Mercurial > hg > nginx-quic
view src/http/modules/ngx_http_ssi_filter_module.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 | 49e7db44b57c |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_HTTP_SSI_FILTER_H_INCLUDED_ #define _NGX_HTTP_SSI_FILTER_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> #define NGX_HTTP_SSI_MAX_PARAMS 16 #define NGX_HTTP_SSI_COMMAND_LEN 32 #define NGX_HTTP_SSI_PARAM_LEN 32 #define NGX_HTTP_SSI_PARAMS_N 4 #define NGX_HTTP_SSI_COND_IF 1 #define NGX_HTTP_SSI_COND_ELSE 2 #define NGX_HTTP_SSI_NO_ENCODING 0 #define NGX_HTTP_SSI_URL_ENCODING 1 #define NGX_HTTP_SSI_ENTITY_ENCODING 2 typedef struct { ngx_hash_t hash; ngx_hash_keys_arrays_t commands; } ngx_http_ssi_main_conf_t; typedef struct { ngx_buf_t *buf; u_char *pos; u_char *copy_start; u_char *copy_end; ngx_uint_t key; ngx_str_t command; ngx_array_t params; ngx_table_elt_t *param; ngx_table_elt_t params_array[NGX_HTTP_SSI_PARAMS_N]; ngx_chain_t *in; ngx_chain_t *out; ngx_chain_t **last_out; ngx_chain_t *busy; ngx_chain_t *free; ngx_uint_t state; ngx_uint_t saved_state; size_t saved; size_t looked; size_t value_len; ngx_list_t *variables; ngx_array_t *blocks; #if (NGX_PCRE) ngx_uint_t ncaptures; int *captures; u_char *captures_data; #endif unsigned conditional:2; unsigned encoding:2; unsigned block:1; unsigned output:1; unsigned output_chosen:1; ngx_http_request_t *wait; void *value_buf; ngx_str_t timefmt; ngx_str_t errmsg; } ngx_http_ssi_ctx_t; typedef ngx_int_t (*ngx_http_ssi_command_pt) (ngx_http_request_t *r, ngx_http_ssi_ctx_t *ctx, ngx_str_t **); typedef struct { ngx_str_t name; ngx_uint_t index; unsigned mandatory:1; unsigned multiple:1; } ngx_http_ssi_param_t; typedef struct { ngx_str_t name; ngx_http_ssi_command_pt handler; ngx_http_ssi_param_t *params; unsigned conditional:2; unsigned block:1; unsigned flush:1; } ngx_http_ssi_command_t; extern ngx_module_t ngx_http_ssi_filter_module; #endif /* _NGX_HTTP_SSI_FILTER_H_INCLUDED_ */