ch.ledcom.tomcat.valves.SessionSizeValve.java Source code

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Here is the source code for ch.ledcom.tomcat.valves.SessionSizeValve.java

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/**
 * Copyright (C) 2013 LedCom (guillaume.lederrey@gmail.com)
 *
 * Licensed 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 ch.ledcom.tomcat.valves;

import static java.lang.String.format;

import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.Enumeration;

import javax.annotation.Nullable;
import javax.servlet.ServletException;
import javax.servlet.http.HttpSession;

import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.valves.ValveBase;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

import com.google.common.io.ByteStreams;
import com.google.common.io.Closer;
import com.google.common.io.CountingOutputStream;

/**
 * Logs the size of the HTTP session.
 *
 * For this valve to work, a Java Agent must be registered to initialize the
 * object-explorer introspection. See README.md for details.
 *
 * @author gehel
 */
public class SessionSizeValve extends ValveBase {

    /** logger. */
    private static Log log = LogFactory.getLog(SessionSizeValve.class);

    /**
     * Logs the size of the HTTP session.
     *
     * @param request
     *            the request being served
     * @param response
     *            the response being generated
     * @throws IOException
     * @throws ServletException
     */
    @Override
    public final void invoke(final Request request, final Response response) throws IOException, ServletException {
        try {
            getNext().invoke(request, response);
        } finally {
            try {
                final long sessionSize = measureSerializedSessionSize(request.getSession(false));
                log.info(format("Session size = %d.", sessionSize));
            } catch (final IOException ioe) {
                log.warn("Problem measuring session size", ioe);
            }
        }
    }

    private long measureSerializedSessionSize(@Nullable final HttpSession session) throws IOException {
        if (session == null) {
            return 0;
        }
        @SuppressWarnings("unchecked")
        final Enumeration<String> attibuteNames = session.getAttributeNames();
        long sessionSize = 0;
        while (attibuteNames.hasMoreElements()) {
            final String attributeName = attibuteNames.nextElement();
            sessionSize += measureSerializedSize(session.getAttribute(attributeName));
        }
        return sessionSize;
    }

    private long measureSerializedSize(final Object attribute) throws IOException {
        final Closer closer = Closer.create();
        try {
            final CountingOutputStream countingStream = closer
                    .register(new CountingOutputStream(ByteStreams.nullOutputStream()));
            final ObjectOutputStream out = closer.register(new ObjectOutputStream(countingStream));
            out.writeObject(attribute);
            return countingStream.getCount();
        } finally {
            closer.close();
        }
    }
}