gaborgsomogyi commented on code in PR #26134: URL: https://github.com/apache/flink/pull/26134#discussion_r1954542463
########## flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/state/rocksdb/iterator/RocksMultiStateKeysIterator.java: ########## @@ -0,0 +1,180 @@ +/* + * 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.flink.state.rocksdb.iterator; + +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.core.memory.DataInputDeserializer; +import org.apache.flink.runtime.state.CompositeKeySerializationUtils; +import org.apache.flink.state.rocksdb.RocksIteratorWrapper; +import org.apache.flink.util.FlinkRuntimeException; + +import javax.annotation.Nonnull; +import javax.annotation.Nullable; + +import java.io.IOException; +import java.util.Arrays; +import java.util.Iterator; +import java.util.List; +import java.util.NoSuchElementException; +import java.util.Objects; + +import static org.apache.flink.state.rocksdb.iterator.AbstractRocksStateKeysIterator.isMatchingNameSpace; + +/** + * Adapter class to bridge between {@link RocksIteratorWrapper} and {@link Iterator} to iterate over + * the keys. This class is not thread safe. + * + * @param <K> the type of the iterated objects, which are keys in RocksDB. + */ +public class RocksMultiStateKeysIterator<K> implements AutoCloseable, Iterator<K> { + + private final List<RocksIteratorWrapper> iterators; + private final List<String> states; + private final TypeSerializer<K> keySerializer; + private final List<Boolean> ambiguousKeyPossibles; + private final int keyGroupPrefixBytes; + private final byte[] namespaceBytes; + private final DataInputDeserializer byteArrayDataInputView; + + private final byte[][] iteratorKeys; + private K previousKey; + private K nextKey; + + public RocksMultiStateKeysIterator( + List<RocksIteratorWrapper> iterators, + List<String> states, + @Nonnull TypeSerializer<K> keySerializer, + int keyGroupPrefixBytes, + List<Boolean> ambiguousKeyPossibles, + @Nonnull byte[] namespaceBytes) { + this.iterators = iterators; + this.states = states; + this.keySerializer = keySerializer; + this.ambiguousKeyPossibles = ambiguousKeyPossibles; + this.keyGroupPrefixBytes = keyGroupPrefixBytes; + this.namespaceBytes = namespaceBytes; + this.byteArrayDataInputView = new DataInputDeserializer(); + this.iteratorKeys = new byte[iterators.size()][]; + Arrays.fill(iteratorKeys, null); + this.previousKey = null; + this.nextKey = null; + } + + @Override + public boolean hasNext() { + try { + while (nextKey == null && hasDataToProcess()) { + pullKeysFromIterators(); + K smallestIteratorKey = calculateSmallestKeyFromLocalData(); + if (smallestIteratorKey != null) { + previousKey = smallestIteratorKey; + nextKey = smallestIteratorKey; + } + } + } catch (Exception e) { + throw new FlinkRuntimeException( + "Failed to access states [" + String.join(",", states) + "]", e); + } + return nextKey != null; + } + + private boolean hasDataToProcess() { + boolean result = iterators.stream().anyMatch(RocksIteratorWrapper::isValid); + if (!result) { + for (int i = 0; i < iterators.size(); ++i) { + if (iteratorKeys[i] != null) { + result = true; + break; + } + } + } + return result; + } + + private void pullKeysFromIterators() { + for (int i = 0; i < iterators.size(); ++i) { + RocksIteratorWrapper iterator = iterators.get(i); + if (iteratorKeys[i] == null && iterator.isValid()) { + iteratorKeys[i] = iterator.key(); + iterator.next(); + } + } + } + + @Nullable + private K calculateSmallestKeyFromLocalData() throws IOException { + int smallestIteratorKeyIndex = -1; + byte[] smallestIteratorKey = null; + for (int i = 0; i < iteratorKeys.length; ++i) { + byte[] iteratorKey = iteratorKeys[i]; + if (iteratorKey != null + && (smallestIteratorKey == null + || Arrays.compare(iteratorKey, smallestIteratorKey) < 0)) { + smallestIteratorKeyIndex = i; + smallestIteratorKey = iteratorKey; + } + } + + if (smallestIteratorKey != null) { + for (int i = 0; i < iteratorKeys.length; ++i) { + if (Arrays.equals(iteratorKeys[i], smallestIteratorKey)) { + iteratorKeys[i] = null; + } + } + + byteArrayDataInputView.setBuffer( + smallestIteratorKey, + keyGroupPrefixBytes, + smallestIteratorKey.length - keyGroupPrefixBytes); + final K smallestIteratorKeyValue = + CompositeKeySerializationUtils.readKey( + keySerializer, + byteArrayDataInputView, + ambiguousKeyPossibles.get(smallestIteratorKeyIndex)); + if (isMatchingNameSpace( + smallestIteratorKey, + byteArrayDataInputView.getPosition(), + namespaceBytes) + && !Objects.equals(previousKey, smallestIteratorKeyValue)) { Review Comment: It took me some time why I've put it here but now I remember. It comes from this logic: https://github.com/apache/flink/blob/cd0cfe42c15042a3c27a0c341416aa32c0d594b6/flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/state/rocksdb/iterator/RocksStateKeysIterator.java#L59-L77 It handles the case when we get the same key from an iterator. Honestly I've no idea whether and/or how this is possible but not wanted to miss this guard. If we could eliminate this then I think that could be quite a boost... -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
