view src/os/unix/ngx_freebsd_sendfile_chain.c @ 5860:c9787372f16d

Limit conn: use complex value in limit_conn_zone (ticket #121). One intentional side effect of this change is that key is allowed only in the first position. Previously, it was possible to specify the key variable at any position, but that was never documented, and is contrary to nginx configuration practice for positional parameters.
author Valentin Bartenev <vbart@nginx.com>
date Wed, 24 Sep 2014 21:55:19 +0400
parents b63e829621ab
children 6bbad2e73245
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


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


/*
 * Although FreeBSD sendfile() allows to pass a header and a trailer,
 * it cannot send a header with a part of the file in one packet until
 * FreeBSD 5.3.  Besides, over the fast ethernet connection sendfile()
 * may send the partially filled packets, i.e. the 8 file pages may be sent
 * as the 11 full 1460-bytes packets, then one incomplete 324-bytes packet,
 * and then again the 11 full 1460-bytes packets.
 *
 * Therefore we use the TCP_NOPUSH option (similar to Linux's TCP_CORK)
 * to postpone the sending - it not only sends a header and the first part of
 * the file in one packet, but also sends the file pages in the full packets.
 *
 * But until FreeBSD 4.5 turning TCP_NOPUSH off does not flush a pending
 * data that less than MSS, so that data may be sent with 5 second delay.
 * So we do not use TCP_NOPUSH on FreeBSD prior to 4.5, although it can be used
 * for non-keepalive HTTP connections.
 */


ngx_chain_t *
ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
{
    int              rc, flags;
    u_char          *prev;
    off_t            size, send, prev_send, aligned, sent, fprev;
    size_t           header_size, file_size;
    ngx_uint_t       eintr, eagain;
    ngx_err_t        err;
    ngx_buf_t       *file;
    ngx_array_t      header, trailer;
    ngx_event_t     *wev;
    ngx_chain_t     *cl;
    struct sf_hdtr   hdtr;
    struct iovec    *iov;
    struct iovec     headers[NGX_IOVS_PREALLOCATE];
    struct iovec     trailers[NGX_IOVS_PREALLOCATE];

    wev = c->write;

    if (!wev->ready) {
        return in;
    }

#if (NGX_HAVE_KQUEUE)

    if ((ngx_event_flags & NGX_USE_KQUEUE_EVENT) && wev->pending_eof) {
        (void) ngx_connection_error(c, wev->kq_errno,
                               "kevent() reported about an closed connection");
        wev->error = 1;
        return NGX_CHAIN_ERROR;
    }

#endif

    /* the maximum limit size is the maximum size_t value - the page size */

    if (limit == 0 || limit > (off_t) (NGX_MAX_SIZE_T_VALUE - ngx_pagesize)) {
        limit = NGX_MAX_SIZE_T_VALUE - ngx_pagesize;
    }

    send = 0;
    eagain = 0;
    flags = 0;

    header.elts = headers;
    header.size = sizeof(struct iovec);
    header.nalloc = NGX_IOVS_PREALLOCATE;
    header.pool = c->pool;

    trailer.elts = trailers;
    trailer.size = sizeof(struct iovec);
    trailer.nalloc = NGX_IOVS_PREALLOCATE;
    trailer.pool = c->pool;

    for ( ;; ) {
        file = NULL;
        file_size = 0;
        header_size = 0;
        eintr = 0;
        prev_send = send;

        header.nelts = 0;
        trailer.nelts = 0;

        /* create the header iovec and coalesce the neighbouring bufs */

        prev = NULL;
        iov = NULL;

        for (cl = in; cl && send < limit; cl = cl->next) {

            if (ngx_buf_special(cl->buf)) {
                continue;
            }

            if (!ngx_buf_in_memory_only(cl->buf)) {
                break;
            }

            size = cl->buf->last - cl->buf->pos;

            if (send + size > limit) {
                size = limit - send;
            }

            if (prev == cl->buf->pos) {
                iov->iov_len += (size_t) size;

            } else {
                if (header.nelts >= IOV_MAX){
                    break;
                }

                iov = ngx_array_push(&header);
                if (iov == NULL) {
                    return NGX_CHAIN_ERROR;
                }

                iov->iov_base = (void *) cl->buf->pos;
                iov->iov_len = (size_t) size;
            }

            prev = cl->buf->pos + (size_t) size;
            header_size += (size_t) size;
            send += size;
        }


        if (cl && cl->buf->in_file && send < limit) {
            file = cl->buf;

            /* coalesce the neighbouring file bufs */

            do {
                size = cl->buf->file_last - cl->buf->file_pos;

                if (send + size > limit) {
                    size = limit - send;

                    aligned = (cl->buf->file_pos + size + ngx_pagesize - 1)
                               & ~((off_t) ngx_pagesize - 1);

                    if (aligned <= cl->buf->file_last) {
                        size = aligned - cl->buf->file_pos;
                    }
                }

                file_size += (size_t) size;
                send += size;
                fprev = cl->buf->file_pos + size;
                cl = cl->next;

