并发请求处理：EventProxy

|| 这个世界上不存在所谓回调函数深度嵌套的问题。 —— Jackson Tian

|| 世界上本没有嵌套回调，写得人多了，也便有了}}}}}}}}}}}}。 —— fengmk2

API文档: API Documentation
jscoverage: 97%
源码注解：注解文档

EventProxy 仅仅是一个很轻量的工具，但是能够带来一种事件式编程的思维变化。有几个特点：

1. 利用事件机制解耦复杂业务逻辑
2. 移除被广为诟病的深度callback嵌套问题
3. 将串行等待变成并行等待，提升多异步协作场景下的执行效率
4. 友好的Error handling
5. 无平台依赖，适合前后端，能用于浏览器和Node.js
6. 兼容CMD，AMD以及CommonJS模块环境
   现在的，无深度嵌套的，并行的

安装在这里不过多介绍了,直接进去主题

调用方法

var ep = new EventProxy();
    ep.after('got_resource_details', events.length, function(list) {
        // parse data before callback
        var idx = 0;
        list.forEach(function(it) {
            // add resource url_prefix
            it.forEach(function(one) {
                if (!one) {
                    return;
                }
                var loc = one.location;
                if (loc.indexOf("http") !== 0) {
                    one.location = CONFIG.RES_URL_PREFIX + loc;
                }
            });
            events[idx++].res_list = it;
        });
        // ! RETURN HERE !
        callback(null, events);
    });
    ep.fail(callback);
    var http_prefix = '/' + CONFIG.COLL_NAME_RESOURCE + '/';
    for (var i = 0; i < events.length; i++) {
        epHttpRequestsWithPattern('got_list_resource_details',
            ['name', 'type', 'location', 'duration'],
            events[i].res_list,
            null,  // pattern
            false, // ignore_invalid
            http_prefix,
            module_db_crud_request_headers,
            ep.group('got_resource_details'));
    }

封装方法

///////////////////////////////////////////////////////////////////////
// UTILS: HTTP requests by EventProxy, WITH SEQUENCE.
//  ep_idname: name of EventProxy
//  items_need: items need to keep in result, others will be delete from result
//  objs: objects list
//  pattern: pattern in objects list which need to be request
//  ignore_invalid: if invalid result need to be ignored?
//  http_prefix: http prefix for requesting
//  callback: callback function
var epHttpRequestsWithPattern = function(ep_idname, items_need, objs, pattern, ignore_invalid, http_prefix, headers, callback) {
    if (ep_idname == undefined || ep_idname == null || ep_idname == "") {
        return callback(null, []);
    }
    if (items_need == undefined || items_need == null || items_need.constructor != Array || items_need.length == 0) {
        return callback(null, []);
    }
    if (objs == undefined || objs == null || objs.constructor != Array || objs.length == 0) {
        return callback(null, []);
    }
    var ep = new EventProxy();
    ep.after(ep_idname, objs.length, function(list) {
        // parse data before callback
        var idx = 0;
        list.forEach(function(it) {
            if (it.statusCode != 200 && ignore_invalid == true) {return;}
            var jdata;
            if (it.statusCode == 200) {
                // parse json string
                try {
                    jdata = JSON.parse(it.body);
                    utils.deleteUselessItem(jdata, items_need);
                } catch (e) {
                    if (ignore_invalid == true) {return;}
                }
            }
            if (pattern) {
                if (jdata) {
                    objs[idx++][pattern] = jdata;
                } else {
                    objs[idx++][pattern] = null;
                }
            } else {
                if (jdata) {
                    objs[idx++] = jdata;
                } else {
                    objs[idx++] = null;
                }
            }
        });
        // ! RETURN HERE !
        callback(null, objs);
    });
    ep.fail(callback);
    for (var i = 0; i < objs.length; i++) {
        var uuid;
        if (pattern) {
            uuid = objs[i][pattern];
        } else {
            uuid = objs[i];
        }
        var api_uri = http_prefix + uuid;
        var cur_timestamp = Math.floor((new Date()).getTime() / 1000);
        var token = utils.generateAccessToken(
            headers.ApiCalleeId
            , headers.ApiAccessKey
            , cur_timestamp, api_uri, '', SECRET_KEY
        );
        var request_headers = {
            ApiRequestType: headers.ApiRequestType,
            ApiCalleeId: headers.ApiCalleeId,
            ApiAccessKey: headers.ApiAccessKey,
            ApiTimestamp: cur_timestamp,
            ApiToken: token,
        };
        // send request to query event details
        request({
            uri: CONFIG.API_ADDRESS + request_headers.ApiCalleeId + api_uri,
            method: "GET",
            timeout: 5000,
            followRedirect: false,
            headers: request_headers,
        }, ep.group(ep_idname));
    }
};

主要解决的问题是在于，针对数组中的每个对象里面存在我们想要的字段。
需要用到这个字段来进行去请求，才写出以下方法。

EventProxy原始链接

EventProxy原始链接