Function collapseOpLog

onecache/replicator.go:420–446

Collapses the passed operation log returning the final replication task.

(log []replicationTask)

// Collapses the passed operation log returning the final replication task.
func collapseOpLog(log []replicationTask) (replicationTask, error) {
	if len(log) == 0 {
		return task_DIRTY_VALUE, errors.New("can not collapse empty operation log")
	}

	op := log[0]
	for _, s := range log[1:] {
		switch s {
		case task_DELETE:
			if op == task_DELETE {
				return task_DIRTY_VALUE, errors.New("invalid op log: two deletes in a row")
			}

			op = s
		case task_DIRTY_VALUE:
			op = s
		case task_TOUCH:
			if op == task_DELETE {
				return task_DIRTY_VALUE, errors.New("invalid op log: metadata can not be marked dirty after the key has been deleted")
			}
		case task_BACKFILL:
			op = s
		}
	}

	return op, nil
}