cleanup of SHOW STATUS code, as a preparation for WL#2935

(MySQL plugin interface: status variables)

adding SHOW_FUNC, removing SHOW_some_specific_value,
only generic SHOW_LONG/SHOW_CHAR/etc are recognized.
changing to use SHOW_FUNC instead of ha_update_statistics

sql/ha_innodb.h

@@ -277,7 +277,6 @@ void innobase_store_binlog_offset_and_flush_log(char *binlog_name,longlong offse
 
 void innobase_drop_database(char *path);
 bool innobase_show_status(THD* thd, stat_print_fn*, enum ha_stat_type);
-int innodb_export_status(void);
 
 int innobase_release_temporary_latches(THD *thd);
 

sql/handler.cc

@@ -1180,15 +1180,6 @@ int ha_release_temporary_latches(THD *thd)
 #endif
 }
 
-
-int ha_update_statistics()
-{
-#ifdef WITH_INNOBASE_STORAGE_ENGINE
-  innodb_export_status();
-#endif
-  return 0;
-}
-
 int ha_rollback_to_savepoint(THD *thd, SAVEPOINT *sv)
 {
   int error=0;

sql/handler.h

@@ -1538,7 +1538,7 @@ inline bool ha_check_storage_engine_flag(const handlerton *db_type, uint32 flag)
 
 inline bool ha_storage_engine_is_enabled(const handlerton *db_type)
 {
-  return (db_type && db_type->create) ? 
+  return (db_type && db_type->create) ?
          (db_type->state == SHOW_OPTION_YES) : FALSE;
 }
 
@@ -1549,7 +1549,6 @@ int ha_initialize_handlerton(handlerton *hton);
 
 TYPELIB *ha_known_exts(void);
 int ha_panic(enum ha_panic_function flag);
-int ha_update_statistics();
 void ha_close_connection(THD* thd);
 bool ha_flush_logs(handlerton *db_type);
 void ha_drop_database(char* path);

sql/mysqld.cc

@@ -6186,6 +6186,335 @@ The minimum value for this variable is 4096.",
   {0, 0, 0, 0, 0, 0, GET_NO_ARG, NO_ARG, 0, 0, 0, 0, 0, 0}
 };
 
+static int show_question(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONGLONG;
+  var->value= (char *)&thd->query_id;
+  return 0;
+}
+
+static int show_net_compression(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_MY_BOOL;
+  var->value= (char *)&thd->net.compress;
+  return 0;
+}
+
+static int show_starttime(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (long) (thd->query_start() - start_time);
+  return 0;
+}
+
+#ifdef HAVE_REPLICATION
+static int show_rpl_status(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_CHAR;
+  var->value= const_cast<char*>(rpl_status_type[(int)rpl_status]);
+  return 0;
+}
+
+static int show_slave_running(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_CHAR;
+  pthread_mutex_lock(&LOCK_active_mi);
+  var->value= const_cast<char*>((active_mi && active_mi->slave_running &&
+               active_mi->rli.slave_running) ? "ON" : "OFF");
+  pthread_mutex_unlock(&LOCK_active_mi);
+  return 0;
+}
+
+static int show_slave_retried_trans(THD *thd, show_var_st *var, char *buff)
+{
+  /*
+    TODO: with multimaster, have one such counter per line in
+    SHOW SLAVE STATUS, and have the sum over all lines here.
+  */
+  pthread_mutex_lock(&LOCK_active_mi);
+  if (active_mi)
+  {
+    var->type=SHOW_LONG;
+    var->value= buff;
+    pthread_mutex_lock(&active_mi->rli.data_lock);
+    *((long *)buff)= (long)active_mi->rli.retried_trans;
+    pthread_mutex_unlock(&active_mi->rli.data_lock);
+  }
+  else
+    var->type=SHOW_UNDEF;
+  pthread_mutex_unlock(&LOCK_active_mi);
+  return 0;
+}
+#endif /* HAVE_REPLICATION */
+
+static int show_open_tables(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (long)cached_open_tables();
+  return 0;
+}
+
+static int show_table_definitions(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (long)cached_table_definitions();
+  return 0;
+}
+
+#ifdef HAVE_OPENSSL
+/* Functions relying on CTX */
+static int show_ssl_ctx_sess_accept(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_accept(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_accept_good(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_accept_good(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_connect_good(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_connect_good(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_accept_renegotiate(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_accept_renegotiate(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_connect_renegotiate(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_connect_renegotiate(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_cb_hits(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_cb_hits(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_hits(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_hits(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_cache_full(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_cache_full(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_misses(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_misses(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_timeouts(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_timeouts(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_number(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_number(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_connect(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_connect(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_sess_get_cache_size(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_sess_get_cache_size(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_get_verify_mode(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_get_verify_mode(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_get_verify_depth(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (!ssl_acceptor_fd ? 0 :
+                     SSL_CTX_get_verify_depth(ssl_acceptor_fd->ssl_context));
+  return 0;
+}
+
+static int show_ssl_ctx_get_session_cache_mode(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_CHAR;
+  if (!ssl_acceptor_fd)
+    var->value= "NONE";
+  else
+    switch (SSL_CTX_get_session_cache_mode(ssl_acceptor_fd->ssl_context))
+    {
+    case SSL_SESS_CACHE_OFF:
+      var->value= "OFF"; break;
+    case SSL_SESS_CACHE_CLIENT:
+      var->value= "CLIENT"; break;
+    case SSL_SESS_CACHE_SERVER:
+      var->value= "SERVER"; break;
+    case SSL_SESS_CACHE_BOTH:
+      var->value= "BOTH"; break;
+    case SSL_SESS_CACHE_NO_AUTO_CLEAR:
+      var->value= "NO_AUTO_CLEAR"; break;
+    case SSL_SESS_CACHE_NO_INTERNAL_LOOKUP:
+      var->value= "NO_INTERNAL_LOOKUP"; break;
+    default:
+      var->value= "Unknown"; break;
+    }
+  return 0;
+}
+
+/* Functions relying on SSL */
+static int show_ssl_get_version(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_CHAR;
+  var->value= const_cast<char*>(thd->net.vio->ssl_arg ?
+        SSL_get_version((SSL*) thd->net.vio->ssl_arg) : "");
+  return 0;
+}
+
+static int show_ssl_session_reused(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
+                         SSL_session_reused((SSL*) thd->net.vio->ssl_arg) :
+                         0;
+}
+
+static int show_ssl_get_default_timeout(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
+                         SSL_get_default_timeout((SSL*)thd->net.vio->ssl_arg) :
+                         0;
+  return 0;
+}
+
+static int show_ssl_get_verify_mode(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
+                         SSL_get_verify_mode((SSL*)thd->net.vio->ssl_arg) :
+                         0;
+  return 0;
+}
+
+static int show_ssl_get_verify_depth(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_LONG;
+  var->value= buff;
+  *((long *)buff)= (long)thd->net.vio->ssl_arg ?
+                         SSL_get_verify_depth((SSL*)thd->net.vio->ssl_arg) :
+                         0;
+  return 0;
+}
+
+static int show_ssl_get_cipher(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_CHAR;
+  var->value= const_cast<char*>(thd->net.vio->ssl_arg ?
+              SSL_get_cipher((SSL*) thd->net.vio->ssl_arg) : "");
+  return 0;
+}
+
+static int show_ssl_get_cipher_list(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_CHAR;
+  var->value= buff;
+  if (thd->net.vio->ssl_arg)
+  {
+    int i;
+    const char *p;
+    for (i=0 ; (p= SSL_get_cipher_list((SSL*) thd->net.vio->ssl_arg,i)); i++)
+    {
+      buff= strmov(buff, p);
+      *buff++= ':';
+    }
+    if (i)
+      buff--;
+  }
+  *buff=0;
+  return 0;
+}
+
+#endif /* HAVE_OPENSSL */
+
+#ifdef WITH_INNOBASE_STORAGE_ENGINE
+int innodb_export_status(void);
+static int show_innodb_vars(THD *thd, show_var_st *var, char *buff)
+{
+  innodb_export_status();
+  var->type= SHOW_ARRAY;
+  var->value= (char *) &innodb_status_variables;
+  return 0;
+}
+#endif
 
