Mercurial > hg > nginx-quic
view src/core/ngx_resolver.h @ 4621:c90801720a0c
Upstream: smooth weighted round-robin balancing.
For edge case weights like { 5, 1, 1 } we now produce { a, a, b, a, c, a, a }
sequence instead of { c, b, a, a, a, a, a } produced previously.
Algorithm is as follows: on each peer selection we increase current_weight
of each eligible peer by its weight, select peer with greatest current_weight
and reduce its current_weight by total number of weight points distributed
among peers.
In case of { 5, 1, 1 } weights this gives the following sequence of
current_weight's:
a b c
0 0 0 (initial state)
5 1 1 (a selected)
-2 1 1
3 2 2 (a selected)
-4 2 2
1 3 3 (b selected)
1 -4 3
6 -3 4 (a selected)
-1 -3 4
4 -2 5 (c selected)
4 -2 -2
9 -1 -1 (a selected)
2 -1 -1
7 0 0 (a selected)
0 0 0
To preserve weight reduction in case of failures the effective_weight
variable was introduced, which usually matches peer's weight, but is
reduced temporarily on peer failures.
This change also fixes loop with backup servers and proxy_next_upstream
http_404 (ticket #47), and skipping alive upstreams in some cases if there
are multiple dead ones (ticket #64).
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 14 May 2012 09:57:20 +0000 |
parents | d620f497c50f |
children | 07dd5bd222ac |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #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; void *dummy; ngx_log_t *log; /* ident must be after 3 pointers */ ngx_int_t ident; /* simple round robin DNS peers balancer */ ngx_array_t udp_connections; ngx_uint_t last_connection; 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; 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_str_t *names, ngx_uint_t n); 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_ */