| /** |
| * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. The ASF licenses this file to you 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.apache.storm.trident.state.map; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| import org.apache.storm.trident.util.LRUMap; |
| |
| /** |
| * Useful to layer over a map that communicates with a database. you generally layer opaque map over this over your database store |
| * |
| * @param <T> |
| */ |
| public class CachedMap<T> implements IBackingMap<T> { |
| LRUMap<List<Object>, T> _cache; |
| IBackingMap<T> _delegate; |
| |
| public CachedMap(IBackingMap<T> delegate, int cacheSize) { |
| _cache = new LRUMap<List<Object>, T>(cacheSize); |
| _delegate = delegate; |
| } |
| |
| @Override |
| public List<T> multiGet(List<List<Object>> keys) { |
| Map<List<Object>, T> results = new HashMap<List<Object>, T>(); |
| List<List<Object>> toGet = new ArrayList<List<Object>>(); |
| for (List<Object> key : keys) { |
| if (_cache.containsKey(key)) { |
| results.put(key, _cache.get(key)); |
| } else { |
| toGet.add(key); |
| } |
| } |
| |
| List<T> fetchedVals = _delegate.multiGet(toGet); |
| for (int i = 0; i < toGet.size(); i++) { |
| List<Object> key = toGet.get(i); |
| T val = fetchedVals.get(i); |
| _cache.put(key, val); |
| results.put(key, val); |
| } |
| |
| List<T> ret = new ArrayList<T>(keys.size()); |
| for (List<Object> key : keys) { |
| ret.add(results.get(key)); |
| } |
| return ret; |
| } |
| |
| @Override |
| public void multiPut(List<List<Object>> keys, List<T> values) { |
| cache(keys, values); |
| _delegate.multiPut(keys, values); |
| } |
| |
| private void cache(List<List<Object>> keys, List<T> values) { |
| for (int i = 0; i < keys.size(); i++) { |
| _cache.put(keys.get(i), values.get(i)); |
| } |
| } |
| |
| } |