view src/http/modules/ngx_http_random_index_module.c @ 7985:ec2e6893caaa

Simplified sendfile(SF_NODISKIO) usage. Starting with FreeBSD 11, there is no need to use AIO operations to preload data into cache for sendfile(SF_NODISKIO) to work. Instead, sendfile() handles non-blocking loading data from disk by itself. It still can, however, return EBUSY if a page is already being loaded (for example, by a different process). If this happens, we now post an event for the next event loop iteration, so sendfile() is retried "after a short period", as manpage recommends. The limit of the number of EBUSY tolerated without any progress is preserved, but now it does not result in an alert, since on an idle system event loop iteration might be very short and EBUSY can happen many times in a row. Instead, SF_NODISKIO is simply disabled for one call once the limit is reached. With this change, sendfile(SF_NODISKIO) is now used automatically as long as sendfile() is enabled, and no longer requires "aio on;".
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 27 Dec 2021 19:48:33 +0300
parents 061ec464813f
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>


typedef struct {
    ngx_flag_t  enable;
} ngx_http_random_index_loc_conf_t;


#define NGX_HTTP_RANDOM_INDEX_PREALLOCATE  50


static ngx_int_t ngx_http_random_index_error(ngx_http_request_t *r,
    ngx_dir_t *dir, ngx_str_t *name);
static ngx_int_t ngx_http_random_index_init(ngx_conf_t *cf);
static void *ngx_http_random_index_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_random_index_merge_loc_conf(ngx_conf_t *cf,
    void *parent, void *child);


static ngx_command_t  ngx_http_random_index_commands[] = {

    { ngx_string("random_index"),
      NGX_HTTP_LOC_CONF|NGX_CONF_FLAG,
      ngx_conf_set_flag_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_random_index_loc_conf_t, enable),
      NULL },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_random_index_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_http_random_index_init,            /* postconfiguration */

    NULL,                                  /* create main configuration */
    NULL,                                  /* init main configuration */

    NULL,                                  /* create server configuration */
    NULL,                                  /* merge server configuration */

    ngx_http_random_index_create_loc_conf, /* create location configuration */
    ngx_http_random_index_merge_loc_conf   /* merge location configuration */
};


ngx_module_t  ngx_http_random_index_module = {
    NGX_MODULE_V1,
    &ngx_http_random_index_module_ctx,     /* module context */
    ngx_http_random_index_commands,        /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    NULL,                                  /* init master */
    NULL,                                  /* init module */
    NULL,                                  /* init process */
    NULL,                                  /* init thread */
    NULL,                                  /* exit thread */
    NULL,                                  /* exit process */
    NULL,                                  /* exit master */
    NGX_MODULE_V1_PADDING
};


static ngx_int_t
ngx_http_random_index_handler(ngx_http_request_t *r)
{
    u_char                            *last, *filename;
    size_t                             len, allocated, root;
    ngx_err_t                          err;
    ngx_int_t                          rc;
    ngx_str_t                          path, uri, *name;
    ngx_dir_t                          dir;
    ngx_uint_t                         n, level;
    ngx_array_t                        names;
    ngx_http_random_index_loc_conf_t  *rlcf;

    if (r->uri.data[r->uri.len - 1] != '/') {
        return NGX_DECLINED;
    }

    if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD|NGX_HTTP_POST))) {
        return NGX_DECLINED;
    }

    rlcf = ngx_http_get_module_loc_conf(r, ngx_http_random_index_module);

    if (!rlcf->enable) {
        return NGX_DECLINED;
    }

#if (NGX_HAVE_D_TYPE)
    len = 0;
#else
    len = NGX_HTTP_RANDOM_INDEX_PREALLOCATE;
#endif

    last = ngx_http_map_uri_to_path(r, &path, &root, len);
    if (last == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    allocated = path.len;

    path.len = last - path.data - 1;
    path.data[path.len] = '\0';

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http random index: \"%s\"", path.data);

    if (ngx_open_dir(&path, &dir) == NGX_ERROR) {
        err = ngx_errno;

        if (err == NGX_ENOENT
            || err == NGX_ENOTDIR
            || err == NGX_ENAMETOOLONG)
        {
            level = NGX_LOG_ERR;
            rc = NGX_HTTP_NOT_FOUND;

        } else if (err == NGX_EACCES) {
            level = NGX_LOG_ERR;
            rc = NGX_HTTP_FORBIDDEN;

