view src/mysql/ngx_mysql.h @ 4207:4fc91bae6f83

Better recheck of dead upstream servers. Previously nginx used to mark backend again as live as soon as fail_timeout passes (10s by default) since last failure. On the other hand, detecting dead backend takes up to 60s (proxy_connect_timeout) in typical situation "backend is down and doesn't respond to any packets". This resulted in suboptimal behaviour in the above situation (up to 23% of requests were directed to dead backend with default settings). More detailed description of the problem may be found here (in Russian): http://mailman.nginx.org/pipermail/nginx-ru/2011-August/042172.html Fix is to only allow one request after fail_timeout passes, and mark backend as "live" only if this request succeeds. Note that with new code backend will not be marked "live" unless "check" request is completed, and this may take a while in some specific workloads (e.g. streaming). This is believed to be acceptable.
author Maxim Dounin <mdounin@mdounin.ru>
date Wed, 12 Oct 2011 14:22:48 +0000
parents 7cbef16c71a1
children d620f497c50f
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/*
 * Copyright (C) Igor Sysoev
 */


#ifndef _NGX_MYSQL_H_INCLUDED_
#define _NGX_MYSQL_H_INCLUDED_


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#include <ngx_event_connect.h>


typedef struct ngx_mysql_s  ngx_mysql_t;

typedef void (*ngx_mysql_handler_pt)(ngx_mysql_t *m);


struct ngx_mysql_s {
    ngx_peer_connection_t   peer;

    ngx_buf_t              *buf;
    ngx_pool_t             *pool;

    ngx_str_t              *login;
    ngx_str_t              *passwd;
    ngx_str_t              *database;

    ngx_str_t               query;

    ngx_uint_t              pktn;

    ngx_mysql_handler_pt    handler;
    void                   *data;
    ngx_int_t               state;

};


#define NGX_MYSQL_CMDPKT_LEN  5


#if (NGX_HAVE_LITTLE_ENDIAN && NGX_HAVE_NONALIGNED && 0)

#define ngx_m16toh(n)      (*(uint32_t *) n & 0x0000ffff)
#define ngx_m24toh(n)      (*(uint32_t *) n & 0x00ffffff)
#define ngx_m32toh(n)      *(uint32_t *) n

#define ngx_htom16(n, m)   *(uint16_t *) n = (uint16_t) ((m) & 0xffff)

#define ngx_htom24(n, m)   (n)[0] = (u_char) ((m) & 0xff);                   \
                           (n)[1] = (u_char) (((m) >> 8) & 0xff);            \
                           (n)[2] = (u_char) (((m) >> 16) & 0xff)

#define ngx_htom32(n, m)   *(uint32_t *) (n) = (m)

#else

#define ngx_m16toh(n)      (n[0] | n[1] << 8)
#define ngx_m24toh(n)      (n[0] | n[1] << 8 | n[2] << 16)
#define ngx_m32toh(n)      (n[0] | n[1] << 8 | n[2] << 16 | n[3] << 24)

#define ngx_htom16(n, m)   (n)[0] = (u_char) (m); (n)[1] = (u_char) ((m) >> 8)

#define ngx_htom24(n, m)   (n)[0] = (u_char) ((m) & 0xff);                   \
                           (n)[1] = (u_char) (((m) >> 8) & 0xff);            \
                           (n)[2] = (u_char) (((m) >> 16) & 0xff)

#define ngx_htom32(n, m)   (n)[0] = (u_char) ((m) & 0xff);                   \
                           (n)[1] = (u_char) (((m) >> 8) & 0xff);            \
                           (n)[2] = (u_char) (((m) >> 16) & 0xff);           \
                           (n)[3] = (u_char) (((m) >> 24) & 0xff)

#endif


ngx_int_t ngx_mysql_connect(ngx_mysql_t *m);
ngx_int_t ngx_mysql_query(ngx_mysql_t *m);


#endif /* _NGX_MYSQL_H_INCLUDED_ */