[GitHub] azagrebin commented on a change in pull request #7288: [FLINK-9702] Improvement in (de)serialization of keys and values for RocksDB state

[GitBox <gi...@apache.org>]

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_r241699307
 
 

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 File path: flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBSerializedCompositeKeyBuilder.java
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 @@ -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.
 
 Review comment:
   folloWed

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