Address #1551 - better timers handling

mongoose.c

@@ -4158,12 +4158,13 @@ size_t mg_vsnprintf(char *buf, size_t len, const char *fmt, va_list ap) {
 
 
 
+#define MG_TIMER_CALLED 4
+
 void mg_timer_init(struct mg_timer **head, struct mg_timer *t, uint64_t ms,
                    unsigned flags, void (*fn)(void *), void *arg) {
   struct mg_timer tmp = {ms, 0U, 0U, flags, fn, arg, *head};
   *t = tmp;
   *head = t;
-  if (flags & MG_TIMER_RUN_NOW) fn(arg);
 }
 
 void mg_timer_free(struct mg_timer **head, struct mg_timer *t) {
@@ -4178,14 +4179,21 @@ void mg_timer_poll(struct mg_timer **head, uint64_t now_ms) {
     tmp = t->next;
     if (t->prev_ms > now_ms) t->expire = 0;  // Handle time wrap
     t->prev_ms = now_ms;
-    if (t->expire == 0) t->expire = now_ms + t->period_ms;
+    if (t->expire == 0 && (t->flags & MG_TIMER_RUN_NOW) &&
+        !(t->flags & MG_TIMER_CALLED)) {
+      // Handle MG_TIMER_NOW only once
+    } else if (t->expire == 0) {
+      t->expire = now_ms + t->period_ms;
+    }
     if (t->expire > now_ms) continue;
-    t->fn(t->arg);
+    if ((t->flags & MG_TIMER_REPEAT) || !(t->flags & MG_TIMER_CALLED)) {
+      t->fn(t->arg);
+    }
+    t->flags |= MG_TIMER_CALLED;
     // Try to tick timers with the given period as accurate as possible,
     // even if this polling function is called with some random period.
     t->expire = now_ms - t->expire > t->period_ms ? now_ms + t->period_ms
                                                   : t->expire + t->period_ms;
-    if (!(t->flags & MG_TIMER_REPEAT)) mg_timer_free(head, t);
   }
 }