New event_base_update_cache_time() to set cached_tv to current time

This function is particularly useful for selectively increasing
the accuracy of the cached time value in 'base' during callbacks
that take a long time to execute.

This function has no effect if the base is currently not in its
event loop or if timeval caching is disabled via EVENT_BASE_FLAG_NO_CACHE_TIME.

event.c

@@ -435,6 +435,22 @@ update_time_cache(struct event_base *base)
 	    gettime(base, &base->tv_cache);
 }
 
+int
+event_base_update_cache_time(struct event_base *base)
+{
+
+	if (!base) {
+		base = current_base;
+		if (!current_base)
+			return -1;
+	}
+
+	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
+	update_time_cache(base);
+	EVBASE_RELEASE_LOCK(base, th_base_lock);
+	return 0;
+}
+
 struct event_base *
 event_init(void)
 {

include/event2/event.h

@@ -1255,6 +1255,20 @@ void event_base_dump_events(struct event_base *, FILE *);
 int event_base_gettimeofday_cached(struct event_base *base,
     struct timeval *tv);
 
+/** Update cached_tv in the 'base' to the current time
+ *
+ * You can use this function is useful for selectively increasing
+ * the accuracy of the cached time value in 'base' during callbacks
+ * that take a long time to execute.
+ *
+ * This function has no effect if the base is currently not in its
+ * event loop, or if timeval caching is disabled via
+ * EVENT_BASE_FLAG_NO_CACHE_TIME.
+ *
+ * @return 0 on success, -1 on failure
+ */
+int event_base_update_cache_time(struct event_base *base);
+
 #ifdef __cplusplus
 }
 #endif