And move the HB balancer there

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@722919 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 364 insertions, 0 deletions

diff --git a/modules/proxy/balancers/mod_lbmethod_heartbeat.c b/modules/proxy/balancers/mod_lbmethod_heartbeat.c
new file mode 100644
index 0000000000..aa88f280de
--- /dev/null
+++ b/modules/proxy/balancers/mod_lbmethod_heartbeat.c
@@ -0,0 +1,364 @@
+/* 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_heartbeat_module;
+
+typedef struct lb_hb_ctx_t
+{
+    const char *path;
+} lb_hb_ctx_t;
+
+typedef struct hb_server_t {
+    const char *ip;
+    int busy;
+    int ready;
+    int seen;
+    proxy_worker *worker;
+} hb_server_t;
+
+static void
+argstr_to_table(apr_pool_t *p, char *str, apr_table_t *parms)
+{
+    char *key;
+    char *value;
+    char *strtok_state;
+    
+    key = apr_strtok(str, "&", &strtok_state);
+    while (key) {
+        value = strchr(key, '=');
+        if (value) {
+            *value = '\0';      /* Split the string in two */
+            value++;            /* Skip passed the = */
+        }
+        else {
+            value = "1";
+        }
+        ap_unescape_url(key);
+        ap_unescape_url(value);
+        apr_table_set(parms, key, value);
+        /*
+         ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+         "Found query arg: %s = %s", key, value);
+         */
+        key = apr_strtok(NULL, "&", &strtok_state);
+    }
+}
+
+static apr_status_t read_heartbeats(const char *path, apr_hash_t *servers,
+                                    apr_pool_t *pool)
+{
+    apr_finfo_t fi;
+    apr_status_t rv;
+    apr_file_t *fp;
+
+    if (!path) {
+        return APR_SUCCESS;
+    }
+
+    rv = apr_file_open(&fp, path, APR_READ|APR_BINARY|APR_BUFFERED,
+                       APR_OS_DEFAULT, pool);
+
+    if (rv) {
+        return rv;
+    }
+
+    rv = apr_file_info_get(&fi, APR_FINFO_SIZE, fp);
+
+    if (rv) {
+        return rv;
+    }
+
+    {
+        char *t;
+        int lineno = 0;
+        apr_bucket_alloc_t *ba = apr_bucket_alloc_create(pool);
+        apr_bucket_brigade *bb = apr_brigade_create(pool, ba);
+        apr_bucket_brigade *tmpbb = apr_brigade_create(pool, ba);
+        apr_table_t *hbt = apr_table_make(pool, 10);
+
+        apr_brigade_insert_file(bb, fp, 0, fi.size, pool);
+
+        do {
+            hb_server_t *server;
+            char buf[4096];
+            apr_size_t bsize = sizeof(buf);
+
+            apr_brigade_cleanup(tmpbb);
+
+            if (APR_BRIGADE_EMPTY(bb)) {
+                break;
+            }
+
+            rv = apr_brigade_split_line(tmpbb, bb,
+                                        APR_BLOCK_READ, sizeof(buf));
+            lineno++;
+
+            if (rv) {
+                return rv;
+            }
+
+            apr_brigade_flatten(tmpbb, buf, &bsize);
+
+            if (bsize == 0) {
+                break;
+            }
+
+            buf[bsize - 1] = 0;
+
+            /* comment */
+            if (buf[0] == '#') {
+                continue;
+            }
+
+            /* line format: <IP> <query_string>\n */
+            t = strchr(buf, ' ');
+            if (!t) {
+                continue;
+            }
+            
+            const char *ip = apr_pstrndup(pool, buf, t - buf);
+            t++;
+
+            server = apr_hash_get(servers, ip, APR_HASH_KEY_STRING);
+            
+            if (server == NULL) {
+                server = apr_pcalloc(pool, sizeof(hb_server_t));
+                server->ip = ip;
+                server->seen = -1;
+
+                apr_hash_set(servers, server->ip, APR_HASH_KEY_STRING, server);
+            }
+            
+            apr_table_clear(hbt);
+
+            argstr_to_table(pool, apr_pstrdup(pool, t), hbt);
+
+            if (apr_table_get(hbt, "busy")) {
+                server->busy = atoi(apr_table_get(hbt, "busy"));
+            }
+
+            if (apr_table_get(hbt, "ready")) {
+                server->ready = atoi(apr_table_get(hbt, "ready"));
+            }
+
+            if (apr_table_get(hbt, "lastseen")) {
+                server->seen = atoi(apr_table_get(hbt, "lastseen"));
+            }
+
+            if (server->busy == 0 && server->ready != 0) {
+                /* Server has zero threads active, but lots of them ready, 
+                 * it likely just started up, so lets /4 the number ready, 
+                 * to prevent us from completely flooding it with all new 
+                 * requests.
+                 */
+                server->ready = server->ready / 4;
+            }
+
+        } while (1);
+    }
+
+    return APR_SUCCESS;
+}
+
+/*
+ * Finding a random number in a range. 
+ *      n' = a + n(b-a+1)/(M+1)
+ * where:
+ *      n' = random number in range
+ *      a  = low end of range
+ *      b  = high end of range
+ *      n  = random number of 0..M
+ *      M  = maxint
+ * Algorithm 'borrowed' from PHP's rand() function.
