Bug #30389: connection_id() always return 0 in embedded server

  
Initialize thd->variables.pseudo_thread_id when a new embedded
thd is created.


libmysqld/lib_sql.cc:
  Add comment regarding duplication of code in create_embedded_thd()
  vs. create_new_thread() and prepare_new_connection_state().  This
  was a cause for not properly initializing the pseudo_thread_id variable.
mysql-test/r/func_misc.result:
  Add test case to ensure connection_id() returns a sane value
mysql-test/t/func_misc.test:
  Add test case to ensure connection_id() returns a sane value
sql/mysqld.cc:
  Add comment warning of the duplication of code between create_new_thread()
  and create_embedded_thd()
sql/sql_connect.cc:
  Add comment warning of the duplication of code between
  prepare_new_connection_state() and create_embedded_thd()

libmysqld/lib_sql.cc

@@ -564,6 +564,17 @@ void init_embedded_mysql(MYSQL *mysql, int client_flag)
   init_alloc_root(&mysql->field_alloc, 8192, 0);
 }
 
+/**
+  @brief Initialize a new THD for a connection in the embedded server
+
+  @param client_flag  Client capabilities which this thread supports
+  @return pointer to the created THD object
+
+  @todo
+  This function copies code from several places in the server, including
+  create_new_thread(), and prepare_new_connection_state().  This should
+  be refactored to avoid code duplication.
+*/
 void *create_embedded_thd(int client_flag)
 {
   THD * thd= new THD;

mysql-test/r/func_misc.result

@@ -191,3 +191,7 @@ drop table table_26093;
 drop function func_26093_a;
 drop function func_26093_b;
 End of 5.0 tests
+select connection_id() > 0;
+connection_id() > 0
+1
+End of tests

mysql-test/t/func_misc.test

@@ -199,3 +199,11 @@ drop function func_26093_a;
 drop function func_26093_b;
 
 --echo End of 5.0 tests
+
+#
+# Bug #30389: connection_id() always return 0 in embedded server
+#
+
+select connection_id() > 0;
+
+--echo End of tests

sql/mysqld.cc

@@ -4355,6 +4355,11 @@ static void create_new_thread(THD *thd)
     DBUG_VOID_RETURN;
   }
   pthread_mutex_lock(&LOCK_thread_count);
+  /*
+    The initialization of thread_id is done in create_embedded_thd() for
+    the embedded library.
+    TODO: refactor this to avoid code duplication there
+  */
   thd->thread_id= thd->variables.pseudo_thread_id= thread_id++;
 
   /* Start a new thread to handle connection */

sql/sql_connect.cc

@@ -1008,6 +1008,11 @@ void prepare_new_connection_state(THD* thd)
   if (thd->client_capabilities & CLIENT_COMPRESS)
     thd->net.compress=1;				// Use compression
 
+  /*
+    Much of this is duplicated in create_embedded_thd() for the
+    embedded server library.
+    TODO: refactor this to avoid code duplication there
+  */
   thd->version= refresh_version;
   thd->proc_info= 0;
   thd->command= COM_SLEEP;