FileHandlerCleanup.java

/*******************************************************************************
 * Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
 * which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *     Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.tools.workbench.utility.log;

import java.io.File;
import java.util.logging.FileHandler;

import org.eclipse.persistence.tools.workbench.utility.ClassTools;
import org.eclipse.persistence.tools.workbench.utility.string.StringTools;


/**
 * This runnable will delete a jdk logging file handle's lock file on system exit.
 * This is a work-around to a known issue with the jdk logging system.
 * The bug (4775533) is supposed to be fixed in jdk 1.5 (Tiger).
 */
// TODO remove when we move to jdk 1.5(?) ~bjv
public class FileHandlerCleanup implements Runnable {
    private FileHandler fileHandler;
    private String lockFileName;

    /**
     * Register a shut down hook for the specified file handler.
     */
    public static void register(FileHandler fileHandler) {
        Runtime.getRuntime().addShutdownHook(buildFileHandlerCleanupThread(fileHandler));
    }

    /**
     * Build a thread to be executed at system exit. The thread will
     * clean up after the specified handler.
     */
    private static Thread buildFileHandlerCleanupThread(FileHandler fileHandler) {
        return new Thread(new FileHandlerCleanup(fileHandler), "File Handler Cleanup");
    }

    /**
     * Construct a clean-up runnable for the specified file handler.
     */
    private FileHandlerCleanup(FileHandler fileHandler) {
        super();
        this.fileHandler = fileHandler;
        this.initialize();
    }

    /**
     * Hack into the file handler for the lock file name.
     */
    private void initialize() {
        this.lockFileName = (String) ClassTools.getFieldValue(this.fileHandler, "lockFileName");
    }

    /**
     * First make sure the file handler is closed...
     * (It may have already been closed by the LogManager.Cleaner,
     * but we can't be sure of that since it takes place in different
     * shutdown thread.)
     * ...then delete the file handler's lock file.
     * @see Runnable#run()
     */
    public void run() {
        this.fileHandler.close();
        new File(this.lockFileName).delete();
    }

    /**
     * @see Object#toString()
     */
    public String toString() {
        return StringTools.buildToStringFor(this, this.lockFileName);
    }

}