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DEFINITIONS
This source file includes following definitions.
- proxy_balancer_canon
- init_balancer_members
- get_path_param
- get_cookie_param
- find_route_worker
- find_session_route
- find_best_worker
- rewrite_url
- proxy_balancer_pre_request
- proxy_balancer_post_request
- recalc_factors
- balancer_init
- balancer_handler
- child_init
- find_best_byrequests
- find_best_bytraffic
- ap_proxy_balancer_register_hook
/* 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.
*/
/* Load balancer module for Apache proxy */
#define CORE_PRIVATE
#include "mod_proxy.h"
#include "scoreboard.h"
#include "ap_mpm.h"
#include "apr_version.h"
#include "apr_hooks.h"
#include "apr_uuid.h"
module AP_MODULE_DECLARE_DATA proxy_balancer_module;
static char balancer_nonce[APR_UUID_FORMATTED_LENGTH + 1];
static int proxy_balancer_canon(request_rec *r, char *url)
{
char *host, *path;
char *search = NULL;
const char *err;
apr_port_t port = 0;
if (strncasecmp(url, "balancer:", 9) == 0) {
url += 9;
}
else {
return DECLINED;
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy: BALANCER: canonicalising URL %s", url);
/* do syntatic check.
* We break the URL into host, port, path, search
*/
err = ap_proxy_canon_netloc(r->pool, &url, NULL, NULL, &host, &port);
if (err) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
"error parsing URL %s: %s",
url, err);
return HTTP_BAD_REQUEST;
}
/*
* now parse path/search args, according to rfc1738:
* process the path. With proxy-noncanon set (by
* mod_proxy) we use the raw, unparsed uri
*/
if (apr_table_get(r->notes, "proxy-nocanon")) {
path = url; /* this is the raw path */
}
else {
path = ap_proxy_canonenc(r->pool, url, strlen(url), enc_path, 0,
r->proxyreq);
search = r->args;
}
if (path == NULL)
return HTTP_BAD_REQUEST;
r->filename = apr_pstrcat(r->pool, "proxy:balancer://", host,
"/", path, (search) ? "?" : "", (search) ? search : "", NULL);
return OK;
}
static int init_balancer_members(proxy_server_conf *conf, server_rec *s,
proxy_balancer *balancer)
{
int i;
proxy_worker *workers;
int worker_is_initialized;
proxy_worker_stat *slot;
workers = (proxy_worker *)balancer->workers->elts;
for (i = 0; i < balancer->workers->nelts; i++) {
worker_is_initialized = PROXY_WORKER_IS_INITIALIZED(workers);
if (!worker_is_initialized) {
/*
* If the worker is not initialized check whether its scoreboard
* slot is already initialized.
*/
slot = (proxy_worker_stat *) ap_get_scoreboard_lb(workers->id);
if (slot) {
worker_is_initialized = slot->status & PROXY_WORKER_INITIALIZED;
}
else {
worker_is_initialized = 0;
}
}
ap_proxy_initialize_worker_share(conf, workers, s);
ap_proxy_initialize_worker(workers, s);
if (!worker_is_initialized) {
/* Set to the original configuration */
workers->s->lbstatus = workers->s->lbfactor =
(workers->lbfactor ? workers->lbfactor : 1);
workers->s->lbset = workers->lbset;
}
++workers;
}
/* Set default number of attempts to the number of
* workers.
