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From StefanRRichter <...@git.apache.org>
Subject [GitHub] flink pull request #6196: [FLINK-9513] Implement TTL state wrappers factory ...
Date Mon, 02 Jul 2018 12:09:15 GMT
Github user StefanRRichter commented on a diff in the pull request:

    https://github.com/apache/flink/pull/6196#discussion_r199474873
  
    --- Diff: flink-core/src/main/java/org/apache/flink/api/common/typeutils/CompositeSerializer.java
---
    @@ -0,0 +1,258 @@
    +/*
    + * 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.api.common.typeutils;
    +
    +import org.apache.flink.api.java.tuple.Tuple2;
    +import org.apache.flink.core.memory.DataInputView;
    +import org.apache.flink.core.memory.DataOutputView;
    +import org.apache.flink.util.Preconditions;
    +
    +import javax.annotation.Nonnull;
    +
    +import java.io.IOException;
    +import java.util.Arrays;
    +import java.util.List;
    +import java.util.Objects;
    +
    +/**
    + * Base class for composite serializers.
    + *
    + * <p>This class serializes a composite type using array of its field serializers.
    + * Fields are indexed the same way as their serializers.
    + *
    + * @param <T> type of custom serialized value
    + */
    +public abstract class CompositeSerializer<T> extends TypeSerializer<T> {
    +	private static final long serialVersionUID = 1L;
    +
    +	protected final TypeSerializer<Object>[] fieldSerializers;
    +	final boolean isImmutableTargetType;
    +	private final int length;
    +
    +	@SuppressWarnings("unchecked")
    +	protected CompositeSerializer(boolean isImmutableTargetType, TypeSerializer<?>
... fieldSerializers) {
    +		Preconditions.checkNotNull(fieldSerializers);
    +		Preconditions.checkArgument(Arrays.stream(fieldSerializers).allMatch(Objects::nonNull));
    +		this.isImmutableTargetType = isImmutableTargetType;
    +		this.fieldSerializers = (TypeSerializer<Object>[]) fieldSerializers;
    +		this.length = calcLength();
    +	}
    +
    +	/** Create new instance from its fields.  */
    +	public abstract T createInstance(@Nonnull Object ... values);
    +
    +	/** Modify field of existing instance. Supported only by mutable types. */
    +	protected abstract void setField(@Nonnull T value, int index, Object fieldValue);
    +
    +	/** Get field of existing instance. */
    +	protected abstract Object getField(@Nonnull T value, int index);
    +
    +	/** Factory for concrete serializer. */
    +	protected abstract CompositeSerializer<T> createSerializerInstance(TypeSerializer<?>
... originalSerializers);
    +
    +	@Override
    +	public CompositeSerializer<T> duplicate() {
    +		TypeSerializer[] duplicatedSerializers = new TypeSerializer[fieldSerializers.length];
    +		boolean stateful = false;
    +		for (int index = 0; index < fieldSerializers.length; index++) {
    +			duplicatedSerializers[index] = fieldSerializers[index].duplicate();
    +			if (fieldSerializers[index] != duplicatedSerializers[index]) {
    +				stateful = true;
    +			}
    +		}
    +		return stateful ? createSerializerInstance(duplicatedSerializers) : this;
    +	}
    +
    +	@Override
    +	public boolean isImmutableType() {
    +		for (TypeSerializer<Object> fieldSerializer : fieldSerializers) {
    --- End diff --
    
    We can compute many things like length, immutability, etc already in the constructor.
Statelessness is the one thing that we might want to figure out and remember on the first
attempt.


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