Mercurial > hg > nginx-quic
view src/http/ngx_http_variables.h @ 4667:d05ab8793a69 stable-1.2
Merge of r4622, r4623: balancing changes.
*) 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).
*) Upstream: fixed ip_hash rebalancing with the "down" flag.
Due to weight being set to 0 for down peers, order of peers after sorting
wasn't the same as without the "down" flag (with down peers at the end),
resulting in client rebalancing for clients on other servers. The only
rebalancing which should happen after adding "down" to a server is one
for clients on the server.
The problem was introduced in r1377 (which fixed endless loop by setting
weight to 0 for down servers). The loop is no longer possible with new
smooth algorithm, so preserving original weight is safe.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 04 Jun 2012 11:21:58 +0000 |
parents | d620f497c50f |
children | a33b8c3aa975 |
line wrap: on
line source
/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_HTTP_VARIABLES_H_INCLUDED_ #define _NGX_HTTP_VARIABLES_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef ngx_variable_value_t ngx_http_variable_value_t; #define ngx_http_variable(v) { sizeof(v) - 1, 1, 0, 0, 0, (u_char *) v } typedef struct ngx_http_variable_s ngx_http_variable_t; typedef void (*ngx_http_set_variable_pt) (ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data); typedef ngx_int_t (*ngx_http_get_variable_pt) (ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data); #define NGX_HTTP_VAR_CHANGEABLE 1 #define NGX_HTTP_VAR_NOCACHEABLE 2 #define NGX_HTTP_VAR_INDEXED 4 #define NGX_HTTP_VAR_NOHASH 8 struct ngx_http_variable_s { ngx_str_t name; /* must be first to build the hash */ ngx_http_set_variable_pt set_handler; ngx_http_get_variable_pt get_handler; uintptr_t data; ngx_uint_t flags; ngx_uint_t index; }; ngx_http_variable_t *ngx_http_add_variable(ngx_conf_t *cf, ngx_str_t *name, ngx_uint_t flags); ngx_int_t ngx_http_get_variable_index(ngx_conf_t *cf, ngx_str_t *name); ngx_http_variable_value_t *ngx_http_get_indexed_variable(ngx_http_request_t *r, ngx_uint_t index); ngx_http_variable_value_t *ngx_http_get_flushed_variable(ngx_http_request_t *r, ngx_uint_t index); ngx_http_variable_value_t *ngx_http_get_variable(ngx_http_request_t *r, ngx_str_t *name, ngx_uint_t key); ngx_int_t ngx_http_variable_unknown_header(ngx_http_variable_value_t *v, ngx_str_t *var, ngx_list_part_t *part, size_t prefix); #define ngx_http_clear_variable(r, index) r->variables0[index].text.data = NULL; #if (NGX_PCRE) typedef struct { ngx_uint_t capture; ngx_int_t index; } ngx_http_regex_variable_t; typedef struct { ngx_regex_t *regex; ngx_uint_t ncaptures; ngx_http_regex_variable_t *variables; ngx_uint_t nvariables; ngx_str_t name; } ngx_http_regex_t; typedef struct { ngx_http_regex_t *regex; void *value; } ngx_http_map_regex_t; ngx_http_regex_t *ngx_http_regex_compile(ngx_conf_t *cf, ngx_regex_compile_t *rc); ngx_int_t ngx_http_regex_exec(ngx_http_request_t *r, ngx_http_regex_t *re, ngx_str_t *s); #endif typedef struct { ngx_hash_combined_t hash; #if (NGX_PCRE) ngx_http_map_regex_t *regex; ngx_uint_t nregex; #endif } ngx_http_map_t; void *ngx_http_map_find(ngx_http_request_t *r, ngx_http_map_t *map, ngx_str_t *match); ngx_int_t ngx_http_variables_add_core_vars(ngx_conf_t *cf); ngx_int_t ngx_http_variables_init_vars(ngx_conf_t *cf); extern ngx_http_variable_value_t ngx_http_variable_null_value; extern ngx_http_variable_value_t ngx_http_variable_true_value; #endif /* _NGX_HTTP_VARIABLES_H_INCLUDED_ */