hdfs/src/java/org/apache/hadoop/hdfs/server/namenode/FileJournalManager.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 at
 *
 *     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 org.apache.hadoop.hdfs.server.namenode;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.File;
import java.io.IOException;
import java.util.List;

import org.apache.hadoop.fs.FileUtil;
import org.apache.hadoop.hdfs.server.common.Storage.StorageDirectory;
import org.apache.hadoop.hdfs.server.namenode.FSImageTransactionalStorageInspector.FoundEditLog;
import org.apache.hadoop.hdfs.server.namenode.NNStorageRetentionManager.StoragePurger;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;

/**
 * Journal manager for the common case of edits files being written
 * to a storage directory.
 * 
 * Note: this class is not thread-safe and should be externally
 * synchronized.
 */
class FileJournalManager implements JournalManager {
  private static final Log LOG = LogFactory.getLog(FileJournalManager.class);

  private final StorageDirectory sd;
  private int outputBufferCapacity = 512*1024;

  public FileJournalManager(StorageDirectory sd) {
    this.sd = sd;
  }

  @Override
  public EditLogOutputStream startLogSegment(long txid) throws IOException {    
    File newInProgress = NNStorage.getInProgressEditsFile(sd, txid);
    EditLogOutputStream stm = new EditLogFileOutputStream(newInProgress,
        outputBufferCapacity);
    stm.create();
    return stm;
  }

  @Override
  public void finalizeLogSegment(long firstTxId, long lastTxId)
      throws IOException {
    File inprogressFile = NNStorage.getInProgressEditsFile(
        sd, firstTxId);
    File dstFile = NNStorage.getFinalizedEditsFile(
        sd, firstTxId, lastTxId);
    LOG.debug("Finalizing edits file " + inprogressFile + " -> " + dstFile);
    
    Preconditions.checkState(!dstFile.exists(),
        "Can't finalize edits file " + inprogressFile + " since finalized file " +
        "already exists");
    if (!inprogressFile.renameTo(dstFile)) {
      throw new IOException("Unable to finalize edits file " + inprogressFile);
    }
  }

  @VisibleForTesting
  public StorageDirectory getStorageDirectory() {
    return sd;
  }

  @Override
  public String toString() {
    return "FileJournalManager for storage directory " + sd;
  }

  @Override
  public void setOutputBufferCapacity(int size) {
    this.outputBufferCapacity = size;
  }

  @Override
  public void purgeLogsOlderThan(long minTxIdToKeep, StoragePurger purger)
      throws IOException {
    File[] files = FileUtil.listFiles(sd.getCurrentDir());
    List<FoundEditLog> editLogs = 
      FSImageTransactionalStorageInspector.matchEditLogs(files);
    for (FoundEditLog log : editLogs) {
      if (log.getStartTxId() < minTxIdToKeep &&
          log.getLastTxId() < minTxIdToKeep) {
        purger.purgeLog(log);
      }
    }
  }

  @Override
  public EditLogInputStream getInProgressInputStream(long segmentStartsAtTxId)
      throws IOException {
    File f = NNStorage.getInProgressEditsFile(sd, segmentStartsAtTxId);
    return new EditLogFileInputStream(f);
  }

}