zhengbuqian commented on code in PR #23491: URL: https://github.com/apache/beam/pull/23491#discussion_r1036790447
########## sdks/java/core/src/main/java/org/apache/beam/sdk/state/MultimapState.java: ########## @@ -0,0 +1,83 @@ +/* + * 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.beam.sdk.state; + +import java.util.Map; +import org.apache.beam.sdk.annotations.Experimental; +import org.apache.beam.sdk.annotations.Experimental.Kind; + +/** + * A {@link ReadableState} cell mapping keys to bags of values. + * + * <p>Implementations of this form of state are expected to implement multimap operations + * efficiently as supported by some associated backing key-value store. + * + * @param <K> the type of keys maintained by this multimap + * @param <V> the type of mapped values + */ +@Experimental(Kind.STATE) +public interface MultimapState<K, V> extends State { + + /** + * Associates the specified value with the specified key in this multimap. + * + * <p>Changes will not be reflected in the results returned by previous calls to {@link + * ReadableState#read} on the results any of the reading methods({@link #get}, {@link #keys}, + * {@link #entries}). + */ + void put(K key, V value); + + /** + * A deferred lookup, using null values if the item is not found. + * + * <p>A user is encouraged to call {@code get} for all relevant keys and call {@code readLater()} + * on the results. + * + * <p>When {@code read} is called, a particular state implementation is encouraged to perform all + * pending reads in a single batch. + */ + ReadableState<Iterable<V>> get(K key); + + /** + * Removes all values associated with the key from this multimap if exists. + * + * <p>Changes will not be reflected in the results returned by previous calls to {@link + * ReadableState#read} on the results any of the reading methods({@link #get}, {@link #keys}, + * {@link #entries}). + */ + void remove(K key); + + /** Returns an {@link Iterable} over the keys contained in this multimap. */ + ReadableState<Iterable<K>> keys(); + + /** Returns an {@link Iterable} over all key-values pairs contained in this multimap. */ Review Comment: Agreed, done. ########## runners/core-java/src/main/java/org/apache/beam/runners/core/InMemoryStateInternals.java: ########## @@ -463,6 +476,116 @@ public InMemoryBag<T> copy() { } } + /** An {@link InMemoryState} implementation of {@link MultimapState}. */ + public static final class InMemoryMultimap<K, V> + implements MultimapState<K, V>, InMemoryState<InMemoryMultimap<K, V>> { + private final Coder<K> keyCoder; + private final Coder<V> valueCoder; + private Multimap<K, V> contents = ArrayListMultimap.create(); + + public InMemoryMultimap(Coder<K> keyCoder, Coder<V> valueCoder) { + this.keyCoder = keyCoder; + this.valueCoder = valueCoder; + } + + @Override + public void clear() { + contents = ArrayListMultimap.create(); Review Comment: I think we should create a new container instead of `clear()`, this is also how Bag/Map/Set do `clear()`. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
