MDEV-36839: Revert MDEV-7409

MDEV-6247 added PROCESSLIST states for when a Replication
SQL thread processes Row events, including a WSRep variant
that dynamically includes the Galera Sequence Number.
MDEV-7409 further expanded on it by adding the table name to the states.

However, PROCESSLIST __cannot__ support generated states.
Because it loads the state texts asynchronously,
only permanently static strings are safe.
Even thread-local memory can become invalid when the thread terminates,
which can happen in the middle of generating a PROCESSLIST.

To prioritize memory safety, this commit reverts both variants to
static strings as the non-WSRep variant was before MDEV-7409.
* __Fully__ revert MDEV-7409 (d9898c9)
* Remove the WSRep override from MDEV-6247
  * Remove `THD::wsrep_info` and its compiler
    flag `WSREP_PROC_INFO` as they are now unused

This commit also includes small optimizations
from MDEV-36839’s previous draft, #4133.

Reviewed-by: Brandon Nesterenko <brandon.nesterenko@mariadb.com>

Author: ParadoxV5

cmake/wsrep.cmake

@@ -49,8 +49,6 @@ Then restart the build.
   SET(WSREP_VERSION "${WSREP_API_VERSION}.${WSREP_PATCH_VERSION}"
       CACHE INTERNAL "WSREP version")
 
-  SET(WSREP_PROC_INFO ${WITH_WSREP})
-
   SET(WSREP_PATCH_VERSION "wsrep_${WSREP_VERSION}")
   if (NOT WITH_WSREP_ALL)
     SET(WSREP_LIB_WITH_UNIT_TESTS OFF CACHE BOOL

config.h.cmake

@@ -549,7 +549,6 @@ this is the case with Microsoft Windows VirtualFree(MEM_DECOMMIT) */
 #ifndef EMBEDDED_LIBRARY
 #cmakedefine WSREP_INTERFACE_VERSION "@WSREP_INTERFACE_VERSION@"
 #cmakedefine WITH_WSREP 1
-#cmakedefine WSREP_PROC_INFO 1
 #endif
 
 #if !defined(__STDC_FORMAT_MACROS)

mysql-test/suite/rpl/r/rpl_rbr_monitor.result

@@ -6212,6 +6212,7 @@ int Rows_log_event::do_apply_event(rpl_group_info *rgi)
         table->in_use= thd;
 
       error= do_exec_row(rgi);
+      THD_STAGE_INFO(thd, stage_executing);
 
       if (unlikely(error))
         DBUG_PRINT("info", ("error: %s", HA_ERR(error)));
@@ -8084,36 +8085,10 @@ int Rows_log_event::update_sequence()
 int
 Write_rows_log_event::do_exec_row(rpl_group_info *rgi)
 {
-  DBUG_ASSERT(m_table != NULL);
-  const char *tmp= thd->get_proc_info();
-  char *message, msg[128];
-  const LEX_CSTRING &table_name= m_table->s->table_name;
-  const char quote_char=
-    get_quote_char_for_identifier(thd, table_name.str, table_name.length);
-  my_snprintf(msg, sizeof msg,
-              "Write_rows_log_event::write_row() on table %c%.*s%c",
-              quote_char, int(table_name.length), table_name.str, quote_char);
-  message= msg;
   int error;
-
-#ifdef WSREP_PROC_INFO
-  my_snprintf(thd->wsrep_info, sizeof(thd->wsrep_info) - 1,
-              "Write_rows_log_event::write_row(%lld) on table %c%.*s%c",
-              (long long) wsrep_thd_trx_seqno(thd), quote_char,
-              int(table_name.length), table_name.str, quote_char);
-  message= thd->wsrep_info;
-#endif /* WSREP_PROC_INFO */
-
-  thd_proc_info(thd, message);
+  thd_proc_info(thd, "Write_rows_log_event::write_row()");
   error= write_row(rgi, slave_exec_mode == SLAVE_EXEC_MODE_IDEMPOTENT);
-  thd_proc_info(thd, tmp);
-
-  if (unlikely(error) && unlikely(!thd->is_error()))
-  {
-    DBUG_ASSERT(0);
-    my_error(ER_UNKNOWN_ERROR, MYF(0));
-  }
-
+  DBUG_ASSERT(!error || thd->is_error());
   return error;
 }
 
