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?