Java tutorial
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); } 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(ByteBuf buf) { buf.writeLong(crc.get().getValueAndReset()); } @Override void update(ByteBuf data) { crc.get().update(data); } }