content: /*
   * 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.activemq.store.kahadb.disk.journal;
  
  import java.io.IOException;
  import java.util.Map;
  
  import org.apache.activemq.util.ByteSequence;
  import org.apache.activemq.util.RecoverableRandomAccessFile;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Optimized Store reader and updater. Single threaded and synchronous. Use in
   * conjunction with the DataFileAccessorPool of concurrent use.
   */
  final class DataFileAccessor {
  
      private static final Logger LOG = LoggerFactory.getLogger(DataFileAccessor.class);
      private final DataFile dataFile;
      private final Map<Journal.WriteKey, Journal.WriteCommand> inflightWrites;
      private final RecoverableRandomAccessFile file;
      private boolean disposed;
  
      /**
       * Construct a Store reader
       *
       * @throws IOException
       */
      public DataFileAccessor(Journal dataManager, DataFile dataFile) throws IOException {
          this.dataFile = dataFile;
          this.inflightWrites = dataManager.getInflightWrites();
          this.file = dataFile.openRandomAccessFile();
      }
  
      public DataFile getDataFile() {
          return dataFile;
      }
  
      public void dispose() {
          if (disposed) {
              return;
          }
          disposed = true;
          try {
              dataFile.closeRandomAccessFile(file);
          } catch (IOException e) {
              LOG.warn("Failed to close file", e);
          }
      }
  
      public ByteSequence readRecord(Location location) throws IOException {
  
          if (!location.isValid()) {
              throw new IOException("Invalid location: " + location);
          }
  
          Journal.WriteCommand asyncWrite = inflightWrites.get(new Journal.WriteKey(location));
          if (asyncWrite != null) {
              return asyncWrite.data;
          }
  
          try {
              if (location.getSize() == Location.NOT_SET) {
                  file.seek(location.getOffset());
                  location.setSize(file.readInt());
                  location.setType(file.readByte());
              } else {
                  file.seek(location.getOffset() + Journal.RECORD_HEAD_SPACE);
              }
              validateFileLength(location);
              byte[] data = new byte[location.getSize() - Journal.RECORD_HEAD_SPACE];
              file.readFully(data);
              return new ByteSequence(data, 0, data.length);
  
          } catch (RuntimeException e) {
              throw new IOException("Invalid location: " + location + " : " + e, e);
          }
      }
  
      public void readFully(long offset, byte data[]) throws IOException {
         file.seek(offset);
         file.readFully(data);
      }
  
      public int read(long offset, byte data[]) throws IOException {
         file.seek(offset);
         return file.read(data);
      }
  
      public void readLocationDetails(Location location) throws IOException {
          Journal.WriteCommand asyncWrite = inflightWrites.get(new Journal.WriteKey(location));
          if (asyncWrite != null) {
              location.setSize(asyncWrite.location.getSize());
              location.setType(asyncWrite.location.getType());
          } else {
              file.seek(location.getOffset());
              location.setSize(file.readInt());
              location.setType(file.readByte());
          }
      }
  
      public void updateRecord(Location location, ByteSequence data, boolean sync) throws IOException {
  
          file.seek(location.getOffset() + Journal.RECORD_HEAD_SPACE);
          int size = Math.min(data.getLength(), location.getSize());
          file.write(data.getData(), data.getOffset(), size);
          if (sync) {
              file.sync();
          }
      }
  
      public RecoverableRandomAccessFile getRaf() {
          return file;
      }
  
      void validateFileLength(final Location location) throws IOException {
          final long recordEnd = location.getOffset() + location.getSize();
  
          //Check if the end of the record will go past the file length
          if (recordEnd > dataFile.length) {
              /*
               * AMQ-9254 if the read request is outside expected dataFile length,
               * perform expensive OS file length lookup operation to allow read
               * operation if it will succeed
               */
              final long osFileLength = dataFile.getFile().length();
              if(recordEnd > osFileLength) {
                  throw new IOException("Invalid location size: " + location + ", size: " + location.getSize());
              } else {
                  LOG.warn("DataFile:{} actual length:{} larger than expected:{} for readRecord location:{} size:{}",
                      dataFile.file.getName(), osFileLength, dataFile.length, location, location.getSize());
              }
          }
      }
  }
  