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.rocksdb;
  
  import java.lang.ref.Cleaner;
  import org.apache.bifromq.basekv.localengine.KVEngineException;
  import org.rocksdb.ColumnFamilyHandle;
  import org.rocksdb.ReadOptions;
  import org.rocksdb.RocksDB;
  import org.rocksdb.RocksIterator;
  import org.rocksdb.Slice;
  import org.rocksdb.Snapshot;
  
  class RocksDBKVEngineIterator implements AutoCloseable {
      private static final Cleaner CLEANER = Cleaner.create();
      private final RocksIterator rocksIterator;
      private final Cleaner.Cleanable onClose;
  
      RocksDBKVEngineIterator(RocksDB db,
                              ColumnFamilyHandle cfHandle,
                              Snapshot snapshot,
                              byte[] startKey,
                              byte[] endKey) {
          this(db, cfHandle, snapshot, startKey, endKey, true);
      }
  
      RocksDBKVEngineIterator(RocksDB db,
                              ColumnFamilyHandle cfHandle,
                              Snapshot snapshot,
                              byte[] startKey,
                              byte[] endKey,
                              boolean fillCache) {
          ReadOptions readOptions = new ReadOptions().setPinData(true).setFillCache(fillCache);
          Slice lowerSlice = null;
          if (startKey != null) {
              lowerSlice = new Slice(startKey);
              readOptions.setIterateLowerBound(lowerSlice);
          }
          Slice upperSlice = null;
          if (endKey != null) {
              upperSlice = new Slice(endKey);
              readOptions.setIterateUpperBound(upperSlice);
          }
          if (snapshot != null) {
              readOptions.setSnapshot(snapshot);
          }
          rocksIterator = db.newIterator(cfHandle, readOptions);
          onClose = CLEANER.register(this, new NativeState(rocksIterator, readOptions, lowerSlice, upperSlice));
  
      }
  
      public byte[] key() {
          return rocksIterator.key();
      }
  
      public byte[] value() {
          return rocksIterator.value();
      }
  
      public boolean isValid() {
          return rocksIterator.isValid();
      }
  
      public void next() {
          rocksIterator.next();
      }
  
      public void prev() {
          rocksIterator.prev();
      }
  
      public void seekToFirst() {
          rocksIterator.seekToFirst();
      }
  
      public void seekToLast() {
          rocksIterator.seekToLast();
      }
  
      public void seek(byte[] target) {
          rocksIterator.seek(target);
      }
  
      public void seekForPrev(byte[] target) {
          rocksIterator.seekForPrev(target);
      }
  
      public void refresh() {
          try {
              rocksIterator.refresh();
          } catch (Throwable e) {
              throw new KVEngineException("Unable to refresh iterator", e);
          }
      }
  
      @Override
      public void close() {
          onClose.clean();
      }
  
      private record NativeState(RocksIterator itr, ReadOptions readOptions, Slice lowerSlice, Slice upperSlice)
          implements Runnable {
  
          @Override
          public void run() {
              itr.close();
              readOptions.close();
              if (lowerSlice != null) {
                  lowerSlice.close();
              }
              if (upperSlice != null) {
                  upperSlice.close();
              }
          }
      }
  }
  