available may be negative here because some additional
                 * bytes may be received between kevent() and recv()
                 */

                if (rev->available <= 0) {
                    if (!rev->pending_eof) {
                        rev->ready = 0;
                    }

                    rev->available = 0;
                }

                return n;
            }

#endif

#if (NGX_HAVE_FIONREAD)

            if (rev->available >= 0) {
                rev->available -= n;

                /*
                 * negative rev->available means some additional bytes
                 * were received between kernel notification and recv(),
                 * and therefore ev->ready can be safely reset even for
                 * edge-triggered event methods
                 */

                if (rev->available < 0) {
                    rev->available = 0;
                    rev->ready = 0;
                }

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                               "recv: avail:%d", rev->available);

            } else if ((size_t) n == size) {

                if (ngx_socket_nread(c->fd, &rev->available) == -1) {
                    n = ngx_connection_error(c, ngx_socket_errno,
                                             ngx_socket_nread_n " failed");
                    break;
                }

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                               "recv: avail:%d", rev->available);
            }

#endif

#if (NGX_HAVE_EPOLLRDHUP)

            if ((ngx_event_flags & NGX_USE_EPOLL_EVENT)
                && ngx_use_epoll_rdhup)
            {
                if ((size_t) n < size) {
                    if (!rev->pending_eof) {
                        rev->ready = 0;
                    }

                    rev->available = 0;
                }

                return n;
            }

#endif

            if ((size_t) n < size
                && !(ngx_event_flags & NGX_USE_GREEDY_EVENT))
            {
                rev->ready = 0;
            }

            return n;
        }

        err = ngx_socket_errno;

        if (err == NGX_EAGAIN || err == NGX_EINTR) {
            ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
                           "recv() not ready");
            n = NGX_AGAIN;

        } else {
            n = ngx_connection_error(c, err, "recv() failed");
            break;
        }

    } while (err == NGX_EINTR);

    rev->ready = 0;

    if (n == NGX_ERROR) {
        rev->error = 1;
    }

    return n;
}