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.kafka.streams.state.internals;
  
  import org.apache.kafka.common.metrics.Sensor;
  import org.apache.kafka.common.utils.Time;
  import org.apache.kafka.streams.state.VersionedRecord;
  import org.apache.kafka.streams.state.VersionedRecordIterator;
  
  import java.util.Set;
  import java.util.concurrent.atomic.LongAdder;
  import java.util.function.Function;
  
  class MeteredMultiVersionedKeyQueryIterator<V> implements VersionedRecordIterator<V>, MeteredIterator {
  
      private final VersionedRecordIterator<byte[]> iterator;
      private final Function<VersionedRecord<byte[]>, VersionedRecord<V>> deserializeValue;
      private final LongAdder numOpenIterators;
      private final Sensor sensor;
      private final Time time;
      private final long startNs;
      private final long startTimestampMs;
      private final Set<MeteredIterator> openIterators;
  
      public MeteredMultiVersionedKeyQueryIterator(final VersionedRecordIterator<byte[]> iterator,
                                                   final Sensor sensor,
                                                   final Time time,
                                                   final Function<VersionedRecord<byte[]>, VersionedRecord<V>> deserializeValue,
                                                   final LongAdder numOpenIterators,
                                                   final Set<MeteredIterator> openIterators) {
          this.iterator = iterator;
          this.deserializeValue = deserializeValue;
          this.numOpenIterators = numOpenIterators;
          this.openIterators = openIterators;
          this.sensor = sensor;
          this.time = time;
          this.startNs = time.nanoseconds();
          this.startTimestampMs = time.milliseconds();
          numOpenIterators.increment();
          openIterators.add(this);
      }
  
      @Override
      public long startTimestamp() {
          return startTimestampMs;
      }
  
      @Override
      public void close() {
          try {
              iterator.close();
          } finally {
              sensor.record(time.nanoseconds() - startNs);
              numOpenIterators.decrement();
              openIterators.remove(this);
          }
      }
  
      @Override
      public boolean hasNext() {
          return iterator.hasNext();
      }
  
      @Override
      public VersionedRecord<V> next() {
          return deserializeValue.apply(iterator.next());
      }
  }
  