1 files changed, 135 insertions, 0 deletions
diff --git a/modules/proxy/balancers/mod_lbmethod_bytraffic.c b/modules/proxy/balancers/mod_lbmethod_bytraffic.c
new file mode 100644
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+++ b/modules/proxy/balancers/mod_lbmethod_bytraffic.c
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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.
+ */
+
+#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_bytraffic_module;
+
+static APR_OPTIONAL_FN_TYPE(proxy_balancer_get_best_worker)
+                            *ap_proxy_balancer_get_best_worker_fn = NULL;
+
+static int is_best_bytraffic(proxy_worker *current, proxy_worker *prev_best, void *baton)
+{
+    apr_off_t *min_traffic = (apr_off_t *)baton;
+    apr_off_t traffic = (current->s->transferred / current->s->lbfactor)
+                        + (current->s->read / current->s->lbfactor);
+
+    if (!prev_best || (traffic < *min_traffic)) {
+        *min_traffic = traffic;
+
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+/*
+ * 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)
+{
+    apr_off_t min_traffic = 0;
+
+    return ap_proxy_balancer_get_best_worker_fn(balancer, r, is_best_bytraffic,
+                                             &min_traffic);
+}
+
+/* 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;
+        (*worker)->s->transferred = 0;
+        (*worker)->s->read = 0;
+    }
+    return APR_SUCCESS;
+}
+
+static apr_status_t age(proxy_balancer *balancer, server_rec *s)
+{
+    return APR_SUCCESS;
+}
+
+static const proxy_balancer_method bytraffic =
+{
+    "bytraffic",
+    &find_best_bytraffic,
+    NULL,
+    &reset,
+    &age,
+    NULL
+};
+
+/* post_config hook: */
+static int lbmethod_bytraffic_post_config(apr_pool_t *pconf, apr_pool_t *plog,
+        apr_pool_t *ptemp, server_rec *s)
+{
+
+    /* lbmethod_bytraffic_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(10150)
+                     "mod_proxy must be loaded for mod_lbmethod_bytraffic");
+        return !OK;
+    }
+
+    return OK;
+}
+
+static void register_hook(apr_pool_t *p)
+{
+    ap_register_provider(p, PROXY_LBMETHOD, "bytraffic", "0", &bytraffic);
+    ap_hook_post_config(lbmethod_bytraffic_post_config, NULL, NULL, APR_HOOK_MIDDLE);
+}
+
+AP_DECLARE_MODULE(lbmethod_bytraffic) = {
+    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 */
+};