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.KeyValue;
  import org.apache.kafka.streams.StreamsMetrics;
  import org.apache.kafka.streams.state.WindowStoreIterator;
  
  import java.util.Set;
  import java.util.concurrent.atomic.LongAdder;
  import java.util.function.Function;
  
  class MeteredWindowStoreIterator<V> implements WindowStoreIterator<V>, MeteredIterator {
  
      private final WindowStoreIterator<byte[]> iter;
      private final Sensor operationSensor;
      private final Sensor iteratorSensor;
      private final StreamsMetrics metrics;
      private final Function<byte[], V> valueFrom;
      private final long startNs;
      private final long startTimestampMs;
      private final Time time;
      private final LongAdder numOpenIterators;
      private final Set<MeteredIterator> openIterators;
  
      MeteredWindowStoreIterator(final WindowStoreIterator<byte[]> iter,
                                 final Sensor operationSensor,
                                 final Sensor iteratorSensor,
                                 final StreamsMetrics metrics,
                                 final Function<byte[], V> valueFrom,
                                 final Time time,
                                 final LongAdder numOpenIterators,
                                 final Set<MeteredIterator> openIterators) {
          this.iter = iter;
          this.operationSensor = operationSensor;
          this.iteratorSensor = iteratorSensor;
          this.metrics = metrics;
          this.valueFrom = valueFrom;
          this.startNs = time.nanoseconds();
          this.startTimestampMs = time.milliseconds();
          this.time = time;
          this.numOpenIterators = numOpenIterators;
          this.openIterators = openIterators;
          numOpenIterators.increment();
          openIterators.add(this);
      }
  
      @Override
      public long startTimestamp() {
          return startTimestampMs;
      }
  
      @Override
      public boolean hasNext() {
          return iter.hasNext();
      }
  
      @Override
      public KeyValue<Long, V> next() {
          final KeyValue<Long, byte[]> next = iter.next();
          return KeyValue.pair(next.key, valueFrom.apply(next.value));
      }
  
      @Override
      public void close() {
          try {
              iter.close();
          } finally {
              final long duration = time.nanoseconds() - startNs;
              operationSensor.record(duration);
              iteratorSensor.record(duration);
              numOpenIterators.decrement();
              openIterators.remove(this);
          }
      }
  
      @Override
      public Long peekNextKey() {
          return iter.peekNextKey();
      }
  }
  