com.moz.fiji.schema.util.JvmId.java Source code

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Here is the source code for com.moz.fiji.schema.util.JvmId.java

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/**
 * (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 com.moz.fiji.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 com.moz.fiji.annotations.ApiAudience;
import com.moz.fiji.schema.FijiIOException;
import com.moz.fiji.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 FijiIOException(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 FijiIOException(ioe);
        }
    }

    /** Utility class may not be instantiated. */
    private JvmId() {
    }
}