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/* 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 APR_OPTIONAL_FN_TYPE(proxy_balancer_get_best_worker)
*ap_proxy_balancer_get_best_worker_fn = NULL;
static int is_best_bytraffic(proxy_worker *current, proxy_worker *prev_best, void *baton)
{
apr_off_t *min_traffic = (apr_off_t *)baton;
apr_off_t traffic = (current->s->transferred / current->s->lbfactor)
+ (current->s->read / current->s->lbfactor);
if (!prev_best || (traffic < *min_traffic)) {
*min_traffic = traffic;
return TRUE;
}
return FALSE;
}
/*
* 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)
{
apr_off_t min_traffic = 0;
return ap_proxy_balancer_get_best_worker_fn(balancer, r, is_best_bytraffic,
&min_traffic);
}
/* 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
};
/* post_config hook: */
static int lbmethod_bytraffic_post_config(apr_pool_t *pconf, apr_pool_t *plog,
apr_pool_t *ptemp, server_rec *s)
{
/* lbmethod_bytraffic_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(10150)
"mod_proxy must be loaded for mod_lbmethod_bytraffic");
return !OK;
}
return OK;
}
static void register_hook(apr_pool_t *p)
{
ap_register_provider(p, PROXY_LBMETHOD, "bytraffic", "0", &bytraffic);
ap_hook_post_config(lbmethod_bytraffic_post_config, NULL, NULL, APR_HOOK_MIDDLE);
}
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 */
};
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