content: package org.apache.bookkeeper.proto.checksum;
  
  /*
  * 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.
  */
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  import io.netty.util.concurrent.FastThreadLocal;
  
  /**
   * Digest manager for CRC32 checksum.
   */
  class CRC32DigestManager extends DigestManager {
  
      /**
       * Interface that abstracts different implementations of the CRC32 digest.
       */
      interface CRC32Digest {
          long getValueAndReset();
  
          void update(ByteBuf buf, int offset,  int len);
          void update(byte[] buffer, int offset, int len);
      }
  
      private static final FastThreadLocal<CRC32Digest> crc = new FastThreadLocal<CRC32Digest>() {
          @Override
          protected CRC32Digest initialValue() {
              if (DirectMemoryCRC32Digest.isSupported()) {
                  return new DirectMemoryCRC32Digest();
              } else {
                  return new StandardCRC32Digest();
              }
          }
      };
  
      public CRC32DigestManager(long ledgerId, boolean useV2Protocol, ByteBufAllocator allocator) {
          super(ledgerId, useV2Protocol, allocator);
      }
  
      @Override
      int getMacCodeLength() {
          return 8;
      }
  
      @Override
      void populateValueAndReset(int digest, ByteBuf buf) {
          buf.writeLong(crc.get().getValueAndReset());
      }
  
      @Override
      int internalUpdate(int digest, ByteBuf data, int offset, int len) {
          crc.get().update(data, offset, len);
          return 0;
      }
  
      @Override
      int internalUpdate(int digest, byte[] buffer, int offset, int len) {
          crc.get().update(buffer, offset, len);
          return 0;
      }
  
      @Override
      boolean isInt32Digest() {
          // This is stored as 8 bytes
          return false;
      }
  
      @Override
      boolean acceptsMemoryAddressBuffer() {
          return DirectMemoryCRC32Digest.isSupported();
      }
  }
  