嵌套节点async.eachSeries [英] Nesting node async.eachSeries

问题描述

与异步模块争夺了半天但是在嵌套几个级别时无法使其正常工作。

Been fighting with async module for half a day but can't get it to work properly when nesting few levels.

所以这样可行：

    var async = require('async')

    var myarr = ["Outer - A", "Outer - B"];
    var myarr2 = ["Inner - A", "Inner - B"];
    var innerComplete = true;

    async.eachSeries(myarr, function( item, outerCallback) {
        console.log('Processing item ' + item);
        async.series([
            function(callback) {
                takeTime(2000, item, callback)
            },
            function(callback) {
                takeTime(1000, item, callback)
            },
            function(callback) {


                outerCallback();
            }
        ], function(err) {
            console.log("---OUTER SEQUENCE---")

        })
    }, function(err){
        console.log("---OUTER LOOP---")

    });

    function takeTime(ms, msg, callback) {
        console.log("Starting " + ms + " ms task from " + msg);
        setTimeout( function() { 
            console.log("Finished " + ms + " ms task from " + msg);
            callback();
        }, ms);
    } 

它按顺序输出一切顺序如下：

And it outputs everything nicely in sequence like this:

Processing item Outer - A
Starting 2000 ms task from Outer - A
Finished 2000 ms task from Outer - A
Starting 1000 ms task from Outer - A
Finished 1000 ms task from Outer - A
Processing item Outer - B
Starting 2000 ms task from Outer - B
Finished 2000 ms task from Outer - B
Starting 1000 ms task from Outer - B
Finished 1000 ms task from Outer - B
---OUTER LOOP---

但当我尝试将另一个eachSeries循环嵌入其中时：

But when I try to nest another eachSeries loop into it like this:

    var async = require('async')

    var myarr = ["Outer - A", "Outer - B"];
    var myarr2 = ["Inner - A", "Inner - B"];
    var innerComplete = true;

    async.eachSeries(myarr, function( item, outerCallback) {
        console.log('Processing item ' + item);
        async.series([
            function(callback) {
                takeTime(2000, item, callback)
            },
            function(callback) {
                takeTime(1000, item, callback)
            },
            function(callback) {
                async.eachSeries(myarr2, function( item2, outerCallback2) {
                    console.log('Processing item ' + item2);
                    async.series([
                        function(callback2) {
                            takeTime(2000, item2, callback2)
                        },
                        function(callback2) {
                            takeTime(1000, item2, callback2)
                        }
                    ], function(err) {
                        console.log('---INNER SEQUENCE---')

                    })
                }, function(err){
                    console.log("---INNER LOOP---")
                });

                outerCallback();
            }
        ], function(err) {
            console.log("---OUTER SEQUENCE---")

        })
    }, function(err){
        console.log("---OUTER LOOP---")

    });

    function takeTime(ms, msg, callback) {
        console.log("Starting " + ms + " ms task from " + msg);
        setTimeout( function() { 
            console.log("Finished " + ms + " ms task from " + msg);
            callback();
        }, ms);
    } 

在输入第二个eachSeries循环时丢失执行顺序如下：

It loses the execution order when entering the second eachSeries loop like this:

Processing item Outer - A
Starting 2000 ms task from Outer - A
Finished 2000 ms task from Outer - A
Starting 1000 ms task from Outer - A
Finished 1000 ms task from Outer - A
Processing item Inner - A
Starting 2000 ms task from Inner - A
Processing item Outer - B
Starting 2000 ms task from Outer - B
Finished 2000 ms task from Inner - A
Starting 1000 ms task from Inner - A
Finished 2000 ms task from Outer - B
Starting 1000 ms task from Outer - B
Finished 1000 ms task from Inner - A
---INNER SEQUENCE---
Finished 1000 ms task from Outer - B
Processing item Inner - A
Starting 2000 ms task from Inner - A
---OUTER LOOP---
Finished 2000 ms task from Inner - A
Starting 1000 ms task from Inner - A
Finished 1000 ms task from Inner - A
---INNER SEQUENCE---

我也尝试过瀑布，mapSeries等，但是使用相同或其他混乱的执行顺序。我做错了什么或异步模块不支持这样的嵌套？

I also tried out waterfall, mapSeries etc, but with same or otherwise messed up sequence of execution. Am I doing something wrong or doesn't the async module support such nesting?

推荐答案

你没有调用 outerCallback2 ，你没有调用回调，而你正在调用 outerCallback 立即。

You're not calling the outerCallback2, you're not calling the callback, and you're calling the outerCallback immediately.

修正：

async.eachSeries(myarr, function( item, outerCallback) {
  ,----------------------------------------'
  |  console.log('Processing item ' + item);
  |  async.series([
  |      function(callback) {
  |                 `--------------,
  |          takeTime(2000, item, callback)
  |      },
  |      function(callback) {
  |                 `--------------,
  |          takeTime(1000, item, callback)
  |      },
  |      function(callback) {
  |     ,-----------'
  |     |     async.eachSeries(myarr2, function( item2, outerCallback2) {
  |     |    ,---------------------------------------------'
  |     |    |   console.log('Processing item ' + item2);
  |     |    |   async.series([
  |     |    |      function(callback2) {
  |     |    |          takeTime(2000, item2, callback2)
  |     |    |      },
  |     |    |      function(callback2) {
  |     |    |          takeTime(1000, item2, callback2)
  |     |    |      }
  |     |    |  ], function(err) {
  |     |    |      console.log('---INNER SEQUENCE---')
  |     |    `--->  outerCallback2(err); // <<<
  |     |       })
  |     |   }, function(err){
  |     |      console.log("---INNER LOOP---");
  |     `--->  callback(err); // <<<
  |         });
  |     }
  | ], function(err) {
  |      console.log("---OUTER SEQUENCE---")
  `--->  outerCallback(err); // <<<
    })
}, function(err){
    console.log("---OUTER LOOP---")
    console.log("everything done");
});

这篇关于嵌套节点async.eachSeries的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！