domotz-remote-pawn/src/utils/mutex.js

Domotz Agent

/** This file is part of Domotz Agent.
  * Copyright (C) 2016  Domotz Ltd
  *
  * Domotz Agent 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, either version 3 of the License, or
  * (at your option) any later version.
  *
  * Domotz Agent 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 Domotz Agent.  If not, see <http://www.gnu.org/licenses/>.
  **/
/**
 *
 * Created by Tommaso Latini <tommaso@domotz.com> on 14/09/15.
 */

var locks = {};

function lock(semaphore, id) {
    if (id === undefined){
        throw "Cannot lock semaphore " + semaphore + " with undefined id";
    }
    if (locks[semaphore] === undefined){
        locks[semaphore] = id;
        console.info('MUTEX - (%s): Lock obtained with id %s', semaphore.toUpperCase(), id);
        return true;
    } else {
        console.info('MUTEX - (%s): Cannot lock semaphore with id %s', semaphore.toUpperCase(), id);
        return false;
    }
}

function unlock(semaphore, id) {
    if (id === undefined || locks[semaphore] !== id){
        throw new Error("MUTEX - (" + semaphore.toUpperCase() + "): Cannot unlock with id: " + id);
    }
    console.info('MUTEX - (%s): Released lock with id %s', semaphore.toUpperCase(), id);
    locks[semaphore] = undefined;
}

function isLocked(semaphore) {
    var locked = (locks[semaphore] !== undefined);
    console.debug('MUTEX - (%s): %s', semaphore.toUpperCase(), locked ? 'locked' : 'unlocked');
    return locked;
}

module.exports.lock     = lock;
module.exports.unlock   = unlock;
module.exports.isLocked = isLocked;