Mercurial > hg > nginx-quic
view src/http/modules/ngx_http_upstream_keepalive_module.c @ 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 | 5b5c07dee156 |
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/* * Copyright (C) Maxim Dounin * Copyright (C) Nginx, Inc. */ #include <ngx_config.h> #include <ngx_core.h> #include <ngx_http.h> typedef struct { ngx_uint_t max_cached; ngx_uint_t single; /* unsigned:1 */ ngx_queue_t cache; ngx_queue_t free; ngx_http_upstream_init_pt original_init_upstream; ngx_http_upstream_init_peer_pt original_init_peer; } ngx_http_upstream_keepalive_srv_conf_t; typedef struct { ngx_http_upstream_keepalive_srv_conf_t *conf; ngx_http_upstream_t *upstream; void *data; ngx_event_get_peer_pt original_get_peer; ngx_event_free_peer_pt original_free_peer; #if (NGX_HTTP_SSL) ngx_event_set_peer_session_pt original_set_session; ngx_event_save_peer_session_pt original_save_session; #endif ngx_uint_t failed; /* unsigned:1 */ } ngx_http_upstream_keepalive_peer_data_t; typedef struct { ngx_http_upstream_keepalive_srv_conf_t *conf; ngx_queue_t queue; ngx_connection_t *connection; socklen_t socklen; u_char sockaddr[NGX_SOCKADDRLEN]; } ngx_http_upstream_keepalive_cache_t; static ngx_int_t ngx_http_upstream_init_keepalive_peer(ngx_http_request_t *r, ngx_http_upstream_srv_conf_t *us); static ngx_int_t ngx_http_upstream_get_keepalive_peer(ngx_peer_connection_t *pc, void *data); static void ngx_http_upstream_free_keepalive_peer(ngx_peer_connection_t *pc, void *data, ngx_uint_t state); static void ngx_http_upstream_keepalive_dummy_handler(ngx_event_t *ev); static void ngx_http_upstream_keepalive_close_handler(ngx_event_t *ev); static void ngx_http_upstream_keepalive_close(ngx_connection_t *c); #if (NGX_HTTP_SSL) static ngx_int_t ngx_http_upstream_keepalive_set_session( ngx_peer_connection_t *pc, void *data); static void ngx_http_upstream_keepalive_save_session(ngx_peer_connection_t *pc, void *data); #endif static void *ngx_http_upstream_keepalive_create_conf(ngx_conf_t *cf); static char *ngx_http_upstream_keepalive(ngx_conf_t *cf, ngx_command_t *cmd, void *conf); static ngx_command_t ngx_http_upstream_keepalive_commands[] = { { ngx_string("keepalive"), NGX_HTTP_UPS_CONF|NGX_CONF_TAKE12, ngx_http_upstream_keepalive, 0, 0, NULL }, ngx_null_command }; static ngx_http_module_t ngx_http_upstream_keepalive_module_ctx = { NULL, /* preconfiguration */ NULL, /* postconfiguration */ NULL, /* create main configuration */ NULL, /* init main configuration */ ngx_http_upstream_keepalive_create_conf, /* create server configuration */ NULL, /* merge server configuration */ NULL, /* create location configuration */ NULL /* merge location configuration */ }; ngx_module_t ngx_http_upstream_keepalive_module = { NGX_MODULE_V1, &ngx_http_upstream_keepalive_module_ctx, /* module context */ ngx_http_upstream_keepalive_commands, /* module directives */ NGX_HTTP_MODULE, /* module type */ NULL, /* init master */ NULL, /* init module */ NULL, /* init process */ NULL, /* init thread */ NULL, /* exit thread */ NULL, /* exit process */ NULL, /* exit master */ NGX_MODULE_V1_PADDING }; static ngx_int_t ngx_http_upstream_init_keepalive(ngx_conf_t *cf, ngx_http_upstream_srv_conf_t *us) { ngx_uint_t i; ngx_http_upstream_keepalive_srv_conf_t *kcf; ngx_http_upstream_keepalive_cache_t *cached; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0, "init keepalive"); kcf = ngx_http_conf_upstream_srv_conf(us, ngx_http_upstream_keepalive_module); if (kcf->original_init_upstream(cf, us) != NGX_OK) { return NGX_ERROR; } kcf->original_init_peer = us->peer.init; us->peer.init = ngx_http_upstream_init_keepalive_peer; /* allocate cache items and add to free queue */ cached = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_keepalive_cache_t) * kcf->max_cached); if (cached == NULL) { return NGX_ERROR; } ngx_queue_init(&kcf->cache); ngx_queue_init(&kcf->free); for (i = 0; i < kcf->max_cached; i++) { ngx_queue_insert_head(&kcf->free, &cached[i].queue); cached[i].conf = kcf; } return NGX_OK; } static ngx_int_t ngx_http_upstream_init_keepalive_peer(ngx_http_request_t *r, ngx_http_upstream_srv_conf_t *us) { ngx_http_upstream_keepalive_peer_data_t *kp; ngx_http_upstream_keepalive_srv_conf_t *kcf; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, "init keepalive peer"); kcf = ngx_http_conf_upstream_srv_conf(us, ngx_http_upstream_keepalive_module); kp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_keepalive_peer_data_t)); if (kp == NULL) { return NGX_ERROR; } if (kcf->original_init_peer(r, us) != NGX_OK) { return NGX_ERROR; } kp->conf = kcf; kp->upstream = r->upstream; kp->data = r->upstream->peer.data; kp->original_get_peer = r->upstream->peer.get; kp->original_free_peer = r->upstream->peer.free; r->upstream->peer.data = kp; r->upstream->peer.get = ngx_http_upstream_get_keepalive_peer; r->upstream->peer.free = ngx_http_upstream_free_keepalive_peer; #if (NGX_HTTP_SSL) kp->original_set_session = r->upstream->peer.set_session; kp->original_save_session = r->upstream->peer.save_session; r->upstream->peer.set_session = ngx_http_upstream_keepalive_set_session; r->upstream->peer.save_session = ngx_http_upstream_keepalive_save_session; #endif return NGX_OK; } static ngx_int_t ngx_http_upstream_get_keepalive_peer(ngx_peer_connection_t *pc, void *data) { ngx_http_upstream_keepalive_peer_data_t *kp = data; ngx_http_upstream_keepalive_cache_t *item; ngx_int_t rc; ngx_queue_t *q, *cache; ngx_connection_t *c; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get keepalive peer"); kp->failed = 0; /* single pool of cached connections */ if (kp->conf->single && !ngx_queue_empty(&kp->conf->cache)) { q = ngx_queue_head(&kp->conf->cache); item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); c = item->connection; ngx_queue_remove(q); ngx_queue_insert_head(&kp->conf->free, q); ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get keepalive peer: using connection %p", c); c->idle = 0; c->log = pc->log; c->read->log = pc->log; c->write->log = pc->log; c->pool->log = pc->log; pc->connection = c; pc->cached = 1; return NGX_DONE; } rc = kp->original_get_peer(pc, kp->data); if (kp->conf->single || rc != NGX_OK) { return rc; } /* search cache for suitable connection */ cache = &kp->conf->cache; for (q = ngx_queue_head(cache); q != ngx_queue_sentinel(cache); q = ngx_queue_next(q)) { item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); c = item->connection; if (ngx_memn2cmp((u_char *) &item->sockaddr, (u_char *) pc->sockaddr, item->socklen, pc->socklen) == 0) { ngx_queue_remove(q); ngx_queue_insert_head(&kp->conf->free, q); ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, "get keepalive peer: using connection %p", c); c->idle = 0; c->log = pc->log; c->read->log = pc->log; c->write->log = pc->log; c->pool->log = pc->log; pc->connection = c; pc->cached = 1; return NGX_DONE; } } return NGX_OK; } static void ngx_http_upstream_free_keepalive_peer(ngx_peer_connection_t *pc, void *data, ngx_uint_t state) { ngx_http_upstream_keepalive_peer_data_t *kp = data; ngx_http_upstream_keepalive_cache_t *item; ngx_queue_t *q; ngx_connection_t *c; ngx_http_upstream_t *u; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, "free keepalive peer"); /* remember failed state - peer.free() may be called more than once */ if (state & NGX_PEER_FAILED) { kp->failed = 1; } /* cache valid connections */ u = kp->upstream; c = pc->connection; if (kp->failed || c == NULL || c->read->eof || c->read->error || c->read->timedout || c->write->error || c->write->timedout) { goto invalid; } if (!u->keepalive) { goto invalid; } if (ngx_handle_read_event(c->read, 0) != NGX_OK) { goto invalid; } ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, "free keepalive peer: saving connection %p", c); if (ngx_queue_empty(&kp->conf->free)) { q = ngx_queue_last(&kp->conf->cache); ngx_queue_remove(q); item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); ngx_http_upstream_keepalive_close(item->connection); } else { q = ngx_queue_head(&kp->conf->free); ngx_queue_remove(q); item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue); } item->connection = c; ngx_queue_insert_head(&kp->conf->cache, q); pc->connection = NULL; if (c->read->timer_set) { ngx_del_timer(c->read); } if (c->write->timer_set) { ngx_del_timer(c->write); } c->write->handler = ngx_http_upstream_keepalive_dummy_handler; c->read->handler = ngx_http_upstream_keepalive_close_handler; c->data = item; c->idle = 1; c->log = ngx_cycle->log; c->read->log = ngx_cycle->log; c->write->log = ngx_cycle->log; c->pool->log = ngx_cycle->log; item->socklen = pc->socklen; ngx_memcpy(&item->sockaddr, pc->sockaddr, pc->socklen); if (c->read->ready) { ngx_http_upstream_keepalive_close_handler(c->read); } invalid: kp->original_free_peer(pc, kp->data, state); } static void ngx_http_upstream_keepalive_dummy_handler(ngx_event_t *ev) { ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0, "keepalive dummy handler"); } static void ngx_http_upstream_keepalive_close_handler(ngx_event_t *ev) { ngx_http_upstream_keepalive_srv_conf_t *conf; ngx_http_upstream_keepalive_cache_t *item; int n; char buf[1]; ngx_connection_t *c; ngx_log_debug0(NGX_LOG_DEBUG_HTTP, ev->log, 0, "keepalive close handler"); c = ev->data; if (c->close) { goto close; } n = recv(c->fd, buf, 1, MSG_PEEK); if (n == -1 && ngx_socket_errno == NGX_EAGAIN) { /* stale event */ if (ngx_handle_read_event(c->read, 0) != NGX_OK) { goto close; } return; } close: item = c->data; conf = item->conf; ngx_http_upstream_keepalive_close(c); ngx_queue_remove(&item->queue); ngx_queue_insert_head(&conf->free, &item->queue); } static void ngx_http_upstream_keepalive_close(ngx_connection_t *c) { #if (NGX_HTTP_SSL) if (c->ssl) { c->ssl->no_wait_shutdown = 1; c->ssl->no_send_shutdown = 1; if (ngx_ssl_shutdown(c) == NGX_AGAIN) { c->ssl->handler = ngx_http_upstream_keepalive_close; return; } } #endif ngx_destroy_pool(c->pool); ngx_close_connection(c); } #if (NGX_HTTP_SSL) static ngx_int_t ngx_http_upstream_keepalive_set_session(ngx_peer_connection_t *pc, void *data) { ngx_http_upstream_keepalive_peer_data_t *kp = data; return kp->original_set_session(pc, kp->data); } static void ngx_http_upstream_keepalive_save_session(ngx_peer_connection_t *pc, void *data) { ngx_http_upstream_keepalive_peer_data_t *kp = data; kp->original_save_session(pc, kp->data); return; } #endif static void * ngx_http_upstream_keepalive_create_conf(ngx_conf_t *cf) { ngx_http_upstream_keepalive_srv_conf_t *conf; conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_keepalive_srv_conf_t)); if (conf == NULL) { return NULL; } /* * set by ngx_pcalloc(): * * conf->original_init_upstream = NULL; * conf->original_init_peer = NULL; */ conf->max_cached = 1; return conf; } static char * ngx_http_upstream_keepalive(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) { ngx_http_upstream_srv_conf_t *uscf; ngx_http_upstream_keepalive_srv_conf_t *kcf; ngx_int_t n; ngx_str_t *value; ngx_uint_t i; uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module); kcf = ngx_http_conf_upstream_srv_conf(uscf, ngx_http_upstream_keepalive_module); kcf->original_init_upstream = uscf->peer.init_upstream ? uscf->peer.init_upstream : ngx_http_upstream_init_round_robin; uscf->peer.init_upstream = ngx_http_upstream_init_keepalive; /* read options */ value = cf->args->elts; n = ngx_atoi(value[1].data, value[1].len); if (n == NGX_ERROR || n == 0) { ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid value \"%V\" in \"%V\" directive", &value[1], &cmd->name); return NGX_CONF_ERROR; } kcf->max_cached = n; for (i = 2; i < cf->args->nelts; i++) { if (ngx_strcmp(value[i].data, "single") == 0) { kcf->single = 1; continue; } goto invalid; } return NGX_CONF_OK; invalid: ngx_conf_log_error(NGX_LOG_EMERG, cf, 0, "invalid parameter \"%V\"", &value[i]); return NGX_CONF_ERROR; }