| /** |
| * 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.hadoop.ipc; |
| |
| import java.nio.ByteBuffer; |
| import java.util.UUID; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| |
| import com.google.common.base.Preconditions; |
| |
| /** |
| * A class defining a set of static helper methods to provide conversion between |
| * bytes and string for UUID-based client Id. |
| */ |
| @InterfaceAudience.Private |
| public class ClientId { |
| |
| /** The byte array of a UUID should be 16 */ |
| public static final int BYTE_LENGTH = 16; |
| private static final int shiftWidth = 8; |
| |
| /** |
| * Return clientId as byte[] |
| */ |
| public static byte[] getClientId() { |
| UUID uuid = UUID.randomUUID(); |
| ByteBuffer buf = ByteBuffer.wrap(new byte[BYTE_LENGTH]); |
| buf.putLong(uuid.getMostSignificantBits()); |
| buf.putLong(uuid.getLeastSignificantBits()); |
| return buf.array(); |
| } |
| |
| /** Convert a clientId byte[] to string */ |
| public static String toString(byte[] clientId) { |
| // clientId can be null or an empty array |
| if (clientId == null || clientId.length == 0) { |
| return ""; |
| } |
| // otherwise should be 16 bytes |
| Preconditions.checkArgument(clientId.length == BYTE_LENGTH); |
| long msb = getMsb(clientId); |
| long lsb = getLsb(clientId); |
| return (new UUID(msb, lsb)).toString(); |
| } |
| |
| public static long getMsb(byte[] clientId) { |
| long msb = 0; |
| for (int i = 0; i < BYTE_LENGTH/2; i++) { |
| msb = (msb << shiftWidth) | (clientId[i] & 0xff); |
| } |
| return msb; |
| } |
| |
| public static long getLsb(byte[] clientId) { |
| long lsb = 0; |
| for (int i = BYTE_LENGTH/2; i < BYTE_LENGTH; i++) { |
| lsb = (lsb << shiftWidth) | (clientId[i] & 0xff); |
| } |
| return lsb; |
| } |
| |
| /** Convert from clientId string byte[] representation of clientId */ |
| public static byte[] toBytes(String id) { |
| if (id == null || "".equals(id)) { |
| return new byte[0]; |
| } |
| UUID uuid = UUID.fromString(id); |
| ByteBuffer buf = ByteBuffer.wrap(new byte[BYTE_LENGTH]); |
| buf.putLong(uuid.getMostSignificantBits()); |
| buf.putLong(uuid.getLeastSignificantBits()); |
| return buf.array(); |
| } |
| |
| } |