hyracks/hyracks-storage-am-common/src/main/java/edu/uci/ics/hyracks/storage/am/common/api/IModificationOperationCallback.java

/*
 * Copyright 2009-2013 by The Regents of the University of California
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * you may obtain a copy of the License from
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package edu.uci.ics.hyracks.storage.am.common.api;

import edu.uci.ics.hyracks.api.exceptions.HyracksDataException;
import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;

/**
 * This operation callback allows for arbitrary actions to be taken while traversing 
 * an index structure. The {@link IModificationOperationCallback} will be called on 
 * all modifying operations (e.g. insert, update, delete...) for all indexes.
 * 
 * @author zheilbron
 */
public interface IModificationOperationCallback {

    /**
     * This method is called on a tuple that is about to traverse an index's structure 
     * (i.e. before any pages are pinned or latched). 
     *
     * The format of the tuple is the format that would be stored in the index itself.
     * 
     * @param tuple the tuple that is about to be operated on
     */
    public void before(ITupleReference tuple) throws HyracksDataException;

    /**
     * This method is called on a tuple when a tuple with a matching key is found for the 
     * current operation. It is possible that tuple is null, in which case no tuple with a 
     * matching key was found.
     * 
     * When found is called, the leaf page where the tuple resides will be pinned and latched, 
     * so blocking operations should be avoided.
     * 
     * @param tuple a tuple with a matching key, otherwise null if none exists
     */
    public void found(ITupleReference before, ITupleReference after) throws HyracksDataException;
}