feat(NODE-6258): add signal support to find and aggregate

[nbbeeken]

Description

What is changing?

• Adds signal support to cursor APIs
  • This now attaches a signal to an operation which is used the following steps:
    • surrounding autoConnect (not interrupting)
    • server selection
    • connection checkout
    • connection r/w
    • connection encrypt/decrypt (kms request and fetchCollectionInfo interrupt)

Is there new documentation needed for these changes?

Yes, API docs.

What is the motivation for this change?

AbortController/AbortSignal has become the defacto interruption mechanism for async operations. We're starting small by linking an abort signal to the lifetime of a cursor so that .next() / toArray() / for-await usage can be interrupted by external means.

Release Highlight

🧪 Experimental AbortSignal support added to Find and Aggregate! 🚥

A signal argument can now be passed to the following APIs:

• collection.find() & collection.findOne()
• collection.aggregate() & collection.countDocuments()

In order to support field level encryption properly, also:

• db.listCollections()
• db.command()

When aborted, the signal will interrupt the execution of each of each of these APIs. For the cursor-based APIs, this will be observed when attempting to consume from the cursor via toArray(), next(), for-await, etc.

There is a known limitation: aborting a signal closes a perfectly healthy connection which can cause unnecessary connection reestablishment so we're releasing this as experimental for evaluation in use cases that can tolerate the shortcoming.

Double check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[baileympearson]

Just some minor clarification