view src/http/modules/ngx_http_degradation_module.c @ 6927:c36d160cd4e0

Access log: removed dead ev->timedout check in flush timer handler. The ev->timedout flag is set on first timer expiration, and never reset after it. Due to this the code to stop the timer when the timer was canceled never worked (except in a very specific time frame immediately after start), and the timer was always armed again. This essentially resulted in a buffer flush at the end of an event loop iteration. This behaviour actually seems to be better than just stopping the flush timer for the whole shutdown, so it is preserved as is instead of fixing the code to actually remove the timer. It will be further improved by upcoming changes to preserve cancelable timers if there are other timers blocking shutdown.
author Maxim Dounin <mdounin@mdounin.ru>
date Tue, 07 Mar 2017 18:51:12 +0300
parents 67653855682e
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 {
    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;
}