Add some additional debugging, disable websockets processing while polling for data.

Author: Mark Jessop

js/tracker.js

@@ -3526,7 +3526,7 @@ function refresh() {
         $("#stText").text("");
     },
     error: function() {
-        $("#stText").text("error |");
+        $("#stText").text("poll error |");
         document.getElementById("timeperiod").disabled = false;
         ajax_inprogress = false;
     },
@@ -3535,6 +3535,7 @@ function refresh() {
             document.getElementById("timeperiod").disabled = false;
         }
         clientActive = true;
+        console.log("WebSockets - Resuming Websockets updates.")
         clearTimeout(periodical);
         ajax_inprogress = false;
     }
@@ -3628,29 +3629,38 @@ function liveData() {
 
                 } else {
                     var frame = JSON.parse(message.payloadString.toString());
+
                     if (wvar.query == "" || sondePrefix.indexOf(wvar.query) > -1 || wvar.query == frame.serial) {
                         if (frame.length == null) {
                             var tempDate = new Date(frame.datetime).getTime();
                         } else {
                             var tempDate = new Date(frame[frame.length - 1].datetime).getTime()
                         }
-                        if ((dateNow - tempDate) < 45000) {
+                        if ((dateNow - tempDate) < 30000) {
+                            // Data is recent enough. 
                             var test = formatData(frame, true);
                             if (clientActive) {
                                 live_data_buffer.positions.position.push.apply(live_data_buffer.positions.position,test.positions.position)
                             }
                             $("#stTimer").attr("data-timestamp", dateNow);
                             $("#stText").text("websocket ("+ ((dateNow - tempDate)/1000).toFixed(1) +" s) |");
                         } else if ((dateNow - new Date(frame.datetime).getTime()) > 150000) {
+                            // Data is very old, which may indicate that our tab has probably been suspended.
+                            // We now poll for data.
                             $("#stText").text("data error ("+ ((dateNow - tempDate)/1000).toFixed(1) +" s) |");
-                            console.log("WebSockets Error: Data Age was " + ((dateNow - tempDate)/1000).toFixed(1) + " s, frame length: " + frame.length);
-                            //refresh();
+                            console.log("WebSockets - Data Age was " + ((dateNow - tempDate)/1000).toFixed(1) + " s, frame length: " + frame.length + ". Discarding and polling for data.");
+                            // Discard all further messages until we have finished the next poll.
+                            console.log("WebSockets - Tab possibly suspended, polling for updates.")
+                            clientActive = false;
+                            refresh();
                         } else {
                             $("#stText").text("data error ("+ ((dateNow - tempDate)/1000).toFixed(1) +" s) |");
-                            console.log("WebSockets Error: Data Age was " + ((dateNow - tempDate)/1000).toFixed(1) + " s, frame length: " + frame.length);
+                            console.log("WebSockets - Data Age was " + ((dateNow - tempDate)/1000).toFixed(1) + " s, frame length: " + frame.length + ". Discarding frame.");
                         }
                     }
                 }
+            } else {
+                console.log("WebSockets - Discarding Message.")
             }
         }
         catch(err) {}