ks3/lib/common/async.js

本代码库为`金山云存储KS3`服务.主要提供`KS3 nodejs SDK`和`命令行工具`.

/**
 * @param {Array|Iterable|AsyncIterable|Object} coll - A collection to iterate over.
 * @param {number} limit - The maximum number of async operations at a time.
 * @param {AsyncFunction} iteratee - An async function to apply to each item in
 * `coll`.
 * @param {Function} [callback] - A callback which is called when all
 * `iteratee` functions have finished, or an error occurs. Invoked with (err).
 */
var eachLimit = function (coll, limit, iteratee, callback) {
    callback = callback || function () {};
    if (!coll.length || limit <= 0) {
        return callback();
    }

    var completed = 0;
    var started = 0;
    var running = 0;

    var isError = false;

    (function replenish () {
        if (completed >= coll.length) {
            return callback();
        }

        while (running < limit && started < coll.length && !isError) {
            started += 1;
            running += 1;
            iteratee(coll[started - 1], function (err) {

                if (err) {
                    callback(err);
                    callback = function () {};
                    isError = true
                } else {
                    completed += 1;
                    running -= 1;
                    if (completed >= coll.length) {
                        callback();
                    } else {
                        replenish()
                    }
                }
            });
        }
    })();
};

var retry = function (times, iteratee, callback) {
    var next = function (index) {
        iteratee(function (err, data) {
            if (err && index < times) {
                next(index + 1);
            } else {
                callback(err, data);
            }
        });
    };
    if (times < 1) {
        callback();
    } else {
        next(1);
    }
};

var async = {
    eachLimit: eachLimit,
    retry: retry
};

module.exports = async;