diff -Nur -x bdb mysql-5.0.25-nightly-20060823.host_cache04/client/mysql_priv.h mysql-5.0.25-nightly-20060823.host_cache05/client/mysql_priv.h
--- mysql-5.0.25-nightly-20060823.host_cache04/client/mysql_priv.h	2006-09-25 21:38:21.000000000 -0700
+++ mysql-5.0.25-nightly-20060823.host_cache05/client/mysql_priv.h	2006-09-26 14:03:53.000000000 -0700
@@ -1481,10 +1481,13 @@
 {
 public:
   uint32 ip;
-  uint	 errors;
+  uint32 errors;
+  uint32 hits;
   char	 *hostname;
 };
 extern hash_filo *hostname_cache;
+extern hash_filo_metrics hostname_cache_metrics;
+
 struct in_addr;
 my_string ip_to_hostname(struct in_addr *in,uint *errors);
 void hostname_cache_inc_errors(struct in_addr *in);
diff -Nur -x bdb mysql-5.0.25-nightly-20060823.host_cache04/sql/hash_filo.cc mysql-5.0.25-nightly-20060823.host_cache05/sql/hash_filo.cc
--- mysql-5.0.25-nightly-20060823.host_cache04/sql/hash_filo.cc	2006-09-25 21:35:50.000000000 -0700
+++ mysql-5.0.25-nightly-20060823.host_cache05/sql/hash_filo.cc	2006-09-26 15:01:55.000000000 -0700
@@ -27,12 +27,22 @@
 #include "mysql_priv.h"
 #include "hash_filo.h"
 
+hash_filo_metrics::hash_filo_metrics()
+{
+  reset();
+}
+
+void hash_filo_metrics::reset()
+{
+  hits= misses= inserts= prunes= 0;
+}
+
 hash_filo::hash_filo(uint size_arg, uint key_offset_arg, uint key_length_arg,
           hash_get_key get_key_arg, hash_free_key free_element_arg,
           CHARSET_INFO *hash_charset_arg)
   :size(size_arg), key_offset(key_offset_arg), key_length(key_length_arg),
    get_key(get_key_arg), free_element(free_element_arg), init(0),
-   hash_charset(hash_charset_arg)
+   hash_charset(hash_charset_arg), metrics(NULL)
 {
   bzero((char*) &cache, sizeof(cache));
 }
@@ -46,6 +56,11 @@
     pthread_mutex_destroy(&lock);
   }
 }
+
+void hash_filo::set_metrics(hash_filo_metrics *in_metrics)
+{
+  metrics= in_metrics;
+}
   
 void hash_filo::clear(bool locked)
 {
@@ -59,9 +74,15 @@
   (void) hash_free(&cache);
   (void) hash_init(&cache, hash_charset, size, key_offset, 
                    key_length, get_key, free_element, 0);
+  if(metrics) metrics->reset();
   if (!locked)
     (void) pthread_mutex_unlock(&lock);
   newest_element_p= oldest_element_p= NULL;
+  if(metrics)
+  {
+    metrics->used= 0;
+    metrics->free= size;
+  }
 }
 
 void hash_filo::resize(uint new_size)
@@ -79,6 +100,7 @@
                                                              length);
   if (entry)
   {						// Found; link it first
+    if(metrics) statistic_increment(metrics->hits, &metrics->lock);
     if (entry != newest_element_p)
     {						// Relink used-chain
       if (entry == oldest_element_p)
@@ -91,6 +113,8 @@
         newest_element_p->newer_element_p= entry;
       newest_element_p= entry;
     }
+  } else {
+    if(metrics) statistic_increment(metrics->misses, &metrics->lock);
   }
   return entry;
 }
@@ -114,6 +138,7 @@
       newest_element_p = NULL;
 
     hash_delete(&cache, (byte*) tmp);
+    if(metrics) statistic_increment(metrics->prunes, &metrics->lock);
   }
     
   if (my_hash_insert(&cache, (byte*) entry))
@@ -122,11 +147,19 @@
       (*free_element)(entry);		// This should never happen
     return 1;
   }
+  if(metrics) statistic_increment(metrics->inserts, &metrics->lock);
 
