gsender

/*
 * Copyright (C) 2021 Sienci Labs Inc.
 *
 * This file is part of gSender.
 *
 * gSender is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, under version 3 of the License.
 *
 * gSender is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with gSender.  If not, see <https://www.gnu.org/licenses/>.
 *
 * Contact for information regarding this program and its license
 * can be sent through gSender@sienci.com or mailed to the main office
 * of Sienci Labs Inc. in Waterloo, Ontario, Canada.
 *
 */

import events from "events";
import without from "lodash/without";
import shortid from "shortid";
import defaultShell from "spawn-default-shell";
import logger from "../../lib/logger";

const log = logger("service:taskrunner");

class TaskRunner extends events.EventEmitter {
	tasks = [];

	run(command, title, options) {
		if (options === undefined && typeof title === "object") {
			options = title;
			title = "";
		}

		const taskId = shortid.generate(); // task id
		const child = defaultShell.spawn(command, {
			detached: true,
			...options,
		});
		child.unref();

		this.tasks.push(taskId);
		this.emit("start", taskId);

		child.stdout.on("data", (data) => {
			process.stdout.write(`PID:${child.pid}> ${data}`);
		});
		child.stderr.on("data", (data) => {
			process.stderr.write(`PID:${child.pid}> ${data}`);
		});
		child.on("error", (err) => {
			// Listen for error event can prevent from throwing an unhandled exception
			log.error(`Failed to start a child process: err=${JSON.stringify(err)}`);

			this.tasks = without(this.tasks, taskId);
			this.emit("error", taskId, err);
		});
		// The 'exit' event is emitted after the child process ends.
		// Note that the 'exit' event may or may not fire after an error has occurred.
		// It is important to guard against accidentally invoking handler functions multiple times.
		child.on("exit", (code) => {
			if (this.contains(taskId)) {
				this.tasks = without(this.tasks, taskId);
				this.emit("finish", taskId, code);
			}
		});

		return taskId;
	}

	contains(taskId) {
		return this.tasks.indexOf(taskId) >= 0;
	}
}

export default TaskRunner;