以同步的方式执行异步调用 [英] Executing asynchronous calls in a synchronous manner

问题描述

我一直在试图总结我的头解决这个问题的最后几个小时，但不能弄明白。我想我还是要习惯的函数式编程风格;）

我写道，通过目录结构和遍历做事某些文件递归函数。该功能使用异步IO的方法。现在，我想执行的时候这整个穿越是做了一些动作。

我将如何确保这一行动已经完成所有解析来电之后进行，但仍然使用异步IO功能？

 变种FS =要求（FS），
    PATH =要求（'路径'）;功能解析（DIR）{
    fs.readdir（DIR，函数（ERR文件）{
        如果（ERR）{
            console.error（ERR）;
        }其他{
            // F =文件名，P =路径
            VAR每个=功能（F，P）{
                返回功能（ERR，统计数据）{
                    如果（ERR）{
                        console.error（ERR）;
                    }其他{
                        如果（stats.isDirectory（））{
                            解析（P）;
                        }否则如果（stats.isFile（））{
                            //做一些东西
                        }
                    }
                };
            };            VAR我;
            对于（i = 0; I＆LT; files.length;我++）{
                变种F =文件[I]
                VAR P = path.join（DIR，F）;
                fs.stat（P，每个（F，P））;
            }
        }
    }）;
}解析（'。'）;//做一些东西在这里当异步解析完全汉化
 

解决方案

查找步骤模块。它可以异步链函数的调用，并通过从一个结果到另一个。

I've been trying to wrap my head around this issue for the last hours but can't figure it out. I guess I still have to get used to the functional programming style ;)

I wrote a recursive function that traverses through a directory structure and does things to certain files. This functions uses the asynchronous IO methods. Now I want to perform some action when this whole traversing is done.

How would I make sure that this action is performed after all parse calls have been performed but still use the asynchronous IO functions?

var fs = require('fs'),
    path = require('path');

function parse(dir) {
    fs.readdir(dir, function (err, files) {
        if (err) {
            console.error(err);
        } else {                
            // f = filename, p = path
            var each = function (f, p) {
                return function (err, stats) {
                    if (err) {
                        console.error(err);
                    } else {
                        if (stats.isDirectory()) {
                            parse(p);
                        } else if (stats.isFile()) {
                            // do some stuff
                        }
                    }
                };
            };

            var i;
            for (i = 0; i < files.length; i++) {
                var f = files[i];
                var p = path.join(dir, f);
                fs.stat(p, each(f, p));
            }
        }
    });
}

parse('.');

// do some stuff here when async parse completely finished

解决方案

Look for Step module. It can chain asynchronous functions calls and pass results from one to another.

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