Fixed small race condition, when global query_id was modified

without proper locking.


sql/sp_head.cc:
  Added missing locking of LOCK_thread_count to place where ::query_id is 
  modified.
sql/sql_parse.cc:
  Added comment to the only place where we are modifying ::query_id
  without following locking protocol, to avoid mistakes in future.
BitKeeper/etc/logging_ok:
  Logging to logging@openlogging.org accepted

BitKeeper/etc/logging_ok

@@ -24,6 +24,7 @@ bk@admin.bk
 bk@mysql.r18.ru
 carsten@tsort.bitbybit.dk
 davida@isil.mysql.com
+dlenev@brandersnatch.localdomain
 dlenev@build.mysql.com
 dlenev@mysql.com
 gerberb@ou800.zenez.com

sql/sp_head.cc

@@ -796,7 +796,10 @@ sp_instr_stmt::exec_stmt(THD *thd, LEX *lex)
   thd->lex->unit.thd= thd;	// QQ Not reentrant
   freelist= thd->free_list;
   thd->free_list= NULL;
+
+  VOID(pthread_mutex_lock(&LOCK_thread_count));
   thd->query_id= query_id++;
+  VOID(pthread_mutex_unlock(&LOCK_thread_count));
 
   // Copy WHERE clause pointers to avoid damaging by optimisation
   // Also clear ref_pointer_arrays.

sql/sql_parse.cc

@@ -1086,6 +1086,10 @@ extern "C" pthread_handler_decl(handle_bootstrap,arg)
     thd->query_length=length;
     thd->query= thd->memdup_w_gap(buff, length+1, thd->db_length+1);
     thd->query[length] = '\0';
+    /*
+      We don't need to obtain LOCK_thread_count here because in bootstrap
+      mode we have only one thread.
+    */
     thd->query_id=query_id++;
     if (mqh_used && thd->user_connect && check_mqh(thd, SQLCOM_END))
     {