350 lines
11 KiB
Scala
350 lines
11 KiB
Scala
package spark
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import java.util.concurrent.atomic.AtomicLong
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import java.util.concurrent.ConcurrentHashMap
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import java.util.HashSet
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import java.util.Random
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import scala.collection.mutable.ArrayBuffer
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import scala.collection.mutable.Map
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import scala.collection.mutable.HashMap
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import mesos._
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import com.google.common.collect.MapMaker
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@serializable
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abstract class RDD[T: ClassManifest](@transient sc: SparkContext) {
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def splits: Array[Split]
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def iterator(split: Split): Iterator[T]
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def preferredLocations(split: Split): Seq[String]
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def taskStarted(split: Split, slot: SlaveOffer) {}
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def sparkContext = sc
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def map[U: ClassManifest](f: T => U) = new MappedRDD(this, sc.clean(f))
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def filter(f: T => Boolean) = new FilteredRDD(this, sc.clean(f))
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def cache() = new CachedRDD(this)
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def sample(withReplacement: Boolean, frac: Double, seed: Int) =
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new SampledRDD(this, withReplacement, frac, seed)
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def flatMap[U: ClassManifest](f: T => Traversable[U]) =
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new FlatMappedRDD(this, sc.clean(f))
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def foreach(f: T => Unit) {
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val cleanF = sc.clean(f)
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val tasks = splits.map(s => new ForeachTask(this, s, cleanF)).toArray
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sc.runTaskObjects(tasks)
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}
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def collect(): Array[T] = {
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val tasks = splits.map(s => new CollectTask(this, s))
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val results = sc.runTaskObjects(tasks)
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Array.concat(results: _*)
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}
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def toArray(): Array[T] = collect()
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def reduce(f: (T, T) => T): T = {
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val cleanF = sc.clean(f)
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val tasks = splits.map(s => new ReduceTask(this, s, f))
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val results = new ArrayBuffer[T]
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for (option <- sc.runTaskObjects(tasks); elem <- option)
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results += elem
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if (results.size == 0)
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throw new UnsupportedOperationException("empty collection")
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else
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return results.reduceLeft(f)
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}
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def take(num: Int): Array[T] = {
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if (num == 0)
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return new Array[T](0)
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val buf = new ArrayBuffer[T]
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for (split <- splits; elem <- iterator(split)) {
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buf += elem
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if (buf.length == num)
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return buf.toArray
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}
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return buf.toArray
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}
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def first: T = take(1) match {
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case Array(t) => t
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case _ => throw new UnsupportedOperationException("empty collection")
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}
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def count(): Long = {
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try {
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map(x => 1L).reduce(_+_)
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} catch {
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case e: UnsupportedOperationException => 0L // No elements in RDD
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}
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}
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def union(other: RDD[T]) = new UnionRDD(sc, Array(this, other))
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def ++(other: RDD[T]) = this.union(other)
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def splitRdd() = new SplitRDD(this)
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def cartesian[U: ClassManifest](other: RDD[U]) =
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new CartesianRDD(sc, this, other)
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}
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@serializable
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abstract class RDDTask[U: ClassManifest, T: ClassManifest](
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val rdd: RDD[T], val split: Split)
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extends Task[U] {
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override def preferredLocations() = rdd.preferredLocations(split)
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override def markStarted(slot: SlaveOffer) { rdd.taskStarted(split, slot) }
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}
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class ForeachTask[T: ClassManifest](
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rdd: RDD[T], split: Split, func: T => Unit)
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extends RDDTask[Unit, T](rdd, split) with Logging {
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override def run() {
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logInfo("Processing " + split)
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rdd.iterator(split).foreach(func)
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}
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}
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class CollectTask[T](
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rdd: RDD[T], split: Split)(implicit m: ClassManifest[T])
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extends RDDTask[Array[T], T](rdd, split) with Logging {
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override def run(): Array[T] = {
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logInfo("Processing " + split)
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rdd.iterator(split).toArray(m)
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}
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}
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class ReduceTask[T: ClassManifest](
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rdd: RDD[T], split: Split, f: (T, T) => T)
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extends RDDTask[Option[T], T](rdd, split) with Logging {
