diff options
Diffstat (limited to 'modules/proxy/balancers/mod_lbmethod_byrequests.c')
| -rw-r--r-- | modules/proxy/balancers/mod_lbmethod_byrequests.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/modules/proxy/balancers/mod_lbmethod_byrequests.c b/modules/proxy/balancers/mod_lbmethod_byrequests.c new file mode 100644 index 0000000..b6cd8d8 --- /dev/null +++ b/modules/proxy/balancers/mod_lbmethod_byrequests.c @@ -0,0 +1,165 @@ +/* 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_byrequests_module; + +static APR_OPTIONAL_FN_TYPE(proxy_balancer_get_best_worker) + *ap_proxy_balancer_get_best_worker_fn = NULL; + +static int is_best_byrequests(proxy_worker *current, proxy_worker *prev_best, void *baton) +{ + int *total_factor = (int *)baton; + + current->s->lbstatus += current->s->lbfactor; + *total_factor += current->s->lbfactor; + + return (!prev_best || (current->s->lbstatus > prev_best->s->lbstatus)); +} + +/* + * The idea behind the find_best_byrequests scheduler is the following: + * + * lbfactor is "how much we expect this worker to work", or "the worker's + * normalized work quota". + * + * lbstatus is "how urgent this worker has to work to fulfill its quota + * of work". + * + * We distribute each worker's work quota to the worker, and then look + * which of them needs to work most urgently (biggest lbstatus). This + * worker is then selected for work, and its lbstatus reduced by the + * total work quota we distributed to all workers. Thus the sum of all + * lbstatus does not change.(*) + * + * If some workers are disabled, the others will + * still be scheduled correctly. + * + * If a balancer is configured as follows: + * + * worker a b c d + * lbfactor 25 25 25 25 + * + * And b gets disabled, the following schedule is produced: + * + * a c d a c d a c d ... + * + * Note that the above lbfactor setting is the *exact* same as: + * + * worker a b c d + * lbfactor 1 1 1 1 + * + * Asymmetric configurations work as one would expect. For + * example: + * + * worker a b c d + * lbfactor 1 1 1 2 + * + * would have a, b and c all handling about the same + * amount of load with d handling twice what a or b + * or c handles individually. So we could see: + * + * b a d c d a c d b d ... + * + */ +static proxy_worker *find_best_byrequests(proxy_balancer *balancer, + request_rec *r) +{ + int total_factor = 0; + proxy_worker *worker = ap_proxy_balancer_get_best_worker_fn(balancer, r, is_best_byrequests, &total_factor); + + if (worker) { + worker->s->lbstatus -= total_factor; + } + + return worker; +} + +/* 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; + } + return APR_SUCCESS; +} + +static apr_status_t age(proxy_balancer *balancer, server_rec *s) +{ + return APR_SUCCESS; +} + +/* + * How to add additional lbmethods: + * 1. Create func which determines "best" candidate worker + * (eg: find_best_bytraffic, above) + * 2. Register it as a provider. + */ +static const proxy_balancer_method byrequests = +{ + "byrequests", + &find_best_byrequests, + NULL, + &reset, + &age, + NULL +}; + +/* post_config hook: */ +static int lbmethod_byrequests_post_config(apr_pool_t *pconf, apr_pool_t *plog, + apr_pool_t *ptemp, server_rec *s) +{ + + /* lbmethod_byrequests_post_config() will be called twice during startup. So, don't + * set up the static data the 1st time through. */ + if (ap_state_query(AP_SQ_MAIN_STATE) == AP_SQ_MS_CREATE_PRE_CONFIG) { + return OK; + } + + ap_proxy_balancer_get_best_worker_fn = + APR_RETRIEVE_OPTIONAL_FN(proxy_balancer_get_best_worker); + if (!ap_proxy_balancer_get_best_worker_fn) { + ap_log_error(APLOG_MARK, APLOG_EMERG, 0, s, APLOGNO(10152) + "mod_proxy must be loaded for mod_lbmethod_byrequests"); + return !OK; + } + + return OK; +} + +static void register_hook(apr_pool_t *p) +{ + ap_register_provider(p, PROXY_LBMETHOD, "byrequests", "0", &byrequests); + ap_hook_post_config(lbmethod_byrequests_post_config, NULL, NULL, APR_HOOK_MIDDLE); +} + +AP_DECLARE_MODULE(lbmethod_byrequests) = { + 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 */ +}; |