coordinator-node-client/lib/async.js

分布式协调服务node客户端，用于获取微服务的可用地址，参照eureka-js-client.

/**
 * Copyright (c) 2010-2015 EEFUNG Software Co.Ltd. All rights reserved.
 * 版权所有 (c) 2010-2015 湖南蚁坊软件有限公司。保留所有权利。
 * Created by liwenjun on 2016/4/14.
 */

(function () {
    var async = {
        logger: null
    };
    //仿async， https://github.com/caolan/async
    //// cross-browser compatiblity functions ////
    var _toString = Object.prototype.toString;

    var _isArray = Array.isArray || function (obj) {
            return _toString.call(obj) === '[object Array]';
        };

    function _isArrayLike(arr) {
        return _isArray(arr) || (
                // has a positive integer length property
                typeof arr.length === "number" &&
                arr.length >= 0 &&
                arr.length % 1 === 0
            );
    }

    // capture the global reference to guard against fakeTimer mocks
    var _setImmediate = typeof setImmediate === 'function' && setImmediate;

    var _delay = _setImmediate ? function (fn) {
        // not a direct alias for IE10 compatibility
        _setImmediate(fn);
    } : function (fn) {
        setTimeout(fn, 0);
    };

    if (typeof process === 'object' && typeof process.nextTick === 'function') {
        async.nextTick = process.nextTick;
    } else {
        async.nextTick = _delay;
    }
    async.setImmediate = _setImmediate ? _delay : async.nextTick;

    function _keyIterator(coll) {
        var i = -1;
        var len;
        var keys;
        if (_isArrayLike(coll)) {
            len = coll.length;
            return function next() {
                i++;
                return i < len ? i : null;
            };
        } else {
            keys = _keys(coll);
            len = keys.length;
            return function next() {
                i++;
                return i < len ? keys[i] : null;
            };
        }
    }

    var _keys = Object.keys || function (obj) {
            var keys = [];
            for (var k in obj) {
                if (obj.hasOwnProperty(k)) {
                    keys.push(k);
                }
            }
            return keys;
        };
    async.setLogger = function (logger) {
        async.logger = logger;
    };
    async.eachOfSeries = function (urls, fn, callback) {
        callback = _once(callback || noop);
        urls = urls || [];
        var nextKey = _keyIterator(urls);
        var key = nextKey();

        function iterate() {
            function innercallback(err, httpResponse, body) {
                if (err) {
                    key = nextKey();
                    if (key === null) {
                        if (async.logger) {
                            async.logger.debug("协调中心没有可用服务!");
                        }
                        //返回错误信息
                        callback(err, httpResponse, body);
                    } else {
                        //立即执行
                        iterate();
                    }
                } else {
                    //返回正确信息
                    callback(err, httpResponse, body);
                }
            }

            if (key === null) {
                if (async.logger) {
                    async.logger.debug("协调中心没有可用服务!");
                }
                callback(new Error("协调中心没有可用服务!"));
            } else {
                if (async.logger) {
                    async.logger.debug("调用第" + (key + 1) + "个服务实例:" + urls[key]);
                }
                fn(urls[key], innercallback);
            }
        }

        iterate();
    };

    function only_once(fn) {
        return function () {
            if (fn === null) throw new Error("Callback was already called.");
            fn.apply(this, arguments);
            fn = null;
        };
    }

    function _once(fn) {
        return function () {
            if (fn === null) return;
            fn.apply(this, arguments);
            fn = null;
        };
    }

    // Node.js
    if (typeof module === 'object' && module.exports) {
        module.exports = async;
    }
    // AMD / RequireJS
    else if (typeof define === 'function' && define.amd) {
        define([], function () {
            return async;
        });
    }
    // included directly via <script> tag
    else {
        root.async = async;
    }

}());