UserUtil.java

/**
 * Copyright (C) 2014 cherimojava (http://github.com/cherimojava/orchidae) 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.github.cherimojava.orchidae.util;

import java.util.concurrent.ExecutionException;

import javax.annotation.PreDestroy;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.security.core.context.SecurityContextHolder;

import com.github.cherimojava.data.mongo.entity.Entity;
import com.github.cherimojava.data.mongo.entity.EntityFactory;
import com.github.cherimojava.orchidae.api.entities.User;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.cache.RemovalListener;
import com.google.common.cache.RemovalNotification;

/**
 * Utility class for working with Users
 * 
 * @author philnate
 */
public class UserUtil
{

    private static final Logger LOG = LogManager.getLogger();

    @Autowired
    EntityFactory factory;

    int cacheSize;

    private LoadingCache<String, User> registry;

    @SuppressWarnings( "unchecked" )
    public UserUtil( int cacheSize, int concurrencyLevel )
    {
        registry = CacheBuilder.newBuilder().maximumSize( cacheSize ).concurrencyLevel( concurrencyLevel )
            .removalListener( new RemovalListener()
            {
                @Override
                public void onRemoval( RemovalNotification notification )
                {
                    // save user before dropped from cache
                    if ( notification.getValue() != null )
                    {
                        ( (Entity) notification.getValue() ).save();
                    }
                }
            } ).build( new CacheLoader<String, User>()
            {
                @Override
                public User load( String key )
                    throws Exception
                {
                    return factory.load( User.class, key );
                }
            } );
        this.cacheSize = cacheSize;
    }

    /**
     * get the requested user or null if the user couldn't be loaded(not found or somethign else happened)
     * 
     * @param userId
     * @return
     */
    public User getUser( String userId )
    {
        try
        {
            return registry.get( userId );
        }
        catch ( ExecutionException e )
        {
            LOG.warn( "failed to load user", e );
            return null;
        }
    }

    /**
     * returns the currently logged in User or null, if no user is currently logged in
     * 
     * @return the username or null if no user is logged in
     */
    public static String getLoggedInUser()
    {
        return (String) SecurityContextHolder.getContext().getAuthentication().getPrincipal();
    }

    /**
     * on shutdown save all users and clear cache
     */
    @PreDestroy
    public void _clear()
    {
        for ( User user : registry.asMap().values() )
        {
            user.save();
        }
        registry.invalidateAll();
    }
}