Storage

Kathikon v0.2.0 introduces a formal Kathikon.Storage behaviour. Mnesia remains the default backend (Kathikon.Storage.Mnesia), but the public API does not assume Mnesia.

Why a behaviour?

Alternate backends (ETS-only tests, future Postgres adapters) can implement the same atomic callbacks without changing dispatchers or management APIs.

Atomic operations

All lifecycle transitions (claim_job, complete_job, fail_job, retry_job, discard_job, cancel_job, move_to_dead_letter) run inside Mnesia transactions. Avoid read-then-update patterns across separate calls.

Result storage

Configure per job:

Kathikon.insert(MyWorker, args, result: :store)   # default
Kathikon.insert(MyWorker, args, result: :discard)

Errors are always stored in an inspectable form on the job record and in history events.

Mnesia term storage tradeoff

Jobs are serialized with :erlang.term_to_binary/1. This is fast and native on the BEAM, but:

• Payloads are not portable across languages
• Large or deeply nested terms increase memory and copy cost
• Untrusted binary input must never be decoded with :safe disabled

For cross-node clusters, keep args small and prefer IDs referencing external data.

Tables