Task Queue#

Background job processing with real cancellation and easy testing.

The Problem#

Background jobs need retries, timeouts, and error handling. In vanilla TypeScript:

• Promise.race doesn't actually cancel the losing promise
• Dependencies are hardcoded, making tests awkward
• Error context gets lost after retries

Run Both Versions#

bun run examples/task-queue/without-purus.ts
bun run examples/task-queue/with-purus.ts

Without purus#

See without-purus.ts:

• Promise.race for timeout (but the job keeps running!)
• Hardcoded logger - can't mock without a DI framework
• Errors are unknown after retry exhaustion

With purus#

See with-purus.ts:

• timeout() returns cleanup function - job actually stops
• provide(env) injects dependencies - swap for tests
• Typed errors preserved through the pipeline

Key Takeaways#

• Return a cleanup function from async() for real cancellation
• provide() makes testing easy without frameworks
• catchAll() preserves error context