            } while (cl
                     && cl->buf->in_file
                     && send < limit
                     && file->file->fd == cl->buf->file->fd
                     && fprev == cl->buf->file_pos);
        }


        if (file) {

            /* create the trailer iovec and coalesce the neighbouring bufs */

            prev = NULL;
            iov = NULL;

            while (cl && send < limit) {

                if (ngx_buf_special(cl->buf)) {
                    cl = cl->next;
                    continue;
                }

                if (!ngx_buf_in_memory_only(cl->buf)) {
                    break;
                }

                size = cl->buf->last - cl->buf->pos;

                if (send + size > limit) {
                    size = limit - send;
                }

                if (prev == cl->buf->pos) {
                    iov->iov_len += (size_t) size;

                } else {
                    if (trailer.nelts >= IOV_MAX){
                        break;
                    }

                    iov = ngx_array_push(&trailer);
                    if (iov == NULL) {
                        return NGX_CHAIN_ERROR;
                    }

                    iov->iov_base = (void *) cl->buf->pos;
                    iov->iov_len = (size_t) size;
                }

                prev = cl->buf->pos + (size_t) size;
                send += size;
                cl = cl->next;
            }
        }

        if (file) {

            if (ngx_freebsd_use_tcp_nopush
                && c->tcp_nopush == NGX_TCP_NOPUSH_UNSET)
            {
                if (ngx_tcp_nopush(c->fd) == NGX_ERROR) {
                    err = ngx_socket_errno;

                    /*
                     * there is a tiny chance to be interrupted, however,
                     * we continue a processing without the TCP_NOPUSH
                     */

                    if (err != NGX_EINTR) {
                        wev->error = 1;
                        (void) ngx_connection_error(c, err,
                                                    ngx_tcp_nopush_n " failed");
                        return NGX_CHAIN_ERROR;
                    }

                } else {
                    c->tcp_nopush = NGX_TCP_NOPUSH_SET;

                    ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, 0,
                                   "tcp_nopush");
                }
            }

            /*
             * sendfile() does unneeded work if sf_hdtr's count is 0,
             * but corresponding pointer is not NULL
             */

            hdtr.headers = header.nelts ? (struct iovec *) header.elts: NULL;
            hdtr.hdr_cnt = header.nelts;
            hdtr.trailers = trailer.nelts ? (struct iovec *) trailer.elts: NULL;
            hdtr.trl_cnt = trailer.nelts;

            /*
             * the "nbytes bug" of the old sendfile() syscall:
             * http://bugs.freebsd.org/33771
             */

            if (!ngx_freebsd_sendfile_nbytes_bug) {
                header_size = 0;
            }

            sent = 0;

#if (NGX_HAVE_AIO_SENDFILE)
            flags = c->aio_sendfile ? SF_NODISKIO : 0;
#endif

            rc = sendfile(file->file->fd, c->fd, file->file_pos,
                          file_size + header_size, &hdtr, &sent, flags);

            if (rc == -1) {
                err = ngx_errno;

                switch (err) {
                case NGX_EAGAIN:
                    eagain = 1;
                    break;

                case NGX_EINTR:
                    eintr = 1;
                    break;

#if (NGX_HAVE_AIO_SENDFILE)
                case NGX_EBUSY:
                    c->busy_sendfile = file;
                    break;
#endif

                default:
                    wev->error = 1;
                    (void) ngx_connection_error(c, err, "sendfile() failed");
                    return NGX_CHAIN_ERROR;
                }

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, err,
                               "sendfile() sent only %O bytes", sent);

            /*
             * sendfile() in FreeBSD 3.x-4.x may return value >= 0
             * on success, although only 0 is documented
             */

            } else if (rc >= 0 && sent == 0) {

                /*
                 * if rc is OK and sent equal to zero, then someone
                 * has truncated the file, so the offset became beyond
                 * the end of the file
                 */

                ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                         "sendfile() reported that \"%s\" was truncated at %O",
                         file->file->name.data, file->file_pos);

                return NGX_CHAIN_ERROR;
            }

            ngx_log_debug4(NGX_LOG_DEBUG_EVENT, c->log, 0,
                           "sendfile: %d, @%O %O:%uz",
                           rc, file->file_pos, sent, file_size + header_size);

        } else {
            rc = writev(c->fd, header.elts, header.nelts);

            ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
                           "writev: %d of %uz", rc, header_size);

            if (rc == -1) {
                err = ngx_errno;

                switch (err) {
                case NGX_EAGAIN:
                    break;

                case NGX_EINTR:
                    eintr = 1;
                    break;

                default:
                    wev->error = 1;
                    ngx_connection_error(c, err, "writev() failed");
                    return NGX_CHAIN_ERROR;
                }

                ngx_log_debug0(NGX_LOG_DEBUG_EVENT, c->log, err,
                               "writev() not ready");
            }

            sent = rc > 0 ? rc : 0;
        }

        c->sent += sent;

        in = ngx_handle_sent_chain(in, sent);

#if (NGX_HAVE_AIO_SENDFILE)
        if (c->busy_sendfile) {
            return in;
        }
#endif

        if (eagain) {

            /*
             * sendfile() may return EAGAIN, even if it has sent a whole file
             * part, it indicates that the successive sendfile() call would
             * return EAGAIN right away and would not send anything.
             * We use it as a hint.
             */

            wev->ready = 0;
            return in;
        }

        if (eintr) {
            continue;
        }

        if (send - prev_send != sent) {
            wev->ready = 0;
            return in;
        }

        if (send >= limit || in == NULL) {
            return in;
        }
    }
}