Adding upstream version 2.4.38.upstream/2.4.38upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 165 insertions, 0 deletions

diff --git a/modules/proxy/balancers/mod_lbmethod_byrequests.c b/modules/proxy/balancers/mod_lbmethod_byrequests.c
new file mode 100644
index 0000000..b6cd8d8
--- /dev/null
+++ b/modules/proxy/balancers/mod_lbmethod_byrequests.c
@@ -0,0 +1,165 @@
+/* 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 */
+};