Node.js Stream Transform是否保持块的顺序? [英] Does Node.js Stream Transform maintain the order of the chunks?
问题描述
我看到,Node.js Stream API中的Transform Streams使用异步函数在块到达时转换块:
https://nodejs.org/api/stream.html#stream_transform_transform_chunk_encoding_callback
I see in that the Transform Streams in the Node.js Stream API uses an asynchronous function to transform the chunks when they arrive: https://nodejs.org/api/stream.html#stream_transform_transform_chunk_encoding_callback
转换流是否发送他们到达时的顺序是多少?因为使用异步函数,这不是明确的情况。
Does the Transform stream sends the chunks at the same order as they arrive? Because with an asynchronous function, that is not explicitly the case.
推荐答案
简短回答是:是的,转换流保证以相同的顺序发送块。 (因为Streams可能用于顺序敏感操作(用于加密或压缩 - 解压缩文件)
Short answer is: yes, transform stream guaranties that chunks are sent in the same order. (Because Streams might be used for order-sensative operations (for cryptography, or zipping-unzipping files)
这是一个可以运行的剪切,以确保:
Here is a snipped that you could run to make sure:
const {Transform} = require('stream');
const _ = require('lodash');
const h = require('highland');
const myTransform = new Transform({
transform(chunk, encoding, callback) {
//Callback fires in a random amount of time 1-500 ms
setTimeout(() => callback(null, chunk), _.random(1, 500));
},
//Using objectMode to pass-trough Numbers, not strings/buffers
objectMode: true
});
//I'm using 'highland' here to create a read stream
//The read stream emits numbers from 1 to 100
h(_.range(1, 100))
.pipe(myTransform)
//Simply logging them as they go out of transform stream
.on('data', chunk => console.log(chunk.toString()));
//The output is:
// 1
// 2
// 3
// 4 ...
//Although the callbacks fire in random order
这篇关于Node.js Stream Transform是否保持块的顺序?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!