src/main/java/org/opencord/sadis/SubscriberAndDeviceInformationAdapter.java

/*
 * Copyright 2017-present Open Networking Laboratory
 *
 * 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 org.opencord.sadis;

import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.concurrent.TimeUnit;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;

public abstract class SubscriberAndDeviceInformationAdapter implements SubscriberAndDeviceInformationService {
    private static final int DEFAULT_MAXIMUM_CACHE_SIZE = 0;
    private static final long DEFAULT_TTL = 0;

    private String url;
    private Cache<String, SubscriberAndDeviceInformation> cache;
    private int maxiumCacheSize = DEFAULT_MAXIMUM_CACHE_SIZE;
    private long cacheEntryTtl = DEFAULT_TTL;

    public SubscriberAndDeviceInformationAdapter() {
        cache = CacheBuilder.newBuilder().maximumSize(maxiumCacheSize)
                .expireAfterAccess(cacheEntryTtl, TimeUnit.SECONDS).build();
    }

    public void configure(String url, int maximumCacheSeize, long cacheEntryTtl) {
        // Rebuild cache if needed
        if (url != this.url || maximumCacheSeize != this.maxiumCacheSize || cacheEntryTtl != this.cacheEntryTtl) {
            this.url = url;
            this.maxiumCacheSize = maximumCacheSeize;
            this.cacheEntryTtl = cacheEntryTtl;
            Cache<String, SubscriberAndDeviceInformation> newCache = CacheBuilder.newBuilder()
                    .maximumSize(maxiumCacheSize).expireAfterAccess(cacheEntryTtl, TimeUnit.SECONDS).build();
            Cache<String, SubscriberAndDeviceInformation> oldCache = cache;

            synchronized (this) {
                cache = newCache;
            }

            oldCache.invalidateAll();
            oldCache.cleanUp();
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.opencord.sadis.SubscriberAndDeviceInformationService#clearCache()
     */
    @Override
    public void invalidateAll() {
        cache.invalidateAll();
    }

    /*
     * (non-Javadoc)
     *
     * @see
     * org.opencord.sadis.SubscriberAndDeviceInformationService#get(java.lang.
     * String)
     */
    @Override
    public SubscriberAndDeviceInformation get(String id) {
        Cache<String, SubscriberAndDeviceInformation> local;
        synchronized (this) {
            local = cache;
        }

        SubscriberAndDeviceInformation info = local.getIfPresent(id);
        if (info != null) {
            return info;
        }

        /*
         * Not in cache, if we have a URL configured we can attempt to get it
         * from there.
         */
        if (this.url == null) {
            return null;
        }

        // Augment URL with query parameters
        StringBuilder buf = new StringBuilder(this.url);
        if (buf.charAt(buf.length() - 1) != '/') {
            buf.append('/');
        }

        buf.append(id);

        try (InputStream io = new URL(buf.toString()).openStream()) {
            ObjectMapper mapper = new ObjectMapper();
            info = mapper.readValue(io, SubscriberAndDeviceInformation.class);
            local.put(id, info);
            return info;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return null;
    }
}