Simplified away scheduler_functions::end_thread()

Code properly integrated into callers instead.

do_handle_one_connection(): no need to reset thd and thd->thread_stack
as they're not updated by cache_thread().

Part of MDEV-19515 - Improve connect speed

sql/mysqld.cc

@@ -2663,7 +2663,7 @@ void unlink_thd(THD *thd)
 */
 
 
-static bool cache_thread(THD *thd)
+bool cache_thread(THD *thd)
 {
   struct timespec abstime;
   DBUG_ENTER("cache_thread");
@@ -2748,51 +2748,6 @@ static bool cache_thread(THD *thd)
 }
 
 
-/*
-  End thread for the current connection
-
-  SYNOPSIS
-    one_thread_per_connection_end()
-    thd		  Thread handler. This may be null if we run out of resources.
-    put_in_cache  Store thread in cache, if there is room in it
-                  Normally this is true in all cases except when we got
-                  out of resources initializing the current thread
-
-  NOTES
-    If thread is cached, we will wait until thread is scheduled to be
-    reused and then we will return.
-    If thread is not cached, we end the thread.
-
-  RETURN
-    0    Signal to handle_one_connection to reuse connection
-*/
-
-bool one_thread_per_connection_end(THD *thd, bool put_in_cache)
-{
-  DBUG_ENTER("one_thread_per_connection_end");
-
-  if (thd)
-  {
-    const bool wsrep_applier= IF_WSREP(thd->wsrep_applier, false);
-
-    unlink_thd(thd);
-    if (!wsrep_applier && put_in_cache && cache_thread(thd))
-      DBUG_RETURN(0);                             // Thread is reused
-    delete thd;
-  }
-
-  DBUG_PRINT("info", ("killing thread"));
-  DBUG_LEAVE;                                   // Must match DBUG_ENTER()
-#if defined(HAVE_OPENSSL) && !defined(EMBEDDED_LIBRARY)
-  ERR_remove_state(0);
-#endif
-  my_thread_end();
-
-  pthread_exit(0);
-  return 0;                                     // Avoid compiler warnings
-}
-
-
 void flush_thread_cache()
 {
   DBUG_ENTER("flush_thread_cache");
@@ -6177,8 +6132,7 @@ void inc_thread_created(void)
 
 void handle_connection_in_main_thread(CONNECT *connect)
 {
-  thread_cache_size= 0;			// Safety
-  do_handle_one_connection(connect);
+  do_handle_one_connection(connect, false);
 }
 
 

sql/mysqld.h

@@ -79,7 +79,7 @@ void close_connection(THD *thd, uint sql_errno= 0);
 void handle_connection_in_main_thread(CONNECT *thd);
 void create_thread_to_handle_connection(CONNECT *connect);
 void unlink_thd(THD *thd);
-bool one_thread_per_connection_end(THD *thd, bool put_in_cache);
+bool cache_thread(THD *thd);
 void flush_thread_cache();
 void refresh_status(THD *thd);
 bool is_secure_file_path(char *path);

sql/scheduler.cc

@@ -29,20 +29,6 @@
 #include "sql_callback.h"
 #include <violite.h>
 
-/*
-  End connection, in case when we are using 'no-threads'
-*/
-
-static bool no_threads_end(THD *thd, bool put_in_cache)
-{
-  if (thd)
-  {
-    unlink_thd(thd);
-    delete thd;
-  }
-  return 1;                                     // Abort handle_one_connection
-}
-
 /** @internal
   Helper functions to allow mysys to call the thread scheduler when
   waiting for locks.
@@ -133,7 +119,6 @@ void one_thread_per_connection_scheduler(scheduler_functions *func,
   func->max_connections= arg_max_connections;
   func->connection_count= arg_connection_count;
   func->add_connection= create_thread_to_handle_connection;
-  func->end_thread= one_thread_per_connection_end;
   func->post_kill_notification= post_kill_notification;
 }
 #else
@@ -153,5 +138,4 @@ void one_thread_scheduler(scheduler_functions *func)
   func->max_connections= &max_connections;
   func->connection_count= &connection_count;
   func->add_connection= handle_connection_in_main_thread;
-  func->end_thread= no_threads_end;
 }

sql/scheduler.h

@@ -38,7 +38,6 @@ struct scheduler_functions
   void (*thd_wait_begin)(THD *thd, int wait_type);
   void (*thd_wait_end)(THD *thd);
   void (*post_kill_notification)(THD *thd);
-  bool (*end_thread)(THD *thd, bool cache_thread);
   void (*end)(void);
 };
 

