Quelle mod_lbmethod_byrequests.c Sprache: C

/* 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 */
};

quality93%

¤ Dauer der Verarbeitung: 0.15 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.