taskSingler.ts

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/


/**
 * Taken from https://github.com/microsoft/vscode/blob/e8e6e1f69c34232ea2668d3ea2c1c0393303474f/src/vs/workbench/api/common/extHostAuthentication.ts#L122-L136
 * Given a task with the same key, it will only run one at a time and will return the same promise for all calls with the same key.
 */
export class TaskSingler<T> {
	private _inFlightPromises = new Map<string, Promise<T>>();
	getOrCreate(key: string, promiseFactory: () => Promise<T>) {
		const inFlight = this._inFlightPromises.get(key);
		if (inFlight) {
			return inFlight;
		}

		const promise = promiseFactory().finally(() => this._inFlightPromises.delete(key));
		this._inFlightPromises.set(key, promise);

		return promise;
	}
}