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view src/event/ngx_event_connect.h @ 4207:4fc91bae6f83

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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 fcd98af88df3
children d620f497c50f
line wrap: on
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/*
 * Copyright (C) Igor Sysoev
 */


#ifndef _NGX_EVENT_CONNECT_H_INCLUDED_
#define _NGX_EVENT_CONNECT_H_INCLUDED_


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


#define NGX_PEER_KEEPALIVE           1
#define NGX_PEER_NEXT                2
#define NGX_PEER_FAILED              4


typedef struct ngx_peer_connection_s  ngx_peer_connection_t;

typedef ngx_int_t (*ngx_event_get_peer_pt)(ngx_peer_connection_t *pc,
    void *data);
typedef void (*ngx_event_free_peer_pt)(ngx_peer_connection_t *pc, void *data,
    ngx_uint_t state);
#if (NGX_SSL)

typedef ngx_int_t (*ngx_event_set_peer_session_pt)(ngx_peer_connection_t *pc,
    void *data);
typedef void (*ngx_event_save_peer_session_pt)(ngx_peer_connection_t *pc,
    void *data);
#endif


struct ngx_peer_connection_s {
    ngx_connection_t                *connection;

    struct sockaddr                 *sockaddr;
    socklen_t                        socklen;
    ngx_str_t                       *name;

    ngx_uint_t                       tries;

    ngx_event_get_peer_pt            get;
    ngx_event_free_peer_pt           free;
    void                            *data;

#if (NGX_SSL)
    ngx_event_set_peer_session_pt    set_session;
    ngx_event_save_peer_session_pt   save_session;
#endif

#if (NGX_THREADS)
    ngx_atomic_t                    *lock;
#endif

    ngx_addr_t                      *local;

    int                              rcvbuf;

    ngx_log_t                       *log;

    unsigned                         cached:1;

                                     /* ngx_connection_log_error_e */
    unsigned                         log_error:2;
};


ngx_int_t ngx_event_connect_peer(ngx_peer_connection_t *pc);
ngx_int_t ngx_event_get_peer(ngx_peer_connection_t *pc, void *data);


#endif /* _NGX_EVENT_CONNECT_H_INCLUDED_ */