@@ -8725,46 +8700,15 @@ Delete_rows_log_event::do_after_row_operations(const Slave_reporting_capability
 int Delete_rows_log_event::do_exec_row(rpl_group_info *rgi)
 {
   int error;
-  const char *tmp= thd->get_proc_info();
-  char *message, msg[128];
-  const LEX_CSTRING &table_name= m_table->s->table_name;
-  const char quote_char=
-    get_quote_char_for_identifier(thd, table_name.str, table_name.length);
-  my_snprintf(msg, sizeof msg,
-              "Delete_rows_log_event::find_row() on table %c%.*s%c",
-              quote_char, int(table_name.length), table_name.str, quote_char);
-  message= msg;
-  const bool invoke_triggers= (m_table->triggers && do_invoke_trigger());
-  DBUG_ASSERT(m_table != NULL);
-
-#ifdef WSREP_PROC_INFO
-  my_snprintf(thd->wsrep_info, sizeof(thd->wsrep_info) - 1,
-              "Delete_rows_log_event::find_row(%lld) on table %c%.*s%c",
-              (long long) wsrep_thd_trx_seqno(thd), quote_char,
-              int(table_name.length), table_name.str,
-              quote_char);
-  message= thd->wsrep_info;
-#endif /* WSREP_PROC_INFO */
-
-  thd_proc_info(thd, message);
+  const bool invoke_triggers= m_table->triggers && do_invoke_trigger();
+
+  thd_proc_info(thd, "Delete_rows_log_event::find_row()");
   if (likely(!(error= find_row(rgi))))
   {
     /*
       Delete the record found, located in record[0]
     */
-    my_snprintf(msg, sizeof msg,
-                "Delete_rows_log_event::ha_delete_row() on table %c%.*s%c",
-                quote_char, int(table_name.length), table_name.str,
-                quote_char);
-    message= msg;
-#ifdef WSREP_PROC_INFO
-    snprintf(thd->wsrep_info, sizeof(thd->wsrep_info) - 1,
-             "Delete_rows_log_event::ha_delete_row(%lld) on table %c%.*s%c",
-             (long long) wsrep_thd_trx_seqno(thd), quote_char,
-             int(table_name.length), table_name.str, quote_char);
-    message= thd->wsrep_info;
-#endif
-    thd_proc_info(thd, message);
+    thd_proc_info(thd, "Delete_rows_log_event::ha_delete_row()");
 
     if (invoke_triggers &&
         unlikely(process_triggers(TRG_EVENT_DELETE, TRG_ACTION_BEFORE, FALSE)))
@@ -8791,7 +8735,6 @@ int Delete_rows_log_event::do_exec_row(rpl_group_info *rgi)
       error= HA_ERR_GENERIC; // in case if error is not set yet
     m_table->file->ha_index_or_rnd_end();
   }
-  thd_proc_info(thd, tmp);
   return error;
 }
 
@@ -8885,28 +8828,7 @@ int
 Update_rows_log_event::do_exec_row(rpl_group_info *rgi)
 {
   const bool invoke_triggers= (m_table->triggers && do_invoke_trigger());
-  const char *tmp= thd->get_proc_info();
-  DBUG_ASSERT(m_table != NULL);
-  char *message, msg[128];
-  const LEX_CSTRING &table_name= m_table->s->table_name;
-  const char quote_char=
-    get_quote_char_for_identifier(thd, table_name.str, table_name.length);
-  my_snprintf(msg, sizeof msg,
-              "Update_rows_log_event::find_row() on table %c%.*s%c",
-              quote_char, int(table_name.length), table_name.str, quote_char);
-  message= msg;
-
-#ifdef WSREP_PROC_INFO
-  my_snprintf(thd->wsrep_info, sizeof(thd->wsrep_info) - 1,
-              "Update_rows_log_event::find_row(%lld) on table %c%.*s%c",
-              (long long) wsrep_thd_trx_seqno(thd), quote_char,
-              int(table_name.length), table_name.str,
-              quote_char);
-  message= thd->wsrep_info;
-#endif /* WSREP_PROC_INFO */
-
-  thd_proc_info(thd, message);
-
+  thd_proc_info(thd, "Update_rows_log_event::find_row()");
   int error= find_row(rgi);
   if (unlikely(error))
   {
@@ -8916,7 +8838,6 @@ Update_rows_log_event::do_exec_row(rpl_group_info *rgi)
     */
     if ((m_curr_row= m_curr_row_end))
       unpack_current_row(rgi, &m_cols_ai);
-    thd_proc_info(thd, tmp);
     return error;
   }
 
