callbackDepExec.js

// 业务方法定义
const getA = function(cb) {
    cb(a);
}

const getB = function(a, cb) {
    cb(b);
}

const getC = function(a, b, cb) {
    cb(c);
}

const getD = function(b, c, cb) {
    cb(d);
}

const getE = function(d, cb) {
    cb(d);
}

// 依赖关系定义
const depTree = {
    a: {
        deps: [],
        method: getA,
        retryLimit: 3,
    },
    b: {
        deps: ['a'],
        method: getB,
        retryLimit: 3,
    },
    c: {
        deps: ['a', 'b'],
        method: getC,
        retryLimit: 3,
    },
    d: {
        deps: ['b', 'c'],
        method: getD,
        retryLimit: 3,
    },
    main: {
        deps: ['d'],
        method: getE,
        retryLimit: 3,
    },
};

depExec(depTree, e => {
    console.log(e);
});

// TODO: 解析 depTree，尽可能并行地去拉取数据，对外返回 main 任务的 method 结果
function depExec(tree, cb) {
    // fill this
}