   if ((entry->older_element_p= newest_element_p))
     newest_element_p->newer_element_p= entry;
   else
     oldest_element_p= entry;
   newest_element_p= entry;
+
+  if(metrics)
+  {
+    metrics->used= cache.records;
+    metrics->free= size - cache.records;
+  }
+
   return 0;
 }
diff -Nur -x bdb mysql-5.0.25-nightly-20060823.host_cache04/sql/hash_filo.h mysql-5.0.25-nightly-20060823.host_cache05/sql/hash_filo.h
--- mysql-5.0.25-nightly-20060823.host_cache04/sql/hash_filo.h	2006-09-25 21:35:50.000000000 -0700
+++ mysql-5.0.25-nightly-20060823.host_cache05/sql/hash_filo.h	2006-09-26 14:51:19.000000000 -0700
@@ -37,6 +37,23 @@
   friend class hash_filo;
 };
 
+class hash_filo_metrics
+{
+ public:
+  hash_filo_metrics();
+  void reset();
+
+  uint32 hits;
+  uint32 misses;
+  uint32 inserts;
+  uint32 prunes;
+
+  uint32 used, free;
+
+  pthread_mutex_t lock;
+
+  friend class hash_filo;
+};
 
 class hash_filo
 {
@@ -47,6 +64,7 @@
   bool init;
   CHARSET_INFO *hash_charset;
 
+  hash_filo_metrics *metrics;
   hash_filo_element *newest_element_p, *oldest_element_p;
   
 public:
@@ -58,6 +76,8 @@
             CHARSET_INFO *hash_charset_arg);
   ~hash_filo();
 
+  void set_metrics(hash_filo_metrics *in_metrics);
+
   hash_filo_element *newest_element() { return newest_element_p; }
   hash_filo_element *oldest_element() { return oldest_element_p; }
 
diff -Nur -x bdb mysql-5.0.25-nightly-20060823.host_cache04/sql/hostname.cc mysql-5.0.25-nightly-20060823.host_cache05/sql/hostname.cc
--- mysql-5.0.25-nightly-20060823.host_cache04/sql/hostname.cc	2006-09-26 11:07:19.000000000 -0700
+++ mysql-5.0.25-nightly-20060823.host_cache05/sql/hostname.cc	2006-09-26 16:02:11.000000000 -0700
@@ -40,6 +40,7 @@
 
 
 hash_filo *hostname_cache;
+hash_filo_metrics hostname_cache_metrics;
 
 /*
   A simple inline function to return the hash key for a given entry.
@@ -82,6 +83,7 @@
                                       &my_charset_latin1)))
     DBUG_RETURN(1);
   hostname_cache->clear();
+  hostname_cache->set_metrics(&hostname_cache_metrics);
   DBUG_RETURN(0);
 }
 
@@ -272,6 +274,7 @@
       else
         name=my_strdup(entry->hostname,MYF(0));
       *errors= entry->errors;
+      entry->hits++;
       VOID(pthread_mutex_unlock(&hostname_cache->lock));
       DBUG_RETURN(name);
     }
@@ -281,7 +284,7 @@
   /*
     The IP didn't exist in the hostname cache, we need to resolve it.
   */
-  
+
   struct hostent *reverse, *forward;
   struct hostent he_reverse, he_forward;
   char buf_reverse[GETHOSTBYADDR_BUFF_SIZE];
@@ -308,9 +311,7 @@
   if (!reverse->h_name[0])
   {
     DBUG_PRINT("error", ("Got an empty hostname from reverse lookup"));
-    hostname_cache_add_deny(in);
-    my_gethostbyaddr_r_free();
-    DBUG_RETURN(0);				// Don't allow empty hostnames
+    goto cache_failure_and_return;
   }
   