*/
if (!balancer->max_attempts_set && balancer->workers->nelts > 1) {
balancer->max_attempts = balancer->workers->nelts - 1;
balancer->max_attempts_set = 1;
}
return 0;
}
/* Retrieve the parameter with the given name
* Something like 'JSESSIONID=12345...N'
*/
static char *get_path_param(apr_pool_t *pool, char *url,
const char *name)
{
char *path = NULL;
for (path = strstr(url, name); path; path = strstr(path + 1, name)) {
path += strlen(name);
if (*path == '=') {
/*
* Session path was found, get it's value
*/
++path;
if (strlen(path)) {
char *q;
path = apr_strtok(apr_pstrdup(pool, path), "?&", &q);
return path;
}
}
}
return NULL;
}
static char *get_cookie_param(request_rec *r, const char *name)
{
const char *cookies;
const char *start_cookie;
if ((cookies = apr_table_get(r->headers_in, "Cookie"))) {
for (start_cookie = ap_strstr_c(cookies, name); start_cookie;
start_cookie = ap_strstr_c(start_cookie + 1, name)) {
if (start_cookie == cookies ||
start_cookie[-1] == ';' ||
start_cookie[-1] == ',' ||
isspace(start_cookie[-1])) {
start_cookie += strlen(name);
while(*start_cookie && isspace(*start_cookie))
++start_cookie;
if (*start_cookie == '=' && start_cookie[1]) {
/*
* Session cookie was found, get it's value
*/
char *end_cookie, *cookie;
++start_cookie;
cookie = apr_pstrdup(r->pool, start_cookie);
if ((end_cookie = strchr(cookie, ';')) != NULL)
*end_cookie = '\0';
if((end_cookie = strchr(cookie, ',')) != NULL)
*end_cookie = '\0';
return cookie;
}
}
}
}
return NULL;
}
/* Find the worker that has the 'route' defined
*/
static proxy_worker *find_route_worker(proxy_balancer *balancer,
const char *route, request_rec *r)
{
int i;
int checking_standby;
int checked_standby;
proxy_worker *worker;
checking_standby = checked_standby = 0;
while (!checked_standby) {
worker = (proxy_worker *)balancer->workers->elts;
for (i = 0; i < balancer->workers->nelts; i++, worker++) {
if ( (checking_standby ? !PROXY_WORKER_IS_STANDBY(worker) : PROXY_WORKER_IS_STANDBY(worker)) )
continue;
if (*(worker->s->route) && strcmp(worker->s->route, route) == 0) {
if (worker && PROXY_WORKER_IS_USABLE(worker)) {
return worker;
} else {
/*
* If the worker is in error state run
* retry on that worker. It will be marked as
* operational if the retry timeout is elapsed.
* The worker might still be unusable, but we try
* anyway.
*/
ap_proxy_retry_worker("BALANCER", worker, r->server);
if (PROXY_WORKER_IS_USABLE(worker)) {
return worker;
} else {
/*
* We have a worker that is unusable.
* It can be in error or disabled, but in case
* it has a redirection set use that redirection worker.
* This enables to safely remove the member from the
* balancer. Of course you will need some kind of
* session replication between those two remote.
*/
if (*worker->s->redirect) {
proxy_worker *rworker = NULL;
rworker = find_route_worker(balancer, worker->s->redirect, r);
/* Check if the redirect worker is usable */
if (rworker && !PROXY_WORKER_IS_USABLE(rworker)) {
/*
* If the worker is in error state run
* retry on that worker. It will be marked as
* operational if the retry timeout is elapsed.
* The worker might still be unusable, but we try
* anyway.
*/
ap_proxy_retry_worker("BALANCER", rworker, r->server);
}
if (rworker && PROXY_WORKER_IS_USABLE(rworker))
return rworker;
}
}
}
}
}
checked_standby = checking_standby++;
}
return NULL;
}
static proxy_worker *find_session_route(proxy_balancer *balancer,
request_rec *r,
char **route,
char **sticky_used,
char **url)
{
proxy_worker *worker = NULL;
char *sticky, *sticky_path, *path;
if (!balancer->sticky)
return NULL;
sticky = sticky_path = apr_pstrdup(r->pool, balancer->sticky);
if ((path = strchr(sticky, '|'))) {
*path++ = '\0';
sticky_path = path;
}
/* Try to find the sticky route inside url */
*sticky_used = sticky_path;
*route = get_path_param(r->pool, *url, sticky_path);
if (!*route) {
*route = get_cookie_param(r, sticky);
*sticky_used = sticky;
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy: BALANCER: Found value %s for "
"stickysession %s", *route, balancer->sticky);
/*
* If we found a value for sticksession, find the first '.' within.
* Everything after '.' (if present) is our route.
*/
if ((*route) && ((*route = strchr(*route, '.')) != NULL ))
(*route)++;
if ((*route) && (**route)) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy: BALANCER: Found route %s", *route);
/* We have a route in path or in cookie
* Find the worker that has this route defined.
*/
worker = find_route_worker(balancer, *route, r);
if (worker && strcmp(*route, worker->s->route)) {
/*
* Notice that the route of the worker chosen is different from
* the route supplied by the client.
