Mercurial > hg > nginx
comparison src/http/modules/ngx_http_upstream_least_conn_module.c @ 4654:a2ca3a6ee680
Upstream: least_conn balancer module.
author | Maxim Dounin <mdounin@mdounin.ru> |
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date | Sun, 03 Jun 2012 23:21:26 +0000 |
parents | |
children | 90ddd4abfdd2 |
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4653:134ccdf44647 | 4654:a2ca3a6ee680 |
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1 | |
2 /* | |
3 * Copyright (C) Maxim Dounin | |
4 * Copyright (C) Nginx, Inc. | |
5 */ | |
6 | |
7 | |
8 #include <ngx_config.h> | |
9 #include <ngx_core.h> | |
10 #include <ngx_http.h> | |
11 | |
12 | |
13 typedef struct { | |
14 ngx_uint_t *conns; | |
15 } ngx_http_upstream_least_conn_conf_t; | |
16 | |
17 | |
18 typedef struct { | |
19 /* the round robin data must be first */ | |
20 ngx_http_upstream_rr_peer_data_t rrp; | |
21 | |
22 ngx_uint_t *conns; | |
23 | |
24 ngx_event_get_peer_pt get_rr_peer; | |
25 ngx_event_free_peer_pt free_rr_peer; | |
26 } ngx_http_upstream_lc_peer_data_t; | |
27 | |
28 | |
29 static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r, | |
30 ngx_http_upstream_srv_conf_t *us); | |
31 static ngx_int_t ngx_http_upstream_get_least_conn_peer( | |
32 ngx_peer_connection_t *pc, void *data); | |
33 static void ngx_http_upstream_free_least_conn_peer(ngx_peer_connection_t *pc, | |
34 void *data, ngx_uint_t state); | |
35 static void *ngx_http_upstream_least_conn_create_conf(ngx_conf_t *cf); | |
36 static char *ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, | |
37 void *conf); | |
38 | |
39 | |
40 static ngx_command_t ngx_http_upstream_least_conn_commands[] = { | |
41 | |
42 { ngx_string("least_conn"), | |
43 NGX_HTTP_UPS_CONF|NGX_CONF_NOARGS, | |
44 ngx_http_upstream_least_conn, | |
45 0, | |
46 0, | |
47 NULL }, | |
48 | |
49 ngx_null_command | |
50 }; | |
51 | |
52 | |
53 static ngx_http_module_t ngx_http_upstream_least_conn_module_ctx = { | |
54 NULL, /* preconfiguration */ | |
55 NULL, /* postconfiguration */ | |
56 | |
57 NULL, /* create main configuration */ | |
58 NULL, /* init main configuration */ | |
59 | |
60 ngx_http_upstream_least_conn_create_conf, /* create server configuration */ | |
61 NULL, /* merge server configuration */ | |
62 | |
63 NULL, /* create location configuration */ | |
64 NULL /* merge location configuration */ | |
65 }; | |
66 | |
67 | |
68 ngx_module_t ngx_http_upstream_least_conn_module = { | |
69 NGX_MODULE_V1, | |
70 &ngx_http_upstream_least_conn_module_ctx, /* module context */ | |
71 ngx_http_upstream_least_conn_commands, /* module directives */ | |
72 NGX_HTTP_MODULE, /* module type */ | |
73 NULL, /* init master */ | |
74 NULL, /* init module */ | |
75 NULL, /* init process */ | |
76 NULL, /* init thread */ | |
77 NULL, /* exit thread */ | |
78 NULL, /* exit process */ | |
79 NULL, /* exit master */ | |
80 NGX_MODULE_V1_PADDING | |
81 }; | |
82 | |
83 | |
84 ngx_int_t | |
85 ngx_http_upstream_init_least_conn(ngx_conf_t *cf, | |
86 ngx_http_upstream_srv_conf_t *us) | |
87 { | |
88 ngx_uint_t n; | |
89 ngx_http_upstream_rr_peers_t *peers; | |
90 ngx_http_upstream_least_conn_conf_t *lcf; | |
91 | |
92 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, cf->log, 0, | |
93 "init least conn"); | |
94 | |
95 if (ngx_http_upstream_init_round_robin(cf, us) != NGX_OK) { | |
96 return NGX_ERROR; | |
97 } | |
98 | |
99 peers = us->peer.data; | |
100 | |
101 n = peers->number; | |
102 | |
103 if (peers->next) { | |
104 n += peers->next->number; | |
105 } | |
106 | |
107 lcf = ngx_http_conf_upstream_srv_conf(us, | |
108 ngx_http_upstream_least_conn_module); | |
109 | |
110 lcf->conns = ngx_pcalloc(cf->pool, sizeof(ngx_uint_t) * n); | |
111 if (lcf->conns == NULL) { | |
112 return NGX_ERROR; | |
113 } | |
114 | |
