MDEV-38124 event scheduler spams the error log

event scheduler was printing a lot of info in [Note] in error log.

change to print its startup/shutdown notes only when log_warnings>0.
and runtime notes only when log_warnings>2.
one note was an abnormal error, change to [Error].

Author: vuvova

sql/event_data_objects.cc

@@ -1476,8 +1476,9 @@ Event_job_data::execute(THD *thd, bool drop)
       We must do it here since here we're under the right authentication
       ID of the event definer.
     */
-    sql_print_information("Event Scheduler: Dropping %s.%s",
-                          (const char *) dbname.str, (const char *) name.str);
+    if (global_system_variables.log_warnings > 2)
+      sql_print_information("Event Scheduler: Dropping %s.%s",
+                            dbname.str, name.str);
     /*
       Construct a query for the binary log, to ensure the event is dropped
       on the slave

sql/event_queue.cc

@@ -517,7 +517,7 @@ Event_queue::empty_queue()
   DBUG_ENTER("Event_queue::empty_queue");
   DBUG_PRINT("enter", ("Purging the queue. %u element(s)", queue.elements));
 
-  if (queue.elements)
+  if (queue.elements && global_system_variables.log_warnings > 2)
     sql_print_information("Event Scheduler: Purging the queue. %u events",
                           queue.elements);
   /* empty the queue */
@@ -668,9 +668,10 @@ Event_queue::get_top_for_execution_if_time(THD *thd,
     if (top->status == Event_parse_data::DISABLED)
     {
       DBUG_PRINT("info", ("removing from the queue"));
-      sql_print_information("Event Scheduler: Last execution of %s.%s. %s",
-                            top->dbname.str, top->name.str,
-                            top->dropped? "Dropping.":"");
+      if (global_system_variables.log_warnings > 2)
+        sql_print_information("Event Scheduler: Last execution of %s.%s. %s",
+                              top->dbname.str, top->name.str,
+                              top->dropped? "Dropping.":"");
       delete top;
       queue_remove_top(&queue);
     }

sql/event_scheduler.cc

@@ -319,10 +319,9 @@ Event_worker_thread::run(THD *thd, Event_queue_element_for_exec *event)
 
   print_warnings(thd, &job_data);
 
-  if (res)
-    sql_print_information("Event Scheduler: "
-                          "[%s].[%s.%s] event execution failed.",
-                          job_data.definer.str,
+  if (res && global_system_variables.log_warnings > 2)
+    sql_print_information("Event Scheduler: [%s].[%s.%s] event execution "
+                          "failed.", job_data.definer.str,
                           job_data.dbname.str, job_data.name.str);
 end:
 #ifdef HAVE_PSI_STATEMENT_INTERFACE
@@ -471,8 +470,9 @@ Event_scheduler::run(THD *thd)
   int res= FALSE;
   DBUG_ENTER("Event_scheduler::run");
 
-  sql_print_information("Event Scheduler: scheduler thread started with id %lu",
-                        (ulong) thd->thread_id);
+  if (global_system_variables.log_warnings)
+    sql_print_information("Event Scheduler: scheduler thread started with "
+                          "id %llu", (ulonglong) thd->thread_id);
   /*
     Recalculate the values in the queue because there could have been stops
     in executions of the scheduler and some times could have passed by.
@@ -486,9 +486,8 @@ Event_scheduler::run(THD *thd)
     /* Gets a minimized version */
     if (queue->get_top_for_execution_if_time(thd, &event_name))
     {
-      sql_print_information("Event Scheduler: "
-                            "Serious error during getting next "
-                            "event to execute. Stopping");
+      sql_print_error("Event Scheduler: Serious error during getting next "
+                      "event to execute. Stopping");
       break;
     }
 
@@ -660,14 +659,16 @@ Event_scheduler::stop()
     DBUG_PRINT("info", ("Scheduler thread has id %lu",
                         (ulong) scheduler_thd->thread_id));
     /* This will wake up the thread if it waits on Queue's conditional */
-    sql_print_information("Event Scheduler: Killing the scheduler thread, "
-                          "thread id %lu",
-                          (ulong) scheduler_thd->thread_id);
+    if (global_system_variables.log_warnings)
+      sql_print_information("Event Scheduler: Killing the scheduler thread, "
+                            "thread id %llu",
+                            (ulonglong) scheduler_thd->thread_id);
     scheduler_thd->awake(KILL_CONNECTION);
 
     /* thd could be 0x0, when shutting down */
-    sql_print_information("Event Scheduler: "
-                          "Waiting for the scheduler thread to reply");
+    if (global_system_variables.log_warnings > 1)
+      sql_print_information("Event Scheduler: "
+                            "Waiting for the scheduler thread to reply");
 
     /*
       Wait only 2 seconds, as there is a small chance the thread missed the
@@ -678,7 +679,8 @@ Event_scheduler::stop()
     COND_STATE_WAIT(thd, &top_time, &stage_waiting_for_scheduler_to_stop);
   } while (state == STOPPING);
   DBUG_PRINT("info", ("Scheduler thread has cleaned up. Set state to INIT"));
-  sql_print_information("Event Scheduler: Stopped");
+  if (global_system_variables.log_warnings)
+    sql_print_information("Event Scheduler: Stopped");
 end:
   UNLOCK_DATA();
   DBUG_RETURN(FALSE);