flink-runtime/src/main/java/org/apache/flink/runtime/state/heap/HeapMapState.java

/*
 * 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.runtime.state.heap;

import org.apache.flink.api.common.state.MapState;
import org.apache.flink.api.common.state.State;
import org.apache.flink.api.common.state.StateDescriptor;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.api.common.typeutils.base.MapSerializer;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.queryablestate.client.state.serialization.KvStateSerializer;
import org.apache.flink.runtime.state.internal.InternalMapState;
import org.apache.flink.util.Preconditions;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * Heap-backed partitioned {@link MapState} that is snapshotted into files.
 *
 * @param <K> The type of the key.
 * @param <N> The type of the namespace.
 * @param <UK> The type of the keys in the state.
 * @param <UV> The type of the values in the state.
 */
class HeapMapState<K, N, UK, UV>
	extends AbstractHeapState<K, N, Map<UK, UV>>
	implements InternalMapState<K, N, UK, UV> {

	/**
	 * Creates a new key/value state for the given hash map of key/value pairs.
	 *
	 * @param stateTable The state table for which this state is associated to.
	 * @param keySerializer The serializer for the keys.
	 * @param valueSerializer The serializer for the state.
	 * @param namespaceSerializer The serializer for the namespace.
	 * @param defaultValue The default value for the state.
	 */
	private HeapMapState(
		StateTable<K, N, Map<UK, UV>> stateTable,
		TypeSerializer<K> keySerializer,
		TypeSerializer<Map<UK, UV>> valueSerializer,
		TypeSerializer<N> namespaceSerializer,
		Map<UK, UV> defaultValue) {
		super(stateTable, keySerializer, valueSerializer, namespaceSerializer, defaultValue);

		Preconditions.checkState(valueSerializer instanceof MapSerializer, "Unexpected serializer type.");
	}

	@Override
	public TypeSerializer<K> getKeySerializer() {
		return keySerializer;
	}

	@Override
	public TypeSerializer<N> getNamespaceSerializer() {
		return namespaceSerializer;
	}

	@Override
	public TypeSerializer<Map<UK, UV>> getValueSerializer() {
		return valueSerializer;
	}

	@Override
	public UV get(UK userKey) {

		Map<UK, UV> userMap = stateTable.get(currentNamespace);

		if (userMap == null) {
			return null;
		}

		return userMap.get(userKey);
	}

	@Override
	public void put(UK userKey, UV userValue) {

		Map<UK, UV> userMap = stateTable.get(currentNamespace);
		if (userMap == null) {
			userMap = new HashMap<>();
			stateTable.put(currentNamespace, userMap);
		}

		userMap.put(userKey, userValue);
	}

	@Override
	public void putAll(Map<UK, UV> value) {

		Map<UK, UV> userMap = stateTable.get(currentNamespace);

		if (userMap == null) {
			userMap = new HashMap<>();
			stateTable.put(currentNamespace, userMap);
		}

		userMap.putAll(value);
	}

	@Override
	public void remove(UK userKey) {

		Map<UK, UV> userMap = stateTable.get(currentNamespace);
		if (userMap == null) {
			return;
		}

		userMap.remove(userKey);

		if (userMap.isEmpty()) {
			clear();
		}
	}

	@Override
	public boolean contains(UK userKey) {
		Map<UK, UV> userMap = stateTable.get(currentNamespace);
		return userMap != null && userMap.containsKey(userKey);
	}

	@Override
	public Iterable<Map.Entry<UK, UV>> entries() {
		Map<UK, UV> userMap = stateTable.get(currentNamespace);
		return userMap == null ? null : userMap.entrySet();
	}

	@Override
	public Iterable<UK> keys() {
		Map<UK, UV> userMap = stateTable.get(currentNamespace);
		return userMap == null ? null : userMap.keySet();
	}

	@Override
	public Iterable<UV> values() {
		Map<UK, UV> userMap = stateTable.get(currentNamespace);
		return userMap == null ? null : userMap.values();
	}

	@Override
	public Iterator<Map.Entry<UK, UV>> iterator() {
		Map<UK, UV> userMap = stateTable.get(currentNamespace);
		return userMap == null ? null : userMap.entrySet().iterator();
	}

	@Override
	public byte[] getSerializedValue(
			final byte[] serializedKeyAndNamespace,
			final TypeSerializer<K> safeKeySerializer,
			final TypeSerializer<N> safeNamespaceSerializer,
			final TypeSerializer<Map<UK, UV>> safeValueSerializer) throws Exception {

		Preconditions.checkNotNull(serializedKeyAndNamespace);
		Preconditions.checkNotNull(safeKeySerializer);
		Preconditions.checkNotNull(safeNamespaceSerializer);
		Preconditions.checkNotNull(safeValueSerializer);

		Tuple2<K, N> keyAndNamespace = KvStateSerializer.deserializeKeyAndNamespace(
				serializedKeyAndNamespace, safeKeySerializer, safeNamespaceSerializer);

		Map<UK, UV> result = stateTable.get(keyAndNamespace.f0, keyAndNamespace.f1);

		if (result == null) {
			return null;
		}

		final MapSerializer<UK, UV> serializer = (MapSerializer<UK, UV>) safeValueSerializer;

		final TypeSerializer<UK> dupUserKeySerializer = serializer.getKeySerializer();
		final TypeSerializer<UV> dupUserValueSerializer = serializer.getValueSerializer();

		return KvStateSerializer.serializeMap(result.entrySet(), dupUserKeySerializer, dupUserValueSerializer);
	}

	@SuppressWarnings("unchecked")
	static <UK, UV, K, N, SV, S extends State, IS extends S> IS create(
		StateDescriptor<S, SV> stateDesc,
		StateTable<K, N, SV> stateTable,
		TypeSerializer<K> keySerializer) {
		return (IS) new HeapMapState<>(
			(StateTable<K, N, Map<UK, UV>>) stateTable,
			keySerializer,
			(TypeSerializer<Map<UK, UV>>) stateTable.getStateSerializer(),
			stateTable.getNamespaceSerializer(),
			(Map<UK, UV>) stateDesc.getDefaultValue());
	}
}