33 lines
567 B
JavaScript
33 lines
567 B
JavaScript
|
/*
|
||
|
|
MIT License http://www.opensource.org/licenses/mit-license.php
|
||
|
|
Author Tobias Koppers @sokra
|
||
|
|
*/
|
||
|
|
"use strict";
|
||
|
|
|
||
|
|
class Semaphore {
|
||
|
|
constructor(available) {
|
||
|
|
this.available = available;
|
||
|
|
this.waiters = [];
|
||
|
|
}
|
||
|
|
|
||
|
|
acquire(callback) {
|
||
|
|
if(this.available > 0) {
|
||
|
|
this.available--;
|
||
|
|
callback();
|
||
|
|
} else {
|
||
|
|
this.waiters.push(callback);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
release() {
|
||
|
|
if(this.waiters.length > 0) {
|
||
|
|
const callback = this.waiters.pop();
|
||
|
|
process.nextTick(callback);
|
||
|
|
} else {
|
||
|
|
this.available++;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
module.exports = Semaphore;
|