src/vs/base/parts/ipc/node/ipc.net.ts/WebSocketNodeSocket/drain
class WebSocketNodeSocket:	public async drain(): Promise<void> {
		this.traceSocketEvent(SocketDiagnosticsEventType.WebSocketNodeSocketDrainBegin);
		if (this._flowManager.isProcessingWriteQueue()) {
			await Event.toPromise(this._flowManager.onDidFinishProcessingWriteQueue);
		}
		await this.socket.drain();
		this.traceSocketEvent(SocketDiagnosticsEventType.WebSocketNodeSocketDrainEnd);
	}