re-acquire global lock for transactions from scheduled fns

[ianmacartney]

Currently a scheduled function uses setTimeout, which can fire mid-way through a transaction if real timers are used.

And scheduling multiple functions can also race. This is because they detect the current global transaction lock and infer they're a nested transaction call.

This PR waits until the nested transaction has finished before starting the next scheduled function, allowing it to use the global transaction lock to serialize scheduled mutations, regardless of where they're scheduled from or whether real timers are used or not.

Fixes #112

Closes #82

[ianmacartney]

• re-acquire global lock for transactions from scheduled fns #114 👈 (View in Graphite)
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[coderabbitai]

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ℹ️ Recent review info

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Reviewing files that changed from the base of the PR and between 90cffdb and 7be113a.

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• index.ts

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📝 Walkthrough

Walkthrough

This PR replaces DatabaseFake’s listener-based scheduled-function completion with a per-test Scheduler that tracks fired scheduled-callback promises. setTimeout callbacks now run outside nested-transaction ALS via nestedTxStorage.exit and register their execution promises; scheduled-function state transitions are performed inline. finishInProgressScheduledFunctions and finishAllScheduledFunctions now drain the Scheduler while coordinating timer advancement. Added scheduler test helpers in convex/scheduler.ts and refactored scheduler tests to centralize fake/real timer lifecycle.

Sequence Diagram(s)

sequenceDiagram
  participant Test as Test Code
  participant Timer as setTimeout
  participant ALS as nestedTxStorage
  participant Scheduler as Scheduler
  participant DB as _scheduled_functions
  participant UDF as Scheduled UDF

  Test->>DB: schedule job (pending)
  DB->>Timer: setTimeout fires
  Timer->>ALS: exit() then invoke callback
  ALS->>Scheduler: add(executionPromise)
  Scheduler->>DB: read job row and patch pending->inProgress
  Scheduler->>UDF: invoke scheduled UDF
  UDF->>DB: patch inProgress->success | inProgress->failed
  UDF-->>Scheduler: executionPromise settles
  Scheduler->>Scheduler: remove(executionPromise)
  Test->>Scheduler: finishInProgressScheduledFunctions() awaits drain

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Possibly Related PRs

• get-convex/convex-test#77: Modifies index.ts scheduling and execution context handling—touches the same scheduling/control-flow code paths.
• get-convex/convex-test#69: Adds nestedTxStorage/AsyncLocalStorage and modifies TransactionManager to support nested execution impacting scheduled-callback ALS interactions.
• get-convex/convex-test#78: Adjusts finishAllScheduledFunctions and timer handling for orphaned-scheduled-function cleanup and overlaps with drain/timer coordination logic.

Suggested Reviewers

• Nicolapps

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: re-acquiring the global transaction lock for scheduled functions, which directly addresses the core issue of transaction state corruption when scheduled functions run.
Description check	✅ Passed	The description explains the problem (scheduled functions inheriting transaction locks, causing races), the solution (waiting for nested transactions to finish), and links to specific issues (#112, #82), all relevant to the changeset.
Linked Issues check	✅ Passed	The PR addresses both linked issues: #112 by preventing stale transaction state inheritance via explicit control of scheduled function execution timing, and #82 by implementing explicit scheduling via finishInProgressScheduledFunctions() and tracking in-flight executions without relying solely on setTimeout.
Out of Scope Changes check	✅ Passed	All changes are focused on the core objective: test refactoring to separate real/fake timer cases, new scheduler functions for testing, and rewriting scheduled execution tracking in index.ts to prevent transaction state inheritance through explicit async-local-storage exit before scheduling.

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✨ Finishing Touches

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• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ian/serialize-scheduled-functions

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[Nicolapps]

Thanks! This sounds much more simple than the previous fix