/*- * See the file LICENSE for redistribution information. * * Copyright (c) 2002,2008 Oracle. All rights reserved. * * $Id: KeySelector.java,v 1.1 2008/02/07 17:12:26 mark Exp $ */ package com.sleepycat.persist; /** * This is package-private to hide it until we implemented unsorted access. * * Implemented to select keys to be returned by an unsorted {@code * ForwardCursor}. * * <p>The reason for implementing a selector, rather than filtering the objects * returned by the {@link ForwardCursor}, is to improve performance when not * all keys are to be processed. Keys are passed to this interface without * retrieving record data or locking, so it is less expensive to return false * from this method than to retrieve the object from the cursor.</p> * * see EntityIndex#unsortedKeys * see EntityIndex#unsortedEntities * * @author Mark Hayes */ interface KeySelector<K> { /** * Returns whether a given key should be returned via the cursor. * * <p>This method should not assume that the given key is for a committed * record or not, nor should it assume that the key will be returned via * the cursor if this method returns true. The record for this key will * not be locked until this method returns. If, when the record is locked, * the record is found to be uncommitted or deleted, the key will not be * returned via the cursor.</p> */ boolean selectKey(K key); }