spark HadoopFileLinesReader 源码
spark HadoopFileLinesReader 代码
文件路径：/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/HadoopFileLinesReader.scala
/*
* 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.execution.datasources
import java.io.Closeable
import java.net.URI
import org.apache.hadoop.conf.Configuration
import org.apache.hadoop.fs.Path
import org.apache.hadoop.io.Text
import org.apache.hadoop.mapreduce._
import org.apache.hadoop.mapreduce.lib.input.{FileSplit, LineRecordReader}
import org.apache.hadoop.mapreduce.task.TaskAttemptContextImpl
/**
* An adaptor from a [[PartitionedFile]] to an [[Iterator]] of [[Text]], which are all of the lines
* in that file.
*
* @param file A part (i.e. "block") of a single file that should be read line by line.
* @param lineSeparator A line separator that should be used for each line. If the value is `None`,
* it covers `\r`, `\r\n` and `\n`.
* @param conf Hadoop configuration
*
* @note The behavior when `lineSeparator` is `None` (covering `\r`, `\r\n` and `\n`) is defined
* by [[LineRecordReader]], not within Spark.
*/
class HadoopFileLinesReader(
file: PartitionedFile,
lineSeparator: Option[Array[Byte]],
conf: Configuration) extends Iterator[Text] with Closeable {
def this(file: PartitionedFile, conf: Configuration) = this(file, None, conf)
private val _iterator = {
val fileSplit = new FileSplit(
new Path(new URI(file.filePath)),
file.start,
file.length,
// The locality is decided by `getPreferredLocations` in `FileScanRDD`.
Array.empty)
val attemptId = new TaskAttemptID(new TaskID(new JobID(), TaskType.MAP, 0), 0)
val hadoopAttemptContext = new TaskAttemptContextImpl(conf, attemptId)
val reader = lineSeparator match {
case Some(sep) => new LineRecordReader(sep)
// If the line separator is `None`, it covers `\r`, `\r\n` and `\n`.
case _ => new LineRecordReader()
}
reader.initialize(fileSplit, hadoopAttemptContext)
new RecordReaderIterator(reader)
}
override def hasNext: Boolean = _iterator.hasNext
override def next(): Text = _iterator.next()
override def close(): Unit = _iterator.close()
}
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