| /* |
| * Copyright 2014 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.onosproject.store.hz; |
| |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| import org.onosproject.store.serializers.StoreSerializer; |
| |
| import com.google.common.base.Optional; |
| import com.google.common.cache.CacheLoader; |
| import com.hazelcast.core.IMap; |
| |
| /** |
| * CacheLoader to wrap Map value with Optional, |
| * to handle negative hit on underlying IMap. |
| * |
| * @param <K> IMap key type after deserialization |
| * @param <V> IMap value type after deserialization |
| */ |
| public final class OptionalCacheLoader<K, V> extends |
| CacheLoader<K, Optional<V>> { |
| |
| private final StoreSerializer serializer; |
| private IMap<byte[], byte[]> rawMap; |
| |
| /** |
| * Constructor. |
| * |
| * @param serializer to use for serialization |
| * @param rawMap underlying IMap |
| */ |
| public OptionalCacheLoader(StoreSerializer serializer, IMap<byte[], byte[]> rawMap) { |
| this.serializer = checkNotNull(serializer); |
| this.rawMap = checkNotNull(rawMap); |
| } |
| |
| @Override |
| public Optional<V> load(K key) throws Exception { |
| byte[] keyBytes = serializer.encode(key); |
| byte[] valBytes = rawMap.get(keyBytes); |
| if (valBytes == null) { |
| return Optional.absent(); |
| } |
| V dev = serializer.decode(valBytes); |
| return Optional.of(dev); |
| } |
| } |