stream: How to destroy and stop Readable?

[ronag]

I ran into this today:

const { Readable } = require('stream');

const someOtherResource = {
  doStuff () {
    if (this.destroyed) {
      throw new Error('destroyed!')
    }
  },
  destroy () {
    this.destroyed = true
  }
}

const r = new Readable({})

r.on('data', () => {
  someOtherResource.doStuff()
})
someOtherResource.destroy()
r.push('asd')
r.destroy() // or r.destroy(new Error('kaboom'))
r.read()

This will crash with destroyed! since read() will emit already buffered 'data' even though the stream is destroyed.

I can fix my above example by replacing r.destroy() with:

function destroy (r) {
  r.removeAllListeners('data')
  r.destroy()
}

I find this a bit unfortunate.

Questions:

• Is this expected behaviour?
• Can we fix it without breaking the ecosystem?
• If no, can we provide another method to Readable that makes it possible to fully destroy and silence a readable?

In order to fix this in readable we would have to check for destroyed and return early inside Readable.read().

[ronag]

@jasnell maybe?