 struct show_var_st status_vars[]= {
   {"Aborted_clients",          (char*) &aborted_threads,        SHOW_LONG},
@@ -6296,7 +6625,7 @@ struct show_var_st status_vars[]= {
   {"Com_xa_recover",           (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_XA_RECOVER]),SHOW_LONG_STATUS},
   {"Com_xa_rollback",          (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_XA_ROLLBACK]),SHOW_LONG_STATUS},
   {"Com_xa_start",             (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_XA_START]),SHOW_LONG_STATUS},
-  {"Compression",              (char*) 0,                        SHOW_NET_COMPRESSION},
+  {"Compression",              (char*) &show_net_compression, SHOW_FUNC},
   {"Connections",              (char*) &thread_id,              SHOW_LONG_CONST},
   {"Created_tmp_disk_tables",  (char*) offsetof(STATUS_VAR, created_tmp_disk_tables), SHOW_LONG_STATUS},
   {"Created_tmp_files",	       (char*) &my_tmp_file_created,	SHOW_LONG},
@@ -6321,25 +6650,25 @@ struct show_var_st status_vars[]= {
   {"Handler_update",           (char*) offsetof(STATUS_VAR, ha_update_count), SHOW_LONG_STATUS},
   {"Handler_write",            (char*) offsetof(STATUS_VAR, ha_write_count), SHOW_LONG_STATUS},
 #ifdef WITH_INNOBASE_STORAGE_ENGINE
-  {"Innodb_",                  (char*) &innodb_status_variables, SHOW_VARS},
+  {"Innodb_",                  (char*) &show_innodb_vars, SHOW_FUNC},
 #endif /* WITH_INNOBASE_STORAGE_ENGINE */
-  {"Key_blocks_not_flushed",   (char*) &dflt_key_cache_var.global_blocks_changed, SHOW_KEY_CACHE_LONG},
-  {"Key_blocks_unused",        (char*) &dflt_key_cache_var.blocks_unused, SHOW_KEY_CACHE_CONST_LONG},
-  {"Key_blocks_used",          (char*) &dflt_key_cache_var.blocks_used, SHOW_KEY_CACHE_CONST_LONG},
-  {"Key_read_requests",        (char*) &dflt_key_cache_var.global_cache_r_requests, SHOW_KEY_CACHE_LONGLONG},
-  {"Key_reads",                (char*) &dflt_key_cache_var.global_cache_read, SHOW_KEY_CACHE_LONGLONG},
-  {"Key_write_requests",       (char*) &dflt_key_cache_var.global_cache_w_requests, SHOW_KEY_CACHE_LONGLONG},
-  {"Key_writes",               (char*) &dflt_key_cache_var.global_cache_write, SHOW_KEY_CACHE_LONGLONG},
+  {"Key_blocks_not_flushed",   (char*) offsetof(KEY_CACHE, global_blocks_changed), SHOW_KEY_CACHE_LONG},
+  {"Key_blocks_unused",        (char*) offsetof(KEY_CACHE, blocks_unused), SHOW_KEY_CACHE_CONST_LONG},
+  {"Key_blocks_used",          (char*) offsetof(KEY_CACHE, blocks_used), SHOW_KEY_CACHE_CONST_LONG},
+  {"Key_read_requests",        (char*) offsetof(KEY_CACHE, global_cache_r_requests), SHOW_KEY_CACHE_LONGLONG},
+  {"Key_reads",                (char*) offsetof(KEY_CACHE, global_cache_read), SHOW_KEY_CACHE_LONGLONG},
+  {"Key_write_requests",       (char*) offsetof(KEY_CACHE, global_cache_w_requests), SHOW_KEY_CACHE_LONGLONG},
+  {"Key_writes",               (char*) offsetof(KEY_CACHE, global_cache_write), SHOW_KEY_CACHE_LONGLONG},
   {"Last_query_cost",          (char*) offsetof(STATUS_VAR, last_query_cost), SHOW_DOUBLE_STATUS},
   {"Max_used_connections",     (char*) &max_used_connections,  SHOW_LONG},
 #ifdef WITH_NDBCLUSTER_STORAGE_ENGINE
-  {"Ndb_",                     (char*) &ndb_status_variables,   SHOW_VARS},
+  {"Ndb_",                     (char*) &ndb_status_variables,   SHOW_ARRAY},
 #endif /* WITH_NDBCLUSTER_STORAGE_ENGINE */
   {"Not_flushed_delayed_rows", (char*) &delayed_rows_in_use,    SHOW_LONG_CONST},
   {"Open_files",               (char*) &my_file_opened,         SHOW_LONG_CONST},
   {"Open_streams",             (char*) &my_stream_opened,       SHOW_LONG_CONST},
-  {"Open_table_definitions",   (char*) 0,			SHOW_TABLE_DEFINITIONS},
-  {"Open_tables",              (char*) 0,                       SHOW_OPEN_TABLES},
+  {"Open_table_definitions",   (char*) &show_table_definitions, SHOW_FUNC},
+  {"Open_tables",              (char*) &show_open_tables,       SHOW_FUNC},
   {"Opened_tables",            (char*) offsetof(STATUS_VAR, opened_tables), SHOW_LONG_STATUS},
 #ifdef HAVE_QUERY_CACHE
   {"Qcache_free_blocks",       (char*) &query_cache.free_memory_blocks, SHOW_LONG_CONST},
@@ -6351,16 +6680,20 @@ struct show_var_st status_vars[]= {
   {"Qcache_queries_in_cache",  (char*) &query_cache.queries_in_cache, SHOW_LONG_CONST},
   {"Qcache_total_blocks",      (char*) &query_cache.total_blocks, SHOW_LONG_CONST},
 #endif /*HAVE_QUERY_CACHE*/
-  {"Questions",                (char*) 0,                       SHOW_QUESTION},
-  {"Rpl_status",               (char*) 0,                 SHOW_RPL_STATUS},
+  {"Questions",                (char*) &show_question,            SHOW_FUNC},
+#ifdef HAVE_REPLICATION
+  {"Rpl_status",               (char*) &show_rpl_status,          SHOW_FUNC},
+#endif
   {"Select_full_join",         (char*) offsetof(STATUS_VAR, select_full_join_count), SHOW_LONG_STATUS},
   {"Select_full_range_join",   (char*) offsetof(STATUS_VAR, select_full_range_join_count), SHOW_LONG_STATUS},
   {"Select_range",             (char*) offsetof(STATUS_VAR, select_range_count), SHOW_LONG_STATUS},
   {"Select_range_check",       (char*) offsetof(STATUS_VAR, select_range_check_count), SHOW_LONG_STATUS},
   {"Select_scan",	       (char*) offsetof(STATUS_VAR, select_scan_count), SHOW_LONG_STATUS},
