Merge pull request alteryx#201 from rxin/mappartitions

Use the proper partition index in mapPartitionsWIthIndex

mapPartitionsWithIndex uses TaskContext.partitionId as the partition index. TaskContext.partitionId used to be identical to the partition index in a RDD. However, pull request alteryx#186 introduced a scenario (with partition pruning) that the two can be different. This pull request uses the right partition index in all mapPartitionsWithIndex related calls.

Also removed the extra MapPartitionsWIthContextRDD and put all the mapPartitions related functionality in MapPartitionsRDD.

(cherry picked from commit 14bb465)
Signed-off-by: Reynold Xin <[email protected]>

Author: mateiz

core/src/main/scala/org/apache/spark/rdd/MapPartitionsRDD.scala

@@ -20,18 +20,16 @@ package org.apache.spark.rdd
 import org.apache.spark.{Partition, TaskContext}
 
 
-private[spark]
-class MapPartitionsRDD[U: ClassManifest, T: ClassManifest](
+private[spark] class MapPartitionsRDD[U: ClassManifest, T: ClassManifest](
     prev: RDD[T],
-    f: Iterator[T] => Iterator[U],
+    f: (TaskContext, Int, Iterator[T]) => Iterator[U],  // (TaskContext, partition index, iterator)
     preservesPartitioning: Boolean = false)
   extends RDD[U](prev) {
 
-  override val partitioner =
-    if (preservesPartitioning) firstParent[T].partitioner else None
+  override val partitioner = if (preservesPartitioning) firstParent[T].partitioner else None
 
   override def getPartitions: Array[Partition] = firstParent[T].partitions
 
   override def compute(split: Partition, context: TaskContext) =
-    f(firstParent[T].iterator(split, context))
+    f(context, split.index, firstParent[T].iterator(split, context))
 }

core/src/main/scala/org/apache/spark/rdd/MapPartitionsWithContextRDD.scala

@@ -408,7 +408,6 @@ abstract class RDD[T: ClassManifest](
   def pipe(command: String, env: Map[String, String]): RDD[String] =
     new PipedRDD(this, command, env)
 
-
   /**
    * Return an RDD created by piping elements to a forked external process.
    * The print behavior can be customized by providing two functions.
@@ -442,7 +441,8 @@ abstract class RDD[T: ClassManifest](
    */
   def mapPartitions[U: ClassManifest](
       f: Iterator[T] => Iterator[U], preservesPartitioning: Boolean = false): RDD[U] = {
-    new MapPartitionsRDD(this, sc.clean(f), preservesPartitioning)
+    val func = (context: TaskContext, index: Int, iter: Iterator[T]) => f(iter)
+    new MapPartitionsRDD(this, sc.clean(func), preservesPartitioning)
   }
 
   /**
@@ -451,8 +451,8 @@ abstract class RDD[T: ClassManifest](
    */
   def mapPartitionsWithIndex[U: ClassManifest](
       f: (Int, Iterator[T]) => Iterator[U], preservesPartitioning: Boolean = false): RDD[U] = {
-    val func = (context: TaskContext, iter: Iterator[T]) => f(context.partitionId, iter)
-    new MapPartitionsWithContextRDD(this, sc.clean(func), preservesPartitioning)
+    val func = (context: TaskContext, index: Int, iter: Iterator[T]) => f(index, iter)
+    new MapPartitionsRDD(this, sc.clean(func), preservesPartitioning)
   }
 
   /**
@@ -462,7 +462,8 @@ abstract class RDD[T: ClassManifest](
   def mapPartitionsWithContext[U: ClassManifest](
       f: (TaskContext, Iterator[T]) => Iterator[U],
       preservesPartitioning: Boolean = false): RDD[U] = {
-    new MapPartitionsWithContextRDD(this, sc.clean(f), preservesPartitioning)
+    val func = (context: TaskContext, index: Int, iter: Iterator[T]) => f(context, iter)
+    new MapPartitionsRDD(this, sc.clean(func), preservesPartitioning)
   }
 
   /**
@@ -483,11 +484,10 @@ abstract class RDD[T: ClassManifest](
   def mapWith[A: ClassManifest, U: ClassManifest]
       (constructA: Int => A, preservesPartitioning: Boolean = false)
       (f: (T, A) => U): RDD[U] = {
-    def iterF(context: TaskContext, iter: Iterator[T]): Iterator[U] = {
-      val a = constructA(context.partitionId)
+    mapPartitionsWithIndex((index, iter) => {
+      val a = constructA(index)
       iter.map(t => f(t, a))
-    }
-    new MapPartitionsWithContextRDD(this, sc.clean(iterF _), preservesPartitioning)
+    }, preservesPartitioning)
   }
 
   /**
@@ -498,11 +498,10 @@ abstract class RDD[T: ClassManifest](
   def flatMapWith[A: ClassManifest, U: ClassManifest]
       (constructA: Int => A, preservesPartitioning: Boolean = false)
       (f: (T, A) => Seq[U]): RDD[U] = {
-    def iterF(context: TaskContext, iter: Iterator[T]): Iterator[U] = {
-      val a = constructA(context.partitionId)
+    mapPartitionsWithIndex((index, iter) => {
+      val a = constructA(index)
       iter.flatMap(t => f(t, a))
-    }
-    new MapPartitionsWithContextRDD(this, sc.clean(iterF _), preservesPartitioning)
+    }, preservesPartitioning)
   }
 
   /**
@@ -511,11 +510,10 @@ abstract class RDD[T: ClassManifest](
    * partition with the index of that partition.
    */
   def foreachWith[A: ClassManifest](constructA: Int => A)(f: (T, A) => Unit) {
-    def iterF(context: TaskContext, iter: Iterator[T]): Iterator[T] = {
-      val a = constructA(context.partitionId)
+    mapPartitionsWithIndex { (index, iter) =>
+      val a = constructA(index)
       iter.map(t => {f(t, a); t})
-    }
-    new MapPartitionsWithContextRDD(this, sc.clean(iterF _), true).foreach(_ => {})
+    }.foreach(_ => {})
   }
 
   /**
@@ -524,11 +522,10 @@ abstract class RDD[T: ClassManifest](
    * partition with the index of that partition.
    */
   def filterWith[A: ClassManifest](constructA: Int => A)(p: (T, A) => Boolean): RDD[T] = {
-    def iterF(context: TaskContext, iter: Iterator[T]): Iterator[T] = {
-      val a = constructA(context.partitionId)
+    mapPartitionsWithIndex((index, iter) => {
+      val a = constructA(index)
       iter.filter(t => p(t, a))
-    }
-    new MapPartitionsWithContextRDD(this, sc.clean(iterF _), true)
+    }, preservesPartitioning = true)
   }
 
   /**

core/src/main/scala/org/apache/spark/rdd/RDD.scala

@@ -62,8 +62,6 @@ class CheckpointSuite extends FunSuite with LocalSparkContext with Logging {
     testCheckpointing(_.sample(false, 0.5, 0))
     testCheckpointing(_.glom())
     testCheckpointing(_.mapPartitions(_.map(_.toString)))
-    testCheckpointing(r => new MapPartitionsWithContextRDD(r,
-      (context: TaskContext, iter: Iterator[Int]) => iter.map(_.toString), false ))
     testCheckpointing(_.map(x => (x % 2, 1)).reduceByKey(_ + _).mapValues(_.toString))
     testCheckpointing(_.map(x => (x % 2, 1)).reduceByKey(_ + _).flatMapValues(x => 1 to x))
     testCheckpointing(_.pipe(Seq("cat")))