Store¶

Store()

What a journal needs of a store (streaming.md, The rules a store keeps).

append(event) keeps one event and answers "kept" or "duplicate", or raises EventRefused (event-malformed, event-conflict, event-gap, event-after-end, event-start). Any other answer is taken as a refusal; any other exception means no answer came (the event may have been kept: it is sent again). read(tree, after) gives the kept events after a position (all of them after None), or raises EventRefused("event-unknown").

A store may also have extend(events) (a batch of one log, kept whole or not at all), and the writer then sends every event through it, what waits as one batch, when extend is defined where append is or further down (a subclass that changes only append is sent every event alone, through it; one that changes only extend, every event through it, a lone one as a batch of one); batches = True or False says so outright. And claim(tree) (a later writer's claim, which fences earlier writers; JournalError.settle(claim=True) needs it). A store times out its own I/O; a journal also stops waiting at its barriers after its timeout.