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comparison src/http/modules/ngx_http_upstream_keepalive_module.c @ 4694:5b5c07dee156

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Upstream keepalive: "single" parameter deprecated. The original idea was to optimize edge cases in case of interchangeable backends, i.e. don't establish a new connection if we have any one cached. This causes more harm than good though, as it screws up underlying balancer's idea about backends used and may result in various unexpected problems.
author Maxim Dounin <mdounin@mdounin.ru>
date Mon, 18 Jun 2012 14:23:42 +0000
parents d620f497c50f
children 82336a9ce26d
comparison
equal deleted inserted replaced
4693:f1a0de6eb505 4694:5b5c07dee156
10 #include <ngx_http.h> 10 #include <ngx_http.h>
11 11
12 12
13 typedef struct { 13 typedef struct {
14 ngx_uint_t max_cached; 14 ngx_uint_t max_cached;
15 ngx_uint_t single; /* unsigned:1 */
16 15
17 ngx_queue_t cache; 16 ngx_queue_t cache;
18 ngx_queue_t free; 17 ngx_queue_t free;
19 18
20 ngx_http_upstream_init_pt original_init_upstream; 19 ngx_http_upstream_init_pt original_init_upstream;
221 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, 220 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
222 "get keepalive peer"); 221 "get keepalive peer");
223 222
224 kp->failed = 0; 223 kp->failed = 0;
225 224
226 /* single pool of cached connections */ 225 /* ask balancer */
227
228 if (kp->conf->single && !ngx_queue_empty(&kp->conf->cache)) {
229
230 q = ngx_queue_head(&kp->conf->cache);
231
232 item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue);
233 c = item->connection;
234
235 ngx_queue_remove(q);
236 ngx_queue_insert_head(&kp->conf->free, q);
237
238 ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
239 "get keepalive peer: using connection %p", c);
240
241 c->idle = 0;
242 c->log = pc->log;
243 c->read->log = pc->log;
244 c->write->log = pc->log;
245 c->pool->log = pc->log;
246
247 pc->connection = c;
248 pc->cached = 1;
249
250 return NGX_DONE;
251 }
252 226
253 rc = kp->original_get_peer(pc, kp->data); 227 rc = kp->original_get_peer(pc, kp->data);
254 228
255 if (kp->conf->single || rc != NGX_OK) { 229 if (rc != NGX_OK) {
256 return rc; 230 return rc;
257 } 231 }
258 232
259 /* search cache for suitable connection */ 233 /* search cache for suitable connection */
260 234
550 kcf->max_cached = n; 524 kcf->max_cached = n;
551 525
552 for (i = 2; i < cf->args->nelts; i++) { 526 for (i = 2; i < cf->args->nelts; i++) {
553 527
554 if (ngx_strcmp(value[i].data, "single") == 0) { 528 if (ngx_strcmp(value[i].data, "single") == 0) {
555 kcf->single = 1; 529 ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
530 "the \"single\" parameter is deprecated");
556 continue; 531 continue;
557 } 532 }
558 533
559 goto invalid; 534 goto invalid;
560 } 535 }