Should ReadableStreams with pull sources call pull until full?

[jplaisted]

Quick question, there's probably already been a consensus on this but it looks like ReadableStreams with pull sources do not call pull until full, at least with the default controller.

IE given a high water mark of 3 chunks and a pull source a ReadableStream will only call pull once rather than three times, assuming no read requests.

I assume the internal queues are meant to act as buffers. So shouldn't a ReadableStream attempt to fill its buffer? Simple solution seems to be to get rid of the pullAgain variable and just always call callPullIfNeeded after a successful pull.

[domenic]

Pull is called three times in your example. You can run the following code in Chrome Canary (or with the reference implementation) to confirm:

let counter = 0;
const rs = new ReadableStream({
    pull(c) {
        c.enqueue("a");
        console.log(`pull called ${++counter} times`);
    }
}, {
    highWaterMark: 3
});

This is tested in the web-platform-test general.js, "ReadableStream: should call pull after enqueueing from inside pull (with no read requests), if strategy allows".

Going to close since this doesn't appear to be an issue, but happy to continue discussing and will reopen if I missed something!

[jplaisted]

Yep my mistake. Reading through the spec I must have missed 3.9.5. step 6 (call pull again if needed after enqueue).

https://streams.spec.whatwg.org/#enqueue-in-readable-stream