/**
* (c) Copyright 2013 WibiData, Inc.
*
* See the NOTICE file distributed with this work for additional
* information regarding copyright ownership.
*
* Licensed 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.kiji.schema.util;
import java.io.IOException;
import java.net.InetAddress;
import java.net.UnknownHostException;
import com.google.common.base.Preconditions;
import org.apache.commons.io.IOUtils;
import org.kiji.annotations.ApiAudience;
import org.kiji.schema.KijiIOException;
import org.kiji.schema.RuntimeInterruptedException;
/** Utility class to generate unique client IDs. */
@ApiAudience.Private
public final class JvmId {
private static final String JVM_ID = generateJvmId();
/**
* Returns the unique ID for this JVM.
*
* <p> The ID is formatted as "hostname;unix-pid;timestamp". </p>
*
* @return the unique ID for this JVM.
*/
public static String get() {
return JVM_ID;
}
/**
* Generates a unique ID for this JVM.
*
* <p> The ID is formatted as "hostname;unix-pid;timestamp". </p>
*
* @return a unique ID for this JVM.
*/
private static String generateJvmId() {
try {
final String hostname = InetAddress.getLocalHost().getHostName();
final int pid = getPid();
final long timestamp = System.currentTimeMillis();
return String.format("%s;%d;%d", hostname, pid, timestamp);
} catch (UnknownHostException uhe) {
throw new KijiIOException(uhe);
}
}
/**
* Returns the Unix process ID of this JVM.
*
* @return the Unix process ID of this JVM.
*/
public static int getPid() {
try {
final Process process = new ProcessBuilder("/bin/sh", "-c", "echo $PPID").start();
try {
Preconditions.checkState(process.waitFor() == 0);
} catch (InterruptedException ie) {
throw new RuntimeInterruptedException(ie);
}
final String pidStr = IOUtils.toString(process.getInputStream()).trim();
return Integer.parseInt(pidStr);
} catch (IOException ioe) {
throw new KijiIOException(ioe);
}
}
/** Utility class may not be instantiated. */
private JvmId() {
}
}