view src/http/ngx_http_busy_lock.c @ 5923:2c10db908b8c

SPDY: push pending data while closing a stream as with keepalive. This helps to avoid delays in sending the last chunk of data because of bad interaction between Nagle's algorithm on nginx side and delayed ACK on the client side. Delays could also be caused by TCP_CORK/TCP_NOPUSH if SPDY was working without SSL and sendfile() was used.
author Valentin Bartenev <vbart@nginx.com>
date Fri, 21 Nov 2014 22:51:49 +0300
parents 14411ee4d89f
children
line wrap: on
line source


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


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



static int ngx_http_busy_lock_look_cacheable(ngx_http_busy_lock_t *bl,
                                             ngx_http_busy_lock_ctx_t *bc,
                                             int lock);


int ngx_http_busy_lock(ngx_http_busy_lock_t *bl, ngx_http_busy_lock_ctx_t *bc)
{
    if (bl->busy < bl->max_busy) {
        bl->busy++;

        if (bc->time) {
            bc->time = 0;
            bl->waiting--;
        }

        return NGX_OK;
    }

    if (bc->time) {
        if (bc->time < bl->timeout) {
            ngx_add_timer(bc->event, 1000);
            return NGX_AGAIN;
        }

        bl->waiting--;
        return NGX_DONE;

    }

    if (bl->timeout == 0) {
        return NGX_DONE;
    }

    if (bl->waiting < bl->max_waiting) {
        bl->waiting++;

#if 0
        ngx_add_timer(bc->event, 1000);
        bc->event->event_handler = bc->event_handler;
#endif

        /* TODO: ngx_handle_level_read_event() */

        return NGX_AGAIN;
    }

    return NGX_ERROR;
}


int ngx_http_busy_lock_cacheable(ngx_http_busy_lock_t *bl,
                                 ngx_http_busy_lock_ctx_t *bc, int lock)
{
    int  rc;

    rc = ngx_http_busy_lock_look_cacheable(bl, bc, lock);

    ngx_log_debug3(NGX_LOG_DEBUG_HTTP, bc->event->log, 0,
                   "http busylock: %d w:%d mw::%d",
                   rc, bl->waiting, bl->max_waiting);

    if (rc == NGX_OK) {  /* no the same request, there's free slot */
        return NGX_OK;
    }

    if (rc == NGX_ERROR && !lock) { /* no the same request, no free slot */
        return NGX_OK;
    }

    /* rc == NGX_AGAIN:  the same request */

    if (bc->time) {
        if (bc->time < bl->timeout) {
            ngx_add_timer(bc->event, 1000);
            return NGX_AGAIN;
        }

        bl->waiting--;
        return NGX_DONE;

    }

    if (bl->timeout == 0) {
        return NGX_DONE;
    }

    if (bl->waiting < bl->max_waiting) {
#if 0
        bl->waiting++;
        ngx_add_timer(bc->event, 1000);
        bc->event->event_handler = bc->event_handler;
#endif

        /* TODO: ngx_handle_level_read_event() */

        return NGX_AGAIN;
    }

    return NGX_ERROR;
}


void ngx_http_busy_unlock(ngx_http_busy_lock_t *bl,
                          ngx_http_busy_lock_ctx_t *bc)
{
    if (bl == NULL) {
        return;
    }

    if (bl->md5) {
        bl->md5_mask[bc->slot / 8] &= ~(1 << (bc->slot & 7));
        bl->cacheable--;
    }

    bl->busy--;
}


static int ngx_http_busy_lock_look_cacheable(ngx_http_busy_lock_t *bl,
                                             ngx_http_busy_lock_ctx_t *bc,
                                             int lock)
{
    int    i, b, cacheable, free;
    u_int  mask;

    b = 0;
    cacheable = 0;
    free = -1;

#if (NGX_SUPPRESS_WARN)
    mask = 0;
#endif

    for (i = 0; i < bl->max_busy; i++) {

        if ((b & 7) == 0) {
            mask = bl->md5_mask[i / 8];
        }

        if (mask & 1) {
            if (ngx_memcmp(&bl->md5[i * 16], bc->md5, 16) == 0) {
                return NGX_AGAIN;
            }
            cacheable++;

        } else if (free == -1) {
            free = i;
        }

#if 1
        if (cacheable == bl->cacheable) {
            if (free == -1 && cacheable < bl->max_busy) {
                free = i + 1;
            }

            break;
        }
#endif

        mask >>= 1;
        b++;
    }

    if (free == -1) {
        return NGX_ERROR;
    }

    if (lock) {
        if (bl->busy == bl->max_busy) {
            return NGX_ERROR;
        }

        ngx_memcpy(&bl->md5[free * 16], bc->md5, 16);
        bl->md5_mask[free / 8] |= 1 << (free & 7);
        bc->slot = free;

        bl->cacheable++;
        bl->busy++;
    }

    return NGX_OK;
}


char *ngx_http_set_busy_lock_slot(ngx_conf_t *cf, ngx_command_t *cmd,
                                  void *conf)
{
    char  *p = conf;

    ngx_uint_t             i, dup, invalid;
    ngx_str_t             *value, line;
    ngx_http_busy_lock_t  *bl, **blp;

    blp = (ngx_http_busy_lock_t **) (p + cmd->offset);
    if (*blp) {
        return "is duplicate";
    }

    /* ngx_calloc_shared() */
    bl = ngx_pcalloc(cf->pool, sizeof(ngx_http_busy_lock_t));
    if (bl == NULL) {
        return NGX_CONF_ERROR;
    }
    *blp = bl;

    /* ngx_calloc_shared() */
    bl->mutex = ngx_pcalloc(cf->pool, sizeof(ngx_event_mutex_t));
    if (bl->mutex == NULL) {
        return NGX_CONF_ERROR;
    }

    dup = 0;
    invalid = 0;
    value = cf->args->elts;

    for (i = 1; i < cf->args->nelts; i++) {

        if (value[i].data[1] != '=') {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid value \"%s\"", value[i].data);
            return NGX_CONF_ERROR;
        }

        switch (value[i].data[0]) {

        case 'b':
            if (bl->max_busy) {
                dup = 1;
                break;
            }

            bl->max_busy = ngx_atoi(value[i].data + 2, value[i].len - 2);
            if (bl->max_busy == NGX_ERROR) {
                invalid = 1;
                break;
            }

            continue;

        case 'w':
            if (bl->max_waiting) {
                dup = 1;
                break;
            }

            bl->max_waiting = ngx_atoi(value[i].data + 2, value[i].len - 2);
            if (bl->max_waiting == NGX_ERROR) {
                invalid = 1;
                break;
            }

            continue;

        case 't':
            if (bl->timeout) {
                dup = 1;
                break;
            }

            line.len = value[i].len - 2;
            line.data = value[i].data + 2;

            bl->timeout = ngx_parse_time(&line, 1);
            if (bl->timeout == (time_t) NGX_ERROR) {
                invalid = 1;
                break;
            }

            continue;

        default:
            invalid = 1;
        }

        if (dup) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "duplicate value \"%s\"", value[i].data);
            return NGX_CONF_ERROR;
        }

        if (invalid) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid value \"%s\"", value[i].data);
            return NGX_CONF_ERROR;
        }
    }

    if (bl->timeout == 0 && bl->max_waiting) {
        ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                   "busy lock waiting is useless with zero timeout, ignoring");
    }

    return NGX_CONF_OK;
}