org.apache.nifi.components.state.StateMap Maven / Gradle / Ivy
/*
* 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.nifi.components.state;
import java.util.Map;
/**
* Provides a representation of a component's state at some point in time.
*/
public interface StateMap {
/**
* Each time that a component's state is updated, the state is assigned a new version.
* This version can then be used to atomically update state by the backing storage mechanism.
* Though this number is monotonically increasing, it should not be expected to increment always
* from X to X+1. I.e., version numbers may be skipped.
*
* @return the version associated with the state
*/
long getVersion();
/**
* Returns the value associated with the given key
*
* @param key the key whose value should be retrieved
* @return the value associated with the given key, or null if no value is associated
* with this key.
*/
String get(String key);
/**
* Returns an immutable Map representation of all keys and values for the state of a component.
*
* @return an immutable Map representation of all keys and values for the state of a component.
*/
Map toMap();
}