   {"Slave_open_temp_tables",   (char*) &slave_open_temp_tables, SHOW_LONG},
-  {"Slave_retried_transactions",(char*) 0,                      SHOW_SLAVE_RETRIED_TRANS},
-  {"Slave_running",            (char*) 0,                       SHOW_SLAVE_RUNNING},
+#ifdef HAVE_REPLICATION
+  {"Slave_retried_transactions",(char*) &show_slave_retried_trans, SHOW_FUNC},
+  {"Slave_running",            (char*) &show_slave_running,     SHOW_FUNC},
+#endif
   {"Slow_launch_threads",      (char*) &slow_launch_threads,    SHOW_LONG},
   {"Slow_queries",             (char*) offsetof(STATUS_VAR, long_query_count), SHOW_LONG_STATUS},
   {"Sort_merge_passes",	       (char*) offsetof(STATUS_VAR, filesort_merge_passes), SHOW_LONG_STATUS},
@@ -6368,29 +6701,29 @@ struct show_var_st status_vars[]= {
   {"Sort_rows",		       (char*) offsetof(STATUS_VAR, filesort_rows), SHOW_LONG_STATUS},
   {"Sort_scan",		       (char*) offsetof(STATUS_VAR, filesort_scan_count), SHOW_LONG_STATUS},
 #ifdef HAVE_OPENSSL
-  {"Ssl_accept_renegotiates",  (char*) 0, 	SHOW_SSL_CTX_SESS_ACCEPT_RENEGOTIATE},
-  {"Ssl_accepts",              (char*) 0,  	SHOW_SSL_CTX_SESS_ACCEPT},
-  {"Ssl_callback_cache_hits",  (char*) 0,	SHOW_SSL_CTX_SESS_CB_HITS},
-  {"Ssl_cipher",               (char*) 0,  	SHOW_SSL_GET_CIPHER},
-  {"Ssl_cipher_list",          (char*) 0,  	SHOW_SSL_GET_CIPHER_LIST},
-  {"Ssl_client_connects",      (char*) 0,	SHOW_SSL_CTX_SESS_CONNECT},
-  {"Ssl_connect_renegotiates", (char*) 0, 	SHOW_SSL_CTX_SESS_CONNECT_RENEGOTIATE},
-  {"Ssl_ctx_verify_depth",     (char*) 0,	SHOW_SSL_CTX_GET_VERIFY_DEPTH},
-  {"Ssl_ctx_verify_mode",      (char*) 0,	SHOW_SSL_CTX_GET_VERIFY_MODE},
-  {"Ssl_default_timeout",      (char*) 0,  	SHOW_SSL_GET_DEFAULT_TIMEOUT},
-  {"Ssl_finished_accepts",     (char*) 0,  	SHOW_SSL_CTX_SESS_ACCEPT_GOOD},
-  {"Ssl_finished_connects",    (char*) 0,  	SHOW_SSL_CTX_SESS_CONNECT_GOOD},
-  {"Ssl_session_cache_hits",   (char*) 0,	SHOW_SSL_CTX_SESS_HITS},
-  {"Ssl_session_cache_misses", (char*) 0,	SHOW_SSL_CTX_SESS_MISSES},
-  {"Ssl_session_cache_mode",   (char*) 0,	SHOW_SSL_CTX_GET_SESSION_CACHE_MODE},
-  {"Ssl_session_cache_overflows", (char*) 0,	SHOW_SSL_CTX_SESS_CACHE_FULL},
-  {"Ssl_session_cache_size",   (char*) 0,	SHOW_SSL_CTX_SESS_GET_CACHE_SIZE},
-  {"Ssl_session_cache_timeouts", (char*) 0,	SHOW_SSL_CTX_SESS_TIMEOUTS},
-  {"Ssl_sessions_reused",      (char*) 0,	SHOW_SSL_SESSION_REUSED},
-  {"Ssl_used_session_cache_entries",(char*) 0,	SHOW_SSL_CTX_SESS_NUMBER},
-  {"Ssl_verify_depth",         (char*) 0,	SHOW_SSL_GET_VERIFY_DEPTH},
-  {"Ssl_verify_mode",          (char*) 0,	SHOW_SSL_GET_VERIFY_MODE},
-  {"Ssl_version",   	       (char*) 0,  	SHOW_SSL_GET_VERSION},
+  {"Ssl_accept_renegotiates",  (char*) &show_ssl_ctx_sess_accept_renegotiate, SHOW_FUNC},
+  {"Ssl_accepts",              (char*) &show_ssl_ctx_sess_accept, SHOW_FUNC},
+  {"Ssl_callback_cache_hits",  (char*) &show_ssl_ctx_sess_cb_hits, SHOW_FUNC},
+  {"Ssl_cipher",               (char*) &show_ssl_get_cipher, SHOW_FUNC},
+  {"Ssl_cipher_list",          (char*) &show_ssl_get_cipher_list, SHOW_FUNC},
+  {"Ssl_client_connects",      (char*) &show_ssl_ctx_sess_connect, SHOW_FUNC},
+  {"Ssl_connect_renegotiates", (char*) &show_ssl_ctx_sess_connect_renegotiate, SHOW_FUNC},
+  {"Ssl_ctx_verify_depth",     (char*) &show_ssl_ctx_get_verify_depth, SHOW_FUNC},
+  {"Ssl_ctx_verify_mode",      (char*) &show_ssl_ctx_get_verify_mode, SHOW_FUNC},
+  {"Ssl_default_timeout",      (char*) &show_ssl_get_default_timeout, SHOW_FUNC},
+  {"Ssl_finished_accepts",     (char*) &show_ssl_ctx_sess_accept_good, SHOW_FUNC},
+  {"Ssl_finished_connects",    (char*) &show_ssl_ctx_sess_connect_good, SHOW_FUNC},
+  {"Ssl_session_cache_hits",   (char*) &show_ssl_ctx_sess_hits, SHOW_FUNC},
+  {"Ssl_session_cache_misses", (char*) &show_ssl_ctx_sess_misses, SHOW_FUNC},
+  {"Ssl_session_cache_mode",   (char*) &show_ssl_ctx_get_session_cache_mode, SHOW_FUNC},
+  {"Ssl_session_cache_overflows", (char*) &show_ssl_ctx_sess_cache_full, SHOW_FUNC},
+  {"Ssl_session_cache_size",   (char*) &show_ssl_ctx_sess_get_cache_size, SHOW_FUNC},
+  {"Ssl_session_cache_timeouts", (char*) &show_ssl_ctx_sess_timeouts, SHOW_FUNC},
+  {"Ssl_sessions_reused",      (char*) &show_ssl_session_reused, SHOW_FUNC},
+  {"Ssl_used_session_cache_entries",(char*) &show_ssl_ctx_sess_number, SHOW_FUNC},
+  {"Ssl_verify_depth",         (char*) &show_ssl_get_verify_depth, SHOW_FUNC},
+  {"Ssl_verify_mode",          (char*) &show_ssl_get_verify_mode, SHOW_FUNC},
+  {"Ssl_version",              (char*) &show_ssl_get_version, SHOW_FUNC},
 #endif /* HAVE_OPENSSL */
   {"Table_locks_immediate",    (char*) &locks_immediate,        SHOW_LONG},
   {"Table_locks_waited",       (char*) &locks_waited,           SHOW_LONG},
@@ -6403,7 +6736,7 @@ struct show_var_st status_vars[]= {
   {"Threads_connected",        (char*) &thread_count,           SHOW_INT_CONST},
   {"Threads_created",	       (char*) &thread_created,		SHOW_LONG_CONST},
   {"Threads_running",          (char*) &thread_running,         SHOW_INT_CONST},
-  {"Uptime",                   (char*) 0,                       SHOW_STARTTIME},
+  {"Uptime",                   (char*) &show_starttime,         SHOW_FUNC},
   {NullS, NullS, SHOW_LONG}
 };
 

