如何将函数/回调传递给Node.js中的子进程？ [英] How to pass function/callback to child process in Node.js?

问题描述

假设我有一个 parent.js ，其中包含名为 parent

Let's say I have a parent.js containing a method named parent

var childProcess = require('child_process');

var options = {
    someData: {a:1, b:2, c:3},
    asyncFn: function (data, callback) { /*do other async stuff here*/ }
};

function Parent(options, callback) {
    var child = childProcess.fork('./child');
    child.send({
        method: method,
        options: options
    });
    child.on('message', function(data){
        callback(data,err, data,result);
        child.kill();
    });
}

同时在 child.js

process.on('message', function(data){
    var method = data.method;
    var options = data.options;
    var someData = options.someData;
    var asyncFn = options.asyncFn; // asyncFn is undefined at here
    asyncFn(someData, function(err, result){
        process.send({
            err: err,
            result: result
        });
    });
});

我想知道Node.js中是否允许将函数传递给子进程。

I was wondering if passing functions to child process is not allowed in Node.js.

为什么 asyncFn 在发送到<$后变为 undefined c $ c>孩子？

Why would asyncFn become undefined after it is sent to the child?

是否与 JSON.stringify 有关？

推荐答案

JSON不支持序列化功能（至少开箱即用）。您可以先将函数转换为其字符串表示形式（通过 asyncFn.toString（）），然后在子进程中再次重新创建该函数。问题是你在这个过程中失去了范围和上下文，所以你的函数必须是独立的。

JSON doesn't support serializing functions (at least out of the box). You could convert the function to its string representation first (via asyncFn.toString()) and then re-create the function again in the child process. The problem though is you lose scope and context with this process, so your function really has to be standalone.

完整的例子：

parent.js ：

var childProcess = require('child_process');

var options = {
  someData: {a:1, b:2, c:3},
  asyncFn: function (data, callback) { /*do other async stuff here*/ }
};
options.asyncFn = options.asyncFn.toString();

function Parent(options, callback) {
  var child = childProcess.fork('./child');
  child.send({
    method: method,
    options: options
  });
  child.on('message', function(data){
    callback(data,err, data,result);
    child.kill();
  });
}

child.js ：

process.on('message', function(data){
  var method = data.method;
  var options = data.options;
  var someData = options.someData;
  var asyncFn = new Function('return ' + options.asyncFn)();
  asyncFn(someData, function(err, result){
    process.send({
      err: err,
      result: result
    });
  });
});

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