util: add function for simple rate limiting.

Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>

util.c

@@ -512,3 +512,17 @@ void parray_extend(void ***a, ...)
 	va_end(ap);
 	(*a)[len - 1] = NULL;
 }
+
+int rate_limited(int interval, time_t *last)
+{
+	struct timespec ts;
+
+	if (clock_gettime(CLOCK_MONOTONIC, &ts))
+		return 1;
+	if (*last + interval > ts.tv_sec)
+		return 1;
+
+	*last = ts.tv_sec;
+
+	return 0;
+}

util.h

@@ -354,4 +354,13 @@ void parray_append(void ***a, void *p);
  */
 void parray_extend(void ***a, ...);
 
+/**
+ * Check if enough time has passed to implement a simple rate limiting.
+ *
+ * @param interval  Minimum interval between two calls returning 0 (in seconds).
+ * @param last      Time of the last call that returned 0, input/output.
+ * @return          1 when rate limited, 0 otherwise.
+ */
+int rate_limited(int interval, time_t *last);
+
 #endif