+#define GNUNET_TIME_UNIT_FOREVER_ABS GNUNET_TIME_absolute_get_forever_ ()
+
+
+
+/**
+ * Threshold after which exponential backoff should not increase (15 m).
+ */
+#define GNUNET_TIME_STD_EXPONENTIAL_BACKOFF_THRESHOLD GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 15)
+
+
+/**
+ * Perform our standard exponential back-off calculation, starting at 1 ms
+ * and then going by a factor of 2 up unto a maximum of 15 m.
+ *
+ * @param r current backoff time, initially zero
+ */
+#define GNUNET_TIME_STD_BACKOFF(r) GNUNET_TIME_relative_min (GNUNET_TIME_STD_EXPONENTIAL_BACKOFF_THRESHOLD, \
+ GNUNET_TIME_relative_multiply (GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_MILLISECONDS, (r)), 2));
+
+
+/**
+ * Randomized exponential back-off, starting at 1 ms
+ * and going up by a factor of 2+r, where 0 <= r <= 0.5, up
+ * to a maximum of the given threshold.
+ *
+ * @param rt current backoff time, initially zero
+ * @param threshold maximum value for backoff
+ * @return the next backoff time
+ */
+struct GNUNET_TIME_Relative
+GNUNET_TIME_randomized_backoff(struct GNUNET_TIME_Relative rt, struct GNUNET_TIME_Relative threshold);
+