src/os/unix/ngx_freebsd_sendfile_chain.c

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


/*
   sendfile() often sends 4K pages over ethernet in 3 packets: 2x1460 and 1176
   or in 6 packets: 5x1460 and 892.  Besides although sendfile() allows
   to pass the header and the trailer it never sends the header or the trailer
   with the part of the file in one packet.  So we use TCP_NOPUSH (similar
   to Linux's TCP_CORK) to postpone the sending - it not only sends the header
   and the first part of the file in one packet but also sends 4K pages
   in the full packets.

   Until FreeBSD 4.5 the turning TCP_NOPUSH off does not not flush
   the pending data that less than MSS and the data sent with 5 second delay.
   So we use TCP_NOPUSH on FreeBSD 4.5+ only.
*/


ngx_chain_t *ngx_freebsd_sendfile_chain(ngx_connection_t *c, ngx_chain_t *in)
{
    int              rc, eintr, tcp_nopush;
    char            *prev;
    size_t           hsize, size;
    off_t            sent;
    struct iovec    *iov;
    struct sf_hdtr   hdtr;
    ngx_err_t        err;
    ngx_array_t      header, trailer;
    ngx_hunk_t      *file;
    ngx_chain_t     *ce, *tail;

    tcp_nopush = 0;

    do {
        ce = in;
        file = NULL;
        hsize = 0;
        eintr = 0;

        ngx_init_array(header, c->pool, 10, sizeof(struct iovec),
                       NGX_CHAIN_ERROR);
        ngx_init_array(trailer, c->pool, 10, sizeof(struct iovec),
                       NGX_CHAIN_ERROR);

        /* create the header iovec */
        if (ngx_hunk_in_memory_only(ce->hunk)) {
            prev = NULL;
            iov = NULL;

            /* create the iovec and coalesce the neighbouring chain entries */
            while (ce && ngx_hunk_in_memory_only(ce->hunk)) {

                if (prev == ce->hunk->pos) {
                    iov->iov_len += ce->hunk->last - ce->hunk->pos;
                    prev = ce->hunk->last;

                } else {
                    ngx_test_null(iov, ngx_push_array(&header),
                                  NGX_CHAIN_ERROR);
                    iov->iov_base = ce->hunk->pos;
                    iov->iov_len = ce->hunk->last - ce->hunk->pos;
                    prev = ce->hunk->last;
                }

                hsize += ce->hunk->last - ce->hunk->pos;

                ce = ce->next;
            }
        }

        /* TODO: coalesce the neighbouring file hunks */
        if (ce && (ce->hunk->type & NGX_HUNK_FILE)) {
            file = ce->hunk;
            ce = ce->next;
        }

        /* create the trailer iovec */
        if (ce && ngx_hunk_in_memory_only(ce->hunk)) {
            prev = NULL;
            iov = NULL;

            /* create the iovec and coalesce the neighbouring chain entries */
            while (ce && ngx_hunk_in_memory_only(ce->hunk)) {

                if (prev == ce->hunk->pos) {
                    iov->iov_len += ce->hunk->last - ce->hunk->pos;
                    prev = ce->hunk->last;

                } else {
                    ngx_test_null(iov, ngx_push_array(&trailer),
                                  NGX_CHAIN_ERROR);
                    iov->iov_base = ce->hunk->pos;
                    iov->iov_len = ce->hunk->last - ce->hunk->pos;
                    prev = ce->hunk->last;
                }

                ce = ce->next;
            }
        }

        tail = ce;

        if (file) {

            if (!c->tcp_nopush && c->tcp_nopush_enabled) {
                c->tcp_nopush = 1;
                tcp_nopush = 1;
                if (ngx_tcp_nopush(c->fd) == NGX_ERROR) {
                    ngx_log_error(NGX_LOG_CRIT, c->log, ngx_socket_errno,
                                  ngx_tcp_nopush_n " failed");
                    return NGX_CHAIN_ERROR;
                }
ngx_log_debug(c->log, "NOPUSH");
            }

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

            if (ngx_freebsd_sendfile_nbytes_bug == 0) {
                hsize = 0;
            }

            rc = sendfile(file->file->fd, c->fd, file->file_pos,
                          (size_t) (file->file_last - file->file_pos) + hsize,
                          &hdtr, &sent, 0);

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

                if (err == NGX_EINTR) {
                    eintr = 1;
                }

                if (err == NGX_EAGAIN || err == NGX_EINTR) {
                    ngx_log_error(NGX_LOG_INFO, c->log, err,
                                  "sendfile() sent only %qd bytes", sent);

                } else {
                    ngx_log_error(NGX_LOG_CRIT, c->log, err,
                                  "sendfile() failed");
                    return NGX_CHAIN_ERROR;
                }
            }

#if (NGX_DEBUG_WRITE_CHAIN)
            ngx_log_debug(c->log, "sendfile: %d, @%qd %qd:%d" _
                          rc _ file->file_pos _ sent _
                          (size_t) (file->file_last - file->file_pos) + hsize);
#endif

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

            if (rc == -1) {
                err = ngx_errno;
                if (err == NGX_EAGAIN) {
                    ngx_log_error(NGX_LOG_INFO, c->log, err, "writev() EAGAIN");

                } else if (err == NGX_EINTR) {
                    eintr = 1;
                    ngx_log_error(NGX_LOG_INFO, c->log, err, "writev() EINTR");

                } else {
                    ngx_log_error(NGX_LOG_CRIT, c->log, err, "writev() failed");
                    return NGX_CHAIN_ERROR;
                }
            }

            sent = rc > 0 ? rc : 0;

#if (NGX_DEBUG_WRITE_CHAIN)
            ngx_log_debug(c->log, "writev: %qd" _ sent);
#endif
        }

        c->sent += sent;

        for (ce = in; ce && sent > 0; ce = ce->next) {

            if (ce->hunk->type & NGX_HUNK_IN_MEMORY) {
                size = ce->hunk->last - ce->hunk->pos;
            } else {
                size = ce->hunk->file_last - ce->hunk->file_pos;
            }

            if (sent >= size) {
                sent -= size;

                if (ce->hunk->type & NGX_HUNK_IN_MEMORY) {
                    ce->hunk->pos = ce->hunk->last;
                }

                if (ce->hunk->type & NGX_HUNK_FILE) {
                    ce->hunk->file_pos = ce->hunk->file_last;
                }

                continue;
            }

            if (ce->hunk->type & NGX_HUNK_IN_MEMORY) {
                ce->hunk->pos += sent;
            }

            if (ce->hunk->type & NGX_HUNK_FILE) {
                ce->hunk->file_pos += sent;
            }

            break;
        }

        ngx_destroy_array(&trailer);
        ngx_destroy_array(&header);

        in = ce;

    } while ((tail && tail == ce) || eintr);

    return ce;
}