org.apache.flink.runtime.state.keyed.KeyedState Maven / Gradle / Ivy
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* 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.keyed;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.runtime.state.StateStorage;
import java.util.Collection;
import java.util.Map;
/**
* Base interface for all keyed states.
*
* @param The type of the keys in the state.
* @param The type of the values in the state.
*/
public interface KeyedState {
/**
* Returns the descriptor of the state.
*
* @return The descriptor of the state.
*/
KeyedStateDescriptor getDescriptor();
/**
* Returns true if the state contains a pair whose key is equal to the given
* object.
*
* @param key The key whose presence in the state to be tested.
* @return True if the state contains the pair for the given key.
*/
boolean contains(K key);
/**
* Returns the value associated with the key in the state.
*
* @param key The key whose value is to be retrieved.
* @return The value associated with the key in the state.
*/
V get(K key);
/**
* Returns the value associated with the key in the state, or
* {@code defaultValue} if the key does not exist in the state.
*
* @param key The key whose associated value is to be returned.
* @param defaultValue The default value of the key.
* @return The value to which the specified key is mapped, or
* {@code defaultValue} if the key does not exist in the state.
*/
V getOrDefault(K key, V defaultValue);
/**
* Returns the values associated with the given keys in the state.
*
* @param keys The keys whose values are to be retrieved.
* @return The values associated with the keys in the state.
*/
Map getAll(Collection keys);
/**
* Removes the pair for the given key from the state if it is present.
*
* @param key The key whose pair is to be removed from the state.
*/
void remove(K key);
/**
* Removes all of the pairs whose keys appear in the given collection from
* the state. The removal of these pairs are atomic, i.e., exceptions will
* be thrown if some of the pairs fail to be removed.
*
* @param keys The keys of the pairs to be removed from the state.
*/
void removeAll(Collection keys);
/**
* Returns all the key/value map in the state.
*
* @return The key/value map in the state.
*/
Map getAll();
/**
* Remove all the items in the state.
*/
void removeAll();
/**
* Returns an iterable over all of the keys in the state.
*
* @return The iterable of all the keys in the state.
*/
Iterable keys();
/**
* Returns the serialized value for the given key.
*
* If no value is associated with key, null is returned.
*
*
TO IMPLEMENTERS: This method is called by multiple threads. Anything
* stateful (e.g. serializers) should be either duplicated or protected from undesired
* consequences of concurrent invocations.
*
* @param serializedKeyAndNamespace Serialized key and namespace
* @param safeKeySerializer A key serializer which is safe to be used even in multi-threaded context
* @param safeValueSerializer A value serializer which is safe to be used even in multi-threaded context
* @return Serialized value or null if no value is associated with the key.
* @throws Exception Exceptions during serialization are forwarded
*/
byte[] getSerializedValue(
final byte[] serializedKeyAndNamespace,
final TypeSerializer safeKeySerializer,
final TypeSerializer safeValueSerializer) throws Exception;
/**
* Returns the state storage within this keyed state.
*
* @return The state storage within this keyed state.
*/
StateStorage getStateStorage();
}