gree_leran/node_modules/webpack/lib/util/Semaphore.js

55 lines
1.0 KiB
JavaScript

/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
class Semaphore {
/**
* Creates an instance of Semaphore.
*
* @param {number} available the amount available number of "tasks"
* in the Semaphore
*/
constructor(available) {
this.available = available;
/** @type {(function(): void)[]} */
this.waiters = [];
/** @private */
this._continue = this._continue.bind(this);
}
/**
* @param {function(): void} callback function block to capture and run
* @returns {void}
*/
acquire(callback) {
if (this.available > 0) {
this.available--;
callback();
} else {
this.waiters.push(callback);
}
}
release() {
this.available++;
if (this.waiters.length > 0) {
process.nextTick(this._continue);
}
}
_continue() {
if (this.available > 0) {
if (this.waiters.length > 0) {
this.available--;
const callback = /** @type {(function(): void)} */ (this.waiters.pop());
callback();
}
}
}
}
module.exports = Semaphore;