Refactor the way allocation stats are fetched

No longer treat it as a property for relationship, just ephemeral
data that can be fetched on demand.

ui/app/models/allocation.js

@@ -1,13 +1,11 @@
 import { inject as service } from '@ember/service';
-import { readOnly } from '@ember/object/computed';
 import { computed } from '@ember/object';
-import RSVP from 'rsvp';
 import Model from 'ember-data/model';
 import attr from 'ember-data/attr';
 import { belongsTo } from 'ember-data/relationships';
 import { fragment, fragmentArray } from 'ember-data-model-fragments/attributes';
-import PromiseObject from '../utils/classes/promise-object';
 import shortUUIDProperty from '../utils/properties/short-uuid';
+import AllocationStats from '../utils/classes/allocation-stats';
 
 const STATUS_ORDER = {
   pending: 1,
@@ -56,48 +54,17 @@ export default Model.extend({
     return taskGroups && taskGroups.findBy('name', this.get('taskGroupName'));
   }),
 
-  memoryUsed: readOnly('stats.ResourceUsage.MemoryStats.RSS'),
-  cpuUsed: computed('stats.ResourceUsage.CpuStats.TotalTicks', function() {
-    return Math.floor(this.get('stats.ResourceUsage.CpuStats.TotalTicks') || 0);
-  }),
-
-  percentMemory: computed('taskGroup.reservedMemory', 'memoryUsed', function() {
-    const used = this.get('memoryUsed') / 1024 / 1024;
-    const total = this.get('taskGroup.reservedMemory');
-    if (!total || !used) {
-      return 0;
-    }
-    return used / total;
-  }),
-
-  percentCPU: computed('cpuUsed', 'taskGroup.reservedCPU', function() {
-    const used = this.get('cpuUsed');
-    const total = this.get('taskGroup.reservedCPU');
-    if (!total || !used) {
-      return 0;
-    }
-    return used / total;
-  }),
-
-  stats: computed('node.{isPartial,httpAddr}', function() {
-    const nodeIsPartial = this.get('node.isPartial');
-
-    // If the node doesn't have an httpAddr, it's a partial record.
-    // Once it reloads, this property will be dirtied and stats will load.
-    if (nodeIsPartial) {
-      return PromiseObject.create({
-        // Never resolve, so the promise object is always in a state of pending
-        promise: new RSVP.Promise(() => {}),
+  fetchStats() {
+    return this.get('token')
+      .authorizedRequest(`/v1/client/allocation/${this.get('id')}/stats`)
+      .then(res => res.json())
+      .then(json => {
+        return new AllocationStats({
+          stats: json,
+          allocation: this,
+        });
       });
-    }
-
-    const url = `/v1/client/allocation/${this.get('id')}/stats`;
-    return PromiseObject.create({
-      promise: this.get('token')
-        .authorizedRequest(url)
-        .then(res => res.json()),
-    });
-  }),
+  },
 
   states: fragmentArray('task-state'),
 });

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

@@ -0,0 +1,33 @@
+import EmberObject, { computed } from '@ember/object';
+import { alias, readOnly } from '@ember/object/computed';
+
+export default EmberObject.extend({
+  allocation: null,
+  stats: null,
+
+  reservedMemory: alias('allocation.taskGroup.reservedMemory'),
+  reservedCPU: alias('allocation.taskGroup.reservedCPU'),
+
+  memoryUsed: readOnly('stats.ResourceUsage.MemoryStats.RSS'),
+  cpuUsed: computed('stats.ResourceUsage.CpuStats.TotalTicks', function() {
+    return Math.floor(this.get('stats.ResourceUsage.CpuStats.TotalTicks') || 0);
+  }),
+
+  percentMemory: computed('reservedMemory', 'memoryUsed', function() {
+    const used = this.get('memoryUsed') / 1024 / 1024;
+    const total = this.get('reservedMemory');
+    if (!total || !used) {
+      return 0;
+    }
+    return used / total;
+  }),
+
+  percentCPU: computed('reservedCPU', 'cpuUsed', function() {
+    const used = this.get('cpuUsed');
+    const total = this.get('reservedCPU');
+    if (!total || !used) {
+      return 0;
+    }
+    return used / total;
+  }),
+});