azagrebin commented on a change in pull request #7288: [FLINK-9702] Improvement in (de)serialization of keys and values for RocksDB state URL: https://github.com/apache/flink/pull/7288#discussion_r241699417
########## File path: flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBSerializedCompositeKeyBuilder.java ########## @@ -0,0 +1,206 @@ +/* + * 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.contrib.streaming.state; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.annotation.VisibleForTesting; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.core.memory.DataOutputSerializer; +import org.apache.flink.util.FlinkRuntimeException; + +import javax.annotation.Nonnegative; +import javax.annotation.Nonnull; +import javax.annotation.concurrent.NotThreadSafe; + +import java.io.IOException; + +/** + * Responsible for serialization of currentKey, currentGroup and namespace. + * Will reuse the previous serialized currentKeyed if possible. + * @param <K> type of the key. + */ +@NotThreadSafe +@Internal +class RocksDBSerializedCompositeKeyBuilder<K> { + + /** The serializer for the key. */ + @Nonnull + private final TypeSerializer<K> keySerializer; + + /** The output to write the key into. */ + @Nonnull + private final DataOutputSerializer keyOutView; + + /** The number of Key-group-prefix bytes for the key. */ + @Nonnegative + private final int keyGroupPrefixBytes; + + /** This flag indicates whether the key type has a variable byte size in serialization. */ + private final boolean keySerializerTypeVariableSized; + + /** Mark for the position after the serialized key. */ + @Nonnegative + private int afterKeyMark; + + public RocksDBSerializedCompositeKeyBuilder( + @Nonnull TypeSerializer<K> keySerializer, + @Nonnegative int keyGroupPrefixBytes, + @Nonnegative int initialSize) { + this( + keySerializer, + new DataOutputSerializer(initialSize), + keyGroupPrefixBytes, + RocksDBKeySerializationUtils.isSerializerTypeVariableSized(keySerializer), + 0); + } + + @VisibleForTesting + RocksDBSerializedCompositeKeyBuilder( + @Nonnull TypeSerializer<K> keySerializer, + @Nonnull DataOutputSerializer keyOutView, + @Nonnegative int keyGroupPrefixBytes, + boolean keySerializerTypeVariableSized, + @Nonnegative int afterKeyMark) { + this.keySerializer = keySerializer; + this.keyOutView = keyOutView; + this.keyGroupPrefixBytes = keyGroupPrefixBytes; + this.keySerializerTypeVariableSized = keySerializerTypeVariableSized; + this.afterKeyMark = afterKeyMark; + } + + /** + * Sets the key and key-group as prefix. This will serialize them into the buffer and the will be used to create + * composite keys with provided namespaces. + * + * @param key the key. + * @param keyGroupId the key-group id for the key. + */ + public void setKeyAndKeyGroup(@Nonnull K key, @Nonnegative int keyGroupId) { + try { + serializeKeyGroupAndKey(key, keyGroupId); + } catch (IOException shouldNeverHappen) { + throw new FlinkRuntimeException(shouldNeverHappen); + } + } + + /** + * Returns a serialized composite key, from the key and key-group provided in a previous call to + * {@link #setKeyAndKeyGroup(Object, int)} and the given namespace. + * + * @param namespace the namespace to concatenate for the serialized composite key bytes. + * @param namespaceSerializer the serializer to obtain the serialized form of the namespace. + * @param <N> the type of the namespace. + * @return the bytes for the serialized composite key of key-group, key, namespace. + */ + @Nonnull + public <N> byte[] buildCompositeKeyNamespace(@Nonnull N namespace, @Nonnull TypeSerializer<N> namespaceSerializer) { + try { + serializeNamespace(namespace, namespaceSerializer); + final byte[] result = keyOutView.getCopyOfBuffer(); + resetToKey(); + return result; + } catch (IOException shouldNeverHappen) { + throw new FlinkRuntimeException(shouldNeverHappen); + } + } + + /** + * Returns a serialized composite key, from the key and key-group provided in a previous call to + * {@link #setKeyAndKeyGroup(Object, int)} and the given namespace, folloed by the given user-key. + * + * @param namespace the namespace to concatenate for the serialized composite key bytes. + * @param namespaceSerializer the serializer to obtain the serialized form of the namespace. + * @param userKey the user-key to concatenate for the serialized composite key, after the namespace. + * @param userKeySerializer the serializer to obtain the serialized form of the user-key. + * @param <N> the type of the namespace. + * @param <UK> the type of the user-key. + * @return the bytes for the serialized composite key of key-group, key, namespace. + */ + @Nonnull + public <N, UK> byte[] buildCompositeKeyNamesSpaceUserKey( + @Nonnull N namespace, + @Nonnull TypeSerializer<N> namespaceSerializer, + @Nonnull UK userKey, + @Nonnull TypeSerializer<UK> userKeySerializer) throws IOException { + serializeNamespace(namespace, namespaceSerializer); + userKeySerializer.serialize(userKey, keyOutView); + byte[] result = keyOutView.getCopyOfBuffer(); + resetToKey(); + return result; + } + + private void serializeKeyGroupAndKey(K key, int keyGroupId) throws IOException { + + // clear buffer and mark + resetFully(); + + // write key-group + RocksDBKeySerializationUtils.writeKeyGroup( + keyGroupId, + keyGroupPrefixBytes, + keyOutView); + // write key + keySerializer.serialize(key, keyOutView); + afterKeyMark = keyOutView.length(); + } + + private <N> void serializeNamespace( + @Nonnull N namespace, + @Nonnull TypeSerializer<N> namespaceSerializer) throws IOException { + + // this should only be called when there is already a key written so that we build the composite. + assert isKeyWritten(); + + final boolean ambiguousCompositeKeyPossible = isAmbiguousCompositeKeyPossible(namespaceSerializer); + if (ambiguousCompositeKeyPossible) { + RocksDBKeySerializationUtils.writeVariableIntBytes( + afterKeyMark - keyGroupPrefixBytes, + keyOutView); + } + RocksDBKeySerializationUtils.writeNameSpace( + namespace, + namespaceSerializer, + keyOutView, + ambiguousCompositeKeyPossible); + } + + private void resetFully() { + afterKeyMark = 0; + keyOutView.clear(); + } + + private void resetToKey() { + keyOutView.setPosition(afterKeyMark); + } + + private boolean isKeyWritten() { + return afterKeyMark > 0; + } + + @VisibleForTesting + boolean isAmbiguousCompositeKeyPossible(TypeSerializer<?> namespaceSerializer) { + return keySerializerTypeVariableSized & + RocksDBKeySerializationUtils.isSerializerTypeVariableSized(namespaceSerializer); + } + + @VisibleForTesting + boolean isKeySerializerTypeVariableSized() { Review comment: is this method used? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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