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.bookkeeper.bookie.storage.directentrylogger;
  
  import io.netty.buffer.ByteBuf;
  import java.io.EOFException;
  import java.io.IOException;
  
  /**
   * Interface for reading from a bookkeeper entry log.
   */
  public interface LogReader extends AutoCloseable {
      /**
       * @return the id of the log being read from.
       */
      int logId();
  
      /**
       * @return the maximum offset in the file that can be read from.
       */
      long maxOffset();
  
      /**
       * Read a buffer from the file. It is the responsibility of the caller to release
       * the returned buffer.
       * @param offset the offset to read at
       * @param size the number of bytes to read
       * @return a bytebuf. The caller must release.
       */
      ByteBuf readBufferAt(long offset, int size) throws IOException, EOFException;
  
      void readIntoBufferAt(ByteBuf buffer, long offset, int size) throws IOException, EOFException;
  
      /**
       * Read an integer at a given offset.
       * @param offset the offset to read from.
       * @return the integer at that offset.
       */
      int readIntAt(long offset) throws IOException, EOFException;
  
      /**
       * Read an long at a given offset.
       * @param offset the offset to read from.
       * @return the long at that offset.
       */
      long readLongAt(long offset) throws IOException, EOFException;
  
      /**
       * Read an entry at a given offset.
       * The size of the entry must be at (offset - Integer.BYTES).
       * The payload of the entry starts at offset.
       * It is the responsibility of the caller to release the returned buffer.
       * @param offset the offset at which to read the entry.
       * @return a bytebuf. The caller must release.
       */
      ByteBuf readEntryAt(int offset) throws IOException, EOFException;
  
      @Override
      void close() throws IOException;
  
      boolean isClosed();
  }
  