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override def run(): Option[T] = {
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logInfo("Processing " + split)
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val iter = rdd.iterator(split)
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if (iter.hasNext)
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Some(iter.reduceLeft(f))
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else
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None
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}
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}
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class MappedRDD[U: ClassManifest, T: ClassManifest](
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prev: RDD[T], f: T => U)
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extends RDD[U](prev.sparkContext) {
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override def splits = prev.splits
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override def preferredLocations(split: Split) = prev.preferredLocations(split)
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override def iterator(split: Split) = prev.iterator(split).map(f)
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override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
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}
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class FilteredRDD[T: ClassManifest](
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prev: RDD[T], f: T => Boolean)
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extends RDD[T](prev.sparkContext) {
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override def splits = prev.splits
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override def preferredLocations(split: Split) = prev.preferredLocations(split)
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override def iterator(split: Split) = prev.iterator(split).filter(f)
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override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
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}
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class FlatMappedRDD[U: ClassManifest, T: ClassManifest](
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prev: RDD[T], f: T => Traversable[U])
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extends RDD[U](prev.sparkContext) {
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override def splits = prev.splits
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override def preferredLocations(split: Split) = prev.preferredLocations(split)
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override def iterator(split: Split) =
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prev.iterator(split).toStream.flatMap(f).iterator
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override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
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}
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class SplitRDD[T: ClassManifest](prev: RDD[T])
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extends RDD[Array[T]](prev.sparkContext) {
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override def splits = prev.splits
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override def preferredLocations(split: Split) = prev.preferredLocations(split)
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override def iterator(split: Split) = Iterator.fromArray(Array(prev.iterator(split).toArray))
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override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split, slot)
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}
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@serializable class SeededSplit(val prev: Split, val seed: Int) extends Split {
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override def getId() =
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"SeededSplit(" + prev.getId() + ", seed " + seed + ")"
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}
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class SampledRDD[T: ClassManifest](
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prev: RDD[T], withReplacement: Boolean, frac: Double, seed: Int)
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extends RDD[T](prev.sparkContext) {
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@transient val splits_ = { val rg = new Random(seed); prev.splits.map(x => new SeededSplit(x, rg.nextInt)) }
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override def splits = splits_.asInstanceOf[Array[Split]]
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override def preferredLocations(split: Split) = prev.preferredLocations(split.asInstanceOf[SeededSplit].prev)
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override def iterator(splitIn: Split) = {
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val split = splitIn.asInstanceOf[SeededSplit]
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val rg = new Random(split.seed);
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// Sampling with replacement (TODO: use reservoir sampling to make this more efficient?)
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if (withReplacement) {
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val oldData = prev.iterator(split.prev).toArray
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val sampleSize = (oldData.size * frac).ceil.toInt
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val sampledData = for (i <- 1 to sampleSize) yield oldData(rg.nextInt(oldData.size)) // all of oldData's indices are candidates, even if sampleSize < oldData.size
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sampledData.iterator
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}
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// Sampling without replacement
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else {
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prev.iterator(split.prev).filter(x => (rg.nextDouble <= frac))
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}
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}
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override def taskStarted(split: Split, slot: SlaveOffer) = prev.taskStarted(split.asInstanceOf[SeededSplit].prev, slot)
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}
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class CachedRDD[T](
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prev: RDD[T])(implicit m: ClassManifest[T])
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extends RDD[T](prev.sparkContext) with Logging {
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val id = CachedRDD.newId()
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@transient val cacheLocs = Map[Split, List[String]]()
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override def splits = prev.splits
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override def preferredLocations(split: Split) = {
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if (cacheLocs.contains(split))
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cacheLocs(split)
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else
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prev.preferredLocations(split)
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}
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override def iterator(split: Split): Iterator[T] = {
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val key = id + "::" + split.getId()
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logInfo("CachedRDD split key is " + key)
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val cache = CachedRDD.cache
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val loading = CachedRDD.loading
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val cachedVal = cache.get(key)
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if (cachedVal != null) {
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// Split is in cache, so just return its values
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return Iterator.fromArray(cachedVal.asInstanceOf[Array[T]])
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} else {
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// Mark the split as loading (unless someone else marks it first)