*/
apr_table_setn(r->subprocess_env, "BALANCER_ROUTE_CHANGED", "1");
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy: BALANCER: Route changed from %s to %s",
*route, worker->s->route);
}
return worker;
}
else
return NULL;
}
static proxy_worker *find_best_worker(proxy_balancer *balancer,
request_rec *r)
{
proxy_worker *candidate = NULL;
apr_status_t rv;
if ((rv = PROXY_THREAD_LOCK(balancer)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
"proxy: BALANCER: (%s). Lock failed for find_best_worker()", balancer->name);
return NULL;
}
candidate = (*balancer->lbmethod->finder)(balancer, r);
if (candidate)
candidate->s->elected++;
/*
PROXY_THREAD_UNLOCK(balancer);
return NULL;
*/
if ((rv = PROXY_THREAD_UNLOCK(balancer)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
"proxy: BALANCER: (%s). Unlock failed for find_best_worker()", balancer->name);
}
if (candidate == NULL) {
/* All the workers are in error state or disabled.
* If the balancer has a timeout sleep for a while
* and try again to find the worker. The chances are
* that some other thread will release a connection.
* By default the timeout is not set, and the server
* returns SERVER_BUSY.
*/
#if APR_HAS_THREADS
if (balancer->timeout) {
/* XXX: This can perhaps be build using some
* smarter mechanism, like tread_cond.
* But since the statuses can came from
* different childs, use the provided algo.
*/
apr_interval_time_t timeout = balancer->timeout;
apr_interval_time_t step, tval = 0;
/* Set the timeout to 0 so that we don't
* end in infinite loop
*/
balancer->timeout = 0;
step = timeout / 100;
while (tval < timeout) {
apr_sleep(step);
/* Try again */
if ((candidate = find_best_worker(balancer, r)))
break;
tval += step;
}
/* restore the timeout */
balancer->timeout = timeout;
}
#endif
}
return candidate;
}
static int rewrite_url(request_rec *r, proxy_worker *worker,
char **url)
{
const char *scheme = strstr(*url, "://");
const char *path = NULL;
if (scheme)
path = ap_strchr_c(scheme + 3, '/');
/* we break the URL into host, port, uri */
if (!worker) {
return ap_proxyerror(r, HTTP_BAD_REQUEST, apr_pstrcat(r->pool,
"missing worker. URI cannot be parsed: ", *url,
NULL));
}
*url = apr_pstrcat(r->pool, worker->name, path, NULL);
return OK;
}
static int proxy_balancer_pre_request(proxy_worker **worker,
proxy_balancer **balancer,
request_rec *r,
proxy_server_conf *conf, char **url)
{
int access_status;
proxy_worker *runtime;
char *route = NULL;
char *sticky = NULL;
apr_status_t rv;
*worker = NULL;
/* Step 1: check if the url is for us
* The url we can handle starts with 'balancer://'
* If balancer is already provided skip the search
* for balancer, because this is failover attempt.
*/
if (!*balancer &&
!(*balancer = ap_proxy_get_balancer(r->pool, conf, *url)))
return DECLINED;
/* Step 2: find the session route */
runtime = find_session_route(*balancer, r, &route, &sticky, url);
/* Lock the LoadBalancer
* XXX: perhaps we need the process lock here
*/
if ((rv = PROXY_THREAD_LOCK(*balancer)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
"proxy: BALANCER: (%s). Lock failed for pre_request",
(*balancer)->name);
return DECLINED;
}
if (runtime) {
int i, total_factor = 0;
proxy_worker *workers;
/* We have a sticky load balancer
* Update the workers status
* so that even session routes get
* into account.
*/
workers = (proxy_worker *)(*balancer)->workers->elts;
for (i = 0; i < (*balancer)->workers->nelts; i++) {
/* Take into calculation only the workers that are
* not in error state or not disabled.
