Koa.js和流媒体.你如何处理错误

Question

有人使用koa.js和streams吗？

考虑这个例子

const fs = require('fs');
const Koa = require('koa');
const app = new Koa();
app.use(async (ctx) => {
  ctx.body = fs.createReadStream('really-large-file');
});
app.listen(4000);

如果用户中止请求，我收到

  Error: read ECONNRESET
      at _errnoException (util.js:1024:11)
      at TCP.onread (net.js:618:25)

或

  Error: write EPIPE
      at _errnoException (util.js:1024:11)
      at WriteWrap.afterWrite [as oncomplete] (net.js:870:14)

处理此类错误的正确方法是什么？

附言请求中止后我没有错误

const fs = require('fs');
const express = require('express');
const app = express();
app.get('/', (req, res) => {
  fs.createReadStream('really-large-file').pipe(res);
});
app.listen(4000);

附言我试过了

app.use(async (ctx) => {
  fs.createReadStream('really-large-file').pipe(ctx.res);
  ctx.respond = false;
});

但它没有效果。

Answer 1

使用 gloabel 错误处理程序。 请参阅 https://github.com/koajs/koa/wiki/Error-Handling

const fs = require('fs');
const Koa = require('koa');
const app = new Koa();

app.use(async (ctx, next) => {
  try {
    await next();
  } catch (err) {
    ctx.status = err.status || 500;
    ctx.body = err.message;
    ctx.app.emit('error', err, ctx);
  }
});
app.use(async (ctx) => {
  ctx.body = await openFile();
});
function openFile(){
  return new Promise((resolve,reject)=>{
    var stream = fs.createReadStream("really-large-file")
    var data
    stream.on("error",err=>reject(err))
    stream.on("data",chunk=>data+=chunk)
    stream.on("end",()=>resolve(data))
  })
}
app.listen(4000);