Merge branch 'development' into patch-1

1 files changed, 35 insertions, 0 deletions

diff --git a/packages/instant/src/util/heartbeater.ts b/packages/instant/src/util/heartbeater.ts
new file mode 100644
index 000000000..e700d489e
--- /dev/null
+++ b/packages/instant/src/util/heartbeater.ts
@@ -0,0 +1,35 @@
+import { intervalUtils } from '@0x/utils';
+import * as _ from 'lodash';
+
+type HeartbeatableFunction = () => Promise<void>;
+export class Heartbeater {
+    private _intervalId?: NodeJS.Timer;
+    private readonly _performImmediatelyOnStart: boolean;
+    private readonly _performFunction: HeartbeatableFunction;
+
+    public constructor(performingFunctionAsync: HeartbeatableFunction, performImmediatelyOnStart: boolean) {
+        this._performFunction = performingFunctionAsync;
+        this._performImmediatelyOnStart = performImmediatelyOnStart;
+    }
+
+    public start(intervalTimeMs: number): void {
+        if (!_.isUndefined(this._intervalId)) {
+            throw new Error('Heartbeat is running, please stop before restarting');
+        }
+
+        if (this._performImmediatelyOnStart) {
+            // tslint:disable-next-line:no-floating-promises
+            this._performFunction();
+        }
+
+        // tslint:disable-next-line:no-unbound-method
+        this._intervalId = intervalUtils.setAsyncExcludingInterval(this._performFunction, intervalTimeMs, _.noop);
+    }
+
+    public stop(): void {
+        if (this._intervalId) {
+            intervalUtils.clearInterval(this._intervalId);
+        }
+        this._intervalId = undefined;
+    }
+}