*
* TODO: Abstract the below, since this is dependent
* on the LB implementation
*/
if (PROXY_WORKER_IS_USABLE(workers)) {
workers->s->lbstatus += workers->s->lbfactor;
total_factor += workers->s->lbfactor;
}
workers++;
}
runtime->s->lbstatus -= total_factor;
runtime->s->elected++;
*worker = runtime;
}
else if (route && (*balancer)->sticky_force) {
int i, member_of = 0;
proxy_worker *workers;
/*
* We have a route provided that doesn't match the
* balancer name. See if the provider route is the
* member of the same balancer in which case return 503
*/
workers = (proxy_worker *)(*balancer)->workers->elts;
for (i = 0; i < (*balancer)->workers->nelts; i++) {
if (*(workers->s->route) && strcmp(workers->s->route, route) == 0) {
member_of = 1;
break;
}
workers++;
}
if (member_of) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
"proxy: BALANCER: (%s). All workers are in error state for route (%s)",
(*balancer)->name, route);
if ((rv = PROXY_THREAD_UNLOCK(*balancer)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
"proxy: BALANCER: (%s). Unlock failed for pre_request",
(*balancer)->name);
}
return HTTP_SERVICE_UNAVAILABLE;
}
}
if ((rv = PROXY_THREAD_UNLOCK(*balancer)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
"proxy: BALANCER: (%s). Unlock failed for pre_request",
(*balancer)->name);
}
if (!*worker) {
runtime = find_best_worker(*balancer, r);
if (!runtime) {
ap_log_error(APLOG_MARK, APLOG_ERR, 0, r->server,
"proxy: BALANCER: (%s). All workers are in error state",
(*balancer)->name);
return HTTP_SERVICE_UNAVAILABLE;
}
if ((*balancer)->sticky && runtime) {
/*
* This balancer has sticky sessions and the client either has not
* supplied any routing information or all workers for this route
* including possible redirect and hotstandby workers are in error
* state, but we have found another working worker for this
* balancer where we can send the request. Thus notice that we have
* changed the route to the backend.
*/
apr_table_setn(r->subprocess_env, "BALANCER_ROUTE_CHANGED", "1");
}
*worker = runtime;
}
/* Add balancer/worker info to env. */
apr_table_setn(r->subprocess_env,
"BALANCER_NAME", (*balancer)->name);
apr_table_setn(r->subprocess_env,
"BALANCER_WORKER_NAME", (*worker)->name);
apr_table_setn(r->subprocess_env,
"BALANCER_WORKER_ROUTE", (*worker)->s->route);
/* Rewrite the url from 'balancer://url'
* to the 'worker_scheme://worker_hostname[:worker_port]/url'
* This replaces the balancers fictional name with the
* real hostname of the elected worker.
*/
access_status = rewrite_url(r, *worker, url);
/* Add the session route to request notes if present */
if (route) {
apr_table_setn(r->notes, "session-sticky", sticky);
apr_table_setn(r->notes, "session-route", route);
/* Add session info to env. */
apr_table_setn(r->subprocess_env,
"BALANCER_SESSION_STICKY", sticky);
apr_table_setn(r->subprocess_env,
"BALANCER_SESSION_ROUTE", route);
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy: BALANCER (%s) worker (%s) rewritten to %s",
(*balancer)->name, (*worker)->name, *url);
return access_status;
}
static int proxy_balancer_post_request(proxy_worker *worker,
proxy_balancer *balancer,
request_rec *r,
proxy_server_conf *conf)
{
#if 0
apr_status_t rv;
if ((rv = PROXY_THREAD_LOCK(balancer)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
"proxy: BALANCER: (%s). Lock failed for post_request",
balancer->name);
return HTTP_INTERNAL_SERVER_ERROR;
}
/* TODO: placeholder for post_request actions
*/
if ((rv = PROXY_THREAD_UNLOCK(balancer)) != APR_SUCCESS) {
ap_log_error(APLOG_MARK, APLOG_ERR, rv, r->server,
