Added new mutex for hostname lookup

Added free of io_cache when using ALTER TABLE ... ORDER BY


Docs/manual.texi:
  Updated from user comments
sql/ha_berkeley.cc:
  Fixed wrong cast
sql/hostname.cc:
  Added new mutex for hostname lookup
sql/sql_table.cc:
  Added free of io_cache when using ALTER TABLE ... ORDER BY

Docs/manual.texi

@@ -15172,7 +15172,8 @@ mysql> select BIT_COUNT(29);
 @node Logical functions, Comparison functions, Bit functions, Functions
 @subsection Logical Operations
 
-All logical functions return @code{1} (TRUE) or @code{0} (FALSE):
+All logical functions return @code{1} (TRUE), @code{0} (FALSE) or
+@code{NULL} (unknown, which is in most cases the same as FALSE):
 
 @table @code
 @findex NOT, logical
@@ -18416,7 +18417,7 @@ swap two tables names, you have to:
 @example
 RENAME TABLE old_table    TO backup_table,
              new_table    TO old_table,
-             backup_table TO old_table;
+             backup_table TO new_table;
 @end example
 
 As long as two databases are on the same disk you can also rename
@@ -24566,7 +24567,8 @@ mysql> SELECT 1 IS NULL, 1 IS NOT NULL;
 +-----------+---------------+
 @end example
 
-In @strong{MySQL}, 0 means false and 1 means true.
+In @strong{MySQL}, 0 or @code{NULL} means false and anything else means true.
+The default trueth value from a boolean operation is 1.
 
 This special treatment of @code{NULL} is why, in the previous section, it
 was necessary to determine which animals are no longer alive using
@@ -40639,6 +40641,10 @@ Our TODO section contains what we plan to have in 4.0. @xref{TODO MySQL 4.0}.
 
 @itemize @bullet
 @item
+Allow @code{SELECT expression LIMIT ...}.
+@item
+Added @code{IDENTITY} as a synonym for @code{AUTO_INCREMENT} (like SyBase).
+@item
 Added @code{ORDER BY} syntax to @code{UPDATE} and @code{DELETE}.
 @item
 Added @code{SELECT .. WITH UPDATE} and @code{SELECT ... IN SHARE MODE} to
@@ -45638,6 +45644,9 @@ New key cache
 When using @code{SET CHARACTER SET} we should translate the whole query
 at once and not only strings. This will enable users to use the translated
 characters in database, table and column names.
+@item
+Add a portable interface over @code{gethostbyaddr_r()} so that we can change
+@code{ip_to_hostname()} to not block other threads while doing DNS lookups.
 @end itemize
 
 @node TODO future, TODO sometime, TODO MySQL 4.0, TODO

sql/ha_berkeley.cc

@@ -247,9 +247,9 @@ int berkeley_show_logs(THD *thd)
   my_pthread_setspecific_ptr(THR_MALLOC,&show_logs_root);
 
   if ((error= log_archive(db_env, &all_logs, DB_ARCH_ABS | DB_ARCH_LOG,
-			  (void* (*)(unsigned int)) sql_alloc)) ||
+			  (void* (*)(size_t)) sql_alloc)) ||
       (error= log_archive(db_env, &free_logs, DB_ARCH_ABS, 
-			  (void* (*)(unsigned int)) sql_alloc)))
+			  (void* (*)(size_t)) sql_alloc)))
   {
     DBUG_PRINT("error", ("log_archive failed (error %d)", error));
     db_env->err(db_env, error, "log_archive: DB_ARCH_ABS");

sql/hostname.cc

@@ -48,6 +48,7 @@ public:
 };
 
 static hash_filo *hostname_cache;
+static pthread_mutex_t LOCK_hostname;
 
 void hostname_cache_refresh()
 {
@@ -56,6 +57,7 @@ void hostname_cache_refresh()
 
 bool hostname_cache_init()
 {
+  (void) pthread_mutex_init(&LOCK_hostname,NULL);
   if (!(hostname_cache=new hash_filo(HOST_CACHE_SIZE,offsetof(host_entry,ip),
 				     sizeof(struct in_addr),NULL,
 				     (void (*)(void*)) free)))
@@ -66,6 +68,7 @@ bool hostname_cache_init()
 
 void hostname_cache_free()
 {
+  (void) pthread_mutex_destroy(&LOCK_hostname);
   delete hostname_cache;
 }
 
@@ -180,26 +183,26 @@ my_string ip_to_hostname(struct in_addr *in, uint *errors)
     DBUG_RETURN(0);				// out of memory
 
 #else
-  VOID(pthread_mutex_lock(&hostname_cache->lock));
+  VOID(pthread_mutex_lock(&LOCK_hostname));
   if (!(hp=gethostbyaddr((char*) in,sizeof(*in), AF_INET)))
   {
-    VOID(pthread_mutex_unlock(&hostname_cache->lock));
+    VOID(pthread_mutex_unlock(&LOCK_hostname));
     DBUG_PRINT("error",("gethostbyaddr returned %d",errno));
     goto err;
   }
   if (!hp->h_name[0])				// Don't allow empty hostnames
   {
-    VOID(pthread_mutex_unlock(&hostname_cache->lock));
+    VOID(pthread_mutex_unlock(&LOCK_hostname));
     DBUG_PRINT("error",("Got an empty hostname"));
     goto err;
   }
   if (!(name=my_strdup(hp->h_name,MYF(0))))
   {
-    VOID(pthread_mutex_unlock(&hostname_cache->lock));
+    VOID(pthread_mutex_unlock(&LOCK_hostname));
     DBUG_RETURN(0);				// out of memory
   }
   check=gethostbyname(name);
-  VOID(pthread_mutex_unlock(&hostname_cache->lock));
+  VOID(pthread_mutex_unlock(&LOCK_hostname));
   if (!check)
   {
     DBUG_PRINT("error",("gethostbyname returned %d",errno));

sql/sql_table.cc

@@ -1690,6 +1690,7 @@ copy_data_between_tables(TABLE *from,TABLE *to,
       found_count++;
   }
   end_read_record(&info);
+  free_io_cache(from);
   delete [] copy;
   uint tmp_error;
   if ((tmp_error=to->file->extra(HA_EXTRA_NO_CACHE)))