/*
* 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.sirona.web.lifecycle;
import org.apache.sirona.web.jsp.factory.JspPerformanceFactory;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.jsp.JspFactory;
import java.io.IOException;
public class LazyJspMonitoringFilterActivator implements Filter {
private volatile JspFactory defaultFactory = null;
private JspPerformanceFactory wrapper = null;
@Override
public void doFilter(final ServletRequest servletRequest, final ServletResponse servletResponse, final FilterChain filterChain) throws IOException, ServletException {
if (defaultFactory == null) {
synchronized (this) {
if (defaultFactory == defaultFactory) {
defaultFactory = JspFactory.getDefaultFactory();
if (!JspPerformanceFactory.class.isInstance(defaultFactory)) {
wrapper = new JspPerformanceFactory(defaultFactory);
JspFactory.setDefaultFactory(wrapper);
}
}
}
}
filterChain.doFilter(servletRequest, servletResponse);
}
@Override
public void destroy() {
if (wrapper != null && wrapper == JspFactory.getDefaultFactory()) {
JspFactory.setDefaultFactory(defaultFactory);
}
}
@Override
public void init(final FilterConfig filterConfig) throws ServletException {
// no-op: too eagerly to init anything, defaultFactory will surely be null
}
}