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comparison ngx_http_upstream_keepalive_module.c @ 45:489c5d4318ff draft

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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, 25 Jun 2012 22:55:53 +0400
parents c53e018dbcf5
children
comparison
equal deleted inserted replaced
44:d9ac9ad67f45 45:489c5d4318ff
9 #include <ngx_http.h> 9 #include <ngx_http.h>
10 10
11 11
12 typedef struct { 12 typedef struct {
13 ngx_uint_t max_cached; 13 ngx_uint_t max_cached;
14 ngx_uint_t single; /* unsigned:1 */
15 14
16 ngx_queue_t cache; 15 ngx_queue_t cache;
17 ngx_queue_t free; 16 ngx_queue_t free;
18 17
19 ngx_http_upstream_init_pt original_init_upstream; 18 ngx_http_upstream_init_pt original_init_upstream;
220 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, 219 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0,
221 "get keepalive peer"); 220 "get keepalive peer");
222 221
223 kp->failed = 0; 222 kp->failed = 0;
224 223
225 /* single pool of cached connections */ 224 /* ask balancer */
226
227 if (kp->conf->single && !ngx_queue_empty(&kp->conf->cache)) {
228
229 q = ngx_queue_head(&kp->conf->cache);
230
231 item = ngx_queue_data(q, ngx_http_upstream_keepalive_cache_t, queue);
232 c = item->connection;
233
234 ngx_queue_remove(q);
235 ngx_queue_insert_head(&kp->conf->free, q);
236
237 ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
238 "get keepalive peer: using connection %p", c);
239
240 c->idle = 0;
241 c->log = pc->log;
242 c->read->log = pc->log;
243 c->write->log = pc->log;
244 #if (NGX_UPSTREAM_KEEPALIVE_PATCHED)
245 c->pool->log = pc->log;
246 #endif
247
248 pc->connection = c;
249 pc->cached = 1;
250
251 return NGX_DONE;
252 }
253 225
254 rc = kp->original_get_peer(pc, kp->data); 226 rc = kp->original_get_peer(pc, kp->data);
255 227
256 if (kp->conf->single || rc != NGX_OK) { 228 if (rc != NGX_OK) {
257 return rc; 229 return rc;
258 } 230 }
259 231
260 /* search cache for suitable connection */ 232 /* search cache for suitable connection */
261 233
597 kcf->max_cached = n; 569 kcf->max_cached = n;
598 570
599 for (i = 2; i < cf->args->nelts; i++) { 571 for (i = 2; i < cf->args->nelts; i++) {
600 572
601 if (ngx_strcmp(value[i].data, "single") == 0) { 573 if (ngx_strcmp(value[i].data, "single") == 0) {
602 kcf->single = 1; 574 ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
575 "the \"single\" parameter is deprecated");
603 continue; 576 continue;
604 } 577 }
605 578
606 goto invalid; 579 goto invalid;
607 } 580 }