NewCursors ctor.

NewEventStorage ctor.

NewIDGenerator ctor.

NewKeyGenerator ctor.

NewMetrics ctor.

CursorStorage persists and retrieves cursors.

EventsIterator is used to iterate over events in the log.

EventStorage persists and retrieves events.

IDGenerator is used to create sortable and collision free IDs for events.

KeyGenerator creates key-value store keys from domain models.

LevelDB interface is only used for testing purposes.

Metrics provides metrics over the storage performance.