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.kafka.snapshot;
  
  import org.apache.kafka.common.record.FileRecords;
  import org.apache.kafka.common.record.Records;
  import org.apache.kafka.common.record.UnalignedRecords;
  import org.apache.kafka.server.common.OffsetAndEpoch;
  
  import java.io.IOException;
  import java.io.UncheckedIOException;
  import java.nio.file.Path;
  
  public final class FileRawSnapshotReader implements RawSnapshotReader, AutoCloseable {
      private final FileRecords fileRecords;
      private final OffsetAndEpoch snapshotId;
  
      private FileRawSnapshotReader(FileRecords fileRecords, OffsetAndEpoch snapshotId) {
          this.fileRecords = fileRecords;
          this.snapshotId = snapshotId;
      }
  
      @Override
      public OffsetAndEpoch snapshotId() {
          return snapshotId;
      }
  
      @Override
      public long sizeInBytes() {
          return fileRecords.sizeInBytes();
      }
  
      @Override
      public UnalignedRecords slice(long position, int size) {
          return fileRecords.sliceUnaligned(Math.toIntExact(position), size);
      }
  
      @Override
      public Records records() {
          return fileRecords;
      }
  
      @Override
      public void close() {
          try {
              fileRecords.close();
          } catch (IOException e) {
              throw new UncheckedIOException(
                  String.format("Unable to close snapshot reader %s at %s", snapshotId, fileRecords),
                  e
              );
          }
      }
  
      /**
       * Opens a snapshot for reading.
       *
       * @param logDir the directory for the topic partition
       * @param snapshotId the end offset and epoch for the snapshotId
       */
      public static FileRawSnapshotReader open(Path logDir, OffsetAndEpoch snapshotId) {
          FileRecords fileRecords;
          Path filePath = Snapshots.snapshotPath(logDir, snapshotId);
          try {
              fileRecords = FileRecords.open(
                  filePath.toFile(),
                  false, // mutable
                  true, // fileAlreadyExists
                  0, // initFileSize
                  false // preallocate
              );
          } catch (IOException e) {
              throw new UncheckedIOException(
                  String.format("Unable to Opens a snapshot file %s", filePath.toAbsolutePath()), e
              );
          }
  
          return new FileRawSnapshotReader(fileRecords, snapshotId);
      }
  }
  