sql/set_var.cc

@@ -623,6 +623,45 @@ sys_var_have_variable sys_have_row_based_replication("have_row_based_replication
 /* Global read-only variable describing server license */
 sys_var_const_str		sys_license("license", STRINGIFY_ARG(LICENSE));
 
+#ifdef HAVE_REPLICATION
+static int show_slave_skip_errors(THD *thd, show_var_st *var, char *buff)
+{
+  var->type=SHOW_CHAR;
+  var->value= buff;
+  if (!use_slave_mask || bitmap_is_clear_all(&slave_error_mask))
+  {
+    var->value= "OFF";
+  }
+  else if (bitmap_is_set_all(&slave_error_mask))
+  {
+    var->value= "ALL";
+  }
+  else
+  {
+    /* 10 is enough assuming errors are max 4 digits */
+    int i;
+    var->value= buff;
+    for (i= 1;
+         i < MAX_SLAVE_ERROR &&
+         (buff - var->value) < SHOW_VAR_FUNC_BUFF_SIZE;
+         i++)
+    {
+      if (bitmap_is_set(&slave_error_mask, i))
+      {
+        buff= int10_to_str(i, buff, 10);
+        *buff++= ',';
+      }
+    }
+    if (var->value != buff)
+      buff--;				// Remove last ','
+    if (i < MAX_SLAVE_ERROR)
+      buff= strmov(buff, "...");  // Couldn't show all errors
+    *buff=0;
+  }
+  return 0;
+}
+#endif /* HAVE_REPLICATION */
+
 
 /*
   Variables shown by SHOW variables in alphabetical order
@@ -863,7 +902,7 @@ struct show_var_st init_vars[]= {
     (char*) &sys_slave_compressed_protocol,           SHOW_SYS},
   {"slave_load_tmpdir",       (char*) &slave_load_tmpdir,           SHOW_CHAR_PTR},
   {sys_slave_net_timeout.name,(char*) &sys_slave_net_timeout,	    SHOW_SYS},
-  {"slave_skip_errors",       (char*) &slave_error_mask,            SHOW_SLAVE_SKIP_ERRORS},
+  {"slave_skip_errors",       (char*) &show_slave_skip_errors,      SHOW_FUNC},
   {sys_slave_trans_retries.name,(char*) &sys_slave_trans_retries,   SHOW_SYS},
 #endif
   {sys_slow_launch_time.name, (char*) &sys_slow_launch_time,        SHOW_SYS},

sql/sql_show.cc

@@ -1516,18 +1516,18 @@ void mysqld_list_processes(THD *thd,const char *user, bool verbose)
   Status functions
 *****************************************************************************/
 
-
 static bool show_status_array(THD *thd, const char *wild,
                               show_var_st *variables,
                               enum enum_var_type value_type,
                               struct system_status_var *status_var,
                               const char *prefix, TABLE *table)
 {
-  char buff[1024], *prefix_end;
+  char buff[SHOW_VAR_FUNC_BUFF_SIZE], *prefix_end;
   /* the variable name should not be longer then 80 characters */
   char name_buffer[80];
   int len;
   LEX_STRING null_lex_str;
+  struct show_var_st tmp, *var;
   DBUG_ENTER("show_status_array");
 
