org.apache.geode.internal.process.LocalProcessLauncher.java Source code

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Here is the source code for org.apache.geode.internal.process.LocalProcessLauncher.java

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/*
 * 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.geode.internal.process;

import static org.apache.commons.lang.Validate.notNull;
import static org.apache.geode.internal.process.ProcessUtils.identifyPid;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

import org.apache.geode.distributed.internal.DistributionConfig;

/**
 * Creates a pid file and writes the process id to the pid file.
 *
 * <p>
 * Related articles and libraries:
 *
 * <ul>
 * <li>http://barelyenough.org/blog/2005/03/java-daemon/
 * <li>http://stackoverflow.com/questions/534648/how-to-daemonize-a-java-program
 * <li>http://commons.apache.org/daemon/
 * <li>http://wrapper.tanukisoftware.com/
 * <li>http://weblogs.java.net/blog/kohsuke/archive/2009/01/writing_a_unix.html
 * <li>http://www.enderunix.org/docs/eng/daemon.php
 * </ul>
 * 
 * @since GemFire 7.0
 */
class LocalProcessLauncher {

    static final String PROPERTY_IGNORE_IS_PID_ALIVE = DistributionConfig.GEMFIRE_PREFIX
            + "test.LocalProcessLauncher.ignoreIsPidAlive";

    private final int pid;
    private final File pidFile;

    /**
     * Constructs a new ProcessLauncher. Parses this process's RuntimeMXBean name for the pid (process
     * id).
     * 
     * @param pidFile the file to create and write pid into
     * @param force if true then the pid file will be replaced if it already exists
     * 
     * @throws FileAlreadyExistsException if the pid file already exists and force is false
     * @throws IOException if unable to write pid (process id) to pid file
     * @throws PidUnavailableException if the pid cannot be parsed from the RuntimeMXBean name
     * 
     * @see java.lang.management.RuntimeMXBean
     */
    LocalProcessLauncher(final File pidFile, final boolean force)
            throws FileAlreadyExistsException, IOException, PidUnavailableException {
        notNull(pidFile, "Invalid pidFile '" + pidFile + "' specified");

        this.pid = identifyPid();
        this.pidFile = pidFile;
        writePid(force);
    }

    /**
     * Returns the process id (pid).
     * 
     * @return the process id (pid)
     */
    int getPid() {
        return pid;
    }

    /**
     * Returns the pid file.
     * 
     * @return the pid file
     */
    File getPidFile() {
        return pidFile;
    }

    /**
     * Delete the pid file now. {@link java.io.File#deleteOnExit()} is set on the pid file.
     *
     */
    void close() {
        pidFile.delete();
    }

    /**
     * Delete the pid file now. {@link java.io.File#deleteOnExit()} is set on the pid file.
     *
     * @param deletePidFileOnClose if true then the pid file will be deleted now instead of during JVM
     *        exit
     */
    void close(final boolean deletePidFileOnClose) {
        if (deletePidFileOnClose) {
            pidFile.delete();
        }
    }

    /**
     * Creates a new pid file and writes this process's pid into it.
     * 
     * @param force if true then the pid file will be replaced if it already exists it
     * 
     * @throws FileAlreadyExistsException if the pid file already exists and force is false
     * @throws IOException if unable to create or write to the file
     */
    private void writePid(final boolean force) throws FileAlreadyExistsException, IOException {
        if (pidFile.exists()) {
            if (!force) {
                checkOtherPid(readOtherPid());
            }
            pidFile.delete();
        }

        File tempPidFile = new File(pidFile.getParent(), pidFile.getName() + ".tmp");
        tempPidFile.createNewFile();

        try (FileWriter writer = new FileWriter(tempPidFile)) {
            writer.write(String.valueOf(pid));
            writer.flush();
        }

        tempPidFile.renameTo(pidFile);
        pidFile.deleteOnExit();
    }

    private int readOtherPid() {
        int otherPid = 0;
        try {
            otherPid = ProcessUtils.readPid(pidFile);
        } catch (NumberFormatException | IOException ignore) {
            // suppress
        }
        return otherPid;
    }

    private void checkOtherPid(final int otherPid) throws FileAlreadyExistsException {
        if (ignoreIsPidAlive() || otherPid != 0 && isProcessAlive(otherPid)) {
            throw new FileAlreadyExistsException("Pid file already exists: " + pidFile + " for "
                    + (otherPid > 0 ? "process " + otherPid : "unknown process"));
        }
    }

    private boolean isProcessAlive(final int pid) {
        return ignoreIsPidAlive() || ProcessUtils.isProcessAlive(pid);
    }

    private static boolean ignoreIsPidAlive() {
        return Boolean.getBoolean(PROPERTY_IGNORE_IS_PID_ALIVE);
    }
}