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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.rdd
import scala.collection.mutable.ArrayBuffer
import org.apache.spark.{Dependency, RangeDependency, RDD, SparkContext, Partition, TaskContext}
import java.io.{ObjectOutputStream, IOException}
private[spark] class UnionPartition[T: ClassManifest](idx: Int, rdd: RDD[T], splitIndex: Int)
extends Partition {
var split: Partition = rdd.partitions(splitIndex)
def iterator(context: TaskContext) = rdd.iterator(split, context)
def preferredLocations() = rdd.preferredLocations(split)
override val index: Int = idx
@throws(classOf[IOException])
private def writeObject(oos: ObjectOutputStream) {
// Update the reference to parent split at the time of task serialization
split = rdd.partitions(splitIndex)
oos.defaultWriteObject()
}
}
class UnionRDD[T: ClassManifest](
sc: SparkContext,
@transient var rdds: Seq[RDD[T]])
extends RDD[T](sc, Nil) { // Nil since we implement getDependencies
override def getPartitions: Array[Partition] = {
val array = new Array[Partition](rdds.map(_.partitions.size).sum)
var pos = 0
for (rdd <- rdds; split <- rdd.partitions) {
array(pos) = new UnionPartition(pos, rdd, split.index)
pos += 1
}
array
}
override def getDependencies: Seq[Dependency[_]] = {
val deps = new ArrayBuffer[Dependency[_]]
var pos = 0
for (rdd <- rdds) {
deps += new RangeDependency(rdd, 0, pos, rdd.partitions.size)
pos += rdd.partitions.size
}
deps
}
override def compute(s: Partition, context: TaskContext): Iterator[T] =
s.asInstanceOf[UnionPartition[T]].iterator(context)
override def getPreferredLocations(s: Partition): Seq[String] =
s.asInstanceOf[UnionPartition[T]].preferredLocations()
}
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