   null_lex_str.str= 0;				// For sys_var->value_ptr()
@@ -1540,18 +1540,22 @@ static bool show_status_array(THD *thd, const char *wild,
   {
     strnmov(prefix_end, variables->name, len);
     name_buffer[sizeof(name_buffer)-1]=0;       /* Safety */
-    SHOW_TYPE show_type=variables->type;
-    if (show_type == SHOW_VARS)
+
+    for (var=variables; var->type == SHOW_FUNC; var= &tmp)
+      ((show_var_func)(var->value))(thd, &tmp, buff);
+
+    SHOW_TYPE show_type=var->type;
+    if (show_type == SHOW_ARRAY)
     {
-      show_status_array(thd, wild, (show_var_st *) variables->value,
-                        value_type, status_var, variables->name, table);
+      show_status_array(thd, wild, (show_var_st *) var->value,
+                        value_type, status_var, name_buffer, table);
     }
     else
     {
       if (!(wild && wild[0] && wild_case_compare(system_charset_info,
                                                  name_buffer, wild)))
       {
-        char *value=variables->value;
+        char *value=var->value;
         const char *pos, *end;                  // We assign a lot of const's
         long nr;
         if (show_type == SHOW_SYS)
@@ -1562,7 +1566,17 @@ static bool show_status_array(THD *thd, const char *wild,
         }
 
