Remove items that are older than 2 minutes in the histogram.

Add didRemove callback in the index.html to display a rolling graph.

Author: ajay-gov

server/src/main/java/swim/tutorial/UnitAgent.java

@@ -1,5 +1,6 @@
 package swim.tutorial;
 
+import java.util.Iterator;
 import swim.api.SwimLane;
 import swim.api.agent.AbstractAgent;
 import swim.api.lane.CommandLane;
@@ -17,9 +18,26 @@ public class UnitAgent extends AbstractAgent {
       .isTransient(true)
       .didUpdate((k,n,o) -> {
         logMessage("histogram: replaced " + k + "'s value to " + Recon.toString(n) + " from " + Recon.toString(o));
-        this.histogram.drop(Math.max(0, this.histogram.size() - 100));
+        dropOldData();
       });
 
+
+  private void dropOldData() {
+    final long now = System.currentTimeMillis();
+    final Iterator<Long> iterator = histogram.keyIterator();
+    while(iterator.hasNext()) {
+      long key = iterator.next();
+      if ((now - key) > 2*60*1000L) {
+        // remove items that are older than 2 minutes
+        histogram.remove(key);
+      } else {
+        // map is sorted by the sort order of the keys, so break out of the loop on the first
+        // key that is newer than 2 minutes
+        break;
+      }
+    }
+  }
+
   @SwimLane("history")
   protected final ListLane<Value> history = this.<Value>listLane()
       .isTransient(true)

ui/index.html

@@ -101,12 +101,17 @@
     .strokeWidth(2);
 chart.addPlot(plot);
 
-function updatePlots(key, value) {
+function addToPlot(key, value) {
   const time = key.numberValue();
   const v = value.get("count").numberValue(0);
   plot.insertDatum({x: time, y: v, opacity: void 0});
 }
 
+function removeFromPlot(key) {
+  const time = key.numberValue();
+  plot.removeDatum(time);
+}
+
 /* Data Subscriptions */
 const valueLink = swim.downlinkValue()
     .hostUri("warp://localhost:9001")
@@ -123,12 +128,15 @@
     })
     .open();
 
-const historyLink = swim.downlinkMap()
+const histogramLink = swim.downlinkMap()
     .hostUri("warp://localhost:9001")
     .nodeUri("/unit/master")
     .laneUri("histogram")
     .didUpdate(function(key, value) {
-      updatePlots(key, value);
+      addToPlot(key, value);
+    })
+    .didRemove(function(key) {
+      removeFromPlot(key);
     })
     .open();
     </script>