Using built in intervalUtils instead of rolling own

packages/instant/src/util/heartbeater.ts

@@ -1,15 +1,14 @@
+import { intervalUtils } from '@0x/utils';
 import * as _ from 'lodash';
 
 type HeartbeatableFunction = () => Promise<void>;
 export class Heartbeater {
-    private _intervalId?: number;
-    private _hasPendingRequest: boolean;
+    private _intervalId?: NodeJS.Timer;
     private readonly _performImmediatelyOnStart: boolean;
     private readonly _performFunction: HeartbeatableFunction;
 
     public constructor(performingFunctionAsync: HeartbeatableFunction, performImmediatelyOnStart: boolean) {
         this._performFunction = performingFunctionAsync;
-        this._hasPendingRequest = false;
         this._performImmediatelyOnStart = performImmediatelyOnStart;
     }
 
@@ -20,30 +19,16 @@ export class Heartbeater {
 
         if (this._performImmediatelyOnStart) {
             // tslint:disable-next-line:no-floating-promises
-            this._trackAndPerformAsync();
+            this._performFunction();
         }
 
-        this._intervalId = window.setInterval(this._trackAndPerformAsync.bind(this), intervalTimeMs);
+        this._intervalId = intervalUtils.setAsyncExcludingInterval(this._performFunction, intervalTimeMs, () => {});
     }
 
     public stop(): void {
         if (this._intervalId) {
-            window.clearInterval(this._intervalId);
+            intervalUtils.clearInterval(this._intervalId);
         }
         this._intervalId = undefined;
-        this._hasPendingRequest = false;
-    }
-
-    private async _trackAndPerformAsync(): Promise<void> {
-        if (this._hasPendingRequest) {
-            return;
-        }
-
-        this._hasPendingRequest = true;
-        try {
-            await this._performFunction();
-        } finally {
-            this._hasPendingRequest = false;
-        }
     }
 }