Mercurial > hg > nginx-quic
view src/core/ngx_array.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 | 65b895cd0dfa |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_ARRAY_H_INCLUDED_ #define _NGX_ARRAY_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> struct ngx_array_s { void *elts; ngx_uint_t nelts; size_t size; ngx_uint_t nalloc; ngx_pool_t *pool; }; ngx_array_t *ngx_array_create(ngx_pool_t *p, ngx_uint_t n, size_t size); void ngx_array_destroy(ngx_array_t *a); void *ngx_array_push(ngx_array_t *a); void *ngx_array_push_n(ngx_array_t *a, ngx_uint_t n); static ngx_inline ngx_int_t ngx_array_init(ngx_array_t *array, ngx_pool_t *pool, ngx_uint_t n, size_t size) { /* * set "array->nelts" before "array->elts", otherwise MSVC thinks * that "array->nelts" may be used without having been initialized */ array->nelts = 0; array->size = size; array->nalloc = n; array->pool = pool; array->elts = ngx_palloc(pool, n * size); if (array->elts == NULL) { return NGX_ERROR; } return NGX_OK; } #endif /* _NGX_ARRAY_H_INCLUDED_ */