"proxy: BALANCER: (%s). Unlock failed for post_request",
balancer->name);
}
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy_balancer_post_request for (%s)", balancer->name);
#endif
return OK;
}
static void recalc_factors(proxy_balancer *balancer)
{
int i;
proxy_worker *workers;
/* Recalculate lbfactors */
workers = (proxy_worker *)balancer->workers->elts;
/* Special case if there is only one worker it's
* load factor will always be 1
*/
if (balancer->workers->nelts == 1) {
workers->s->lbstatus = workers->s->lbfactor = 1;
return;
}
for (i = 0; i < balancer->workers->nelts; i++) {
/* Update the status entries */
workers[i].s->lbstatus = workers[i].s->lbfactor;
}
}
/* post_config hook: */
static int balancer_init(apr_pool_t *p, apr_pool_t *plog,
apr_pool_t *ptemp, server_rec *s)
{
void *data;
const char *userdata_key = "mod_proxy_balancer_init";
apr_uuid_t uuid;
/* balancer_init() will be called twice during startup. So, only
* set up the static data the second time through. */
apr_pool_userdata_get(&data, userdata_key, s->process->pool);
if (!data) {
apr_pool_userdata_set((const void *)1, userdata_key,
apr_pool_cleanup_null, s->process->pool);
return OK;
}
/* Retrieve a UUID and store the nonce for the lifetime of
* the process. */
apr_uuid_get(&uuid);
apr_uuid_format(balancer_nonce, &uuid);
return OK;
}
/* Manages the loadfactors and member status
*/
static int balancer_handler(request_rec *r)
{
void *sconf = r->server->module_config;
proxy_server_conf *conf = (proxy_server_conf *)
ap_get_module_config(sconf, &proxy_module);
proxy_balancer *balancer, *bsel = NULL;
proxy_worker *worker, *wsel = NULL;
apr_table_t *params = apr_table_make(r->pool, 10);
int access_status;
int i, n;
const char *name;
/* is this for us? */
if (strcmp(r->handler, "balancer-manager"))
return DECLINED;
r->allowed = (AP_METHOD_BIT << M_GET);
if (r->method_number != M_GET)
return DECLINED;
if (r->args) {
char *args = apr_pstrdup(r->pool, r->args);
char *tok, *val;
while (args && *args) {
if ((val = ap_strchr(args, '='))) {
*val++ = '\0';
if ((tok = ap_strchr(val, '&')))
*tok++ = '\0';
/*
* Special case: workers are allowed path information
*/
if ((access_status = ap_unescape_url(val)) != OK)
if (strcmp(args, "w") || (access_status != HTTP_NOT_FOUND))
return access_status;
apr_table_setn(params, args, val);
args = tok;
}
else
return HTTP_BAD_REQUEST;
}
}
/* Check that the supplied nonce matches this server's nonce;
* otherwise ignore all parameters, to prevent a CSRF attack. */
if ((name = apr_table_get(params, "nonce")) == NULL
|| strcmp(balancer_nonce, name) != 0) {
apr_table_clear(params);
}
if ((name = apr_table_get(params, "b")))
bsel = ap_proxy_get_balancer(r->pool, conf,
apr_pstrcat(r->pool, "balancer://", name, NULL));
if ((name = apr_table_get(params, "w"))) {
proxy_worker *ws;
ws = ap_proxy_get_worker(r->pool, conf, name);
if (bsel && ws) {
worker = (proxy_worker *)bsel->workers->elts;
for (n = 0; n < bsel->workers->nelts; n++) {
if (strcasecmp(worker->name, ws->name) == 0) {
wsel = worker;
break;
}
++worker;
}
}
}
/* First set the params */
/*
* Note that it is not possible set the proxy_balancer because it is not
* in shared memory.
*/
if (wsel) {
const char *val;
if ((val = apr_table_get(params, "lf"))) {
int ival = atoi(val);
if (ival >= 1 && ival <= 100) {
wsel->s->lbfactor = ival;
if (bsel)
recalc_factors(bsel);
}
}
if ((val = apr_table_get(params, "wr"))) {
if (strlen(val) && strlen(val) < PROXY_WORKER_MAX_ROUTE_SIZ)
strcpy(wsel->s->route, val);
else
*wsel->s->route = '\0';
}
if ((val = apr_table_get(params, "rr"))) {
if (strlen(val) && strlen(val) < PROXY_WORKER_MAX_ROUTE_SIZ)
