| /* Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /* Round Robin lbmethod EXAMPLE module for Apache proxy */ |
| |
| /* NOTE: This is designed simply to provide some info on how to create |
| extra lbmethods via sub-modules... This code is ugly |
| and needs work to actually do round-robin "right" |
| but that is left as an exercise for the reader */ |
| |
| #include "mod_proxy.h" |
| #include "scoreboard.h" |
| #include "ap_mpm.h" |
| #include "apr_version.h" |
| #include "ap_hooks.h" |
| |
| #if APR_HAVE_UNISTD_H |
| #include <unistd.h> /* for getpid() */ |
| #endif |
| |
| module AP_MODULE_DECLARE_DATA proxy_balancer_rr_module; |
| |
| typedef struct { |
| int index; |
| } rr_data ; |
| |
| /* |
| */ |
| static proxy_worker *find_best_roundrobin(proxy_balancer *balancer, |
| request_rec *r) |
| { |
| int i; |
| proxy_worker **worker; |
| proxy_worker *mycandidate = NULL; |
| int checking_standby; |
| int checked_standby; |
| rr_data *ctx; |
| |
| ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(01116) |
| "proxy: Entering roundrobin for BALANCER %s (%d)", |
| balancer->name, (int)getpid()); |
| |
| /* The index of the candidate last chosen is stored in ctx->index */ |
| if (!balancer->context) { |
| /* UGLY */ |
| ctx = apr_pcalloc(r->server->process->pconf, sizeof(rr_data)); |
| balancer->context = (void *)ctx; |
| ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(01117) |
| "proxy: Creating roundrobin ctx for BALANCER %s (%d)", |
| balancer->name, (int)getpid()); |
| } else { |
| ctx = (rr_data *)balancer->context; |
| } |
| ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(01118) |
| "proxy: roundrobin index: %d (%d)", |
| ctx->index, (int)getpid()); |
| |
| checking_standby = checked_standby = 0; |
| while (!mycandidate && !checked_standby) { |
| worker = (proxy_worker **)balancer->workers->elts; |
| |
| for (i = 0; i < balancer->workers->nelts; i++, worker++) { |
| if (i < ctx->index) |
| continue; |
| if ( |
| (checking_standby ? !PROXY_WORKER_IS_STANDBY(*worker) : PROXY_WORKER_IS_STANDBY(*worker)) || |
| (PROXY_WORKER_IS_DRAINING(*worker)) |
| ) { |
| continue; |
| } |
| if (!PROXY_WORKER_IS_USABLE(*worker)) |
| ap_proxy_retry_worker("BALANCER", *worker, r->server); |
| if (PROXY_WORKER_IS_USABLE(*worker)) { |
| mycandidate = *worker; |
| break; |
| } |
| } |
| checked_standby = checking_standby++; |
| } |
| |
| |
| ctx->index += 1; |
| if (ctx->index >= balancer->workers->nelts) { |
| ctx->index = 0; |
| } |
| return mycandidate; |
| } |
| |
| static apr_status_t reset(proxy_balancer *balancer, server_rec *s) |
| { |
| return APR_SUCCESS; |
| } |
| |
| static apr_status_t age(proxy_balancer *balancer, server_rec *s) |
| { |
| return APR_SUCCESS; |
| } |
| |
| static const proxy_balancer_method roundrobin = |
| { |
| "roundrobin", |
| &find_best_roundrobin, |
| NULL, |
| &reset, |
| &age |
| }; |
| |
| static void ap_proxy_rr_register_hook(apr_pool_t *p) |
| { |
| ap_register_provider(p, PROXY_LBMETHOD, "roundrobin", "0", &roundrobin); |
| } |
| |
| AP_DECLARE_MODULE(proxy_balancer_rr) = { |
| STANDARD20_MODULE_STUFF, |
| NULL, /* create per-directory config structure */ |
| NULL, /* merge per-directory config structures */ |
| NULL, /* create per-server config structure */ |
| NULL, /* merge per-server config structures */ |
| NULL, /* command apr_table_t */ |
| ap_proxy_rr_register_hook /* register hooks */ |
| }; |