Fix threadpool after it was broken by MDEV-6150

mysql-test/r/connect2.result

@@ -5,11 +5,11 @@ select 1;
 1
 set global debug_dbug='+d,simulate_failed_connection_1';
 connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
-ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+Got one of the listed errors
 set global debug_dbug=@old_debug;
 set global debug_dbug='+d,simulate_failed_connection_2';
 connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
-ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+Got one of the listed errors
 set global debug_dbug=@old_debug;
 select 1;
 1
@@ -19,11 +19,11 @@ select 1;
 1
 set global debug_dbug='+d,simulate_failed_connection_1';
 connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
-ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+Got one of the listed errors
 set global debug_dbug=@old_debug;
 set global debug_dbug='+d,simulate_failed_connection_2';
 connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
-ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+Got one of the listed errors
 set global debug_dbug=@old_debug;
 select 1;
 1
@@ -37,7 +37,7 @@ select 1;
 1
 set global debug_dbug='+d,simulate_failed_connection_2';
 connect(localhost,root,,test,MASTER_PORT,MASTER_SOCKET);
-ERROR HY000: Lost connection to MySQL server at 'reading initial communication packet', system error: 95 "Operation not supported"
+Got one of the listed errors
 show status like "Threads_connected";
 Variable_name	Value
 Threads_connected	1

mysql-test/t/connect2.test

@@ -16,14 +16,15 @@ disconnect con1;
 connection default;
 set global debug_dbug='+d,simulate_failed_connection_1';
 --replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
---error 2013
+--error 1041,2013
 connect(con1,localhost,root,,test,,);
 connection default;
 set global debug_dbug=@old_debug;
 set global debug_dbug='+d,simulate_failed_connection_2';
 --replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_MYPORT MASTER_PORT
---error 2013
+--error 1041,2013
 connect(con1,localhost,root,,test,,);
+--enable_result_log
 connection default;
 set global debug_dbug=@old_debug;
 connect(con1,localhost,root,,test,,);
@@ -38,13 +39,13 @@ disconnect con1;
 connection default;
 set global debug_dbug='+d,simulate_failed_connection_1';
 --replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_EXTRA_PORT MASTER_PORT
---error 2013
+--error 1041,2013
 connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
 connection default;
 set global debug_dbug=@old_debug;
 set global debug_dbug='+d,simulate_failed_connection_2';
 --replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_EXTRA_PORT MASTER_PORT
---error 2013
+--error 1041,2013
 connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
 connection default;
 set global debug_dbug=@old_debug;
@@ -66,7 +67,7 @@ disconnect con2;
 connection default;
 set global debug_dbug='+d,simulate_failed_connection_2';
 --replace_result $MASTER_MYSOCK MASTER_SOCKET $MASTER_EXTRA_PORT MASTER_PORT
---error 2013
+--error 1041,2013
 connect(con1,localhost,root,,test,$MASTER_EXTRA_PORT,);
 connection default;
 

sql/threadpool.h

@@ -30,7 +30,7 @@ extern uint threadpool_oversubscribe;  /* Maximum active threads in group */
 extern void threadpool_cleanup_connection(THD *thd);
 extern void threadpool_remove_connection(THD *thd);
 extern int  threadpool_process_request(THD *thd);
-extern int  threadpool_add_connection(THD *thd);
+extern THD*  threadpool_add_connection(CONNECT *connect, void *scheduled_data);
 
 /*
   Functions used by scheduler. 

sql/threadpool_common.cc

@@ -94,7 +94,7 @@ struct Worker_thread_context
 /*
   Attach/associate the connection with the OS thread,
 */
-static bool thread_attach(THD* thd)
+static void thread_attach(THD* thd)
 {
   pthread_setspecific(THR_KEY_mysys,thd->mysys_var);
   thd->thread_stack=(char*)&thd;
@@ -103,13 +103,14 @@ static bool thread_attach(THD* thd)
   if (PSI_server)
     PSI_server->set_thread(thd->event_scheduler.m_psi);
 #endif
-  return 0;
 }
 
 
-int threadpool_add_connection(THD *thd)
+THD* threadpool_add_connection(CONNECT *connect, void *scheduler_data)
 {
-  int retval=1;
+  THD *thd= NULL;
+  int error=1;
+
   Worker_thread_context worker_context;
   worker_context.save();
 
@@ -120,13 +121,23 @@ int threadpool_add_connection(THD *thd)
 
   pthread_setspecific(THR_KEY_mysys, 0);
   my_thread_init();
-  thd->mysys_var= (st_my_thread_var *)pthread_getspecific(THR_KEY_mysys);
-  if (!thd->mysys_var)
+  st_my_thread_var* mysys_var= (st_my_thread_var *)pthread_getspecific(THR_KEY_mysys);
+  DBUG_EXECUTE_IF("simulate_failed_connection_1", mysys_var= NULL; my_thread_end(););
+  if (!mysys_var ||!(thd= connect->create_thd()))
   {
     /* Out of memory? */
+    connect->close_and_delete();
+    if (mysys_var)
+    {
+      my_thread_end();
+    }
     worker_context.restore();
-    return 1;
+    return NULL;
   }
+  delete connect;
+  add_to_active_threads(thd);
+  thd->mysys_var= mysys_var;
+  thd->event_scheduler.data= scheduler_data;
 
