001/*
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one
004 * or more contributor license agreements.  See the NOTICE file
005 * distributed with this work for additional information
006 * regarding copyright ownership.  The ASF licenses this file
007 * to you under the Apache License, Version 2.0 (the
008 * "License"); you may not use this file except in compliance
009 * with the License.  You may obtain a copy of the License at
010 *
011 *     http://www.apache.org/licenses/LICENSE-2.0
012 *
013 * Unless required by applicable law or agreed to in writing, software
014 * distributed under the License is distributed on an "AS IS" BASIS,
015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
016 * See the License for the specific language governing permissions and
017 * limitations under the License.
018 */
019package org.apache.hadoop.hbase.regionserver;
020
021import java.io.IOException;
022
023import org.apache.commons.lang3.NotImplementedException;
024import org.apache.yetus.audience.InterfaceAudience;
025import org.apache.hadoop.fs.Path;
026import org.apache.hadoop.hbase.Cell;
027import org.apache.hadoop.hbase.client.Scan;
028
029/**
030 * A "non-lazy" scanner which always does a real seek operation. Most scanners
031 * are inherited from this class.
032 */
033@InterfaceAudience.Private
034public abstract class NonLazyKeyValueScanner implements KeyValueScanner {
035
036  @Override
037  public boolean requestSeek(Cell kv, boolean forward, boolean useBloom)
038      throws IOException {
039    return doRealSeek(this, kv, forward);
040  }
041
042  @Override
043  public boolean realSeekDone() {
044    return true;
045  }
046
047  @Override
048  public void enforceSeek() throws IOException {
049    throw new NotImplementedException("enforceSeek must not be called on a " +
050        "non-lazy scanner");
051  }
052
053  public static boolean doRealSeek(KeyValueScanner scanner,
054      Cell kv, boolean forward) throws IOException {
055    return forward ? scanner.reseek(kv) : scanner.seek(kv);
056  }
057
058  @Override
059  public boolean shouldUseScanner(Scan scan, HStore store, long oldestUnexpiredTS) {
060    // No optimizations implemented by default.
061    return true;
062  }
063
064  @Override
065  public boolean isFileScanner() {
066    // Not a file by default.
067    return false;
068  }
069
070
071  @Override
072  public Path getFilePath() {
073    // Not a file by default.
074    return null;
075  }
076
077  @Override
078  public Cell getNextIndexedKey() {
079    return null;
080  }
081
082  @Override
083  public void shipped() throws IOException {
084    // do nothing
085  }
086}