Reset some longlong global variables as part of FLUSH STATUS

Added SHOW_LONGLONG_NOFLUSH to mark the variables that should not be
flushed.

New variables cleared as part of SHOW STATUS:
- Rpl_semi_sync_master_request_ack
- Rpl_semi_sync_master_get_ac
- Rpl_semi_sync_slave_send_ack
- Slave_skipped_error

sql/mysqld.cc

@@ -7499,7 +7499,7 @@ SHOW_VAR status_vars[]= {
   {"Max_used_connections",     (char*) &max_used_connections,  SHOW_LONG},
   {"Max_used_connections_time",(char*) &show_max_used_connections_time, SHOW_SIMPLE_FUNC},
   {"Memory_used",              (char*) &show_memory_used, SHOW_SIMPLE_FUNC},
-  {"Memory_used_initial",      (char*) &start_memory_used, SHOW_LONGLONG},
+  {"Memory_used_initial",      (char*) &start_memory_used, SHOW_LONGLONG_NOFLUSH},
   {"Resultset_metadata_skipped", (char *) offsetof(STATUS_VAR, skip_metadata_count),SHOW_LONG_STATUS},
   {"Not_flushed_delayed_rows", (char*) &delayed_rows_in_use,    SHOW_LONG_NOFLUSH},
   {"Open_files",               (char*) &my_file_opened,         SHOW_SINT},
@@ -7640,7 +7640,7 @@ SHOW_VAR status_vars[]= {
   {"wsrep_connected",         (char*) &wsrep_connected,         SHOW_BOOL},
   {"wsrep_ready",             (char*) &wsrep_show_ready,        SHOW_FUNC},
   {"wsrep_cluster_state_uuid",(char*) &wsrep_cluster_state_uuid,SHOW_CHAR_PTR},
-  {"wsrep_cluster_conf_id",   (char*) &wsrep_cluster_conf_id,   SHOW_LONGLONG},
+  {"wsrep_cluster_conf_id",   (char*) &wsrep_cluster_conf_id,   SHOW_LONGLONG_NOFLUSH},
   {"wsrep_cluster_status",    (char*) &wsrep_cluster_status,    SHOW_CHAR_PTR},
   {"wsrep_cluster_size",      (char*) &wsrep_cluster_size,      SHOW_LONG_NOFLUSH},
   {"wsrep_local_index",       (char*) &wsrep_local_index,       SHOW_LONG_NOFLUSH},

sql/sql_plugin.h

@@ -23,7 +23,8 @@
 */
 #define SHOW_always_last SHOW_KEY_CACHE_LONG, \
             SHOW_HAVE, SHOW_MY_BOOL, SHOW_HA_ROWS, SHOW_SYS, \
-            SHOW_LONG_NOFLUSH, SHOW_LEX_STRING, SHOW_ATOMIC_COUNTER_UINT32_T, \
+            SHOW_LONG_NOFLUSH, SHOW_LONGLONG_NOFLUSH, SHOW_LEX_STRING,          \
+            SHOW_ATOMIC_COUNTER_UINT32_T,                                       \
       /* SHOW_*_STATUS must be at the end, SHOW_LONG_STATUS being first */ \
             SHOW_LONG_STATUS, SHOW_DOUBLE_STATUS, SHOW_LONGLONG_STATUS, \
             SHOW_UINT32_STATUS

sql/sql_show.cc

@@ -3582,6 +3582,8 @@ void reset_status_vars()
     /* Note that SHOW_LONG_NOFLUSH variables are not reset */
     if (ptr->type == SHOW_LONG)
       *(ulong*) ptr->value= 0;
+    if (ptr->type == SHOW_LONGLONG)
+      *(ulonglong*) ptr->value= 0;
   }
 }
 
@@ -3780,6 +3782,7 @@ const char* get_one_variable(THD *thd,
   case SHOW_SLONG:
     end= int10_to_str(*value.as_long, buff, -10);
     break;
+  case SHOW_LONGLONG_NOFLUSH: // the difference lies in refresh_status()
   case SHOW_SLONGLONG:
     end= longlong10_to_str(*value.as_longlong, buff, -10);
     break;

storage/perfschema/pfs_variable.cc

@@ -54,6 +54,7 @@ static inline SHOW_SCOPE show_scope_from_type(enum enum_mysql_show_type type)
     case SHOW_UINT:
     case SHOW_ULONG:
     case SHOW_ULONGLONG:
+    case SHOW_LONGLONG_NOFLUSH:
       return SHOW_SCOPE_GLOBAL;
 
     case SHOW_DOUBLE_STATUS:
@@ -734,6 +735,7 @@ bool PFS_status_variable_cache::can_aggregate(enum_mysql_show_type variable_type
     case SHOW_DOUBLE_STATUS:
     case SHOW_HA_ROWS:
     case SHOW_LONG_NOFLUSH:
+    case SHOW_LONGLONG_NOFLUSH:
     case SHOW_SLONG:
     default:
       return false;