sql/sql_connect.cc

@@ -1112,7 +1112,6 @@ bool setup_connection_thread_globals(THD *thd)
     close_connection(thd, ER_OUT_OF_RESOURCES);
     statistic_increment(aborted_connects,&LOCK_status);
     statistic_increment(connection_errors_internal, &LOCK_status);
-    thd->scheduler->end_thread(thd, 0);
     return 1;                                   // Error
   }
   return 0;
@@ -1304,14 +1303,15 @@ pthread_handler_t handle_one_connection(void *arg)
   mysql_thread_set_psi_id(connect->thread_id);
 
   if (init_new_connection_handler_thread())
-  {
-    scheduler_functions *scheduler= connect->scheduler;
     connect->close_with_error(0, 0, ER_OUT_OF_RESOURCES);
-    scheduler->end_thread(0, 0);
-    return 0;
-  }
+  else
+    do_handle_one_connection(connect, true);
 
-  do_handle_one_connection(connect);
+  DBUG_PRINT("info", ("killing thread"));
+#if defined(HAVE_OPENSSL) && !defined(EMBEDDED_LIBRARY)
+  ERR_remove_state(0);
+#endif
+  my_thread_end();
   return 0;
 }
 
@@ -1344,15 +1344,13 @@ bool thd_is_connection_alive(THD *thd)
 }
 
 
-void do_handle_one_connection(CONNECT *connect)
+void do_handle_one_connection(CONNECT *connect, bool put_in_cache)
 {
   ulonglong thr_create_utime= microsecond_interval_timer();
   THD *thd;
   if (!(thd= connect->create_thd(NULL)))
   {
-    scheduler_functions *scheduler= connect->scheduler;
     connect->close_with_error(0, 0, ER_OUT_OF_RESOURCES);
-    scheduler->end_thread(0, 0);
     return;
   }
 
@@ -1388,7 +1386,11 @@ void do_handle_one_connection(CONNECT *connect)
   */
   thd->thread_stack= (char*) &thd;
   if (setup_connection_thread_globals(thd))
+  {
+    unlink_thd(thd);
+    delete thd;
     return;
+  }
 
   for (;;)
   {
@@ -1422,16 +1424,12 @@ void do_handle_one_connection(CONNECT *connect)
     if (thd->userstat_running)
       update_global_user_stats(thd, create_user, time(NULL));
 
-    if (thd->scheduler->end_thread(thd, 1))
-      return;                                 // Probably no-threads
-
-    /*
-      If end_thread() returns, this thread has been schedule to
-      handle the next connection.
-    */
-    thd= current_thd;
-    thd->thread_stack= (char*) &thd;
+    unlink_thd(thd);
+    if (IF_WSREP(thd->wsrep_applier, false) || !put_in_cache ||
+        !cache_thread(thd))
+      break;
   }
+  delete thd;
 }
 #endif /* EMBEDDED_LIBRARY */
 

sql/sql_connect.h

@@ -73,7 +73,7 @@ void free_global_index_stats(void);
 void free_global_client_stats(void);
 
 pthread_handler_t handle_one_connection(void *arg);
-void do_handle_one_connection(CONNECT *connect);
+void do_handle_one_connection(CONNECT *connect, bool put_in_cache);
 bool init_new_connection_handler_thread();
 void reset_mqh(LEX_USER *lu, bool get_them);
 bool check_mqh(THD *thd, uint check_command);

sql/threadpool_common.cc

@@ -380,14 +380,6 @@ static int threadpool_process_request(THD *thd)
 }
 
 
-
-/* Dummy functions, do nothing */
-
-static bool tp_end_thread(THD *, bool)
-{
-  return 0;
-}
-
 static TP_pool *pool;
 
 static bool tp_init()
@@ -511,7 +503,6 @@ static scheduler_functions tp_scheduler_functions=
   tp_wait_begin,                      // thd_wait_begin
   tp_wait_end,                        // thd_wait_end
   tp_post_kill_notification,          // post kill notification
-  tp_end_thread,                      // Dummy function
   tp_end                              // end
 };
 

sql/wsrep_mysqld.cc

@@ -2638,7 +2638,7 @@ void* start_wsrep_THD(void *arg)
   {
     close_connection(thd, ER_OUT_OF_RESOURCES);
     statistic_increment(aborted_connects,&LOCK_status);
-    MYSQL_CALLBACK(thread_scheduler, end_thread, (thd, 0));
+    unlink_thd(thd);
     delete thd;
     delete thd_args;
     goto error;
@@ -2685,7 +2685,7 @@ void* start_wsrep_THD(void *arg)
   if (plugins_are_initialized)
   {
     net_end(&thd->net);
-    MYSQL_CALLBACK(thread_scheduler, end_thread, (thd, 1));
+    unlink_thd(thd);
   }
   else
   {