pomelo-upgrade/lib/util/countDownLatch.js

网易Pomelo升级版本

'use strict';
const exp = module.exports;

/**
 * Count down to zero or timeout and invoke cb finally.
 */
const CountDownLatch = function(count, opts, cb)
{
    this.count = count;
    this.cb = cb;
    // const self = this;
    if (opts.timeout)
    {
        this.timerId = setTimeout(this.cb, opts.timeout, true);
    }
};

/**
 * Call when a task finish to count down.
 *
 * @api public
 */
CountDownLatch.prototype.done = function()
{
    if (this.count <= 0)
    {
        throw new Error('illegal state.');
    }

    this.count--;
    if (this.count === 0)
    {
        if (this.timerId)
        {
            clearTimeout(this.timerId);
        }
        this.cb();
    }
};

/**
 * Create a count down latch
 *
 * @param {Integer} count
 * @param {object} opts, opts.timeout indicates timeout, optional param
 * @param {function} cb, cb(isTimeout)
 *
 * @api public
 */
exp.createCountDownLatch = function(count, opts, cb)
{
    if (!count || count <= 0)
    {
        throw new Error('count should be positive.');
    }

    if (!cb && typeof opts === 'function')
    {
        cb = opts;
        opts = {};
    }

    if (typeof cb !== 'function')
    {
        throw new Error('cb should be a function.');
    }

    return new CountDownLatch(count, opts, cb);
};