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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.
*/
/* 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,
NULL
};
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 */
};
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