AdaptiveQueryLimit

The bulkhead's limit, adapted to its store's write pressure (the writes come first), by additive increase and multiplicative decrease, one evaluate per period. The queries contend in a period when the limit held one back (it waited or was refused), or when it ends with queries waiting or running at the limit.

• AdaptiveLimitOptions.periods pressing periods in a row in which the queries contend: the limit halves, down to the floor, and the count starts over, so the next halving waits as long. A pressing period in which they do not contend leaves the limit as it is and starts the count over: lowering a limit the queries do not reach would relieve no write, and would hold back the next queries for writes that did not wait on them.

• A period that does not press: the limit rises by one, up to the bulkhead's ceiling when the queries contend, else up to the limit the bulkhead started with. So a limit lowered under load climbs back once the writes are calm, whether queries come or not; only a demand that the limit holds back takes it above its start, toward the ceiling, which is room for that demand rather than where an idle store rests.

• Otherwise it stays.

Lowering the limit cancels no running query (see QueryBulkhead.limit).