001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.wal;
019
020import java.io.EOFException;
021import java.io.IOException;
022import org.apache.hadoop.conf.Configuration;
023import org.apache.hadoop.fs.FileSystem;
024import org.apache.hadoop.fs.Path;
025import org.apache.hadoop.hbase.wal.WAL.Entry;
026import org.slf4j.Logger;
027import org.slf4j.LoggerFactory;
028
029/**
030 * A helper class for writing UTs, where we will eat the EOF and return null when reaching EOF, so
031 * in UTs we do not need to deal with partial WAL files if this does not affect the correctness. In
032 * production code you usually you should not do this, as it may cause data loss if you always
033 * ignore the EOFException.
034 */
035public final class NoEOFWALStreamReader implements WALStreamReader {
036
037  private static final Logger LOG = LoggerFactory.getLogger(NoEOFWALStreamReader.class);
038
039  private WALStreamReader reader;
040
041  private NoEOFWALStreamReader(WALStreamReader reader) {
042    this.reader = reader;
043  }
044
045  @Override
046  public Entry next(Entry reuse) throws IOException {
047    try {
048      return reader.next(reuse);
049    } catch (EOFException e) {
050      LOG.warn("Got EOF while reading", e);
051      return null;
052    }
053  }
054
055  @Override
056  public long getPosition() throws IOException {
057    return reader.getPosition();
058  }
059
060  @Override
061  public void close() {
062    reader.close();
063  }
064
065  private int count() throws IOException {
066    int count = 0;
067    Entry entry = new Entry();
068    while (next(entry) != null) {
069      count++;
070    }
071    return count;
072  }
073
074  public static NoEOFWALStreamReader create(FileSystem fs, Path path, Configuration conf)
075    throws IOException {
076    return new NoEOFWALStreamReader(WALFactory.createStreamReader(fs, path, conf));
077  }
078
079  public static NoEOFWALStreamReader create(WALFactory walFactory, FileSystem fs, Path path)
080    throws IOException {
081    return new NoEOFWALStreamReader(walFactory.createStreamReader(fs, path));
082  }
083
084  public static int count(FileSystem fs, Path path, Configuration conf) throws IOException {
085    try (NoEOFWALStreamReader reader = create(fs, path, conf)) {
086      return reader.count();
087    }
088  }
089
090  public static int count(WALFactory walFactory, FileSystem fs, Path path) throws IOException {
091    try (NoEOFWALStreamReader reader = create(walFactory, fs, path)) {
092      return reader.count();
093    }
094  }
095}