update how recently a domain has been active

lib/device-tracker.js

@@ -14,6 +14,7 @@ Devices.add = function (store, servername, newDevice, isPort) {
   if (!store._domains) { store._domains = {}; }
   if (!store._domains[servername]) { store._domains[servername] = []; }
   store._domains[servername].push(newDevice);
+  Devices.touch(store, servername);
 
   // add device
   // TODO only use a device id 
@@ -126,7 +127,11 @@ Devices.active = function (store, id) {
 };
 */
 Devices.exist = function (store, servername) {
-  return !!(Devices.list(store, servername).length);
+  if (Devices.list(store, servername).length) {
+    Devices.touch(store, servername);
+    return true;
+  }
+  return false;
 };
 Devices.next = function (store, servername) {
   var devices = Devices.list(store, servername);
@@ -138,5 +143,14 @@ Devices.next = function (store, servername) {
   device = devices[devices._index || 0];
   devices._index = (devices._index || 0) + 1;
 
+  if (device) { Devices.touch(store, servername); }
   return device;
 };
+Devices.touch = function (store, servername) {
+  if (!store._recency) { store._recency = {}; }
+  store._recency[servername] = Date.now();
+};
+Devices.lastSeen = function (store, servername) {
+  if (!store._recency) { store._recency = {}; }
+  return store._recency[servername] || 0;
+};