         pos= end= buff;
+        /*
+          note that value may be == buff. All SHOW_xxx code below
+          should still work in this case
+        */
         switch (show_type) {
+        case SHOW_DOUBLE_STATUS:
+        {
+          value= ((char *) status_var + (ulong) value);
+          end= buff + sprintf(buff, "%f", *(double*) value);
+          break;
+        }
         case SHOW_LONG_STATUS:
         case SHOW_LONG_CONST_STATUS:
           value= ((char *) status_var + (ulong) value);
@@ -1601,80 +1615,6 @@ static bool show_status_array(THD *thd, const char *wild,
           end= strend(pos);
           break;
         }
-        case SHOW_STARTTIME:
-          nr= (long) (thd->query_start() - start_time);
-          end= int10_to_str(nr, buff, 10);
-          break;
-        case SHOW_QUESTION:
-          end= int10_to_str((long) thd->query_id, buff, 10);
-          break;
-#ifdef HAVE_REPLICATION
-        case SHOW_RPL_STATUS:
-          end= strmov(buff, rpl_status_type[(int)rpl_status]);
-          break;
-        case SHOW_SLAVE_RUNNING:
-        {
-          pthread_mutex_lock(&LOCK_active_mi);
-          end= strmov(buff, (active_mi && active_mi->slave_running &&
-                             active_mi->rli.slave_running) ? "ON" : "OFF");
-          pthread_mutex_unlock(&LOCK_active_mi);
-          break;
-        }
-        case SHOW_SLAVE_RETRIED_TRANS:
-        {
-          /*
-            TODO: in 5.1 with multimaster, have one such counter per line in
-            SHOW SLAVE STATUS, and have the sum over all lines here.
-          */
-          pthread_mutex_lock(&LOCK_active_mi);
-          if (active_mi)
-          {
-            pthread_mutex_lock(&active_mi->rli.data_lock);
-            end= int10_to_str(active_mi->rli.retried_trans, buff, 10);
-            pthread_mutex_unlock(&active_mi->rli.data_lock);
-          }
-          pthread_mutex_unlock(&LOCK_active_mi);
-          break;
-        }
-        case SHOW_SLAVE_SKIP_ERRORS:
-        {
-          MY_BITMAP *bitmap= (MY_BITMAP *)value;
-          if (!use_slave_mask || bitmap_is_clear_all(bitmap))
-          {
-            end= strmov(buff, "OFF");
-          }
-          else if (bitmap_is_set_all(bitmap))
-          {
-            end= strmov(buff, "ALL");
-          }
-          else
-          {
-            /* 10 is enough assuming errors are max 4 digits */
-            int i;
-            for (i= 1;
-                 i < MAX_SLAVE_ERROR && (uint) (end-buff) < sizeof(buff)-10;
-                 i++)
-            {
-              if (bitmap_is_set(bitmap, i))
-              {
-                end= int10_to_str(i, (char*) end, 10);
-                *(char*) end++= ',';
-              }
-            }
-            if (end != buff)
-              end--;				// Remove last ','
-            if (i < MAX_SLAVE_ERROR)
-              end= strmov((char*) end, "...");  // Couldn't show all errors
-          }
-          break;
-        }
-#endif /* HAVE_REPLICATION */
-        case SHOW_OPEN_TABLES:
-          end= int10_to_str((long) cached_open_tables(), buff, 10);
-          break;
-        case SHOW_TABLE_DEFINITIONS:
-          end= int10_to_str((long) cached_table_definitions(), buff, 10);
-          break;
         case SHOW_CHAR_PTR:
         {
           if (!(pos= *(char**) value))
@@ -1682,200 +1622,16 @@ static bool show_status_array(THD *thd, const char *wild,
           end= strend(pos);
           break;
         }
-        case SHOW_DOUBLE_STATUS:
-        {
-          value= ((char *) status_var + (ulong) value);
-          end= buff + sprintf(buff, "%f", *(double*) value);
-          break;
-        }
-#ifdef HAVE_OPENSSL
-          /* First group - functions relying on CTX */
-        case SHOW_SSL_CTX_SESS_ACCEPT:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_accept(ssl_acceptor_fd->
-                                                        ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_ACCEPT_GOOD:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_accept_good(ssl_acceptor_fd->
-                                                             ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_CONNECT_GOOD:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_connect_good(ssl_acceptor_fd->
-                                                              ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_ACCEPT_RENEGOTIATE:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_accept_renegotiate(ssl_acceptor_fd->ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_CONNECT_RENEGOTIATE:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_connect_renegotiate(ssl_acceptor_fd-> ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_CB_HITS:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_cb_hits(ssl_acceptor_fd->
-                                                         ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_HITS:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_hits(ssl_acceptor_fd->
-                                                      ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_CACHE_FULL:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_cache_full(ssl_acceptor_fd->
-                                                            ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_MISSES:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_misses(ssl_acceptor_fd->
-                                                        ssl_context)),
-                            buff, 10);
-          break;
-        case SHOW_SSL_CTX_SESS_TIMEOUTS:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_timeouts(ssl_acceptor_fd->ssl_context)),
