Nodejs学习笔记-异步流程控制

安装async

npm install async --g
报错：npm: relocation error: npm: symbol SSL_set_cert_cb, version libssl.so.10 not defined in file libssl.so.10 with link time reference
解决办法：yum -y install openssl
报错：Error: Cannot find module 'async'
解决办法：修改/etc/profile，export NODE_PATH=/usr/lib/node_modules/，source /etc/profile

代码：https://github.com/fengchunjian/nodejs_examples/tree/master/async

交叉执行

//normal.js
function oneFun() {
    ii = 0;
    setInterval(function() {
        console.log("aaa=" + new Date());
        ii++;
        if (ii == 3) {
            clearInterval(this);
        }
    }, 1000);
    console.log("oneFun执行完毕");
}

function twoFun() {
    jj = 0;
    setInterval(function() {
        console.log("bbb=" + new Date());
        jj++;
        if (jj == 3) {
            clearInterval(this);
        }
    }, 1000);
    console.log("twoFun执行完毕");
}

oneFun();
console.log("oneFun执行");
twoFun();
console.log("twoFun执行");
console.log("主进程执行完毕");

串行无关联

//series.js
var async = require("async");

function exec() {
    async.series({
        one : function(done) {
            ii = 0;
            setInterval(function() {
                console.log("aaa=" + new Date());
                ii++;
                if (ii == 3) {
                    clearInterval(this);
                    //done("出错", {one:"one执行完毕"});
                    done(null, {one:"one执行完毕"});
                }
            }, 1000);
        },
        two : function(done) {
            jj = 0;
            setInterval(function() {
                console.log("bbb=" + new Date());
                jj++;
                if (jj == 3) {
                    clearInterval(this);
                    done(null, {two:"two执行完毕"});
                }
            }, 1000);
        }
    }, function(err, rs) {
        console.log(err);
        console.log(rs);
    });
}

exec();
console.log("主进程执行完毕");

并行无关联

//parallel.js
var async = require("async");

function exec() {
    async.parallel({
        one : function(done) {
            ii = 0;
            setInterval(function() {
                console.log("aaa=" + new Date());
                ii++;
                if (ii == 3) {
                    clearInterval(this);
                    //done("出错", {one:"one执行完毕"});
                    done(null, {one:"one执行完毕"});
                }
            }, 1000);
        },
        two : function(done) {
            jj = 0;
            setInterval(function() {
                console.log("bbb=" + new Date());
                jj++;
                if (jj == 5) {
                    clearInterval(this);
                    done(null, {two:"two执行完毕"});
                }
            }, 1000);
        }
    }, function(err, rs) {
        console.log(err);
        console.log(rs);
    });
}

exec();
console.log("主进程执行完毕");

串行有关联

//waterfall.js
var async = require("async");

function exec() {
    async.waterfall([
        function(done) {
            ii = 0;
            setInterval(function() {
                console.log("aaa=" + new Date());
                ii++;
                if (ii == 3) {
                    clearInterval(this);
                    done(null, "one执行完毕");
                }
            }, 1000);
        },
        function(preValue, done) {
            jj = 0;
            setInterval(function() {
                console.log(preValue + ", bbb=" + new Date());
                jj++;
                if (jj == 5) {
                    clearInterval(this);
                    done(null, preValue + ", two执行完毕");
                }
            }, 1000);
        }
    ], function(err, rs) {
        console.log(err);
        console.log(rs);
    });
}

exec();
console.log("主进程执行完毕");

补充

串行无关联：aaa出错，bbb不会执行
并行无关联：aaa出错，bbb继续执行但不执行回调

参考文档

nodejs13_异步流程控制(n13_async)
http://www.yuankuwang.com/web/index.php?r=respool/resview&rpid=46
node.js教程13_异步流程控制(上)
http://edu.51cto.com/center/course/lesson/index?id=124538