   /* Create new PSI thread for use with the THD. */
 #ifdef HAVE_PSI_INTERFACE
@@ -157,14 +168,19 @@ int threadpool_add_connection(THD *thd)
       */
       if (thd_is_connection_alive(thd))
       {
-        retval= 0;
+        error= 0;
         thd->net.reading_or_writing= 1;
         thd->skip_wait_timeout= true;
       }
     }
   }
+  if (error)
+  {
+    threadpool_cleanup_connection(thd);
+    thd= NULL;
+  }
   worker_context.restore();
-  return retval;
+  return thd;
 }
 
 /*

sql/threadpool_unix.cc

@@ -116,6 +116,7 @@ struct connection_t
   connection_t *next_in_queue;
   connection_t **prev_in_queue;
   ulonglong abs_wait_timeout;
+  CONNECT* connect;
   bool logged_in;
   bool bound_to_poll_descriptor;
   bool waiting;
@@ -1215,6 +1216,7 @@ connection_t *alloc_connection()
     connection->logged_in= false;
     connection->bound_to_poll_descriptor= false;
     connection->abs_wait_timeout= ULONGLONG_MAX;
+    connection->thd= 0;
   }
   DBUG_RETURN(connection);
 }
@@ -1228,25 +1230,18 @@ connection_t *alloc_connection()
 void tp_add_connection(CONNECT *connect)
 {
   connection_t *connection;
-  THD *thd;
   DBUG_ENTER("tp_add_connection");
 
-  if (!(connection= alloc_connection()) || !(thd= connect->create_thd()))
+  connection=  alloc_connection();
+  if (!connection)
   {
-    my_free(connection);
-    connect->close_and_delete();
     DBUG_VOID_RETURN;
   }
-  connection->thd= thd;
-  delete connect;
-
-  add_to_active_threads(thd);
-
-  thd->event_scheduler.data= connection;
+  connection->connect= connect;
 
   /* Assign connection to a group. */
   thread_group_t *group= 
-    &all_groups[thd->thread_id%group_count];
+    &all_groups[connect->thread_id%group_count];
 
   connection->thread_group=group;
       
@@ -1272,7 +1267,10 @@ static void connection_abort(connection_t *connection)
   DBUG_ENTER("connection_abort");
   thread_group_t *group= connection->thread_group;
 
+  if (connection->thd)
+  {
     threadpool_remove_connection(connection->thd);
+  }
 
   mysql_mutex_lock(&group->mutex);
   group->connection_count--;
@@ -1442,7 +1440,8 @@ static void handle_event(connection_t *connection)
 
   if (!connection->logged_in)
   {
-    err= threadpool_add_connection(connection->thd);
+    connection->thd = threadpool_add_connection(connection->connect, connection);
+    err= (connection->thd == NULL);
     connection->logged_in= true;
   }
   else 

sql/threadpool_win.cc

@@ -226,11 +226,12 @@ struct connection_t
   PTP_WAIT shm_read;
   /* Callback instance, used to inform treadpool about long callbacks */
   PTP_CALLBACK_INSTANCE callback_instance;
+  CONNECT* connect;
   bool logged_in;
 };
 
 
-void init_connection(connection_t *connection, THD *thd)
+void init_connection(connection_t *connection, CONNECT *connect)
 {
   connection->logged_in = false;
   connection->handle= 0;
@@ -240,11 +241,11 @@ void init_connection(connection_t *connection, THD *thd)
   connection->logged_in = false;
   connection->timeout= ULONGLONG_MAX;
   connection->callback_instance= 0;
+  connection->thd= 0;
   memset(&connection->overlapped, 0, sizeof(OVERLAPPED));
   InitializeThreadpoolEnvironment(&connection->callback_environ);
   SetThreadpoolCallbackPool(&connection->callback_environ, pool);
-  connection->thd = thd;
-  thd->event_scheduler.data= connection;
+  connection->connect= connect;
 }
 
 
@@ -397,7 +398,7 @@ int start_io(connection_t *connection, PTP_CALLBACK_INSTANCE instance)
 
 int login(connection_t *connection, PTP_CALLBACK_INSTANCE instance)
 {
-  if (threadpool_add_connection(connection->thd) == 0
+  if ((connection->thd= threadpool_add_connection(connection->connect, connection))
       && init_io(connection, connection->thd) == 0
       && start_io(connection, instance) == 0)
   {
@@ -660,22 +661,16 @@ static void CALLBACK shm_read_callback(PTP_CALLBACK_INSTANCE instance,
 
 void tp_add_connection(CONNECT *connect)
 {
-  THD *thd;
   connection_t *con;  
-
-  if (!(con = (connection_t *) malloc(sizeof(connection_t))) ||
-      !(thd= connect->create_thd()))
+  con= (connection_t *)malloc(sizeof(connection_t));
+  if (!con)
   {
     tp_log_warning("Allocation failed", "tp_add_connection");
-    free(con);
     connect->close_and_delete();
     return;
   }
-  delete connect;
 
-  add_to_active_threads(thd);
-
-  init_connection(con, thd);
+  init_connection(con, connect);
 
   /* Try to login asynchronously, using threads in the pool */
   PTP_WORK wrk =  CreateThreadpoolWork(login_callback,con, &con->callback_environ);
@@ -687,7 +682,7 @@ void tp_add_connection(CONNECT *connect)
   else
   {
     /* Likely memory pressure */
-    threadpool_cleanup_connection(thd);
+    connect->close_and_delete();
   }
 }