| /* 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. |
| */ |
| |
| #include "mod_proxy.h" |
| #include "scoreboard.h" |
| #include "ap_mpm.h" |
| #include "apr_version.h" |
| #include "ap_hooks.h" |
| |
| module AP_MODULE_DECLARE_DATA lbmethod_bytraffic_module; |
| |
| static int (*ap_proxy_retry_worker_fn)(const char *proxy_function, |
| proxy_worker *worker, server_rec *s) = NULL; |
| |
| /* |
| * The idea behind the find_best_bytraffic scheduler is the following: |
| * |
| * We know the amount of traffic (bytes in and out) handled by each |
| * worker. We normalize that traffic by each workers' weight. So assuming |
| * a setup as below: |
| * |
| * worker a b c |
| * lbfactor 1 1 3 |
| * |
| * the scheduler will allow worker c to handle 3 times the |
| * traffic of a and b. If each request/response results in the |
| * same amount of traffic, then c would be accessed 3 times as |
| * often as a or b. If, for example, a handled a request that |
| * resulted in a large i/o bytecount, then b and c would be |
| * chosen more often, to even things out. |
| */ |
| static proxy_worker *find_best_bytraffic(proxy_balancer *balancer, |
| request_rec *r) |
| { |
| int i; |
| apr_off_t mytraffic = 0; |
| apr_off_t curmin = 0; |
| proxy_worker **worker; |
| proxy_worker *mycandidate = NULL; |
| int cur_lbset = 0; |
| int max_lbset = 0; |
| int checking_standby; |
| int checked_standby; |
| |
| if (!ap_proxy_retry_worker_fn) { |
| ap_proxy_retry_worker_fn = |
| APR_RETRIEVE_OPTIONAL_FN(ap_proxy_retry_worker); |
| if (!ap_proxy_retry_worker_fn) { |
| /* can only happen if mod_proxy isn't loaded */ |
| return NULL; |
| } |
| } |
| |
| ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(01209) |
| "proxy: Entering bytraffic for BALANCER (%s)", |
| balancer->s->name); |
| |
| /* First try to see if we have available candidate */ |
| do { |
| 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 (!checking_standby) { /* first time through */ |
| if ((*worker)->s->lbset > max_lbset) |
| max_lbset = (*worker)->s->lbset; |
| } |
| if ( |
| ((*worker)->s->lbset != cur_lbset) || |
| (checking_standby ? !PROXY_WORKER_IS_STANDBY(*worker) : PROXY_WORKER_IS_STANDBY(*worker)) || |
| (PROXY_WORKER_IS_DRAINING(*worker)) |
| ) { |
| continue; |
| } |
| |
| /* If the worker is in error state run |
| * retry on that worker. It will be marked as |
| * operational if the retry timeout is elapsed. |
| * The worker might still be unusable, but we try |
| * anyway. |
| */ |
| if (!PROXY_WORKER_IS_USABLE(*worker)) |
| ap_proxy_retry_worker_fn("BALANCER", *worker, r->server); |
| /* Take into calculation only the workers that are |
| * not in error state or not disabled. |
| */ |
| if (PROXY_WORKER_IS_USABLE(*worker)) { |
| mytraffic = ((*worker)->s->transferred/(*worker)->s->lbfactor) + |
| ((*worker)->s->read/(*worker)->s->lbfactor); |
| if (!mycandidate || mytraffic < curmin) { |
| mycandidate = *worker; |
| curmin = mytraffic; |
| } |
| } |
| } |
| checked_standby = checking_standby++; |
| } |
| cur_lbset++; |
| } while (cur_lbset <= max_lbset && !mycandidate); |
| |
| if (mycandidate) { |
| ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server, APLOGNO(01210) |
| "proxy: bytraffic selected worker \"%s\" : busy %" APR_SIZE_T_FMT, |
| mycandidate->s->name, mycandidate->s->busy); |
| } |
| |
| return mycandidate; |
| } |
| |
| /* assumed to be mutex protected by caller */ |
| static apr_status_t reset(proxy_balancer *balancer, server_rec *s) |
| { |
| int i; |
| proxy_worker **worker; |
| worker = (proxy_worker **)balancer->workers->elts; |
| for (i = 0; i < balancer->workers->nelts; i++, worker++) { |
| (*worker)->s->lbstatus = 0; |
| (*worker)->s->busy = 0; |
| (*worker)->s->transferred = 0; |
| (*worker)->s->read = 0; |
| } |
| return APR_SUCCESS; |
| } |
| |
| static apr_status_t age(proxy_balancer *balancer, server_rec *s) |
| { |
| return APR_SUCCESS; |
| } |
| |
| static const proxy_balancer_method bytraffic = |
| { |
| "bytraffic", |
| &find_best_bytraffic, |
| NULL, |
| &reset, |
| &age, |
| NULL |
| }; |
| |
| static void register_hook(apr_pool_t *p) |
| { |
| /* Only the mpm_winnt has child init hook handler. |
| * make sure that we are called after the mpm |
| * initializes and after the mod_proxy |
| */ |
| ap_register_provider(p, PROXY_LBMETHOD, "bytraffic", "0", &bytraffic); |
| } |
| |
| AP_DECLARE_MODULE(lbmethod_bytraffic) = { |
| 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 */ |
| register_hook /* register hooks */ |
| }; |