-                            buff,10);
-          break;
-        case SHOW_SSL_CTX_SESS_NUMBER:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_number(ssl_acceptor_fd->ssl_context)),
-                            buff,10);
-          break;
-        case SHOW_SSL_CTX_SESS_CONNECT:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_connect(ssl_acceptor_fd->ssl_context)),
-                            buff,10);
-          break;
-        case SHOW_SSL_CTX_SESS_GET_CACHE_SIZE:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_sess_get_cache_size(ssl_acceptor_fd->ssl_context)),
-                            buff,10);
-          break;
-        case SHOW_SSL_CTX_GET_VERIFY_MODE:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_get_verify_mode(ssl_acceptor_fd->ssl_context)),
-                            buff,10);
-          break;
-        case SHOW_SSL_CTX_GET_VERIFY_DEPTH:
-          end= int10_to_str((long) (!ssl_acceptor_fd ? 0 :
-                                    SSL_CTX_get_verify_depth(ssl_acceptor_fd->ssl_context)),
-                            buff,10);
-          break;
-        case SHOW_SSL_CTX_GET_SESSION_CACHE_MODE:
-          if (!ssl_acceptor_fd)
-          {
-            pos= "NONE";
-            end= pos+4;
-            break;
-          }
-          switch (SSL_CTX_get_session_cache_mode(ssl_acceptor_fd->ssl_context))
-          {
-          case SSL_SESS_CACHE_OFF:
-            pos= "OFF";
-            break;
-          case SSL_SESS_CACHE_CLIENT:
-            pos= "CLIENT";
-            break;
-          case SSL_SESS_CACHE_SERVER:
-            pos= "SERVER";
-            break;
-          case SSL_SESS_CACHE_BOTH:
-            pos= "BOTH";
-            break;
-          case SSL_SESS_CACHE_NO_AUTO_CLEAR:
-            pos= "NO_AUTO_CLEAR";
-            break;
-          case SSL_SESS_CACHE_NO_INTERNAL_LOOKUP:
-            pos= "NO_INTERNAL_LOOKUP";
-            break;
-          default:
-            pos= "Unknown";
-            break;
-          }
-          end= strend(pos);
-          break;
-          /* First group - functions relying on SSL */
-        case SHOW_SSL_GET_VERSION:
-          pos= (thd->net.vio->ssl_arg ?
-                SSL_get_version((SSL*) thd->net.vio->ssl_arg) : "");
-          end= strend(pos);
-          break;
-        case SHOW_SSL_SESSION_REUSED:
-          end= int10_to_str((long) (thd->net.vio->ssl_arg ?
-                                    SSL_session_reused((SSL*) thd->net.vio->
-                                                       ssl_arg) :
-                                    0),
-                            buff, 10);
-          break;
-        case SHOW_SSL_GET_DEFAULT_TIMEOUT:
-          end= int10_to_str((long) (thd->net.vio->ssl_arg ?
-                                    SSL_get_default_timeout((SSL*) thd->net.vio->
-                                                            ssl_arg) :
-                                    0),
-                            buff, 10);
-          break;
-        case SHOW_SSL_GET_VERIFY_MODE:
-          end= int10_to_str((long) (thd->net.vio->ssl_arg ?
-                                    SSL_get_verify_mode((SSL*) thd->net.vio->
-                                                        ssl_arg):
-                                    0),
-                            buff, 10);
-          break;
-        case SHOW_SSL_GET_VERIFY_DEPTH:
-          end= int10_to_str((long) (thd->net.vio->ssl_arg ?
-                                    SSL_get_verify_depth((SSL*) thd->net.vio->
-                                                         ssl_arg):
-                                    0),
-                            buff, 10);
-          break;
-        case SHOW_SSL_GET_CIPHER:
-          pos= (thd->net.vio->ssl_arg ?
-                SSL_get_cipher((SSL*) thd->net.vio->ssl_arg) : "" );
-          end= strend(pos);
-          break;
-        case SHOW_SSL_GET_CIPHER_LIST:
-          if (thd->net.vio->ssl_arg)
-          {
-            char *to= buff;
-            for (int i=0 ; i++ ;)
-            {
-              const char *p= SSL_get_cipher_list((SSL*) thd->net.vio->ssl_arg,i);
-              if (p == NULL)
-                break;
-              to= strmov(to, p);
-              *to++= ':';
-            }
-            if (to != buff)
-              to--;				// Remove last ':'
-            end= to;
-          }
-          break;
-
-#endif /* HAVE_OPENSSL */
         case SHOW_KEY_CACHE_LONG:
         case SHOW_KEY_CACHE_CONST_LONG:
-          value= (value-(char*) &dflt_key_cache_var)+ (char*) dflt_key_cache;
+          value= (char*) dflt_key_cache + (ulong)value;
           end= int10_to_str(*(long*) value, buff, 10);
           break;
         case SHOW_KEY_CACHE_LONGLONG:
-	  value= (value-(char*) &dflt_key_cache_var)+ (char*) dflt_key_cache;
+          value= (char*) dflt_key_cache + (ulong)value;
 	  end= longlong10_to_str(*(longlong*) value, buff, 10);
 	  break;
-        case SHOW_NET_COMPRESSION:
-          end= strmov(buff, thd->net.compress ? "ON" : "OFF");
-          break;
-        case SHOW_UNDEF:				// Show never happen
+        case SHOW_UNDEF:
         case SHOW_SYS:
           break;					// Return empty string
         default:
@@ -3615,7 +3371,6 @@ int fill_status(THD *thd, TABLE_LIST *tables, COND *cond)
   const char *wild= lex->wild ? lex->wild->ptr() : NullS;
   int res= 0;
   STATUS_VAR tmp;
-  ha_update_statistics();                    /* Export engines statistics */
   pthread_mutex_lock(&LOCK_status);
   if (lex->option_type == OPT_GLOBAL)
     calc_sum_of_all_status(&tmp);

