org.apache.ace.deployment/src/org/apache/ace/deployment/servlet/OverloadedFilter.java

/*
 * 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.ace.deployment.servlet;

import java.io.IOException;

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.http.HttpServletResponse;

import org.apache.ace.deployment.provider.OverloadedException;

public class OverloadedFilter implements Filter {

    private static final String HTTP_RETRY_AFTER = "Retry-After";

    @Override
    public void init(FilterConfig config) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        HttpServletResponse httpResponse = (HttpServletResponse) response;
        try {
            filterChain.doFilter(request, response);
        }
        catch (OverloadedException oe) {
            OverloadedException overloadedException = (OverloadedException) oe;
            httpResponse.sendError(HttpServletResponse.SC_SERVICE_UNAVAILABLE);
            httpResponse.setHeader(HTTP_RETRY_AFTER, "" + overloadedException.getBackoffTime());
        }
    }

    @Override
    public void destroy() {
    }
}