+ */
+#define RAND_RANGE(__n, __min, __max, __tmax) \
+(__n) = (__min) + (long) ((double) ((__max) - (__min) + 1.0) * ((__n) / ((__tmax) + 1.0)))
+
+static apr_status_t random_pick(apr_uint32_t *number,
+                                apr_uint32_t min,
+                                apr_uint32_t max)
+{
+    apr_status_t rv = 
+        apr_generate_random_bytes((void*)number, sizeof(apr_uint32_t));
+
+    if (rv) {
+        return rv;
+    }
+
+    RAND_RANGE(*number, min, max, APR_UINT32_MAX);
+
+    return APR_SUCCESS;
+}
+
+static proxy_worker *find_best_hb(proxy_balancer *balancer,
+                                  request_rec *r)
+{
+    apr_status_t rv;
+    int i;
+    apr_uint32_t openslots = 0;
+    proxy_worker *worker;
+    hb_server_t *server;
+    apr_array_header_t *up_servers;
+    proxy_worker *mycandidate = NULL;
+    apr_pool_t *tpool;
+    apr_hash_t *servers;
+
+    lb_hb_ctx_t *ctx = 
+        ap_get_module_config(r->server->module_config,
+                             &lbmethod_heartbeat_module);
+
+    apr_pool_create(&tpool, r->pool);
+
+    servers = apr_hash_make(tpool);
+
+    rv = read_heartbeats(ctx->path, servers, tpool);
+
+    if (rv) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
+                      "lb_heartbeat: Unable to read heartbeats at '%s'",
+                      ctx->path);
+        apr_pool_destroy(tpool);
+        return NULL;
+    }
+
+    up_servers = apr_array_make(tpool, apr_hash_count(servers), sizeof(hb_server_t *));
+
+    for (i = 0; i < balancer->workers->nelts; i++) {
+        worker = &APR_ARRAY_IDX(balancer->workers, i, proxy_worker);
+        server = apr_hash_get(servers, worker->hostname, APR_HASH_KEY_STRING);
+
+        if (!server) {
+            continue;
+        }
+
+        if (!PROXY_WORKER_IS_USABLE(worker)) {
+            ap_proxy_retry_worker("BALANCER", worker, r->server);
+        }
+
+        if (PROXY_WORKER_IS_USABLE(worker)) {
+            server->worker = worker;
+            if (server->seen < 10) {
+                openslots += server->ready;
+                APR_ARRAY_PUSH(up_servers, hb_server_t *) = server;
+            }
+        }
+    }
+
+    if (openslots > 0) {
+        apr_uint32_t c = 0;
+        apr_uint32_t pick = 0;;
+
+        rv = random_pick(&pick, 0, openslots);
+
+        if (rv) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, rv, r,
+                          "lb_heartbeat: failed picking a random number. how random.");
+            apr_pool_destroy(tpool);
+            return NULL;
+        }
+
+        for (i = 0; i < up_servers->nelts; i++) {
+            server = APR_ARRAY_IDX(up_servers, i, hb_server_t *);
+            if (pick > c && pick <= c + server->ready) {
+                mycandidate = server->worker;
+            }
+
+            c += server->ready;
+        }
+    }
+
+    apr_pool_destroy(tpool);
+
+    return mycandidate;
+}
+
+static const proxy_balancer_method heartbeat =
+{
+    "heartbeat",
+    &find_best_hb,
+    NULL
+};
+
+static void register_hooks(apr_pool_t *p)
+{
+    ap_register_provider(p, PROXY_LBMETHOD, "heartbeat", "0", &heartbeat);
+}
+
+static void *lb_hb_create_config(apr_pool_t *p, server_rec *s)
+{
+    lb_hb_ctx_t *ctx = (lb_hb_ctx_t *) apr_palloc(p, sizeof(lb_hb_ctx_t));
+    
+    ctx->path = ap_server_root_relative(p, "logs/hb.dat");
+    
+    return ctx;
+}
+
+static void *lb_hb_merge_config(apr_pool_t *p, void *basev, void *overridesv)
+{
+    lb_hb_ctx_t *ps = apr_pcalloc(p, sizeof(lb_hb_ctx_t));
+    lb_hb_ctx_t *base = (lb_hb_ctx_t *) basev;
+    lb_hb_ctx_t *overrides = (lb_hb_ctx_t *) overridesv;
+
+    if (overrides->path) {
+        ps->path = apr_pstrdup(p, overrides->path);
+    }
+    else {
+        ps->path = apr_pstrdup(p, base->path);
+    }
+
+    return ps;
+}
+
+static const char *cmd_lb_hb_storage(cmd_parms *cmd,
+                                  void *dconf, const char *path)
+{
+    apr_pool_t *p = cmd->pool;
+    lb_hb_ctx_t *ctx =
+    (lb_hb_ctx_t *) ap_get_module_config(cmd->server->module_config,
+                                         &lbmethod_heartbeat_module);
+
+    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
+    
+    if (err != NULL) {
+        return err;
+    }
+
+    ctx->path = ap_server_root_relative(p, path);
+
+    return NULL;
+}
+
+static const command_rec cmds[] = {
+    AP_INIT_TAKE1("HeartbeatStorage", cmd_lb_hb_storage, NULL, RSRC_CONF,
+                  "Path to read heartbeat data."),
+    {NULL}
+};
+
+module AP_MODULE_DECLARE_DATA lbmethod_heartbeat_module = {
+    STANDARD20_MODULE_STUFF,
+    NULL,                       /* create per-directory config structure */
+    NULL,                       /* merge per-directory config structures */
+    lb_hb_create_config,        /* create per-server config structure */
+    lb_hb_merge_config,         /* merge per-server config structures */
+    cmds,                       /* command apr_table_t */
+    register_hooks              /* register hooks */
+};