Java tutorial
/** * 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.distributedlog.protocol.util; import static com.google.common.base.Charsets.UTF_8; import io.netty.buffer.ByteBuf; import java.nio.ByteBuffer; import java.util.zip.CRC32; import org.apache.distributedlog.DLSN; import org.apache.distributedlog.exceptions.DLException; import org.apache.distributedlog.exceptions.OwnershipAcquireFailedException; import org.apache.distributedlog.thrift.service.ResponseHeader; /** * With CRC embedded in the application, we have to keep track of per api crc. Ideally this * would be done by thrift. */ public class ProtocolUtils { // For request payload checksum private static final ThreadLocal<CRC32> requestCRC = new ThreadLocal<CRC32>() { @Override protected CRC32 initialValue() { return new CRC32(); } }; /** * Generate crc32 for WriteOp. */ public static Long writeOpCRC32(String stream, ByteBuf data) { CRC32 crc = requestCRC.get(); try { crc.update(stream.getBytes(UTF_8)); crc.update(data.nioBuffer()); return crc.getValue(); } finally { crc.reset(); } } /** * Generate crc32 for WriteOp. */ public static Long writeOpCRC32(String stream, ByteBuffer data) { CRC32 crc = requestCRC.get(); try { crc.update(stream.getBytes(UTF_8)); crc.update(data); return crc.getValue(); } finally { crc.reset(); } } /** * Generate crc32 for TruncateOp. */ public static Long truncateOpCRC32(String stream, DLSN dlsn) { CRC32 crc = requestCRC.get(); try { crc.update(stream.getBytes(UTF_8)); crc.update(dlsn.serializeBytes()); return crc.getValue(); } finally { crc.reset(); } } /** * Generate crc32 for any op which only passes a stream name. */ public static Long streamOpCRC32(String stream) { CRC32 crc = requestCRC.get(); try { crc.update(stream.getBytes(UTF_8)); return crc.getValue(); } finally { crc.reset(); } } public static DLException exception(ResponseHeader response) { String errMsg; switch (response.getCode()) { case FOUND: if (response.isSetErrMsg()) { errMsg = response.getErrMsg(); } else { errMsg = "Request is redirected to " + response.getLocation(); } return new OwnershipAcquireFailedException(errMsg, response.getLocation()); case SUCCESS: throw new IllegalArgumentException("Can't instantiate an exception for success response."); default: if (response.isSetErrMsg()) { errMsg = response.getErrMsg(); } else { errMsg = response.getCode().name(); } return new DLException(response.getCode().getValue(), errMsg); } } }