Add cancelation support to stats trackers

ui/app/components/primary-metric.js

@@ -79,8 +79,8 @@ export default Component.extend({
 
   poller: task(function*() {
     do {
-      yield this.get('tracker.poll').perform();
-      yield timeout(10);
+      this.get('tracker.poll').perform();
+      yield timeout(100);
     } while (!Ember.testing);
   }),
 
@@ -92,5 +92,6 @@ export default Component.extend({
 
   willDestroy() {
     this.get('poller').cancelAll();
+    this.get('tracker.signalPause').perform();
   },
 });

ui/app/utils/classes/abstract-stats-tracker.js

@@ -17,11 +17,20 @@ export default Mixin.create({
     );
   },
 
+  pause() {
+    assert(
+      'StatsTrackers need a pause method, which takes no arguments but adds a frame of data at the current timestamp with null as the value'
+    );
+  },
+
   // Uses EC as a form of debounce to prevent multiple
   // references to the same tracker from flooding the tracker,
   // but also avoiding the issue where different places where the
   // same tracker is used needs to coordinate.
   poll: task(function*() {
+    // Interrupt any pause attempt
+    this.get('signalPause').cancelAll();
+
     const url = this.get('url');
     assert('Url must be defined', url);
 
@@ -31,4 +40,11 @@ export default Mixin.create({
 
     yield timeout(2000);
   }).drop(),
+
+  signalPause: task(function*() {
+    // wait 2 seconds
+    yield timeout(2000);
+    // if no poll called in 2 seconds, pause
+    this.pause();
+  }).drop(),
 });

ui/app/utils/classes/allocation-stats-tracker.js

@@ -10,6 +10,8 @@ const percent = (numerator, denominator) => {
   return numerator / denominator;
 };
 
+const empty = ts => ({ timestamp: ts, used: null, percent: null });
+
 const AllocationStatsTracker = EmberObject.extend(AbstractStatsTracker, {
   // Set via the stats computed property macro
   allocation: null,
@@ -61,6 +63,16 @@ const AllocationStatsTracker = EmberObject.extend(AbstractStatsTracker, {
     }
   },
 
+  pause() {
+    const ts = new Date();
+    this.get('memory').pushObject(empty(ts));
+    this.get('cpu').pushObject(empty(ts));
+    this.get('tasks').forEach(task => {
+      task.memory.pushObject(empty(ts));
+      task.cpu.pushObject(empty(ts));
+    });
+  },
+
   // Static figures, denominators for stats
   reservedCPU: alias('allocation.taskGroup.reservedCPU'),
   reservedMemory: alias('allocation.taskGroup.reservedMemory'),

ui/app/utils/classes/node-stats-tracker.js

@@ -10,6 +10,8 @@ const percent = (numerator, denominator) => {
   return numerator / denominator;
 };
 
+const empty = ts => ({ timestamp: ts, used: null, percent: null });
+
 const NodeStatsTracker = EmberObject.extend(AbstractStatsTracker, {
   // Set via the stats computed property macro
   node: null,
@@ -39,6 +41,12 @@ const NodeStatsTracker = EmberObject.extend(AbstractStatsTracker, {
     // this.notifyPropertyChange('memory');
   },
 
+  pause() {
+    const ts = new Date();
+    this.get('memory').pushObject(empty(ts));
+    this.get('cpu').pushObject(empty(ts));
+  },
+
   // Static figures, denominators for stats
   reservedCPU: alias('node.resources.cpu'),
   reservedMemory: alias('node.resources.memory'),