Review comments.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/Row.scala

@@ -48,8 +48,8 @@ trait Row extends Seq[Any] with Serializable {
   /** Returns true if there are any NULL values in this row. */
   def anyNull: Boolean = {
     var i = 0
-    while(i < length) {
-      if(isNullAt(i)) return true
+    while (i < length) {
+      if (isNullAt(i)) { return true }
       i += 1
     }
     false

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/predicates.scala

@@ -21,6 +21,12 @@ import org.apache.spark.sql.catalyst.trees
 import org.apache.spark.sql.catalyst.analysis.UnresolvedException
 import org.apache.spark.sql.catalyst.types.{BooleanType, StringType}
 
+object InterpretedPredicate {
+  def apply(expression: Expression): (Row => Boolean) = {
+    (r: Row) => expression.apply(r).asInstanceOf[Boolean]
+  }
+}
+
 trait Predicate extends Expression {
   self: Product =>
 

sql/core/src/main/scala/org/apache/spark/sql/execution/joins.scala

@@ -15,29 +15,20 @@
  * limitations under the License.
  */
 
-package org.apache.spark.sql
-package execution
+package org.apache.spark.sql.execution
 
 import scala.collection.mutable.{ArrayBuffer, BitSet}
 
-import org.apache.spark.rdd.RDD
 import org.apache.spark.SparkContext
 
-import catalyst.errors._
-import catalyst.expressions._
-import catalyst.plans._
-import catalyst.plans.physical.{ClusteredDistribution, Partitioning}
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.catalyst.plans._
+import org.apache.spark.sql.catalyst.plans.physical.{ClusteredDistribution, Partitioning}
 
 sealed abstract class BuildSide
 case object BuildLeft extends BuildSide
 case object BuildRight extends BuildSide
 
-object InterpretCondition {
-  def apply(expression: Expression): (Row => Boolean) = {
-    (r: Row) => expression.apply(r).asInstanceOf[Boolean]
-  }
-}
-
 case class HashJoin(
     leftKeys: Seq[Expression],
     rightKeys: Seq[Expression],
@@ -69,11 +60,12 @@ case class HashJoin(
   def execute() = {
 
     buildPlan.execute().zipPartitions(streamedPlan.execute()) { (buildIter, streamIter) =>
+      // TODO: Use Spark's HashMap implementation.
       val hashTable = new java.util.HashMap[Row, ArrayBuffer[Row]]()
       var currentRow: Row = null
 
       // Create a mapping of buildKeys -> rows
-      while(buildIter.hasNext) {
+      while (buildIter.hasNext) {
         currentRow = buildIter.next()
         val rowKey = buildSideKeyGenerator(currentRow)
         if(!rowKey.anyNull) {
@@ -90,40 +82,49 @@ case class HashJoin(
       }
 
       new Iterator[Row] {
-        private[this] var currentRow: Row = _
-        private[this] var currentMatches: ArrayBuffer[Row] = _
-        private[this] var currentPosition: Int = -1
+        private[this] var currentStreamedRow: Row = _
+        private[this] var currentHashMatches: ArrayBuffer[Row] = _
+        private[this] var currentMatchPosition: Int = -1
 
         // Mutable per row objects.
         private[this] val joinRow = new JoinedRow
 
-        @transient private val joinKeys = streamSideKeyGenerator()
+        private[this] val joinKeys = streamSideKeyGenerator()
 
-        def hasNext: Boolean =
-          (currentPosition != -1 && currentPosition < currentMatches.size) ||
-          (streamIter.hasNext && fetchNext())
+        override final def hasNext: Boolean =
+          if (currentMatchPosition != -1) {
+            currentMatchPosition < currentHashMatches.size
+          } else {
+            fetchNext()
+          }
 
-        def next() = {
-          val ret = joinRow(currentRow, currentMatches(currentPosition))
-          currentPosition += 1
+        override final def next() = {
+          val ret = joinRow(currentStreamedRow, currentHashMatches(currentMatchPosition))
+          currentMatchPosition += 1
           ret
         }
 
-        private def fetchNext(): Boolean = {
-          currentMatches = null
-          currentPosition = -1
-
-          while (currentMatches == null && streamIter.hasNext) {
-            currentRow = streamIter.next()
-            if(!joinKeys(currentRow).anyNull) {
-              currentMatches = hashTable.get(joinKeys.currentValue)
+        /**
+         * Searches the streamed iterator for the next row that has at least one match in hashtable.
+         *
+         * @return true if the search is successful, and false the streamed iterator runs out of
+         *         tuples.
+         */
+        private final def fetchNext(): Boolean = {
+          currentHashMatches = null
+          currentMatchPosition = -1
+
+          while (currentHashMatches == null && streamIter.hasNext) {
+            currentStreamedRow = streamIter.next()
+            if (!joinKeys(currentStreamedRow).anyNull) {
+              currentHashMatches = hashTable.get(joinKeys.currentValue)
             }
           }
 
-          if (currentMatches == null) {
+          if (currentHashMatches == null) {
             false
           } else {
-            currentPosition = 0
+            currentMatchPosition = 0
             true
           }
         }
@@ -158,7 +159,7 @@ case class BroadcastNestedLoopJoin(
   def right = broadcast
 
   @transient lazy val boundCondition =
-    InterpretCondition(
+    InterpretedPredicate(
       condition
         .map(c => BindReferences.bindReference(c, left.output ++ right.output))
         .getOrElse(Literal(true)))
@@ -169,8 +170,8 @@ case class BroadcastNestedLoopJoin(
 
     val streamedPlusMatches = streamed.execute().mapPartitions { streamedIter =>
       val matchedRows = new ArrayBuffer[Row]
-      val includedBroadcastTuples =
-        new scala.collection.mutable.BitSet(broadcastedRelation.value.size)
+      // TODO: Use Spark's BitSet.
+      val includedBroadcastTuples = new BitSet(broadcastedRelation.value.size)
       val joinedRow = new JoinedRow
 
       streamedIter.foreach { streamedRow =>