115 us->peer.init = ngx_http_upstream_init_least_conn_peer; | |
116 | |
117 return NGX_OK; | |
118 } | |
119 | |
120 | |
121 static ngx_int_t | |
122 ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r, | |
123 ngx_http_upstream_srv_conf_t *us) | |
124 { | |
125 ngx_int_t rc; | |
126 ngx_http_upstream_lc_peer_data_t *lcp; | |
127 ngx_http_upstream_least_conn_conf_t *lcf; | |
128 | |
129 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0, | |
130 "init least conn peer"); | |
131 | |
132 lcf = ngx_http_conf_upstream_srv_conf(us, | |
133 ngx_http_upstream_least_conn_module); | |
134 | |
135 lcp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_lc_peer_data_t)); | |
136 if (lcp == NULL) { | |
137 return NGX_ERROR; | |
138 } | |
139 | |
140 lcp->conns = lcf->conns; | |
141 | |
142 r->upstream->peer.data = &lcp->rrp; | |
143 | |
144 rc = ngx_http_upstream_init_round_robin_peer(r, us); | |
145 | |
146 if (ngx_http_upstream_init_round_robin_peer(r, us) != NGX_OK) { | |
147 return NGX_ERROR; | |
148 } | |
149 | |
150 r->upstream->peer.get = ngx_http_upstream_get_least_conn_peer; | |
151 r->upstream->peer.free = ngx_http_upstream_free_least_conn_peer; | |
152 | |
153 lcp->get_rr_peer = ngx_http_upstream_get_round_robin_peer; | |
154 lcp->free_rr_peer = ngx_http_upstream_free_round_robin_peer; | |
155 | |
156 return NGX_OK; | |
157 } | |
158 | |
159 | |
160 static ngx_int_t | |
161 ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data) | |
162 { | |
163 ngx_http_upstream_lc_peer_data_t *lcp = data; | |
164 | |
165 time_t now; | |
166 uintptr_t m; | |
167 ngx_int_t rc, total; | |
168 ngx_uint_t i, n, p, many; | |
169 ngx_http_upstream_rr_peer_t *peer, *best; | |
170 ngx_http_upstream_rr_peers_t *peers; | |
171 | |
172 ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0, | |
173 "get least conn peer, try: %ui", pc->tries); | |
174 | |
175 if (lcp->rrp.peers->single) { | |
176 return lcp->get_rr_peer(pc, &lcp->rrp); | |
177 } | |
178 | |
179 pc->cached = 0; | |
180 pc->connection = NULL; | |
181 | |
182 now = ngx_time(); | |
183 | |
184 peers = lcp->rrp.peers; | |
185 | |
186 best = NULL; | |
187 total = 0; | |
188 | |
189 #if (NGX_SUPPRESS_WARN) | |
190 many = 0; | |
191 p = 0; | |
192 #endif | |
193 | |
194 for (i = 0; i < peers->number; i++) { | |
195 | |
196 n = i / (8 * sizeof(uintptr_t)); | |
197 m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t)); | |
198 | |
199 if (lcp->rrp.tried[n] & m) { | |
200 continue; | |
201 } | |
202 | |
203 peer = &peers->peer[i]; | |
204 | |
205 if (peer->down) { | |
206 continue; | |
207 } | |
208 | |
209 if (peer->max_fails | |
210 && peer->fails >= peer->max_fails | |
211 && now - peer->checked <= peer->fail_timeout) | |
212 { | |
213 continue; | |
214 } | |
215 | |
216 /* | |
217 * select peer with least number of connections; if there are | |
218 * multiple peers with the same number of connections, select | |
219 * based on round-robin | |
220 */ | |
221 | |
222 if (best == NULL | |
223 || lcp->conns[i] * best->weight < lcp->conns[p] * peer->weight) | |
224 { | |
225 best = peer; | |
226 many = 0; | |
227 p = i; | |
228 | |
229 } else if (lcp->conns[i] * best->weight | |
230 == lcp->conns[p] * peer->weight) | |
231 { | |
232 many = 1; | |
233 } | |
234 } | |
235 | |
236 if (best == NULL) { | |
237 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, | |
238 "get least conn peer, no peer found"); | |
239 | |
240 goto failed; | |
241 } | |
242 | |
243 if (many) { | |
244 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, | |
245 "get least conn peer, many"); | |
246 | |
247 for (i = p; i < peers->number; i++) { | |
248 | |
249 n = i / (8 * sizeof(uintptr_t)); | |
250 m = (uintptr_t) 1 << i % (8 * sizeof(uintptr_t)); | |
251 | |
252 if (lcp->rrp.tried[n] & m) { | |
253 continue; | |
254 } | |
255 | |
256 peer = &peers->peer[i]; | |
