/*
* 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;
import org.apache.flink.core.fs.FSDataOutputStream;
import java.io.IOException;
import java.io.OutputStream;
public interface CheckpointStreamFactory {
/**
* Creates an new {@link CheckpointStateOutputStream}. When the stream
* is closed, it returns a state handle that can retrieve the state back.
*
* @param checkpointID The ID of the checkpoint.
* @param timestamp The timestamp of the checkpoint.
*
* @return An output stream that writes state for the given checkpoint.
*
* @throws Exception Exceptions may occur while creating the stream and should be forwarded.
*/
CheckpointStateOutputStream createCheckpointStateOutputStream(
long checkpointID,
long timestamp) throws Exception;
/**
* Closes the stream factory, releasing all internal resources, but does not delete any
* persistent checkpoint data.
*
* @throws Exception Exceptions can be forwarded and will be logged by the system
*/
void close() throws Exception;
/**
* A dedicated output stream that produces a {@link StreamStateHandle} when closed.
*
* <p>Note: This is an abstract class and not an interface because {@link OutputStream}
* is an abstract class.
*/
abstract class CheckpointStateOutputStream extends FSDataOutputStream {
/**
* Closes the stream and gets a state handle that can create an input stream
* producing the data written to this stream.
*
* @return A state handle that can create an input stream producing the data written to this stream.
* @throws IOException Thrown, if the stream cannot be closed.
*/
public abstract StreamStateHandle closeAndGetHandle() throws IOException;
}
}