view src/http/modules/ngx_http_degradation_module.c @ 4248:2fad4d19ea4b stable-1.0

Merging r4151, r4152, r4177: HTTP cache related fixes: *) Cache: fix for sending of empty responses. Revert wrong fix for empty responses introduced in 0.8.31 and apply new one, rewritten to match things done by static module as close as possible. *) Cache: fix for sending of stale responses. For normal cached responses ngx_http_cache_send() sends last buffer and then request finalized via ngx_http_finalize_request() call, i.e. everything is ok. But for stale responses (i.e. when upstream died, but we have something in cache) the same ngx_http_cache_send() sends last buffer, but then in ngx_http_upstream_finalize_request() another last buffer is send. This causes duplicate final chunk to appear if chunked encoding is used (and resulting problems with keepalive connections and so on). Fix this by not sending in ngx_http_upstream_finalize_request() another last buffer if we know response was from cache. *) Fixed cache bypass caching of non-cacheable replies (ticket #21). If cache was bypassed with proxy_cache_bypass, cache-controlling headers (Cache-Control, Expires) wasn't considered and response was cached even if it was actually non-cacheable. Patch by John Ferlito.
author Igor Sysoev <igor@sysoev.ru>
date Tue, 01 Nov 2011 13:49:31 +0000
parents 147d8a86dd02
children d620f497c50f
line wrap: on
line source


/*
 * Copyright (C) Igor Sysoev
 */


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


typedef struct {
    size_t      sbrk_size;
} ngx_http_degradation_main_conf_t;


typedef struct {
    ngx_uint_t  degrade;
} ngx_http_degradation_loc_conf_t;


static ngx_conf_enum_t  ngx_http_degrade[] = {
    { ngx_string("204"), 204 },
    { ngx_string("444"), 444 },
    { ngx_null_string, 0 }
};


static void *ngx_http_degradation_create_main_conf(ngx_conf_t *cf);
static void *ngx_http_degradation_create_loc_conf(ngx_conf_t *cf);
static char *ngx_http_degradation_merge_loc_conf(ngx_conf_t *cf, void *parent,
    void *child);
static char *ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd,
    void *conf);
static ngx_int_t ngx_http_degradation_init(ngx_conf_t *cf);


static ngx_command_t  ngx_http_degradation_commands[] = {

    { ngx_string("degradation"),
      NGX_HTTP_MAIN_CONF|NGX_CONF_TAKE1,
      ngx_http_degradation,
      NGX_HTTP_MAIN_CONF_OFFSET,
      0,
      NULL },

    { ngx_string("degrade"),
      NGX_HTTP_MAIN_CONF|NGX_HTTP_SRV_CONF|NGX_HTTP_LOC_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_enum_slot,
      NGX_HTTP_LOC_CONF_OFFSET,
      offsetof(ngx_http_degradation_loc_conf_t, degrade),
      &ngx_http_degrade },

      ngx_null_command
};


static ngx_http_module_t  ngx_http_degradation_module_ctx = {
    NULL,                                  /* preconfiguration */
    ngx_http_degradation_init,             /* postconfiguration */

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

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

    ngx_http_degradation_create_loc_conf,  /* create location configuration */
    ngx_http_degradation_merge_loc_conf    /* merge location configuration */
};


ngx_module_t  ngx_http_degradation_module = {
    NGX_MODULE_V1,
    &ngx_http_degradation_module_ctx,      /* module context */
    ngx_http_degradation_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_degradation_handler(ngx_http_request_t *r)
{
    ngx_http_degradation_loc_conf_t  *dlcf;

    dlcf = ngx_http_get_module_loc_conf(r, ngx_http_degradation_module);

    if (dlcf->degrade && ngx_http_degraded(r)) {
        return dlcf->degrade;
    }

    return NGX_DECLINED;
}


ngx_uint_t
ngx_http_degraded(ngx_http_request_t *r)
{
    time_t                             now;
    ngx_uint_t                         log;
    static size_t                      sbrk_size;
    static time_t                      sbrk_time;
    ngx_http_degradation_main_conf_t  *dmcf;

    dmcf = ngx_http_get_module_main_conf(r, ngx_http_degradation_module);

    if (dmcf->sbrk_size) {

        log = 0;
        now = ngx_time();

        /* lock mutex */

        if (now != sbrk_time) {

            /*
             * ELF/i386 is loaded at 0x08000000, 128M
             * ELF/amd64 is loaded at 0x00400000, 4M
             *
             * use a function address to substract the loading address
             */

            sbrk_size = (size_t) sbrk(0) - ((uintptr_t) ngx_palloc & ~0x3FFFFF);
            sbrk_time = now;
            log = 1;
        }

        /* unlock mutex */

        if (sbrk_size >= dmcf->sbrk_size) {
            if (log) {
                ngx_log_error(NGX_LOG_NOTICE, r->connection->log, 0,
                              "degradation sbrk:%uzM",
                              sbrk_size / (1024 * 1024));
            }

            return 1;
        }
    }

    return 0;
}


static void *
ngx_http_degradation_create_main_conf(ngx_conf_t *cf)
{
    ngx_http_degradation_main_conf_t  *dmcf;

    dmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_degradation_main_conf_t));
    if (dmcf == NULL) {
        return NULL;
    }

    return dmcf;
}


static void *
ngx_http_degradation_create_loc_conf(ngx_conf_t *cf)
{
    ngx_http_degradation_loc_conf_t  *conf;

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

    conf->degrade = NGX_CONF_UNSET_UINT;

    return conf;
}


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

    ngx_conf_merge_uint_value(conf->degrade, prev->degrade, 0);

    return NGX_CONF_OK;
}


static char *
ngx_http_degradation(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_degradation_main_conf_t  *dmcf = conf;

    ngx_str_t  *value, s;

    value = cf->args->elts;

    if (ngx_strncmp(value[1].data, "sbrk=", 5) == 0) {

        s.len = value[1].len - 5;
        s.data = value[1].data + 5;

        dmcf->sbrk_size = ngx_parse_size(&s);
        if (dmcf->sbrk_size == (size_t) NGX_ERROR) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "invalid sbrk size \"%V\"", &value[1]);
            return NGX_CONF_ERROR;
        }

        return NGX_CONF_OK;
    }

    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                       "invalid parameter \"%V\"", &value[1]);

    return NGX_CONF_ERROR;
}


static ngx_int_t
ngx_http_degradation_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_PREACCESS_PHASE].handlers);
    if (h == NULL) {
        return NGX_ERROR;
    }

    *h = ngx_http_degradation_handler;

    return NGX_OK;
}