content: /**
   * 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 storm.trident.state.map;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import storm.trident.state.ValueUpdater;
  
  public class CachedBatchReadsMap<T> {
      public static class RetVal<T> {
          public boolean cached;
          public T val;
  
          public RetVal(T v, boolean c) {
              val = v;
              cached = c;
          }
      }
  
      Map<List<Object>, T> _cached = new HashMap<List<Object>, T>();
  
      public IBackingMap<T> _delegate;
  
      public CachedBatchReadsMap(IBackingMap<T> delegate) {
          _delegate = delegate;
      }
  
      public void reset() {
          _cached.clear();
      }
  
      public List<RetVal<T>> multiGet(List<List<Object>> keys) {
          // TODO: can optimize further by only querying backing map for keys not in the cache
          List<T> vals = _delegate.multiGet(keys);
          List<RetVal<T>> ret = new ArrayList(vals.size());
          for (int i = 0; i < keys.size(); i++) {
              List<Object> key = keys.get(i);
              if (_cached.containsKey(key)) {
                  ret.add(new RetVal(_cached.get(key), true));
              } else {
                  ret.add(new RetVal(vals.get(i), false));
              }
          }
          return ret;
      }
  
      public void multiPut(List<List<Object>> keys, List<T> vals) {
          _delegate.multiPut(keys, vals);
          cache(keys, vals);
      }
  
      private void cache(List<List<Object>> keys, List<T> vals) {
          for (int i = 0; i < keys.size(); i++) {
              List<Object> key = keys.get(i);
              T val = vals.get(i);
              _cached.put(key, val);
          }
      }
  
  }
  