@@ -8939,20 +8860,8 @@ Update_rows_log_event::do_exec_row(rpl_group_info *rgi)
   store_record(m_table,record[1]);
 
   m_curr_row= m_curr_row_end;
-  my_snprintf(msg, sizeof msg,
-              "Update_rows_log_event::unpack_current_row() on table %c%.*s%c",
-              quote_char, int(table_name.length), table_name.str, quote_char);
-  message= msg;
-#ifdef WSREP_PROC_INFO
-  my_snprintf(thd->wsrep_info, sizeof(thd->wsrep_info) - 1,
-              "Update_rows_log_event::unpack_current_row(%lld) on table %c%.*s%c",
-              (long long) wsrep_thd_trx_seqno(thd), quote_char,
-              int(table_name.length), table_name.str, quote_char);
-  message= thd->wsrep_info;
-#endif /* WSREP_PROC_INFO */
-
   /* this also updates m_curr_row_end */
-  thd_proc_info(thd, message);
+  thd_proc_info(thd, "Update_rows_log_event::unpack_current_row()");
   if (unlikely((error= unpack_current_row(rgi, &m_cols_ai))))
     goto err;
   if (m_table->s->long_unique_table)
@@ -8972,19 +8881,7 @@ Update_rows_log_event::do_exec_row(rpl_group_info *rgi)
   DBUG_DUMP("new values", m_table->record[0], m_table->s->reclength);
 #endif
 
-  my_snprintf(msg, sizeof msg,
-              "Update_rows_log_event::ha_update_row() on table %c%.*s%c",
-              quote_char, int(table_name.length), table_name.str, quote_char);
-  message= msg;
-#ifdef WSREP_PROC_INFO
-  my_snprintf(thd->wsrep_info, sizeof(thd->wsrep_info) - 1,
-              "Update_rows_log_event::ha_update_row(%lld) on table %c%.*s%c",
-              (long long) wsrep_thd_trx_seqno(thd), quote_char,
-              int(table_name.length), table_name.str, quote_char);
-  message= thd->wsrep_info;
-#endif /* WSREP_PROC_INFO */
-
-  thd_proc_info(thd, message);
+  thd_proc_info(thd, "Update_rows_log_event::ha_update_row()");
   if (invoke_triggers &&
       unlikely(process_triggers(TRG_EVENT_UPDATE, TRG_ACTION_BEFORE, TRUE)))
   {
@@ -9016,9 +8913,7 @@ Update_rows_log_event::do_exec_row(rpl_group_info *rgi)
       unlikely(process_triggers(TRG_EVENT_UPDATE, TRG_ACTION_AFTER, TRUE)))
     error= HA_ERR_GENERIC; // in case if error is not set yet
 
-
 err:
-  thd_proc_info(thd, tmp);
   m_table->file->ha_index_or_rnd_end();
   return error;
 }

mysql-test/suite/rpl/t/rpl_rbr_monitor.test

@@ -915,7 +915,6 @@ THD::THD(my_thread_id id, bool is_wsrep_applier)
 
 #ifdef WITH_WSREP
   mysql_cond_init(key_COND_wsrep_thd, &COND_wsrep_thd, NULL);
-  wsrep_info[sizeof(wsrep_info) - 1] = '\0'; /* make sure it is 0-terminated */
 #endif
   /* Call to init() below requires fully initialized Open_tables_state. */
   reset_open_tables_state();

sql/log_event_server.cc

@@ -5553,7 +5553,6 @@ class THD: public THD_count, /* this must be first */
   uint32                    wsrep_rand;
   rpl_group_info            *wsrep_rgi;
   bool                      wsrep_converted_lock_session;
-  char                      wsrep_info[128]; /* string for dynamic proc info */
   ulong                     wsrep_retry_counter; // of autocommit
   bool                      wsrep_PA_safe;
   char*                     wsrep_retry_query;