Mercurial > hg > nginx-quic
view src/core/ngx_rbtree.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 | 1f513d7f1b45 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_RBTREE_H_INCLUDED_ #define _NGX_RBTREE_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> typedef ngx_uint_t ngx_rbtree_key_t; typedef ngx_int_t ngx_rbtree_key_int_t; typedef struct ngx_rbtree_node_s ngx_rbtree_node_t; struct ngx_rbtree_node_s { ngx_rbtree_key_t key; ngx_rbtree_node_t *left; ngx_rbtree_node_t *right; ngx_rbtree_node_t *parent; u_char color; u_char data; }; typedef struct ngx_rbtree_s ngx_rbtree_t; typedef void (*ngx_rbtree_insert_pt) (ngx_rbtree_node_t *root, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel); struct ngx_rbtree_s { ngx_rbtree_node_t *root; ngx_rbtree_node_t *sentinel; ngx_rbtree_insert_pt insert; }; #define ngx_rbtree_init(tree, s, i) \ ngx_rbtree_sentinel_init(s); \ (tree)->root = s; \ (tree)->sentinel = s; \ (tree)->insert = i void ngx_rbtree_insert(ngx_thread_volatile ngx_rbtree_t *tree, ngx_rbtree_node_t *node); void ngx_rbtree_delete(ngx_thread_volatile ngx_rbtree_t *tree, ngx_rbtree_node_t *node); void ngx_rbtree_insert_value(ngx_rbtree_node_t *root, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel); void ngx_rbtree_insert_timer_value(ngx_rbtree_node_t *root, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel); #define ngx_rbt_red(node) ((node)->color = 1) #define ngx_rbt_black(node) ((node)->color = 0) #define ngx_rbt_is_red(node) ((node)->color) #define ngx_rbt_is_black(node) (!ngx_rbt_is_red(node)) #define ngx_rbt_copy_color(n1, n2) (n1->color = n2->color) /* a sentinel must be black */ #define ngx_rbtree_sentinel_init(node) ngx_rbt_black(node) static ngx_inline ngx_rbtree_node_t * ngx_rbtree_min(ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel) { while (node->left != sentinel) { node = node->left; } return node; } #endif /* _NGX_RBTREE_H_INCLUDED_ */