strcpy(wsel->s->redirect, val);
else
*wsel->s->redirect = '\0';
}
if ((val = apr_table_get(params, "dw"))) {
if (!strcasecmp(val, "Disable"))
wsel->s->status |= PROXY_WORKER_DISABLED;
else if (!strcasecmp(val, "Enable"))
wsel->s->status &= ~PROXY_WORKER_DISABLED;
}
if ((val = apr_table_get(params, "ls"))) {
int ival = atoi(val);
if (ival >= 0 && ival <= 99) {
wsel->s->lbset = ival;
}
}
}
if (apr_table_get(params, "xml")) {
ap_set_content_type(r, "text/xml");
ap_rputs("<?xml version=\"1.0\" encoding=\"UTF-8\" ?>\n", r);
ap_rputs("<httpd:manager xmlns:httpd=\"http://httpd.apache.org\">\n", r);
ap_rputs(" <httpd:balancers>\n", r);
balancer = (proxy_balancer *)conf->balancers->elts;
for (i = 0; i < conf->balancers->nelts; i++) {
ap_rputs(" <httpd:balancer>\n", r);
ap_rvputs(r, " <httpd:name>", balancer->name, "</httpd:name>\n", NULL);
ap_rputs(" <httpd:workers>\n", r);
worker = (proxy_worker *)balancer->workers->elts;
for (n = 0; n < balancer->workers->nelts; n++) {
ap_rputs(" <httpd:worker>\n", r);
ap_rvputs(r, " <httpd:scheme>", worker->scheme,
"</httpd:scheme>\n", NULL);
ap_rvputs(r, " <httpd:hostname>", worker->hostname,
"</httpd:hostname>\n", NULL);
ap_rprintf(r, " <httpd:loadfactor>%d</httpd:loadfactor>\n",
worker->s->lbfactor);
ap_rputs(" </httpd:worker>\n", r);
++worker;
}
ap_rputs(" </httpd:workers>\n", r);
ap_rputs(" </httpd:balancer>\n", r);
++balancer;
}
ap_rputs(" </httpd:balancers>\n", r);
ap_rputs("</httpd:manager>", r);
}
else {
ap_set_content_type(r, "text/html; charset=ISO-8859-1");
ap_rputs(DOCTYPE_HTML_3_2
"<html><head><title>Balancer Manager</title></head>\n", r);
ap_rputs("<body><h1>Load Balancer Manager for ", r);
ap_rvputs(r, ap_get_server_name(r), "</h1>\n\n", NULL);
ap_rvputs(r, "<dl><dt>Server Version: ",
ap_get_server_description(), "</dt>\n", NULL);
ap_rvputs(r, "<dt>Server Built: ",
ap_get_server_built(), "\n</dt></dl>\n", NULL);
balancer = (proxy_balancer *)conf->balancers->elts;
for (i = 0; i < conf->balancers->nelts; i++) {
ap_rputs("<hr />\n<h3>LoadBalancer Status for ", r);
ap_rvputs(r, balancer->name, "</h3>\n\n", NULL);
ap_rputs("\n\n<table border=\"0\" style=\"text-align: left;\"><tr>"
"<th>StickySession</th><th>Timeout</th><th>FailoverAttempts</th><th>Method</th>"
"</tr>\n<tr>", r);
if (balancer->sticky) {
ap_rvputs(r, "<td>", balancer->sticky, NULL);
}
else {
ap_rputs("<td> - ", r);
}
ap_rprintf(r, "</td><td>%" APR_TIME_T_FMT "</td>",
apr_time_sec(balancer->timeout));
ap_rprintf(r, "<td>%d</td>\n", balancer->max_attempts);
ap_rprintf(r, "<td>%s</td>\n",
balancer->lbmethod->name);
ap_rputs("</table>\n<br />", r);
ap_rputs("\n\n<table border=\"0\" style=\"text-align: left;\"><tr>"
"<th>Worker URL</th>"
"<th>Route</th><th>RouteRedir</th>"
"<th>Factor</th><th>Set</th><th>Status</th>"
"<th>Elected</th><th>To</th><th>From</th>"
"</tr>\n", r);
worker = (proxy_worker *)balancer->workers->elts;
for (n = 0; n < balancer->workers->nelts; n++) {
char fbuf[50];
ap_rvputs(r, "<tr>\n<td><a href=\"", r->uri, "?b=",
balancer->name + sizeof("balancer://") - 1, "&w=",
ap_escape_uri(r->pool, worker->name),
"&nonce=", balancer_nonce,
"\">", NULL);
ap_rvputs(r, worker->name, "</a></td>", NULL);
ap_rvputs(r, "<td>", ap_escape_html(r->pool, worker->s->route),
NULL);
ap_rvputs(r, "</td><td>",
ap_escape_html(r->pool, worker->s->redirect), NULL);
ap_rprintf(r, "</td><td>%d</td>", worker->s->lbfactor);
ap_rprintf(r, "<td>%d</td><td>", worker->s->lbset);
if (worker->s->status & PROXY_WORKER_DISABLED)
ap_rputs("Dis ", r);
if (worker->s->status & PROXY_WORKER_IN_ERROR)
ap_rputs("Err ", r);
if (worker->s->status & PROXY_WORKER_STOPPED)
