com.netflix.exhibitor.servlet.ExhibitorServletContextListener.java Source code

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Here is the source code for com.netflix.exhibitor.servlet.ExhibitorServletContextListener.java

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/*
 * Copyright 2012 Netflix, Inc.
 *
 *    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 com.netflix.exhibitor.servlet;

import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.io.Closeables;
import com.google.common.io.Resources;
import com.netflix.exhibitor.core.Exhibitor;
import com.netflix.exhibitor.standalone.ExhibitorCLI;
import com.netflix.exhibitor.standalone.ExhibitorCreator;
import com.netflix.exhibitor.standalone.ExhibitorCreatorExit;
import com.netflix.exhibitor.standalone.MissingConfigurationTypeException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.Enumeration;
import java.util.List;
import java.util.Map;
import java.util.Properties;

public class ExhibitorServletContextListener implements ServletContextListener {
    private final Logger log = LoggerFactory.getLogger(getClass());

    private volatile Exhibitor exhibitor;
    private volatile ExhibitorCreator exhibitorCreator;

    private static final String OUR_PREFIX = "exhibitor-";
    private static final String EXHIBITOR_PROPERTIES = "exhibitor.properties";

    @Override
    public void contextInitialized(ServletContextEvent event) {
        Map<String, String> argsBuilder = makeArgsBuilder();

        try {
            exhibitorCreator = new ExhibitorCreator(toArgsArray(argsBuilder));

            exhibitor = new Exhibitor(exhibitorCreator.getConfigProvider(), null,
                    exhibitorCreator.getBackupProvider(), exhibitorCreator.getBuilder().build());
            exhibitor.start();

            event.getServletContext().setAttribute(ExhibitorServletContextListener.class.getName(), exhibitor);
        } catch (MissingConfigurationTypeException exit) {
            log.error("Configuration type (" + OUR_PREFIX + ExhibitorCLI.CONFIG_TYPE + ") must be specified");
            exit.getCli().logHelp(OUR_PREFIX);
            throw new RuntimeException(exit);
        } catch (ExhibitorCreatorExit exit) {
            if (exit.getError() != null) {
                log.error(exit.getError());
            }
            exit.getCli().logHelp(OUR_PREFIX);
            throw new RuntimeException(exit);
        } catch (Exception e) {
            log.error("Trying to create Exhibitor", e);
            throw new RuntimeException(e);
        }
    }

    @Override
    public void contextDestroyed(ServletContextEvent event) {
        if (exhibitor != null) {
            Closeables.closeQuietly(exhibitor);
            exhibitor = null;
        }

        if (exhibitorCreator != null) {
            for (Closeable closeable : exhibitorCreator.getCloseables()) {
                Closeables.closeQuietly(closeable);
            }
        }
    }

    private String[] toArgsArray(Map<String, String> argsBuilder) {
        List<String> args = Lists.newArrayList();
        for (Map.Entry<String, String> entry : argsBuilder.entrySet()) {
            args.add(entry.getKey());
            args.add(entry.getValue());
        }

        return args.toArray(new String[args.size()]);
    }

    private Map<String, String> makeArgsBuilder() {
        Map<String, String> argsBuilder = Maps.newHashMap();

        try {
            URL resource = Resources.getResource(EXHIBITOR_PROPERTIES);
            InputStream stream = resource.openStream();
            try {
                Properties properties = new Properties(System.getProperties());
                properties.load(stream);
                applyProperties(argsBuilder, properties);
            } finally {
                Closeables.closeQuietly(stream);
            }
        } catch (IllegalArgumentException e) {
            log.warn("Could not find " + EXHIBITOR_PROPERTIES);
        } catch (IOException e) {
            log.error("Could not load " + EXHIBITOR_PROPERTIES, e);
        }

        applyProperties(argsBuilder, System.getProperties());

        return argsBuilder;
    }

    private void applyProperties(Map<String, String> argsBuilder, Properties properties) {
        Enumeration parameterNames = properties.propertyNames();
        while (parameterNames.hasMoreElements()) {
            String name = String.valueOf(parameterNames.nextElement());
            if (name.startsWith(OUR_PREFIX)) {
                String value = properties.getProperty(name);
                String argName = name.substring(OUR_PREFIX.length());
                argsBuilder.put("-" + argName, value);

                log.info(String.format("Setting property %s=%s", argName, value));
            }
        }
    }
}