javascript - 在 Koa 发送响应后运行代码

Question

要优化响应延迟，有必要在将响应发送回客户端后执行工作。但是，我似乎可以让代码在发送响应后运行的唯一方法是使用 setTimeout。有没有更好的办法？也许在发送响应后在某个地方插入代码，或者在某个地方异步运行代码？

这是一些代码。

koa                  = require 'koa'
router               = require 'koa-router'

app = koa()

# routing
app.use router app

app
  .get '/mypath', (next) ->
    # ...
    console.log 'Sending response'

    yield next

    # send response???

    console.log 'Do some more work that the response shouldn\'t wait for'

Answer 1

不要调用 ctx.res.end()，它是 hacky 并且规避了 koa 的响应/中间件机制，这意味着你还不如使用 express。这是正确的解决方案，我也将其发布到 https://github.com/koajs/koa/issues/474#issuecomment-153394277

app.use(function *(next) {
  // execute next middleware
  yield next
  // note that this promise is NOT yielded so it doesn't delay the response
  // this means this middleware will return before the async operation is finished
  // because of that, you also will not get a 500 if an error occurs, so better log it manually.
  db.queryAsync('INSERT INTO bodies (?)', ['body']).catch(console.log)
})
app.use(function *() {
  this.body = 'Hello World'
})

不需要ctx.end()
所以简而言之，做

function *process(next) {
  yield next;
  processData(this.request.body);
}

不

function *process(next) {
  yield next;
  yield processData(this.request.body);
}