        } else {
            level = NGX_LOG_CRIT;
            rc = NGX_HTTP_INTERNAL_SERVER_ERROR;
        }

        ngx_log_error(level, r->connection->log, err,
                      ngx_open_dir_n " \"%s\" failed", path.data);

        return rc;
    }

    if (ngx_array_init(&names, r->pool, 32, sizeof(ngx_str_t)) != NGX_OK) {
        return ngx_http_random_index_error(r, &dir, &path);
    }

    filename = path.data;
    filename[path.len] = '/';

    for ( ;; ) {
        ngx_set_errno(0);

        if (ngx_read_dir(&dir) == NGX_ERROR) {
            err = ngx_errno;

            if (err != NGX_ENOMOREFILES) {
                ngx_log_error(NGX_LOG_CRIT, r->connection->log, err,
                              ngx_read_dir_n " \"%V\" failed", &path);
                return ngx_http_random_index_error(r, &dir, &path);
            }

            break;
        }

        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                       "http random index file: \"%s\"", ngx_de_name(&dir));

        if (ngx_de_name(&dir)[0] == '.') {
            continue;
        }

        len = ngx_de_namelen(&dir);

        if (dir.type == 0 || ngx_de_is_link(&dir)) {

            /* 1 byte for '/' and 1 byte for terminating '\0' */

            if (path.len + 1 + len + 1 > allocated) {
                allocated = path.len + 1 + len + 1
                                     + NGX_HTTP_RANDOM_INDEX_PREALLOCATE;

                filename = ngx_pnalloc(r->pool, allocated);
                if (filename == NULL) {
                    return ngx_http_random_index_error(r, &dir, &path);
                }

                last = ngx_cpystrn(filename, path.data, path.len + 1);
                *last++ = '/';
            }

            ngx_cpystrn(last, ngx_de_name(&dir), len + 1);

            if (ngx_de_info(filename, &dir) == NGX_FILE_ERROR) {
                err = ngx_errno;

                if (err != NGX_ENOENT) {
                    ngx_log_error(NGX_LOG_CRIT, r->connection->log, err,
                                  ngx_de_info_n " \"%s\" failed", filename);
                    return ngx_http_random_index_error(r, &dir, &path);
                }

                if (ngx_de_link_info(filename, &dir) == NGX_FILE_ERROR) {
                    ngx_log_error(NGX_LOG_CRIT, r->connection->log, ngx_errno,
                                  ngx_de_link_info_n " \"%s\" failed",
                                  filename);
                    return ngx_http_random_index_error(r, &dir, &path);
                }
            }
        }

        if (!ngx_de_is_file(&dir)) {
            continue;
        }

        name = ngx_array_push(&names);
        if (name == NULL) {
            return ngx_http_random_index_error(r, &dir, &path);
        }

        name->len = len;

        name->data = ngx_pnalloc(r->pool, len);
        if (name->data == NULL) {
            return ngx_http_random_index_error(r, &dir, &path);
        }

        ngx_memcpy(name->data, ngx_de_name(&dir), len);
    }

    if (ngx_close_dir(&dir) == NGX_ERROR) {
        ngx_log_error(NGX_LOG_ALERT, r->connection->log, ngx_errno,
                      ngx_close_dir_n " \"%V\" failed", &path);
    }

    n = names.nelts;

    if (n == 0) {
        return NGX_DECLINED;
    }

    name = names.elts;

    n = (ngx_uint_t) (((uint64_t) ngx_random() * n) / 0x80000000);

    uri.len = r->uri.len + name[n].len;

    uri.data = ngx_pnalloc(r->pool, uri.len);
    if (uri.data == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    last = ngx_copy(uri.data, r->uri.data, r->uri.len);
    ngx_memcpy(last, name[n].data, name[n].len);

    return ngx_http_internal_redirect(r, &uri, &r->args);
}


static ngx_int_t
ngx_http_random_index_error(ngx_http_request_t *r, ngx_dir_t *dir,
    ngx_str_t *name)
{
    if (ngx_close_dir(dir) == NGX_ERROR) {
        ngx_log_error(NGX_LOG_ALERT, r->connection->log, ngx_errno,
                      ngx_close_dir_n " \"%V\" failed", name);
    }

    return NGX_HTTP_INTERNAL_SERVER_ERROR;
}


static void *
ngx_http_random_index_create_loc_conf(ngx_conf_t *cf)
{
    ngx_http_random_index_loc_conf_t  *conf;

    conf = ngx_palloc(cf->pool, sizeof(ngx_http_random_index_loc_conf_t));
    if (conf == NULL) {
        return NULL;
    }

    conf->enable = NGX_CONF_UNSET;

    return conf;
}


static char *
ngx_http_random_index_merge_loc_conf(ngx_conf_t *cf, void *parent, void *child)
{
    ngx_http_random_index_loc_conf_t *prev = parent;
    ngx_http_random_index_loc_conf_t *conf = child;

    ngx_conf_merge_value(conf->enable, prev->enable, 0);

    return NGX_CONF_OK;
}


static ngx_int_t
ngx_http_random_index_init(ngx_conf_t *cf)
{
    ngx_http_handler_pt        *h;
    ngx_http_core_main_conf_t  *cmcf;

    cmcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_core_module);

    h = ngx_array_push(&cmcf->phases[NGX_HTTP_CONTENT_PHASE].handlers);
    if (h == NULL) {
        return NGX_ERROR;
    }

    *h = ngx_http_random_index_handler;

    return NGX_OK;
}