/* 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_bybusyness_module;

static APR_OPTIONAL_FN_TYPE(proxy_balancer_get_best_worker)

                            *ap_proxy_balancer_get_best_worker_fn = NULL;

static int is_best_bybusyness(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->busy < prev_best->s->busy)

        || (

            (current->s->busy == prev_best->s->busy)

            && (current->s->lbstatus > prev_best->s->lbstatus)

        )

    );

}

static proxy_worker *find_best_bybusyness(proxy_balancer *balancer,

                                          request_rec *r)

{

    int total_factor = 0;

    proxy_worker *worker =

        ap_proxy_balancer_get_best_worker_fn(balancer, r, is_best_bybusyness,

                                          &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;

        (*worker)->s->busy = 0;

    }

    return APR_SUCCESS;

}

static apr_status_t age(proxy_balancer *balancer, server_rec *s)

{

    return APR_SUCCESS;

}

static const proxy_balancer_method bybusyness =

{

    "bybusyness",

    &find_best_bybusyness,

    NULL,

    &reset,

    &age,

    NULL

};

/* post_config hook: */

static int lbmethod_bybusyness_post_config(apr_pool_t *pconf, apr_pool_t *plog,

        apr_pool_t *ptemp, server_rec *s)

{

    /* lbmethod_bybusyness_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(10151)

                     "mod_proxy must be loaded for mod_lbmethod_bybusyness");

        return !OK;

    }

    return OK;

}

static void register_hook(apr_pool_t *p)

{

    ap_register_provider(p, PROXY_LBMETHOD, "bybusyness", "0", &bybusyness);

    ap_hook_post_config(lbmethod_bybusyness_post_config, NULL, NULL, APR_HOOK_MIDDLE);

}

AP_DECLARE_MODULE(lbmethod_bybusyness) = {

    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 */

};