257 | |
258 if (peer->down) { | |
259 continue; | |
260 } | |
261 | |
262 if (lcp->conns[i] * best->weight != lcp->conns[p] * peer->weight) { | |
263 continue; | |
264 } | |
265 | |
266 if (peer->max_fails | |
267 && peer->fails >= peer->max_fails | |
268 && now - peer->checked <= peer->fail_timeout) | |
269 { | |
270 continue; | |
271 } | |
272 | |
273 peer->current_weight += peer->effective_weight; | |
274 total += peer->effective_weight; | |
275 | |
276 if (peer->effective_weight < peer->weight) { | |
277 peer->effective_weight++; | |
278 } | |
279 | |
280 if (peer->current_weight > best->current_weight) { | |
281 best = peer; | |
282 p = i; | |
283 } | |
284 } | |
285 } | |
286 | |
287 best->current_weight -= total; | |
288 best->checked = now; | |
289 | |
290 pc->sockaddr = best->sockaddr; | |
291 pc->socklen = best->socklen; | |
292 pc->name = &best->name; | |
293 | |
294 lcp->rrp.current = p; | |
295 | |
296 n = p / (8 * sizeof(uintptr_t)); | |
297 m = (uintptr_t) 1 << p % (8 * sizeof(uintptr_t)); | |
298 | |
299 lcp->rrp.tried[n] |= m; | |
300 lcp->conns[p]++; | |
301 | |
302 if (pc->tries == 1 && peers->next) { | |
303 pc->tries += peers->next->number; | |
304 } | |
305 | |
306 return NGX_OK; | |
307 | |
308 failed: | |
309 | |
310 if (peers->next) { | |
311 ngx_log_debug0(NGX_LOG_DEBUG_HTTP, pc->log, 0, | |
312 "get least conn peer, backup servers"); | |
313 | |
314 lcp->conns += peers->number; | |
315 | |
316 lcp->rrp.peers = peers->next; | |
317 pc->tries = lcp->rrp.peers->number; | |
318 | |
319 n = lcp->rrp.peers->number / (8 * sizeof(uintptr_t)) + 1; | |
320 for (i = 0; i < n; i++) { | |
321 lcp->rrp.tried[i] = 0; | |
322 } | |
323 | |
324 rc = ngx_http_upstream_get_least_conn_peer(pc, lcp); | |
325 | |
326 if (rc != NGX_BUSY) { | |
327 return rc; | |
328 } | |
329 } | |
330 | |
331 /* all peers failed, mark them as live for quick recovery */ | |
332 | |
333 for (i = 0; i < peers->number; i++) { | |
334 peers->peer[i].fails = 0; | |
335 } | |
336 | |
337 pc->name = peers->name; | |
338 | |
339 return NGX_BUSY; | |
340 } | |
341 | |
342 | |
343 static void | |
344 ngx_http_upstream_free_least_conn_peer(ngx_peer_connection_t *pc, | |
345 void *data, ngx_uint_t state) | |
346 { | |
347 ngx_http_upstream_lc_peer_data_t *lcp = data; | |
348 | |
349 ngx_log_debug2(NGX_LOG_DEBUG_HTTP, pc->log, 0, | |
350 "free least conn peer %ui %ui", pc->tries, state); | |
351 | |
352 if (lcp->rrp.peers->single) { | |
353 return lcp->free_rr_peer(pc, &lcp->rrp, state); | |
354 } | |
355 | |
356 if (state == 0 && pc->tries == 0) { | |
357 return; | |
358 } | |
359 | |
360 lcp->conns[lcp->rrp.current]--; | |
361 | |
362 return lcp->free_rr_peer(pc, &lcp->rrp, state); | |
363 } | |
364 | |
365 | |
366 static void * | |
367 ngx_http_upstream_least_conn_create_conf(ngx_conf_t *cf) | |
368 { | |
369 ngx_http_upstream_least_conn_conf_t *conf; | |
370 | |
371 conf = ngx_pcalloc(cf->pool, | |
372 sizeof(ngx_http_upstream_least_conn_conf_t)); | |
373 if (conf == NULL) { | |
374 return NULL; | |
375 } | |
376 | |
377 /* | |
378 * set by ngx_pcalloc(): | |
379 * | |
380 * conf->conns = NULL; | |
381 */ | |
382 | |
383 return conf; | |
384 } | |
385 | |
386 | |
387 static char * | |
388 ngx_http_upstream_least_conn(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) | |
389 { | |
390 ngx_http_upstream_srv_conf_t *uscf; | |
391 | |
392 uscf = ngx_http_conf_get_module_srv_conf(cf, ngx_http_upstream_module); | |
393 | |
394 uscf->peer.init_upstream = ngx_http_upstream_init_least_conn; | |
395 | |
396 uscf->flags = NGX_HTTP_UPSTREAM_CREATE | |
397 |NGX_HTTP_UPSTREAM_WEIGHT | |
398 |NGX_HTTP_UPSTREAM_MAX_FAILS | |
399 |NGX_HTTP_UPSTREAM_FAIL_TIMEOUT | |
400 |NGX_HTTP_UPSTREAM_DOWN | |
401 |NGX_HTTP_UPSTREAM_BACKUP; | |
402 | |
403 return NGX_CONF_OK; | |
404 } |