From 54ab9d06cb2100e7569e603cbaae6d34e4606e61 Mon Sep 17 00:00:00 2001
From: Jim Jagielski <jim@apache.org>
Date: Wed, 3 Dec 2008 16:06:13 +0000
Subject: [PATCH] Add in independent bybusyness lbmethod

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@722948 13f79535-47bb-0310-9956-ffa450edef68
---
 .../proxy/balancers/mod_lbmethod_bybusyness.c | 129 ++++++++++++++++++
 1 file changed, 129 insertions(+)
 create mode 100644 modules/proxy/balancers/mod_lbmethod_bybusyness.c

diff --git a/modules/proxy/balancers/mod_lbmethod_bybusyness.c b/modules/proxy/balancers/mod_lbmethod_bybusyness.c
new file mode 100644
index 0000000000..d3423d2e39
--- /dev/null
+++ b/modules/proxy/balancers/mod_lbmethod_bybusyness.c
@@ -0,0 +1,129 @@
+/* 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 "apr_hooks.h"
+
+module AP_MODULE_DECLARE_DATA lbmethod_bybusyness_module;
+
+static proxy_worker *find_best_bybusyness(proxy_balancer *balancer,
+                                request_rec *r)
+{
+
+    int i;
+    proxy_worker *worker;
+    proxy_worker *mycandidate = NULL;
+    int cur_lbset = 0;
+    int max_lbset = 0;
+    int checking_standby;
+    int checked_standby;
+
+    int total_factor = 0;
+    
+    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                 "proxy: Entering bybusyness 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->busy < mycandidate->s->busy
+                        || (worker->s->busy == mycandidate->s->busy && 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;
+        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, r->server,
+                     "proxy: bybusyness selected worker \"%s\" : busy %" APR_SIZE_T_FMT " : lbstatus %d",
+                     mycandidate->name, mycandidate->s->busy, mycandidate->s->lbstatus);
+
+    }
+
+    return mycandidate;
+
+}
+
+static const proxy_balancer_method bybusyness =
+{
+    "bybusyness",
+    &find_best_bybusyness,
+    NULL
+};
+
+
+static void register_hook(apr_pool_t *p)
+{
+    ap_register_provider(p, PROXY_LBMETHOD, "bybusyness", "0", &bybusyness);
+}
+
+module AP_MODULE_DECLARE_DATA lbmethod_bybusyness_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 */
+    register_hook /* register hooks */
+};
-- 
2.40.0