sql/structs.h

@@ -173,29 +173,12 @@ typedef struct st_known_date_time_format {
 enum SHOW_TYPE
 {
   SHOW_UNDEF,
-  SHOW_LONG, SHOW_LONGLONG, SHOW_INT, SHOW_CHAR, SHOW_CHAR_PTR, 
+  SHOW_LONG, SHOW_LONGLONG, SHOW_INT, SHOW_CHAR, SHOW_CHAR_PTR,
   SHOW_DOUBLE_STATUS, SHOW_BOOL, SHOW_MY_BOOL,
-  SHOW_OPEN_TABLES, SHOW_TABLE_DEFINITIONS, SHOW_STARTTIME, SHOW_QUESTION,
   SHOW_LONG_CONST, SHOW_INT_CONST, SHOW_HAVE, SHOW_SYS, SHOW_HA_ROWS,
-  SHOW_VARS,
-#ifdef HAVE_OPENSSL
-  SHOW_SSL_CTX_SESS_ACCEPT, 	SHOW_SSL_CTX_SESS_ACCEPT_GOOD,
-  SHOW_SSL_GET_VERSION, 	SHOW_SSL_CTX_GET_SESSION_CACHE_MODE,
-  SHOW_SSL_CTX_SESS_CB_HITS, 	SHOW_SSL_CTX_SESS_ACCEPT_RENEGOTIATE,
-  SHOW_SSL_CTX_SESS_NUMBER, 	SHOW_SSL_SESSION_REUSED,
-  SHOW_SSL_CTX_SESS_GET_CACHE_SIZE, SHOW_SSL_GET_CIPHER,
-  SHOW_SSL_GET_DEFAULT_TIMEOUT,	SHOW_SSL_GET_VERIFY_MODE,
-  SHOW_SSL_CTX_GET_VERIFY_MODE, SHOW_SSL_GET_VERIFY_DEPTH,
-  SHOW_SSL_CTX_GET_VERIFY_DEPTH, SHOW_SSL_CTX_SESS_CONNECT,
-  SHOW_SSL_CTX_SESS_CONNECT_RENEGOTIATE, SHOW_SSL_CTX_SESS_CONNECT_GOOD,
-  SHOW_SSL_CTX_SESS_HITS, SHOW_SSL_CTX_SESS_MISSES,
-  SHOW_SSL_CTX_SESS_TIMEOUTS, SHOW_SSL_CTX_SESS_CACHE_FULL,
-  SHOW_SSL_GET_CIPHER_LIST,
-#endif /* HAVE_OPENSSL */
-  SHOW_NET_COMPRESSION,
-  SHOW_RPL_STATUS, SHOW_SLAVE_RUNNING, SHOW_SLAVE_RETRIED_TRANS,
+  SHOW_ARRAY, SHOW_FUNC,
   SHOW_KEY_CACHE_LONG, SHOW_KEY_CACHE_CONST_LONG, SHOW_KEY_CACHE_LONGLONG,
-  SHOW_LONG_STATUS, SHOW_LONG_CONST_STATUS, SHOW_SLAVE_SKIP_ERRORS
+  SHOW_LONG_STATUS, SHOW_LONG_CONST_STATUS
 };
 
 enum SHOW_COMP_OPTION { SHOW_OPTION_YES, SHOW_OPTION_NO, SHOW_OPTION_DISABLED};
@@ -204,19 +187,19 @@ extern const char *show_comp_option_name[];
 
 typedef int *(*update_var)(THD *, struct show_var_st *);
 
-
 typedef struct show_var_st {
   const char *name;
   char *value;
   SHOW_TYPE type;
 } SHOW_VAR;
 
+#define SHOW_VAR_FUNC_BUFF_SIZE 1024
+typedef int (*show_var_func)(THD *, struct show_var_st *, char *);
 
 typedef struct	st_lex_user {
   LEX_STRING user, host, password;
 } LEX_USER;
 
-
 /*
   This structure specifies the maximum amount of resources which
   can be consumed by each account. Zero value of a member means