com.magnet.mmx.server.plugin.mmxmgmt.util.AppEntityDBLoadingEntityCache.java Source code

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Here is the source code for com.magnet.mmx.server.plugin.mmxmgmt.util.AppEntityDBLoadingEntityCache.java

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/*   Copyright (c) 2015 Magnet Systems, 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.magnet.mmx.server.plugin.mmxmgmt.util;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.magnet.mmx.server.common.data.AppEntity;
import com.magnet.mmx.server.plugin.mmxmgmt.db.AppDAO;
import com.magnet.mmx.server.plugin.mmxmgmt.db.AppDAOImpl;
import com.magnet.mmx.server.plugin.mmxmgmt.db.ConnectionProvider;
import com.magnet.mmx.server.plugin.mmxmgmt.db.OpenFireDBConnectionProvider;

import java.util.concurrent.ExecutionException;

/**
 */
public class AppEntityDBLoadingEntityCache implements DBEntityCache<AppEntity> {

    private static AppEntityDBLoadingEntityCache INSTANCE;
    private static int CACHE_SIZE = 100;

    private LoadingCache<String, AppEntity> cache;

    public AppEntityDBLoadingEntityCache(int size, CacheLoader<String, AppEntity> appEntityCacheLoader) {
        cache = CacheBuilder.newBuilder().maximumSize(CACHE_SIZE).build(appEntityCacheLoader);
    }

    @Override
    public AppEntity get(String key) {
        try {
            return cache.get(key);
        } catch (ExecutionException e) {
            return null;
        }
    }

    @Override
    public void purge(String key) {
        cache.refresh(key);
    }

    private static class AppEntityNotFoundException extends Exception {
        private AppEntityNotFoundException(String message) {
            super(message);
        }
    }

    public static class AppEntityDBLoader extends CacheLoader<String, AppEntity> {
        private ConnectionProvider provider;

        public AppEntityDBLoader(ConnectionProvider provider) {
            this.provider = provider;
        }

        public AppEntityDBLoader() {
            this(new OpenFireDBConnectionProvider());
        }

        public AppEntity load(String key) throws AppEntityNotFoundException {
            AppDAO appDAO = new AppDAOImpl(this.provider);
            AppEntity entity = appDAO.getAppForAppKey(key);
            if (entity == null) {
                throw new AppEntityNotFoundException(String.format("AppEntity with key:%s not found", key));
            }
            return entity;
        }
    }

}