org.apache.hadoop.ipc.ClientId Maven / Gradle / Ivy
/**
* 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 org.apache.hadoop.thirdparty.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();
}
}