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.utils.AbstractIterator;
  import org.apache.kafka.common.utils.Bytes;
  import org.apache.kafka.streams.KeyValue;
  import org.apache.kafka.streams.errors.InvalidStateStoreException;
  
  import org.rocksdb.RocksIterator;
  
  import java.util.NoSuchElementException;
  import java.util.function.Consumer;
  
  class RocksDbIterator extends AbstractIterator<KeyValue<Bytes, byte[]>> implements ManagedKeyValueIterator<Bytes, byte[]> {
  
      private final String storeName;
      private final RocksIterator iter;
      private final Consumer<RocksIterator> advanceIterator;
  
      private volatile boolean open = true;
  
      private KeyValue<Bytes, byte[]> next;
      private Runnable closeCallback = null;
  
      RocksDbIterator(final String storeName,
                      final RocksIterator iter,
                      final boolean forward) {
          this.storeName = storeName;
          this.iter = iter;
          this.advanceIterator = forward ? RocksIterator::next : RocksIterator::prev;
      }
  
      @Override
      public synchronized boolean hasNext() {
          if (!open) {
              throw new InvalidStateStoreException(String.format("RocksDB iterator for store %s has closed", storeName));
          }
          return super.hasNext();
      }
  
      @Override
      protected KeyValue<Bytes, byte[]> makeNext() {
          if (!iter.isValid()) {
              return allDone();
          } else {
              next = getKeyValue();
              advanceIterator.accept(iter);
              return next;
          }
      }
  
      private KeyValue<Bytes, byte[]> getKeyValue() {
          return new KeyValue<>(new Bytes(iter.key()), iter.value());
      }
  
      @Override
      public synchronized void close() {
          if (closeCallback == null) {
              throw new IllegalStateException("RocksDbIterator expects close callback to be set immediately upon creation");
          }
          closeCallback.run();
  
          iter.close();
          open = false;
      }
  
      @Override
      public Bytes peekNextKey() {
          if (!hasNext()) {
              throw new NoSuchElementException();
          }
          return next.key;
      }
  
      @Override
      public synchronized void onClose(final Runnable closeCallback) {
          this.closeCallback = closeCallback;
      }
  }
  