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 io.netty.buffer.ByteBufAllocator;
  import io.netty.util.ReferenceCountUtil;
  import java.io.IOException;
  import org.apache.bookkeeper.bookie.storage.EntryLogScanner;
  
  class LogReaderScan {
      static void scan(ByteBufAllocator allocator, LogReader reader, EntryLogScanner scanner) throws IOException {
          int offset = Header.LOGFILE_LEGACY_HEADER_SIZE;
  
          ByteBuf entry = allocator.directBuffer(16 * 1024 * 1024);
  
          try {
              while (offset < reader.maxOffset()) {
                  int initOffset = offset;
                  int entrySize = reader.readIntAt(offset);
                  if (entrySize < 0) { // padding, skip it
                      offset = Buffer.nextAlignment(offset);
                      continue;
                  } else if (entrySize == 0) { // preallocated space, we're done
                      break;
                  }
  
                  // The 4 bytes for the entrySize need to be added only after we
                  // have realigned on the block boundary.
                  offset += Integer.BYTES;
  
                  entry.clear();
                  reader.readIntoBufferAt(entry, offset, entrySize);
                  long ledgerId = entry.getLong(0);
                  if (ledgerId >= 0 && scanner.accept(ledgerId)) {
                      scanner.process(ledgerId, initOffset, entry);
                  }
                  offset += entrySize;
              }
          } finally {
              ReferenceCountUtil.release(entry);
          }
      }
  }
  