const struct GNUNET_CADET_TunnelKeyExchangeAuthMessage *msg);
+/**
+ * Performance metrics for a connection.
+ */
+struct CadetConnectionMetrics
+{
+
+ /**
+ * Our current best estimate of the latency, based on a weighted
+ * average of at least @a latency_datapoints values.
+ */
+ struct GNUNET_TIME_Relative aged_latency;
+
+ /**
+ * When was this connection first established? (by us sending or
+ * receiving the CREATE_ACK for the first time)
+ */
+ struct GNUNET_TIME_Absolute age;
+
+ /**
+ * When was this connection last used? (by us sending or
+ * receiving a PAYLOAD message on it)
+ */
+ struct GNUNET_TIME_Absolute last_use;
+
+ /**
+ * How many packets that ought to generate an ACK did we send via
+ * this connection?
+ */
+ unsigned long long num_acked_transmissions;
+
+ /**
+ * Number of packets that were sent via this connection did actually
+ * receive an ACK? (Note: ACKs may be transmitted and lost via
+ * other connections, so this value should only be interpreted
+ * relative to @e num_acked_transmissions and in relation to other
+ * connections.)
+ */
+ unsigned long long num_successes;
+
+};
+
+
+/**
+ * Obtain performance @a metrics from @a cc.
+ *
+ * @param cc connection to query
+ * @return the metrics
+ */
+const struct CadetConnectionMetrics *
+GCC_get_metrics (struct CadetConnection *cc);
+
+
/**
* Handle encrypted message.
*
const struct GNUNET_CADET_TunnelEncryptedMessage *msg);
+/**
+ * We sent a message for which we expect to receive an ACK via
+ * the connection identified by @a cti.
+ *
+ * @param cid connection identifier where we expect an ACK
+ */
+void
+GCC_ack_expected (const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid);
+
+
+/**
+ * We observed an ACK for a message that was originally sent via
+ * the connection identified by @a cti.
+ *
+ * @param cid connection identifier where we got an ACK for a message
+ * that was originally sent via this connection (the ACK
+ * may have gotten back to us via a different connection).
+ */
+void
+GCC_ack_observed (const struct GNUNET_CADET_ConnectionTunnelIdentifier *cid);
+
+
/**
* We observed some the given @a latency on the connection
* identified by @a cti. (The same connection was taken