ap_rputs("Stop ", r);
if (worker->s->status & PROXY_WORKER_HOT_STANDBY)
ap_rputs("Stby ", r);
if (PROXY_WORKER_IS_USABLE(worker))
ap_rputs("Ok", r);
if (!PROXY_WORKER_IS_INITIALIZED(worker))
ap_rputs("-", r);
ap_rputs("</td>", r);
ap_rprintf(r, "<td>%" APR_SIZE_T_FMT "</td><td>", worker->s->elected);
ap_rputs(apr_strfsize(worker->s->transferred, fbuf), r);
ap_rputs("</td><td>", r);
ap_rputs(apr_strfsize(worker->s->read, fbuf), r);
ap_rputs("</td></tr>\n", r);
++worker;
}
ap_rputs("</table>\n", r);
++balancer;
}
ap_rputs("<hr />\n", r);
if (wsel && bsel) {
ap_rputs("<h3>Edit worker settings for ", r);
ap_rvputs(r, wsel->name, "</h3>\n", NULL);
ap_rvputs(r, "<form method=\"GET\" action=\"", NULL);
ap_rvputs(r, r->uri, "\">\n<dl>", NULL);
ap_rputs("<table><tr><td>Load factor:</td><td><input name=\"lf\" type=text ", r);
ap_rprintf(r, "value=\"%d\"></td></tr>\n", wsel->s->lbfactor);
ap_rputs("<tr><td>LB Set:</td><td><input name=\"ls\" type=text ", r);
ap_rprintf(r, "value=\"%d\"></td></tr>\n", wsel->s->lbset);
ap_rputs("<tr><td>Route:</td><td><input name=\"wr\" type=text ", r);
ap_rvputs(r, "value=\"", ap_escape_html(r->pool, wsel->s->route),
NULL);
ap_rputs("\"></td></tr>\n", r);
ap_rputs("<tr><td>Route Redirect:</td><td><input name=\"rr\" type=text ", r);
ap_rvputs(r, "value=\"", ap_escape_html(r->pool, wsel->s->redirect),
NULL);
ap_rputs("\"></td></tr>\n", r);
ap_rputs("<tr><td>Status:</td><td>Disabled: <input name=\"dw\" value=\"Disable\" type=radio", r);
if (wsel->s->status & PROXY_WORKER_DISABLED)
ap_rputs(" checked", r);
ap_rputs("> | Enabled: <input name=\"dw\" value=\"Enable\" type=radio", r);
if (!(wsel->s->status & PROXY_WORKER_DISABLED))
ap_rputs(" checked", r);
ap_rputs("></td></tr>\n", r);
ap_rputs("<tr><td colspan=2><input type=submit value=\"Submit\"></td></tr>\n", r);
ap_rvputs(r, "</table>\n<input type=hidden name=\"w\" ", NULL);
ap_rvputs(r, "value=\"", ap_escape_uri(r->pool, wsel->name), "\">\n", NULL);
ap_rvputs(r, "<input type=hidden name=\"b\" ", NULL);
ap_rvputs(r, "value=\"", bsel->name + sizeof("balancer://") - 1,
"\">\n</form>\n", NULL);
ap_rvputs(r, "<input type=hidden name=\"nonce\" value=\"",
balancer_nonce, "\">\n", NULL);
ap_rputs("<hr />\n", r);
}
ap_rputs(ap_psignature("",r), r);
ap_rputs("</body></html>\n", r);
}
return OK;
}
static void child_init(apr_pool_t *p, server_rec *s)
{
while (s) {
void *sconf = s->module_config;
proxy_server_conf *conf;
proxy_balancer *balancer;
int i;
conf = (proxy_server_conf *)ap_get_module_config(sconf, &proxy_module);
/* Initialize shared scoreboard data */
balancer = (proxy_balancer *)conf->balancers->elts;
for (i = 0; i < conf->balancers->nelts; i++) {
init_balancer_members(conf, s, balancer);
balancer++;
}
s = s->next;
}
}
/*
* 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 i;
int total_factor = 0;
proxy_worker *worker;
proxy_worker *mycandidate = NULL;
int cur_lbset = 0;
int max_lbset = 0;
int checking_standby;
int checked_standby;
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy: Entering byrequests for BALANCER (%s)",
balancer->name);
/* First try to see if we have available candidate */
do {
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 (!checking_standby) { /* first time through */
if (worker->s->lbset > max_lbset)
max_lbset = worker->s->lbset;
}
if (worker->s->lbset > cur_lbset)
continue;
if ( (checking_standby ? !PROXY_WORKER_IS_STANDBY(worker) : PROXY_WORKER_IS_STANDBY(worker)) )
continue;
/* If the worker is in error state run
* retry on that worker. It will be marked as
* operational if the retry timeout is elapsed.
