Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.core.joran.action;

import org.xml.sax.Attributes;

import ch.qos.logback.core.CoreConstants;
import ch.qos.logback.core.hook.ShutdownHookBase;
import ch.qos.logback.core.joran.spi.ActionException;
import ch.qos.logback.core.joran.spi.InterpretationContext;
import ch.qos.logback.core.util.OptionHelper;

Action which handles  elements in configuration files.
Author:
Mike Reinhold/**
 * Action which handles <shutdownHook> elements in configuration files.
 * 
 * @author Mike Reinhold
 */
public class ShutdownHookAction extends Action {

    ShutdownHookBase hook;
    private boolean inError;

    
Instantiates a shutdown hook of the given class and sets its name. The hook thus generated is placed in the InterpretationContext's shutdown hook bag. /**
     * Instantiates a shutdown hook of the given class and sets its name.
     * 
     * The hook thus generated is placed in the {@link InterpretationContext}'s
     * shutdown hook bag.
     */
    @Override
    public void begin(InterpretationContext ic, String name, Attributes attributes) throws ActionException {
        hook = null;
        inError = false;

        String className = attributes.getValue(CLASS_ATTRIBUTE);
        if (OptionHelper.isEmpty(className)) {
            addError("Missing class name for shutdown hook. Near [" + name + "] line " + getLineNumber(ic));
            inError = true;
            return;
        }

        try {
            addInfo("About to instantiate shutdown hook of type [" + className + "]");

            hook = (ShutdownHookBase) OptionHelper.instantiateByClassName(className, ShutdownHookBase.class, context);
            hook.setContext(context);

            ic.pushObject(hook);
        } catch (Exception e) {
            inError = true;
            addError("Could not create a shutdown hook of type [" + className + "].", e);
            throw new ActionException(e);
        }
    }

    
Once the children elements are also parsed, now is the time to activate the
shutdown hook options.
/**
     * Once the children elements are also parsed, now is the time to activate the
     * shutdown hook options.
     */
    @Override
    public void end(InterpretationContext ic, String name) throws ActionException {
        if (inError) {
            return;
        }

        Object o = ic.peekObject();
        if (o != hook) {
            addWarn("The object at the of the stack is not the hook pushed earlier.");
        } else {
            ic.popObject();

            Thread hookThread = new Thread(hook, "Logback shutdown hook [" + context.getName() + "]");

            context.putObject(CoreConstants.SHUTDOWN_HOOK_THREAD, hookThread);
            Runtime.getRuntime().addShutdownHook(hookThread);
        }
    }
}