MDEV-8931: (server part of) session state tracking

Postreview fixes.
New MySQL tests fixes.

include/mysql.h.pp

@@ -95,7 +95,7 @@ enum enum_session_state_type
   SESSION_TRACK_GTIDS,
   SESSION_TRACK_TRANSACTION_CHARACTERISTICS,
   SESSION_TRACK_TRANSACTION_STATE,
-  SESSION_TRACK_END
+  SESSION_TRACK_always_at_the_end
 };
 my_bool my_net_init(NET *net, Vio* vio, void *thd, unsigned int my_flags);
 void my_net_local_init(NET *net);

include/mysql_com.h

@@ -559,13 +559,13 @@ enum enum_session_state_type
   SESSION_TRACK_GTIDS,
   SESSION_TRACK_TRANSACTION_CHARACTERISTICS,  /* Transaction chistics */
   SESSION_TRACK_TRANSACTION_STATE,            /* Transaction state */
-  SESSION_TRACK_END                           /* must be last */
+  SESSION_TRACK_always_at_the_end             /* must be last */
 };
 
 #define SESSION_TRACK_BEGIN SESSION_TRACK_SYSTEM_VARIABLES
 
 #define IS_SESSION_STATE_TYPE(T) \
-  (((int)(T) >= SESSION_TRACK_BEGIN) && ((T) < SESSION_TRACK_END))
+  (((int)(T) >= SESSION_TRACK_BEGIN) && ((T) < SESSION_TRACK_always_at_the_end))
 
 #define net_new_transaction(net) ((net)->pkt_nr=0)
 

libmysqld/lib_sql.cc

@@ -1172,8 +1172,7 @@ bool
 net_send_ok(THD *thd,
             uint server_status, uint statement_warn_count,
             ulonglong affected_rows, ulonglong id, const char *message,
-            bool unused1,
-            bool unused2)
+            bool, bool)
 {
   DBUG_ENTER("emb_net_send_ok");
   MYSQL_DATA *data;

mysql-test/r/mysqld--help.result

@@ -909,7 +909,11 @@ The following options may be given as the first argument:
  --session-track-state-change 
  Track changes to the session state.
  --session-track-system-variables=name 
- Track changes in registered system variables.
+ Track changes in registered system variables. For
+ compatibility with MySQL defaults this variable should be
+ set to "autocommit, character_set_client,
+ character_set_connection, character_set_results,
+ time_zone"
  --session-track-transaction-info=name 
  Track changes to the transaction attributes. OFF to
  disable; STATE to track just transaction state (Is there
@@ -1403,7 +1407,7 @@ secure-file-priv (No default value)
 server-id 1
 session-track-schema TRUE
 session-track-state-change FALSE
-session-track-system-variables autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+session-track-system-variables 
 session-track-transaction-info OFF
 show-slave-auth-info FALSE
 silent-startup FALSE

mysql-test/suite/sys_vars/r/session_track_system_variables_basic.result

@@ -5,25 +5,25 @@
 # Global - default
 SELECT @@global.session_track_system_variables;
 @@global.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 # Session - default
 SELECT @@session.session_track_system_variables;
 @@session.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 
 # via INFORMATION_SCHEMA.GLOBAL_VARIABLES
 SELECT * FROM INFORMATION_SCHEMA.GLOBAL_VARIABLES WHERE VARIABLE_NAME LIKE 'session_track%' ORDER BY VARIABLE_NAME;
 VARIABLE_NAME	VARIABLE_VALUE
 SESSION_TRACK_SCHEMA	ON
 SESSION_TRACK_STATE_CHANGE	OFF
-SESSION_TRACK_SYSTEM_VARIABLES	autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+SESSION_TRACK_SYSTEM_VARIABLES	
 SESSION_TRACK_TRANSACTION_INFO	OFF
 # via INFORMATION_SCHEMA.SESSION_VARIABLES
 SELECT * FROM INFORMATION_SCHEMA.SESSION_VARIABLES WHERE VARIABLE_NAME LIKE 'session_track%' ORDER BY VARIABLE_NAME;
 VARIABLE_NAME	VARIABLE_VALUE
 SESSION_TRACK_SCHEMA	ON
 SESSION_TRACK_STATE_CHANGE	OFF
-SESSION_TRACK_SYSTEM_VARIABLES	autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+SESSION_TRACK_SYSTEM_VARIABLES	
 SESSION_TRACK_TRANSACTION_INFO	OFF
 SET @global_saved_tmp =  @@global.session_track_system_variables;
 
@@ -34,7 +34,7 @@ SELECT @@global.session_track_system_variables;
 autocommit
 SELECT @@session.session_track_system_variables;
 @@session.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 
 # Altering session variable's value
 SET @@session.session_track_system_variables='autocommit';
@@ -72,25 +72,25 @@ SET @@session.session_track_system_variables = DEFAULT;
 
