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 org.apache.bifromq.basekv.localengine.memory;
  
  import org.apache.bifromq.basekv.localengine.AbstractKVSpaceReader;
  import org.apache.bifromq.basekv.localengine.IKVSpaceIterator;
  import org.apache.bifromq.basekv.localengine.metrics.KVSpaceOpMeters;
  import org.apache.bifromq.basekv.proto.Boundary;
  import com.google.protobuf.ByteString;
  import java.util.Map;
  import java.util.Optional;
  import java.util.SortedMap;
  import java.util.concurrent.ConcurrentSkipListMap;
  import org.slf4j.Logger;
  
  abstract class InMemKVSpaceReader extends AbstractKVSpaceReader {
      protected InMemKVSpaceReader(String id, KVSpaceOpMeters readOpMeters, Logger logger) {
          super(id, readOpMeters, logger);
      }
  
      protected abstract Map<ByteString, ByteString> metadataMap();
  
      protected abstract ConcurrentSkipListMap<ByteString, ByteString> rangeData();
  
      @Override
      protected Optional<ByteString> doMetadata(ByteString metaKey) {
          return Optional.ofNullable(metadataMap().get(metaKey));
      }
  
      @Override
      protected long doSize(Boundary boundary) {
          SortedMap<ByteString, ByteString> sizedData;
          ConcurrentSkipListMap<ByteString, ByteString> rangeData = rangeData();
          if (!boundary.hasStartKey() && !boundary.hasEndKey()) {
              sizedData = rangeData;
          } else if (!boundary.hasStartKey()) {
              sizedData = rangeData.headMap(boundary.getEndKey());
          } else if (!boundary.hasEndKey()) {
              sizedData = rangeData.tailMap(boundary.getStartKey());
          } else {
              sizedData = rangeData.subMap(boundary.getStartKey(), boundary.getEndKey());
          }
          // this may take a long time
          return sizedData.entrySet()
              .stream()
              .map(entry -> entry.getKey().size() + entry.getValue().size())
              .reduce(0, Integer::sum);
      }
  
      @Override
      protected boolean doExist(ByteString key) {
          return rangeData().containsKey(key);
      }
  
      @Override
      protected Optional<ByteString> doGet(ByteString key) {
          return Optional.ofNullable(rangeData().get(key));
      }
  
      @Override
      protected IKVSpaceIterator doNewIterator() {
          return new InMemKVSpaceIterator(rangeData());
      }
  
      @Override
      protected IKVSpaceIterator doNewIterator(Boundary subBoundary) {
          return new InMemKVSpaceIterator(rangeData(), subBoundary);
      }
  }
  