SQL Operations Studio Public Preview 1 (0.23) release source code

dataprotocol-node/client/src/utils/async.ts

@@ -0,0 +1,82 @@
+/* --------------------------------------------------------------------------------------------
+ * Copyright (c) Microsoft Corporation. All rights reserved.
+ * Licensed under the Source EULA. See License.txt in the project root for license information.
+ * ------------------------------------------------------------------------------------------ */
+'use strict';
+
+export interface ITask<T> {
+	(): T;
+}
+
+export class Delayer<T> {
+
+	public defaultDelay: number;
+	private timeout: NodeJS.Timer;
+	private completionPromise: Promise<T>;
+	private onSuccess: (value?: T | Thenable<T>) => void;
+	private task: ITask<T>;
+
+	constructor(defaultDelay: number) {
+		this.defaultDelay = defaultDelay;
+		this.timeout = null;
+		this.completionPromise = null;
+		this.onSuccess = null;
+		this.task = null;
+	}
+
+	public trigger(task: ITask<T>, delay: number = this.defaultDelay): Promise<T> {
+		this.task = task;
+		if (delay >= 0) {
+			this.cancelTimeout();
+		}
+
+		if (!this.completionPromise) {
+			this.completionPromise = new Promise<T>((resolve) => {
+				this.onSuccess = resolve
+			}).then(() => {
+				this.completionPromise = null;
+				this.onSuccess = null;
+				var result = this.task();
+				this.task = null;
+				return result;
+			});
+		}
+
+		if (delay >= 0 || this.timeout === null) {
+			this.timeout = setTimeout(() => {
+				this.timeout = null;
+				this.onSuccess(null);
+			}, delay >= 0 ? delay : this.defaultDelay);
+		}
+
+		return this.completionPromise;
+	}
+
+	public forceDelivery(): T {
+		if (!this.completionPromise) {
+			return null;
+		}
+		this.cancelTimeout();
+		let result: T = this.task();
+		this.completionPromise = null;
+		this.onSuccess = null;
+		this.task = null;
+		return result;
+	}
+
+	public isTriggered(): boolean {
+		return this.timeout !== null;
+	}
+
+	public cancel(): void {
+		this.cancelTimeout();
+		this.completionPromise = null;
+	}
+
+	private cancelTimeout(): void {
+		if (this.timeout !== null) {
+			clearTimeout(this.timeout);
+			this.timeout = null;
+		}
+	}
+}