 SELECT @@global.session_track_system_variables;
 @@global.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 SELECT @@session.session_track_system_variables;
 @@session.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 
 # Variables' values in a new session (con2).
 connect  con2,"127.0.0.1",root,,test,$MASTER_MYPORT,;
 SELECT @@global.session_track_system_variables;
 @@global.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 SELECT @@session.session_track_system_variables;
 @@session.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 
 # Altering session should not affect global.
 SET @@session.session_track_system_variables = 'sql_mode';
 SELECT @@global.session_track_system_variables;
 @@global.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 SELECT @@session.session_track_system_variables;
 @@session.session_track_system_variables
 sql_mode
@@ -104,7 +104,7 @@ SELECT @@global.session_track_system_variables;
 sql_mode
 SELECT @@session.session_track_system_variables;
 @@session.session_track_system_variables
-autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+
 
 # Switching to the default connection.
 connection default;

mysql-test/suite/sys_vars/r/sysvars_server_notembedded.result

@@ -3818,13 +3818,13 @@ ENUM_VALUE_LIST	OFF,ON
 READ_ONLY	NO
 COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	SESSION_TRACK_SYSTEM_VARIABLES
-SESSION_VALUE	autocommit,character_set_client,character_set_connection,character_set_results,time_zone
-GLOBAL_VALUE	autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+SESSION_VALUE	
+GLOBAL_VALUE	
 GLOBAL_VALUE_ORIGIN	COMPILE-TIME
-DEFAULT_VALUE	autocommit,character_set_client,character_set_connection,character_set_results,time_zone
+DEFAULT_VALUE	
 VARIABLE_SCOPE	SESSION
 VARIABLE_TYPE	VARCHAR
-VARIABLE_COMMENT	Track changes in registered system variables.
+VARIABLE_COMMENT	Track changes in registered system variables. For compatibility with MySQL defaults this variable should be set to "autocommit, character_set_client, character_set_connection, character_set_results, time_zone"
 NUMERIC_MIN_VALUE	NULL
 NUMERIC_MAX_VALUE	NULL
 NUMERIC_BLOCK_SIZE	NULL

sql/session_tracker.h

@@ -62,8 +62,8 @@ class State_tracker
   /**
     Is tracking enabled for a particular session state type ?
 
-    @note: It is cache to avoid virtual functions and checking thd
-    when we want mark tracker as changed.
+    @note: it is a cache of the corresponding thd->variables.session_track_xxx
+    variable
   */
   bool m_enabled;
 

sql/sp_head.cc

@@ -2981,8 +2981,10 @@ sp_lex_keeper::reset_lex_and_exec_core(THD *thd, uint *nextp,
 
 #ifndef EMBEDDED_LIBRARY
   /*
-    if there was instruction which changed tracking state before, result
-    can go with this command OK packet, so better do not cache the result.
+    If there was instruction which changed tracking state,
+    the result of changed tracking state send to client in OK packed.
+    So it changes result sent to client and probably can be different
+    independent on query text. So we can't cache such results.
   */
   if ((thd->client_capabilities & CLIENT_SESSION_TRACK) &&
       (thd->server_status & SERVER_SESSION_STATE_CHANGED))

sql/sql_string.h

@@ -566,16 +566,6 @@ class String
     return Ptr+ old_length;			/* Area to use */
   }
 
-  inline bool prep_alloc(uint32 arg_length, uint32 step_alloc)
-  {
-    uint32 new_length= arg_length + str_length;
-    if (new_length > Alloced_length)
-    {
-      if (realloc(new_length + step_alloc))
-        return true;
-    }
-    return false;
-  }
 
   inline bool append(const char *s, uint32 arg_length, uint32 step_alloc)
   {

sql/sys_vars.cc

@@ -5393,10 +5393,12 @@ static Sys_var_ulong Sys_log_tc_size(
 
 static Sys_var_sesvartrack Sys_track_session_sys_vars(
        "session_track_system_variables",
-       "Track changes in registered system variables.",
+       "Track changes in registered system variables. "
+       "For compatibility with MySQL defaults this variable should be set to "
+       "\"autocommit, character_set_client, character_set_connection, "
+       "character_set_results, time_zone\"",
        CMD_LINE(REQUIRED_ARG), IN_SYSTEM_CHARSET,
-       DEFAULT("autocommit,character_set_client,character_set_connection,"
-               "character_set_results,time_zone"),
+       DEFAULT(""),
        NO_MUTEX_GUARD);
 
 static bool update_session_track_schema(sys_var *self, THD *thd,