pub fn checkpoint_once(pool: &ConnectionPool) -> CheckpointTickExpand description
Issue one checkpoint cycle against the writer connection.
Returns CheckpointTick::Skipped when the writer mutex is already held
(the tick is a no-op) and CheckpointTick::Observed with the WAL page
count otherwise. All checkpoint errors are logged at warn level and treated
as non-fatal; the next tick retries.
Uses try_writer_nowait so that a busy active writer causes this tick to
be skipped immediately rather than stalling for up to checkout_timeout.
The caller (run_checkpoint_task) owns all threshold-crossing WARN logging
so that warnings fire at most once per crossing, not every tick.