fix(sdk): cloud.Queue is not FIFO by default

[Chriscbr]

Related to #3897

We have a flakey test in our CI that validates part of the functionality of cloud.Queue. It turns out, our test was assuming that the queue messages are received in FIFO order (first-in-first-out), which wasn't something we meant to guarantee (see the original issue about queue.pop() here). This PR fixes the test, and updates the simulator implementation to reflect the fact that messages can be received out of order.

(Why not FIFO by default? For many distributed apps, the exact order of messages isn't critical, and relaxing this constraint makes it easier to handle higher throughputs of messages. That said, adding a fifo option to cloud.Queue would be reasonable as a future enhancement)

Checklist

• Title matches Winglang's style guide
• Description explains motivation and solution
• Tests added (always)
• Docs updated (only required for features)
• Added pr/e2e-full label if this feature requires end-to-end testing

By submitting this pull request, I confirm that my contribution is made under the terms of the Wing Cloud Contribution License.

[monadabot]

Console preview environment is available at https://wing-console-pr-4173.fly.dev 🚀

Updated (UTC): 2023-09-13 15:39

[hasanaburayyan]

Do you mind adding a quick snippet to https://www.winglang.io/docs/standard-library/cloud/queue about queues not being FIFO?

I was going to open a PR but wonder if we can just sneak it in here? I dont mind doing it separately either.

[Chriscbr]

@hasanaburayyan good idea - done 👍

[garysassano]

That said, adding a fifo option to cloud.Queue would be reasonable as a future enhancement

Wouldn't it be better to add this option already? So we can reuse existing code instead of eliminating it.

[mergify]

Thanks for contributing, @Chriscbr! This PR will now be added to the merge queue, or immediately merged if rybickic/fix-queue-sim is up-to-date with main and the queue is empty.

[monadabot]

Congrats! 🚀 This was released in Wing 0.30.7.