Mercurial > hg > nginx-quic
view src/http/ngx_http_cache.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 | 43ccaf8e8728 |
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/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_HTTP_CACHE_H_INCLUDED_ #define _NGX_HTTP_CACHE_H_INCLUDED_ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> #define NGX_HTTP_CACHE_MISS 1 #define NGX_HTTP_CACHE_BYPASS 2 #define NGX_HTTP_CACHE_EXPIRED 3 #define NGX_HTTP_CACHE_STALE 4 #define NGX_HTTP_CACHE_UPDATING 5 #define NGX_HTTP_CACHE_HIT 6 #define NGX_HTTP_CACHE_SCARCE 7 #define NGX_HTTP_CACHE_KEY_LEN 16 typedef struct { ngx_uint_t status; time_t valid; } ngx_http_cache_valid_t; typedef struct { ngx_rbtree_node_t node; ngx_queue_t queue; u_char key[NGX_HTTP_CACHE_KEY_LEN - sizeof(ngx_rbtree_key_t)]; unsigned count:20; unsigned uses:10; unsigned valid_msec:10; unsigned error:10; unsigned exists:1; unsigned updating:1; unsigned deleting:1; /* 11 unused bits */ ngx_file_uniq_t uniq; time_t expire; time_t valid_sec; size_t body_start; off_t fs_size; } ngx_http_file_cache_node_t; struct ngx_http_cache_s { ngx_file_t file; ngx_array_t keys; uint32_t crc32; u_char key[NGX_HTTP_CACHE_KEY_LEN]; ngx_file_uniq_t uniq; time_t valid_sec; time_t last_modified; time_t date; size_t header_start; size_t body_start; off_t length; off_t fs_size; ngx_uint_t min_uses; ngx_uint_t error; ngx_uint_t valid_msec; ngx_buf_t *buf; ngx_http_file_cache_t *file_cache; ngx_http_file_cache_node_t *node; ngx_msec_t lock_timeout; ngx_msec_t wait_time; ngx_event_t wait_event; unsigned lock:1; unsigned waiting:1; unsigned updated:1; unsigned updating:1; unsigned exists:1; unsigned temp_file:1; }; typedef struct { time_t valid_sec; time_t last_modified; time_t date; uint32_t crc32; u_short valid_msec; u_short header_start; u_short body_start; } ngx_http_file_cache_header_t; typedef struct { ngx_rbtree_t rbtree; ngx_rbtree_node_t sentinel; ngx_queue_t queue; ngx_atomic_t cold; ngx_atomic_t loading; off_t size; } ngx_http_file_cache_sh_t; struct ngx_http_file_cache_s { ngx_http_file_cache_sh_t *sh; ngx_slab_pool_t *shpool; ngx_path_t *path; off_t max_size; size_t bsize; time_t inactive; ngx_uint_t files; ngx_uint_t loader_files; ngx_msec_t last; ngx_msec_t loader_sleep; ngx_msec_t loader_threshold; ngx_shm_zone_t *shm_zone; }; ngx_int_t ngx_http_file_cache_new(ngx_http_request_t *r); ngx_int_t ngx_http_file_cache_create(ngx_http_request_t *r); void ngx_http_file_cache_create_key(ngx_http_request_t *r); ngx_int_t ngx_http_file_cache_open(ngx_http_request_t *r); void ngx_http_file_cache_set_header(ngx_http_request_t *r, u_char *buf); void ngx_http_file_cache_update(ngx_http_request_t *r, ngx_temp_file_t *tf); ngx_int_t ngx_http_cache_send(ngx_http_request_t *); void ngx_http_file_cache_free(ngx_http_cache_t *c, ngx_temp_file_t *tf); time_t ngx_http_file_cache_valid(ngx_array_t *cache_valid, ngx_uint_t status); char *ngx_http_file_cache_set_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); char *ngx_http_file_cache_valid_set_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); extern ngx_str_t ngx_http_cache_status[]; #endif /* _NGX_HTTP_CACHE_H_INCLUDED_ */