view src/http/modules/ngx_http_degradation_module.c @ 6785:d1d0dd69a419

Upstream: added the ngx_http_upstream_resolved_t.name field. This fixes inconsistency in what is stored in the "host" field. Normally it would contain the "host" part of the parsed URL (e.g., proxy_pass with variables), but for the case of an implicit upstream specified with literal address it contained the text representation of the socket address (that is, host including port for IP). Now the "host" field always contains the "host" part of the URL, while the text representation of the socket address is stored in the newly added "name" field. The ngx_http_upstream_create_round_robin_peer() function was modified accordingly in a way to be compatible with the code that does not know about the new "name" field. The "stream" code was similarly modified except for not adding compatibility in ngx_stream_upstream_create_round_robin_peer(). This change is also a prerequisite for the next change.
author Ruslan Ermilov <ru@nginx.com>
date Mon, 31 Oct 2016 18:33:33 +0300
parents 67653855682e
children
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/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#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 subtract 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;
}