Mercurial > hg > nginx-quic
view src/core/ngx_resolver.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 | 71193a456616 |
children | 016352c19049 4919fb357a5d |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> #ifndef _NGX_RESOLVER_H_INCLUDED_ #define _NGX_RESOLVER_H_INCLUDED_ #define NGX_RESOLVE_A 1 #define NGX_RESOLVE_CNAME 5 #define NGX_RESOLVE_PTR 12 #define NGX_RESOLVE_MX 15 #define NGX_RESOLVE_TXT 16 #define NGX_RESOLVE_DNAME 39 #define NGX_RESOLVE_FORMERR 1 #define NGX_RESOLVE_SERVFAIL 2 #define NGX_RESOLVE_NXDOMAIN 3 #define NGX_RESOLVE_NOTIMP 4 #define NGX_RESOLVE_REFUSED 5 #define NGX_RESOLVE_TIMEDOUT NGX_ETIMEDOUT #define NGX_NO_RESOLVER (void *) -1 #define NGX_RESOLVER_MAX_RECURSION 50 typedef struct { ngx_connection_t *connection; struct sockaddr *sockaddr; socklen_t socklen; ngx_str_t server; ngx_log_t log; } ngx_udp_connection_t; typedef struct ngx_resolver_ctx_s ngx_resolver_ctx_t; typedef void (*ngx_resolver_handler_pt)(ngx_resolver_ctx_t *ctx); typedef struct { ngx_rbtree_node_t node; ngx_queue_t queue; /* PTR: resolved name, A: name to resolve */ u_char *name; u_short nlen; u_short qlen; u_char *query; union { in_addr_t addr; in_addr_t *addrs; u_char *cname; } u; u_short naddrs; u_short cnlen; time_t expire; time_t valid; ngx_resolver_ctx_t *waiting; } ngx_resolver_node_t; typedef struct { /* has to be pointer because of "incomplete type" */ ngx_event_t *event; /* TODO: DNS peers balancer */ /* STUB */ ngx_udp_connection_t *udp_connection; ngx_log_t *log; /* ident must be after 3 pointers */ ngx_int_t ident; ngx_rbtree_t name_rbtree; ngx_rbtree_node_t name_sentinel; ngx_rbtree_t addr_rbtree; ngx_rbtree_node_t addr_sentinel; ngx_queue_t name_resend_queue; ngx_queue_t addr_resend_queue; ngx_queue_t name_expire_queue; ngx_queue_t addr_expire_queue; time_t resend_timeout; time_t expire; time_t valid; ngx_uint_t log_level; } ngx_resolver_t; struct ngx_resolver_ctx_s { ngx_resolver_ctx_t *next; ngx_resolver_t *resolver; ngx_udp_connection_t *udp_connection; /* ident must be after 3 pointers */ ngx_int_t ident; ngx_int_t state; ngx_int_t type; ngx_str_t name; ngx_uint_t naddrs; in_addr_t *addrs; in_addr_t addr; /* TODO: DNS peers balancer ctx */ ngx_resolver_handler_pt handler; void *data; ngx_msec_t timeout; ngx_uint_t quick; /* unsigned quick:1; */ ngx_uint_t recursion; ngx_event_t *event; }; ngx_resolver_t *ngx_resolver_create(ngx_conf_t *cf, ngx_addr_t *addr); ngx_resolver_ctx_t *ngx_resolve_start(ngx_resolver_t *r, ngx_resolver_ctx_t *temp); ngx_int_t ngx_resolve_name(ngx_resolver_ctx_t *ctx); void ngx_resolve_name_done(ngx_resolver_ctx_t *ctx); ngx_int_t ngx_resolve_addr(ngx_resolver_ctx_t *ctx); void ngx_resolve_addr_done(ngx_resolver_ctx_t *ctx); char *ngx_resolver_strerror(ngx_int_t err); #endif /* _NGX_RESOLVER_H_INCLUDED_ */