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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 spark.rdd
import java.io.EOFException
import java.util.NoSuchElementException
import org.apache.hadoop.io.LongWritable
import org.apache.hadoop.io.NullWritable
import org.apache.hadoop.io.Text
import org.apache.hadoop.mapred.FileInputFormat
import org.apache.hadoop.mapred.InputFormat
import org.apache.hadoop.mapred.InputSplit
import org.apache.hadoop.mapred.JobConf
import org.apache.hadoop.mapred.TextInputFormat
import org.apache.hadoop.mapred.RecordReader
import org.apache.hadoop.mapred.Reporter
import org.apache.hadoop.util.ReflectionUtils
import spark.{Dependency, Logging, Partition, RDD, SerializableWritable, SparkContext, SparkEnv, TaskContext}
import spark.util.NextIterator
import org.apache.hadoop.conf.Configurable
/**
* A Spark split class that wraps around a Hadoop InputSplit.
*/
private[spark] class HadoopPartition(rddId: Int, idx: Int, @transient s: InputSplit)
extends Partition {
val inputSplit = new SerializableWritable[InputSplit](s)
override def hashCode(): Int = (41 * (41 + rddId) + idx).toInt
override val index: Int = idx
}
/**
* An RDD that reads a Hadoop dataset as specified by a JobConf (e.g. files in HDFS, the local file
* system, or S3, tables in HBase, etc).
*/
class HadoopRDD[K, V](
sc: SparkContext,
@transient conf: JobConf,
inputFormatClass: Class[_ <: InputFormat[K, V]],
keyClass: Class[K],
valueClass: Class[V],
minSplits: Int)
extends RDD[(K, V)](sc, Nil) with Logging {
// A Hadoop JobConf can be about 10 KB, which is pretty big, so broadcast it
private val confBroadcast = sc.broadcast(new SerializableWritable(conf))
override def getPartitions: Array[Partition] = {
val env = SparkEnv.get
env.hadoop.addCredentials(conf)
val inputFormat = createInputFormat(conf)
if (inputFormat.isInstanceOf[Configurable]) {
inputFormat.asInstanceOf[Configurable].setConf(conf)
}
val inputSplits = inputFormat.getSplits(conf, minSplits)
val array = new Array[Partition](inputSplits.size)
for (i <- 0 until inputSplits.size) {
array(i) = new HadoopPartition(id, i, inputSplits(i))
}
array
}
def createInputFormat(conf: JobConf): InputFormat[K, V] = {
ReflectionUtils.newInstance(inputFormatClass.asInstanceOf[Class[_]], conf)
.asInstanceOf[InputFormat[K, V]]
}
override def compute(theSplit: Partition, context: TaskContext) = new NextIterator[(K, V)] {
val split = theSplit.asInstanceOf[HadoopPartition]
logInfo("Input split: " + split.inputSplit)
var reader: RecordReader[K, V] = null
val conf = confBroadcast.value.value
val fmt = createInputFormat(conf)
if (fmt.isInstanceOf[Configurable]) {
fmt.asInstanceOf[Configurable].setConf(conf)
}
reader = fmt.getRecordReader(split.inputSplit.value, conf, Reporter.NULL)
// Register an on-task-completion callback to close the input stream.
context.addOnCompleteCallback{ () => closeIfNeeded() }
val key: K = reader.createKey()
val value: V = reader.createValue()
override def getNext() = {
try {
finished = !reader.next(key, value)
} catch {
case eof: EOFException =>
finished = true
}
(key, value)
}
override def close() {
try {
reader.close()
} catch {
case e: Exception => logWarning("Exception in RecordReader.close()", e)
}
}
}
override def getPreferredLocations(split: Partition): Seq[String] = {
// TODO: Filtering out "localhost" in case of file:// URLs
val hadoopSplit = split.asInstanceOf[HadoopPartition]
hadoopSplit.inputSplit.value.getLocations.filter(_ != "localhost")
}
override def checkpoint() {
// Do nothing. Hadoop RDD should not be checkpointed.
}
}
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