mod_proxy_balancer: Fix balancers and balancer members reuse on

restart when new ones are added.  PR 58024.

Since slotmem_create() issues a strict check on the size of an existing
slot before reusing it, it won't reuse existing balancers and members when
new ones are added during restart (whereas growth margins would allow it).
Fix this by using slotmem_attach() first and if it succeeds do the checks
based on the returned previous number of existing entries.

[Reverted by r1698123]

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1696960 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/CHANGES b/CHANGES
index 0420ab900cd234d85bf87082601261ebc86cd86e..02f4fdf9ef0fe4ccfca97a50a5ceeb51d42cad6c 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,9 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.5.0
 
+  *) mod_proxy_balancer: Fix balancers and balancer members reuse on
+     restart when new ones are added.  PR 58024.  [Yann Ylavic]
+
   *) mod_socache_memcache: Add the 'MemcacheConnTTL' directive to control how 
      long to keep idle connections with the memcache server(s).
      Change default value from 600 usec (!) to 15 sec. PR 58091

diff --git a/docs/log-message-tags/next-number b/docs/log-message-tags/next-number
index ff481a2e55352a91075216c01581435185ad9f03..ec21808e298acce1020bc4b87b287d072db49951 100644 (file)
--- a/docs/log-message-tags/next-number
+++ b/docs/log-message-tags/next-number
@@ -1 +1 @@
-2964
+2966

diff --git a/modules/proxy/mod_proxy_balancer.c b/modules/proxy/mod_proxy_balancer.c
index 5e1d78bc5403071aa4096399ed6bb14072af4e48..be77ef155ec92bf38e6458cb82b726bce7a9a90f 100644 (file)
--- a/modules/proxy/mod_proxy_balancer.c
+++ b/modules/proxy/mod_proxy_balancer.c
@@ -761,8 +761,11 @@ static int balancer_post_config(apr_pool_t *pconf, apr_pool_t *plog,
         char *id;
         proxy_balancer *balancer;
         ap_slotmem_type_t type;
+        apr_size_t attached_size;
+        unsigned int attached_num;
         void *sconf = s->module_config;
         conf = (proxy_server_conf *)ap_get_module_config(sconf, &proxy_module);
+
         /*
          * During create_proxy_config() we created a dummy id. Now that
          * we have identifying info, we can create the real id
@@ -794,11 +797,39 @@ static int balancer_post_config(apr_pool_t *pconf, apr_pool_t *plog,
                          (int)ALIGNED_PROXY_BALANCER_SHARED_SIZE,
                          (int)conf->balancers->nelts, conf->max_balancers);
 
-            rv = storage->create(&new, conf->id,
-                                 ALIGNED_PROXY_BALANCER_SHARED_SIZE,
-                                 conf->max_balancers, type, pconf);
+            /* First try to attach() since the number of configured balancers
+             * may have changed during restart, and we don't want create() to
+             * fail because the overall size * number of entries is not stricly
+             * identical to the previous run.  There may still be enough room
+             * for this new run thanks to bgrowth margin, so if attach()
+             * succeeds we can only check for the number of available entries
+             * to be *greater or* equal to what we need now.  If attach() fails
+             * we simply fall back to create().
+             */
+            rv = storage->attach(&new, conf->id,
+                                 &attached_size, &attached_num,
+                                 pconf);
+            if (rv != APR_SUCCESS) {
+                rv = storage->create(&new, conf->id,
+                                     ALIGNED_PROXY_BALANCER_SHARED_SIZE,
+                                     conf->max_balancers, type, pconf);
+            }
+            else {
+                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02964)
+                             "Balancers attached: %d, %d (%d)",
+                             (int)ALIGNED_PROXY_BALANCER_SHARED_SIZE,
+                             (int)attached_num, conf->max_balancers);
+                if (attached_size == ALIGNED_PROXY_BALANCER_SHARED_SIZE
+                        && attached_num >= conf->balancers->nelts) {
+                    conf->max_balancers = attached_num;
+                }
+                else {
+                    rv = APR_ENOSPC;
+                }
+            }
             if (rv != APR_SUCCESS) {
-                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01179) "balancer slotmem_create failed");
+                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01179)
+                             "balancer slotmem create or attach failed");
                 return !OK;
             }
             conf->bslot = new;
@@ -864,11 +895,32 @@ static int balancer_post_config(apr_pool_t *pconf, apr_pool_t *plog,
                          (int)ALIGNED_PROXY_WORKER_SHARED_SIZE,
                          (int)balancer->max_workers, i);
 
-            rv = storage->create(&new, balancer->s->sname,
-                                 ALIGNED_PROXY_WORKER_SHARED_SIZE,
-                                 balancer->max_workers, type, pconf);
+            /* try to attach first (see rationale from balancers above) */
+            rv = storage->attach(&new, balancer->s->sname,
+                                 &attached_size, &attached_num,
+                                 pconf);
+            if (rv != APR_SUCCESS) {
+                rv = storage->create(&new, balancer->s->sname,
+                                     ALIGNED_PROXY_WORKER_SHARED_SIZE,
+                                     balancer->max_workers, type, pconf);
+            }
+            else {
+                ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s, APLOGNO(02965)
+                             "Workers attached: %s (%s), %d, %d (%d) [%u]",
+                             balancer->s->name, balancer->s->sname,
+                             (int)ALIGNED_PROXY_WORKER_SHARED_SIZE,
+                             (int)attached_num, balancer->max_workers, i);
+                if (attached_size == ALIGNED_PROXY_WORKER_SHARED_SIZE
+                        && attached_num >= balancer->workers->nelts) {
+                    balancer->max_workers = attached_num;
+                }
+                else {
+                    rv = APR_ENOSPC;
+                }
+            }
             if (rv != APR_SUCCESS) {
-                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01185) "worker slotmem_create failed");
+                ap_log_error(APLOG_MARK, APLOG_EMERG, rv, s, APLOGNO(01185)
+                             "worker slotmem create or attach failed");
                 return !OK;
             }
             balancer->wslot = new;