Spark 1271: Co-Group and Group-By should pass Iterable[X]

Author: Holden Karau <holden@pigscanfly.ca>

Closes #242 from holdenk/spark-1320-cogroupandgroupshouldpassiterator and squashes the following commits:

f289536 [Holden Karau] Fix bad merge, should have been Iterable rather than Iterator
77048f8 [Holden Karau] Fix merge up to master
d3fe909 [Holden Karau] use toSeq instead
7a092a3 [Holden Karau] switch resultitr to resultiterable
eb06216 [Holden Karau] maybe I should have had a coffee first. use correct import for guava iterables
c5075aa [Holden Karau] If guava 14 had iterables
2d06e10 [Holden Karau] Fix Java 8 cogroup tests for the new API
11e730c [Holden Karau] Fix streaming tests
66b583d [Holden Karau] Fix the core test suite to compile
4ed579b [Holden Karau] Refactor from iterator to iterable
d052c07 [Holden Karau] Python tests now pass with iterator pandas
3bcd81d [Holden Karau] Revert "Try and make pickling list iterators work"
cd1e81c [Holden Karau] Try and make pickling list iterators work
c60233a [Holden Karau] Start investigating moving to iterators for python API like the Java/Scala one. tl;dr: We will have to write our own iterator since the default one doesn't pickle well
88a5cef [Holden Karau] Fix cogroup test in JavaAPISuite for streaming
a5ee714 [Holden Karau] oops, was checking wrong iterator
e687f21 [Holden Karau] Fix groupbykey test in JavaAPISuite of streaming
ec8cc3e [Holden Karau] Fix test issues\!
4b0eeb9 [Holden Karau] Switch cast in PairDStreamFunctions
fa395c9 [Holden Karau] Revert "Add a join based on the problem in SVD"
ec99e32 [Holden Karau] Revert "Revert this but for now put things in list pandas"
b692868 [Holden Karau] Revert
7e533f7 [Holden Karau] Fix the bug
8a5153a [Holden Karau] Revert me, but we have some stuff to debug
b4e86a9 [Holden Karau] Add a join based on the problem in SVD
c4510e2 [Holden Karau] Revert this but for now put things in list pandas
b4e0b1d [Holden Karau] Fix style issues
71e8b9f [Holden Karau] I really need to stop calling size on iterators, it is the path of sadness.
b1ae51a [Holden Karau] Fix some of the types in the streaming JavaAPI suite. Probably still needs more work
37888ec [Holden Karau] core/tests now pass
249abde [Holden Karau] org.apache.spark.rdd.PairRDDFunctionsSuite passes
6698186 [Holden Karau] Revert "I think this might be a bad rabbit hole. Started work to make CoGroupedRDD use iterator and then went crazy"
fe992fe [Holden Karau] hmmm try and fix up basic operation suite
172705c [Holden Karau] Fix Java API suite
caafa63 [Holden Karau] I think this might be a bad rabbit hole. Started work to make CoGroupedRDD use iterator and then went crazy
88b3329 [Holden Karau] Fix groupbykey to actually give back an iterator
4991af6 [Holden Karau] Fix some tests
be50246 [Holden Karau] Calling size on an iterator is not so good if we want to use it after
687ffbc [Holden Karau] This is the it compiles point of replacing Seq with Iterator and JList with JIterator in the groupby and cogroup signatures

1 files changed, 12 insertions, 8 deletions

diff --git a/bagel/src/main/scala/org/apache/spark/bagel/Bagel.scala b/bagel/src/main/scala/org/apache/spark/bagel/Bagel.scala
index 70c7474a93..70a99b33d7 100644
--- a/bagel/src/main/scala/org/apache/spark/bagel/Bagel.scala
+++ b/bagel/src/main/scala/org/apache/spark/bagel/Bagel.scala
@@ -220,20 +220,23 @@ object Bagel extends Logging {
    */
   private def comp[K: Manifest, V <: Vertex, M <: Message[K], C](
     sc: SparkContext,
-    grouped: RDD[(K, (Seq[C], Seq[V]))],
+    grouped: RDD[(K, (Iterable[C], Iterable[V]))],
     compute: (V, Option[C]) => (V, Array[M]),
     storageLevel: StorageLevel
   ): (RDD[(K, (V, Array[M]))], Int, Int) = {
     var numMsgs = sc.accumulator(0)
     var numActiveVerts = sc.accumulator(0)
-    val processed = grouped.flatMapValues {
-      case (_, vs) if vs.size == 0 => None
-      case (c, vs) =>
+    val processed = grouped.mapValues(x => (x._1.iterator, x._2.iterator))
+      .flatMapValues {
+      case (_, vs) if !vs.hasNext => None
+      case (c, vs) => {
         val (newVert, newMsgs) =
-          compute(vs(0), c match {
-            case Seq(comb) => Some(comb)
-            case Seq() => None
-          })
+          compute(vs.next,
+            c.hasNext match {
+              case true => Some(c.next)
+              case false => None
+            }
+          )
 
         numMsgs += newMsgs.size
         if (newVert.active) {
@@ -241,6 +244,7 @@ object Bagel extends Logging {
         }
 
         Some((newVert, newMsgs))
+      }
     }.persist(storageLevel)
 
     // Force evaluation of processed RDD for accurate performance measurements