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.mob;
019
020import java.io.IOException;
021import java.util.concurrent.atomic.AtomicLong;
022import org.apache.hadoop.conf.Configuration;
023import org.apache.hadoop.fs.FileSystem;
024import org.apache.hadoop.fs.Path;
025import org.apache.hadoop.hbase.io.hfile.CacheConfig;
026import org.apache.hadoop.hbase.regionserver.BloomType;
027import org.apache.hadoop.hbase.regionserver.HStoreFile;
028import org.apache.yetus.audience.InterfaceAudience;
029
030/**
031 * Cached mob file.
032 */
033@InterfaceAudience.Private
034public class CachedMobFile extends MobFile implements Comparable<CachedMobFile> {
035
036  private long accessCount;
037  private AtomicLong referenceCount = new AtomicLong(0);
038
039  public CachedMobFile(HStoreFile sf) {
040    super(sf);
041  }
042
043  public static CachedMobFile create(FileSystem fs, Path path, Configuration conf,
044    CacheConfig cacheConf) throws IOException {
045    // XXX: primaryReplica is only used for constructing the key of block cache so it is not a
046    // critical problem if we pass the wrong value, so here we always pass true. Need to fix later.
047    HStoreFile sf = new HStoreFile(fs, path, conf, cacheConf, BloomType.NONE, true);
048    return new CachedMobFile(sf);
049  }
050
051  public void access(long accessCount) {
052    this.accessCount = accessCount;
053  }
054
055  @Override
056  public int compareTo(CachedMobFile that) {
057    if (this.accessCount == that.accessCount) return 0;
058    return this.accessCount < that.accessCount ? 1 : -1;
059  }
060
061  @Override
062  public boolean equals(Object obj) {
063    if (this == obj) {
064      return true;
065    }
066    if (obj == null) {
067      return false;
068    }
069    if (!(obj instanceof CachedMobFile)) {
070      return false;
071    }
072    return compareTo((CachedMobFile) obj) == 0;
073  }
074
075  @Override
076  public int hashCode() {
077    return (int) (accessCount ^ (accessCount >>> 32));
078  }
079
080  /**
081   * Opens the mob file if it's not opened yet and increases the reference. It's not thread-safe.
082   * Use MobFileCache.openFile() instead. The reader of the mob file is just opened when it's not
083   * opened no matter how many times this open() method is invoked. The reference is a counter that
084   * how many times this reader is referenced. When the reference is 0, this reader is closed.
085   */
086  @Override
087  public void open() throws IOException {
088    super.open();
089    referenceCount.incrementAndGet();
090  }
091
092  /**
093   * Decreases the reference of the underlying reader for the mob file. It's not thread-safe. Use
094   * MobFileCache.closeFile() instead. This underlying reader isn't closed until the reference is 0.
095   */
096  @Override
097  public void close() throws IOException {
098    long refs = referenceCount.decrementAndGet();
099    if (refs == 0) {
100      super.close();
101    }
102  }
103
104  /**
105   * Gets the reference of the current mob file. Internal usage, currently it's for testing.
106   * @return The reference of the current mob file.
107   */
108  public long getReferenceCount() {
109    return this.referenceCount.longValue();
110  }
111}