org.apache.spark.sql.sources.v2.reader.DataReader 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.spark.sql.sources.v2.reader;
import java.io.Closeable;
import java.io.IOException;
import org.apache.spark.annotation.InterfaceStability;
/**
* A data reader returned by {@link DataReaderFactory#createDataReader()} and is responsible for
* outputting data for a RDD partition.
*
* Note that, Currently the type `T` can only be {@link org.apache.spark.sql.Row} for normal data
* source readers, or {@link org.apache.spark.sql.catalyst.expressions.UnsafeRow} for data source
* readers that mix in {@link SupportsScanUnsafeRow}.
*/
@InterfaceStability.Evolving
public interface DataReader extends Closeable {
/**
* Proceed to next record, returns false if there is no more records.
*
* If this method fails (by throwing an exception), the corresponding Spark task would fail and
* get retried until hitting the maximum retry times.
*
* @throws IOException if failure happens during disk/network IO like reading files.
*/
boolean next() throws IOException;
/**
* Return the current record. This method should return same value until `next` is called.
*
* If this method fails (by throwing an exception), the corresponding Spark task would fail and
* get retried until hitting the maximum retry times.
*/
T get();
}