MDEV-16264 - prerequisite patch, periodic thr_timer

Threadpool will need a functionality for periodic thr_timer
(the threadpool maintainence task is a timer that runs periodically).

Also increase the stack size for the timer thread, 8k won't be enough.

include/thr_timer.h

@@ -23,6 +23,7 @@ extern "C" {
 
 typedef struct st_timer {
   struct timespec expire_time;
+  ulonglong period;
   my_bool expired;
   uint index_in_queue;
   void (*func)(void*);
@@ -36,6 +37,7 @@ void end_thr_timer();
 /* Functions for handling one timer */
 void thr_timer_init(thr_timer_t *timer_data, void(*function)(void*),
                     void *arg);
+void thr_timer_set_period(thr_timer_t* timer_data, ulonglong microseconds);
 my_bool thr_timer_settime(thr_timer_t *timer_data, ulonglong microseconds);
 void    thr_timer_end(thr_timer_t *timer_data);
 

mysys/thr_timer.c

@@ -85,7 +85,7 @@ my_bool init_thr_timer(uint alloc_timers)
   /* Create a thread to handle timers */
   pthread_attr_init(&thr_attr);
   pthread_attr_setscope(&thr_attr,PTHREAD_SCOPE_PROCESS);
-  pthread_attr_setstacksize(&thr_attr,8196);
+  pthread_attr_setstacksize(&thr_attr,64*1024);
   thr_timer_inited= 1;
   if (mysql_thread_create(key_thread_timer, &timer_thread, &thr_attr,
                           timer_handler, NULL))
@@ -141,6 +141,18 @@ void thr_timer_init(thr_timer_t *timer_data, void(*function)(void*),
   DBUG_VOID_RETURN;
 }
 
+/*
+  Make timer periodic
+
+  @param timer_data     Timer structure
+  @param micro_seconds  Period
+*/
+void thr_timer_set_period(thr_timer_t* timer_data, ulonglong micro_seconds)
+{
+  DBUG_ENTER("thr_timer_set_period");
+  timer_data->period= micro_seconds;
+  DBUG_VOID_RETURN;
+}
 
 /*
   Request timer after X milliseconds
@@ -240,18 +252,35 @@ static sig_handler process_timers(struct timespec *now)
   {
     void (*function)(void*);
     void *func_arg;
+    my_bool is_periodic;
 
     timer_data= (thr_timer_t*) queue_top(&timer_queue);
     function=   timer_data->func;
     func_arg=   timer_data->func_arg;
+    is_periodic= timer_data->period != 0;
     timer_data->expired= 1;			/* Mark expired */
     /*
       We remove timer before calling timer function to allow thread to
       delete it's timer data any time.
+
+      Deleting timer inside the callback would not work
+      for periodic timers, they need to be removed from
+      queue prior to destroying timer_data.
     */
     queue_remove_top(&timer_queue);		/* Remove timer */
     (*function)(func_arg);                      /* Inform thread of timeout */
 
+    /*
+      If timer is periodic, recalculate next expiration time, and
+      reinsert it into the queue.
+    */
+    if (is_periodic && timer_data->period)
+    {
+      set_timespec_nsec(timer_data->expire_time, timer_data->period * 1000);
+      timer_data->expired= 0;
+      queue_insert(&timer_queue, (uchar*)timer_data);
+    }
+
     /* Check if next one has also expired */
     timer_data= (thr_timer_t*) queue_top(&timer_queue);
     if (cmp_timespec(timer_data->expire_time, (*now)) > 0)