function Mutex() {
this.isLocked = false;
this._waiting = [];
}
module.exports = Mutex;
Mutex.prototype.lock = function (cb) {
if (this.isLocked) {
this._waiting.push(cb);
} else {
this.isLocked = true;
cb.call(this);
}
};
Mutex.prototype.timedLock = function (ttl, cb) {
if (!this.isLocked) {
this.isLocked = true;
return cb.call(this);
}
var timer, that = this;
this._waiting.push(function () {
clearTimeout(timer);
if (!cb) {
that.unlock();
return;
}
cb.call(this);
cb = null;
});
timer = setTimeout(function () {
if (cb) {
cb.call(this, new Error('Lock timed out'));
cb = null;
}
}, ttl);
};
Mutex.prototype.tryLock = function () {
if (this.isLocked) {
return false;
}
this.isLocked = true;
return true;
};
Mutex.prototype.unlock = function () {
if (!this.isLocked) {
throw new Error('Mutex is not locked');
}
var waiter = this._waiting.shift();
if (waiter) {
waiter.call(this);
} else {
this.isLocked = false;
}
};