org.apache.flink.connector.base.source.reader.splitreader.SplitReader 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
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*/
package org.apache.flink.connector.base.source.reader.splitreader;
import org.apache.flink.api.connector.source.SourceSplit;
import org.apache.flink.connector.base.source.reader.RecordsWithSplitIds;
import java.io.IOException;
/**
* An interface used to read from splits. The implementation could either read from a single split
* or from multiple splits.
*
* @param the element type.
* @param the split type.
*/
public interface SplitReader {
/**
* Fetch elements into the blocking queue for the given splits. The fetch call could be blocking
* but it should get unblocked when {@link #wakeUp()} is invoked. In that case, the
* implementation may either decide to return without throwing an exception, or it can just
* throw an interrupted exception. In either case, this method should be reentrant, meaning that
* the next fetch call should just resume from where the last fetch call was waken up or
* interrupted.
*
* @return the Ids of the finished splits.
* @throws IOException when encountered IO errors, such as deserialization failures.
*/
RecordsWithSplitIds fetch() throws IOException;
/**
* Handle the split changes. This call should be non-blocking.
*
* @param splitsChanges the split changes that the SplitReader needs to handle.
*/
void handleSplitsChanges(SplitsChange splitsChanges);
/** Wake up the split reader in case the fetcher thread is blocking in {@link #fetch()}. */
void wakeUp();
/**
* Close the split reader.
*
* @throws Exception if closing the split reader failed.
*/
void close() throws Exception;
}