Refactor scheduled function execution to use explicit timing control

[ianmacartney]

Refactor scheduled function execution to use explicit scheduling instead of setTimeout

This change replaces the setTimeout-based scheduled function execution with an explicit scheduling system to reduce races from setTimeout.

Currently, scheduled functions can execute mid-transaction, especially if you don't mock timers.

Key Changes:

• Explicit execution control: Scheduled functions are no longer automatically executed via setTimeout. Instead, they are executed explicitly through finishInProgressScheduledFunctions() and finishAllScheduledFunctions()
• Function path resolution: Added scheduledFunctionPaths map to track resolved function paths for function handles that may target different components than where the job is stored.
• Improved timer compatibility: Adds an empty empty setTimeout call at the scheduled function time so vi.runAllTimers() still works to fast-forward time until all scheduled functions should be enqueued.
• Sequential execution: Functions are now executed one at a time in order of scheduled time, instead of previously where setTimeout could fire mid-transaction.

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📥 Commits

Reviewing files that changed from the base of the PR and between c94c792 and f9d337c.

📒 Files selected for processing (3)

• convex/scheduler.test.ts
• convex/scheduler.ts
• index.ts

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• Commit unit tests in branch ian/explicit-scheduler-queue

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[ianmacartney]

• Refactor scheduled function execution to use explicit timing control #82 👈 (View in Graphite)
• main

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commit: f9d337c

[ianmacartney]

For context, this approach pre-dated the AsyncLocalStorage overhaul, and was an alternative branch to ALS to solve the problem of serializing transactions. #112 is one such manifestation
It was updated to use ALS after rebasing.
After thinking more on it, I think we could leverage the new ALS-based transaction serialization, without serializing all scheduled functions manually like this.
In particular, serializing scheduled functions I think would deadlock for actions that schedule a function then poll for its completion.
Instead I think we could still use setTimeout, but have it call the serialized entrypoint, so if something is scheduled or executed during a transaction, it'll naturally wait until after the transaction finishes.
So I think it's worth exploring that direction so users don't have to run finishInProgressScheduledFunctions at all, which used to work in trivial cases only but now could work pretty fluidly.

cc @Nicolapps

[Nicolapps]

Replaced by #114