   /*
@@ -370,7 +371,12 @@
   {
     if (*(uint32*)(forward->h_addr_list)[i] == in->s_addr)
     {
-      hostname_cache_add(in, name);
+      if(likely(host_cache_size > 0))
+      {
+        hostname_cache_add(in, name);
+        /* hostname_cache_add calls ::search, which will increment misses */
+        statistic_decrement(hostname_cache_metrics.misses, &hostname_cache_metrics.lock);
+      }
       my_gethostbyname_r_free();
       DBUG_RETURN(name);
     }
diff -Nur -x bdb mysql-5.0.25-nightly-20060823.host_cache04/sql/mysqld.cc mysql-5.0.25-nightly-20060823.host_cache05/sql/mysqld.cc
--- mysql-5.0.25-nightly-20060823.host_cache04/sql/mysqld.cc	2006-09-25 21:50:34.000000000 -0700
+++ mysql-5.0.25-nightly-20060823.host_cache05/sql/mysqld.cc	2006-09-26 14:38:34.000000000 -0700
@@ -6137,6 +6137,12 @@
   {"Handler_savepoint_rollback",(char*) offsetof(STATUS_VAR, ha_savepoint_rollback_count), SHOW_LONG_STATUS},
   {"Handler_update",           (char*) offsetof(STATUS_VAR, ha_update_count), SHOW_LONG_STATUS},
   {"Handler_write",            (char*) offsetof(STATUS_VAR, ha_write_count), SHOW_LONG_STATUS},
+  {"Host_cache_free",          (char*) &hostname_cache_metrics.free, SHOW_LONG},
+  {"Host_cache_hits",          (char*) &hostname_cache_metrics.hits, SHOW_LONG},
+  {"Host_cache_inserts",       (char*) &hostname_cache_metrics.inserts, SHOW_LONG},
+  {"Host_cache_misses",        (char*) &hostname_cache_metrics.misses, SHOW_LONG},
+  {"Host_cache_prunes",        (char*) &hostname_cache_metrics.prunes, SHOW_LONG},
+  {"Host_cache_used",          (char*) &hostname_cache_metrics.used, SHOW_LONG},
 #ifdef HAVE_INNOBASE_DB
   {"Innodb_",                  (char*) &innodb_status_variables, SHOW_VARS},
 #endif /*HAVE_INNOBASE_DB*/
diff -Nur -x bdb mysql-5.0.25-nightly-20060823.host_cache04/sql/mysql_priv.h mysql-5.0.25-nightly-20060823.host_cache05/sql/mysql_priv.h
--- mysql-5.0.25-nightly-20060823.host_cache04/sql/mysql_priv.h	2006-09-25 21:38:21.000000000 -0700
+++ mysql-5.0.25-nightly-20060823.host_cache05/sql/mysql_priv.h	2006-09-26 14:03:53.000000000 -0700
@@ -1481,10 +1481,13 @@
 {
 public:
   uint32 ip;
-  uint	 errors;
+  uint32 errors;
+  uint32 hits;
   char	 *hostname;
 };
 extern hash_filo *hostname_cache;
+extern hash_filo_metrics hostname_cache_metrics;
+
 struct in_addr;
 my_string ip_to_hostname(struct in_addr *in,uint *errors);
 void hostname_cache_inc_errors(struct in_addr *in);
diff -Nur -x bdb mysql-5.0.25-nightly-20060823.host_cache04/sql/sql_show.cc mysql-5.0.25-nightly-20060823.host_cache05/sql/sql_show.cc
--- mysql-5.0.25-nightly-20060823.host_cache04/sql/sql_show.cc	2006-09-26 10:47:41.000000000 -0700
+++ mysql-5.0.25-nightly-20060823.host_cache05/sql/sql_show.cc	2006-09-26 12:44:28.000000000 -0700
@@ -63,6 +63,8 @@
   item->maybe_null= 1;
   field_list.push_back(new Item_return_int("Errors", 10, 
                                            MYSQL_TYPE_LONG));
+  field_list.push_back(new Item_return_int("Hits", 10, 
+                                           MYSQL_TYPE_LONG));
 
   if (protocol->send_fields(&field_list,
                             Protocol::SEND_NUM_ROWS | Protocol::SEND_EOF))
@@ -84,6 +86,7 @@
     else
       protocol->store_null();
     protocol->store((uint)cur->errors);
+    protocol->store((uint)cur->hits);
     if(protocol->write())
       DBUG_RETURN(TRUE);
   }