public static Engine createSnapshotFor(Engine engine) {
if (engine.isReadOnly()) return engine;
if (engine instanceof TxEngine) return ((TxEngine) engine).snapshot();
if (engine instanceof EngineWrapper)
createSnapshotFor(((EngineWrapper) engine).getWrappedEngine());
throw new UnsupportedOperationException(
"Snapshots are not enabled, use DBMaker.snapshotEnable()");
}
/**
* Make readonly snapshot view of DB and all of its collection Collections loaded by this instance
* are not affected (are still mutable). You have to load new collections from DB returned by this
* method
*
* @return readonly snapshot view
*/
public synchronized DB snapshot() {
Engine snapshot = TxEngine.createSnapshotFor(engine);
return new DB(snapshot);
}