storm-client/src/jvm/org/apache/storm/trident/state/map/CachedBatchReadsMap.java

/**
 * 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;


public class CachedBatchReadsMap<T> {
    public IBackingMap<T> delegate;
    Map<List<Object>, T> cached = new HashMap<List<Object>, T>();

    public CachedBatchReadsMap(IBackingMap<T> delegate) {
        this.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);
        }
    }

    public static class RetVal<T> {
        public boolean cached;
        public T val;

        public RetVal(T v, boolean c) {
            val = v;
            cached = c;
        }
    }


}