Journal¶

Journal(store, *, required=False, retries=2, backoff=0.05, timeout=30.0)

Where a call tree's kept log is written while it runs: a store, and how surely (configure(journal=Journal(store, required=True))).

Best effort (the default) never makes a call wait: if the store fails, FunctAI warns once and the log is kept as far as it could be. A required journal makes the call wait until every event so far is confirmed at three barriers: when it starts, before each tool runs, and before it returns. If the start or a tool is not confirmed, the call stops with JournalError (journal-barrier); if its end is not, the caller gets JournalError (journal-end) holding what the call did.

retries: how many times an append is sent again, in a row, when no answer came, waiting backoff seconds before the first resend and twice as long before each next one. timeout: the longest a barrier waits for an answer; past it, no answer came ("unknown": the store may still keep what it was sent). A store should also time out its own I/O. See Store for what a store answers.

A bare store is a best-effort journal: configure(journal=store). Two journals are the same when their store and mode are; when a program names its host's journal again, the host's timing applies.