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loading.synchronized {
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if (loading.contains(key)) {
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while (loading.contains(key)) {
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try {loading.wait()} catch {case _ =>}
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}
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return Iterator.fromArray(cache.get(key).asInstanceOf[Array[T]])
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} else {
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loading.add(key)
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}
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}
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// If we got here, we have to load the split
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logInfo("Loading and caching " + split)
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val array = prev.iterator(split).toArray(m)
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cache.put(key, array)
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loading.synchronized {
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loading.remove(key)
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loading.notifyAll()
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}
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return Iterator.fromArray(array)
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}
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}
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override def taskStarted(split: Split, slot: SlaveOffer) {
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val oldList = cacheLocs.getOrElse(split, Nil)
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val host = slot.getHost
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if (!oldList.contains(host))
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cacheLocs(split) = host :: oldList
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}
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}
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private object CachedRDD {
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val nextId = new AtomicLong(0) // Generates IDs for cached RDDs (on master)
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def newId() = nextId.getAndIncrement()
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// Stores map results for various splits locally (on workers)
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val cache = new MapMaker().softValues().makeMap[String, AnyRef]()
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// Remembers which splits are currently being loaded (on workers)
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val loading = new HashSet[String]
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}
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@serializable
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class UnionSplit[T: ClassManifest](rdd: RDD[T], split: Split)
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extends Split {
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def iterator() = rdd.iterator(split)
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def preferredLocations() = rdd.preferredLocations(split)
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override def getId() = "UnionSplit(" + split.getId() + ")"
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}
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@serializable
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class UnionRDD[T: ClassManifest](sc: SparkContext, rdds: Seq[RDD[T]])
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extends RDD[T](sc) {
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@transient val splits_ : Array[Split] = {
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val splits: Seq[Split] =
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for (rdd <- rdds; split <- rdd.splits)
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yield new UnionSplit(rdd, split)
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splits.toArray
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}
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override def splits = splits_
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override def iterator(s: Split): Iterator[T] =
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s.asInstanceOf[UnionSplit[T]].iterator()
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override def preferredLocations(s: Split): Seq[String] =
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s.asInstanceOf[UnionSplit[T]].preferredLocations()
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}
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@serializable class CartesianSplit(val s1: Split, val s2: Split) extends Split {
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override def getId() =
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"CartesianSplit(" + s1.getId() + ", " + s2.getId() + ")"
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}
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@serializable
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class CartesianRDD[T: ClassManifest, U:ClassManifest](
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sc: SparkContext, rdd1: RDD[T], rdd2: RDD[U])
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extends RDD[Pair[T, U]](sc) {
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@transient val splits_ = {
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// create the cross product split
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rdd2.splits.map(y => rdd1.splits.map(x => new CartesianSplit(x, y))).flatten
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}
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override def splits = splits_.asInstanceOf[Array[Split]]
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override def preferredLocations(split: Split) = {
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val currSplit = split.asInstanceOf[CartesianSplit]
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rdd1.preferredLocations(currSplit.s1) ++ rdd2.preferredLocations(currSplit.s2)
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}
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override def iterator(split: Split) = {
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val currSplit = split.asInstanceOf[CartesianSplit]
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for (x <- rdd1.iterator(currSplit.s1); y <- rdd2.iterator(currSplit.s2)) yield (x, y)
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}
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override def taskStarted(split: Split, slot: SlaveOffer) = {
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val currSplit = split.asInstanceOf[CartesianSplit]
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rdd1.taskStarted(currSplit.s1, slot)
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rdd2.taskStarted(currSplit.s2, slot)
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}
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}
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@serializable class PairRDDExtras[K, V](rdd: RDD[(K, V)]) {
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def reduceByKey(func: (V, V) => V): Map[K, V] = {
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def mergeMaps(m1: HashMap[K, V], m2: HashMap[K, V]): HashMap[K, V] = {
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for ((k, v) <- m2) {
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m1.get(k) match {
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case None => m1(k) = v
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case Some(w) => m1(k) = func(w, v)
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}
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}
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return m1
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}
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rdd.map(pair => HashMap(pair)).reduce(mergeMaps)
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}
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}
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