* The worker might still be unusable, but we try
* anyway.
*/
if (!PROXY_WORKER_IS_USABLE(worker))
ap_proxy_retry_worker("BALANCER", worker, r->server);
/* Take into calculation only the workers that are
* not in error state or not disabled.
*/
if (PROXY_WORKER_IS_USABLE(worker)) {
worker->s->lbstatus += worker->s->lbfactor;
total_factor += worker->s->lbfactor;
if (!mycandidate || worker->s->lbstatus > mycandidate->s->lbstatus)
mycandidate = worker;
}
}
checked_standby = checking_standby++;
}
cur_lbset++;
} while (cur_lbset <= max_lbset && !mycandidate);
if (mycandidate) {
mycandidate->s->lbstatus -= total_factor;
}
return mycandidate;
}
/*
* 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)
{
int i;
apr_off_t mytraffic = 0;
apr_off_t curmin = 0;
proxy_worker *worker;
proxy_worker *mycandidate = NULL;
int cur_lbset = 0;
int max_lbset = 0;
int checking_standby;
int checked_standby;
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
"proxy: Entering bytraffic for BALANCER (%s)",
balancer->name);
/* First try to see if we have available candidate */
do {
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 (!checking_standby) { /* first time through */
if (worker->s->lbset > max_lbset)
max_lbset = worker->s->lbset;
}
if (worker->s->lbset > cur_lbset)
continue;
if ( (checking_standby ? !PROXY_WORKER_IS_STANDBY(worker) : PROXY_WORKER_IS_STANDBY(worker)) )
continue;
/* If the worker is in error state run
* retry on that worker. It will be marked as
* operational if the retry timeout is elapsed.
* The worker might still be unusable, but we try
* anyway.
*/
if (!PROXY_WORKER_IS_USABLE(worker))
ap_proxy_retry_worker("BALANCER", worker, r->server);
/* Take into calculation only the workers that are
* not in error state or not disabled.
*/
if (PROXY_WORKER_IS_USABLE(worker)) {
mytraffic = (worker->s->transferred/worker->s->lbfactor) +
(worker->s->read/worker->s->lbfactor);
if (!mycandidate || mytraffic < curmin) {
mycandidate = worker;
curmin = mytraffic;
}
}
}
checked_standby = checking_standby++;
}
cur_lbset++;
} while (cur_lbset <= max_lbset && !mycandidate);
return mycandidate;
}
/*
* 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
};
static const proxy_balancer_method bytraffic =
{
"bytraffic",
&find_best_bytraffic,
NULL
};
static void ap_proxy_balancer_register_hook(apr_pool_t *p)
{
/* Only the mpm_winnt has child init hook handler.
* make sure that we are called after the mpm
* initializes and after the mod_proxy
*/
static const char *const aszPred[] = { "mpm_winnt.c", "mod_proxy.c", NULL};
/* manager handler */
ap_hook_post_config(balancer_init, NULL, NULL, APR_HOOK_MIDDLE);
ap_hook_handler(balancer_handler, NULL, NULL, APR_HOOK_FIRST);
ap_hook_child_init(child_init, aszPred, NULL, APR_HOOK_MIDDLE);
proxy_hook_pre_request(proxy_balancer_pre_request, NULL, NULL, APR_HOOK_FIRST);
proxy_hook_post_request(proxy_balancer_post_request, NULL, NULL, APR_HOOK_FIRST);
proxy_hook_canon_handler(proxy_balancer_canon, NULL, NULL, APR_HOOK_FIRST);
ap_register_provider(p, PROXY_LBMETHOD, "bytraffic", "0", &bytraffic);
ap_register_provider(p, PROXY_LBMETHOD, "byrequests", "0", &byrequests);
}
module AP_MODULE_DECLARE_DATA proxy_balancer_module = {
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_balancer_register_hook /* register hooks */
};