/*
* Copyright © 2015 Cask Data, Inc.
*
* Licensed 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 co.cask.cdap.api.dataset.lib;
import co.cask.cdap.api.data.DatasetContext;
import javax.annotation.Nullable;
/**
* Defines how some state will be persisted/managed, using a {@link DatasetContext} to read and persist state.
*/
public interface DatasetStatePersistor {
/**
* @param datasetContext context to use to instantiate dataset(s) for reading the state
* @return the serialized bytes of the state of the partition consuming process; return null to indicate a fresh
* state of consuming (defaults to starting from the beginning).
*/
@Nullable
byte[] readState(DatasetContext datasetContext);
/**
* Writes the serialized bytes of the state of the partition consuming process. The bytes written in this method
* should be available in the following call to readBytes(DatasetContext).
*
* @param datasetContext context to use to instantiate dataset(s) for persisting the state
* @param state the bytes to persist
*/
void persistState(DatasetContext datasetContext, byte[] state);
}