[SPARK-19959][SQL] Fix to throw NullPointerException in df[java.lang.Long].collect

## What changes were proposed in this pull request?

This PR fixes `NullPointerException` in the generated code by Catalyst. When we run the following code, we get the following `NullPointerException`. This is because there is no null checks for `inputadapter_value`  while `java.lang.Long inputadapter_value` at Line 30 may have `null`.

This happen when a type of DataFrame is nullable primitive type such as `java.lang.Long` and the wholestage codegen is used. While the physical plan keeps `nullable=true` in `input[0, java.lang.Long, true].longValue`, `BoundReference.doGenCode` ignores `nullable=true`. Thus, nullcheck code will not be generated and `NullPointerException` will occur.

This PR checks the nullability and correctly generates nullcheck if needed.
```java
sparkContext.parallelize(Seq[java.lang.Long](0L, null, 2L), 1).toDF.collect
```

```java
Caused by: java.lang.NullPointerException
	at org.apache.spark.sql.catalyst.expressions.GeneratedClass$GeneratedIterator.processNext(generated.java:37)
	at org.apache.spark.sql.execution.BufferedRowIterator.hasNext(BufferedRowIterator.java:43)
	at org.apache.spark.sql.execution.WholeStageCodegenExec$$anonfun$8$$anon$1.hasNext(WholeStageCodegenExec.scala:393)
...
```

Generated code without this PR
```java
/* 005 */ final class GeneratedIterator extends org.apache.spark.sql.execution.BufferedRowIterator {
/* 006 */   private Object[] references;
/* 007 */   private scala.collection.Iterator[] inputs;
/* 008 */   private scala.collection.Iterator inputadapter_input;
/* 009 */   private UnsafeRow serializefromobject_result;
/* 010 */   private org.apache.spark.sql.catalyst.expressions.codegen.BufferHolder serializefromobject_holder;
/* 011 */   private org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter serializefromobject_rowWriter;
/* 012 */
/* 013 */   public GeneratedIterator(Object[] references) {
/* 014 */     this.references = references;
/* 015 */   }
/* 016 */
/* 017 */   public void init(int index, scala.collection.Iterator[] inputs) {
/* 018 */     partitionIndex = index;
/* 019 */     this.inputs = inputs;
/* 020 */     inputadapter_input = inputs[0];
/* 021 */     serializefromobject_result = new UnsafeRow(1);
/* 022 */     this.serializefromobject_holder = new org.apache.spark.sql.catalyst.expressions.codegen.BufferHolder(serializefromobject_result, 0);
/* 023 */     this.serializefromobject_rowWriter = new org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter(serializefromobject_holder, 1);
/* 024 */
/* 025 */   }
/* 026 */
/* 027 */   protected void processNext() throws java.io.IOException {
/* 028 */     while (inputadapter_input.hasNext() && !stopEarly()) {
/* 029 */       InternalRow inputadapter_row = (InternalRow) inputadapter_input.next();
/* 030 */       java.lang.Long inputadapter_value = (java.lang.Long)inputadapter_row.get(0, null);
/* 031 */
/* 032 */       boolean serializefromobject_isNull = true;
/* 033 */       long serializefromobject_value = -1L;
/* 034 */       if (!false) {
/* 035 */         serializefromobject_isNull = false;
/* 036 */         if (!serializefromobject_isNull) {
/* 037 */           serializefromobject_value = inputadapter_value.longValue();
/* 038 */         }
/* 039 */
/* 040 */       }
/* 041 */       serializefromobject_rowWriter.zeroOutNullBytes();
/* 042 */
/* 043 */       if (serializefromobject_isNull) {
/* 044 */         serializefromobject_rowWriter.setNullAt(0);
/* 045 */       } else {
/* 046 */         serializefromobject_rowWriter.write(0, serializefromobject_value);
/* 047 */       }
/* 048 */       append(serializefromobject_result);
/* 049 */       if (shouldStop()) return;
/* 050 */     }
/* 051 */   }
/* 052 */ }
```

Generated code with this PR

```java
/* 005 */ final class GeneratedIterator extends org.apache.spark.sql.execution.BufferedRowIterator {
/* 006 */   private Object[] references;
/* 007 */   private scala.collection.Iterator[] inputs;
/* 008 */   private scala.collection.Iterator inputadapter_input;
/* 009 */   private UnsafeRow serializefromobject_result;
/* 010 */   private org.apache.spark.sql.catalyst.expressions.codegen.BufferHolder serializefromobject_holder;
/* 011 */   private org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter serializefromobject_rowWriter;
/* 012 */
/* 013 */   public GeneratedIterator(Object[] references) {
/* 014 */     this.references = references;
/* 015 */   }
/* 016 */
/* 017 */   public void init(int index, scala.collection.Iterator[] inputs) {
/* 018 */     partitionIndex = index;
/* 019 */     this.inputs = inputs;
/* 020 */     inputadapter_input = inputs[0];
/* 021 */     serializefromobject_result = new UnsafeRow(1);
/* 022 */     this.serializefromobject_holder = new org.apache.spark.sql.catalyst.expressions.codegen.BufferHolder(serializefromobject_result, 0);
/* 023 */     this.serializefromobject_rowWriter = new org.apache.spark.sql.catalyst.expressions.codegen.UnsafeRowWriter(serializefromobject_holder, 1);
/* 024 */
/* 025 */   }
/* 026 */
/* 027 */   protected void processNext() throws java.io.IOException {
/* 028 */     while (inputadapter_input.hasNext() && !stopEarly()) {
/* 029 */       InternalRow inputadapter_row = (InternalRow) inputadapter_input.next();
/* 030 */       boolean inputadapter_isNull = inputadapter_row.isNullAt(0);
/* 031 */       java.lang.Long inputadapter_value = inputadapter_isNull ? null : ((java.lang.Long)inputadapter_row.get(0, null));
/* 032 */
/* 033 */       boolean serializefromobject_isNull = true;
/* 034 */       long serializefromobject_value = -1L;
/* 035 */       if (!inputadapter_isNull) {
/* 036 */         serializefromobject_isNull = false;
/* 037 */         if (!serializefromobject_isNull) {
/* 038 */           serializefromobject_value = inputadapter_value.longValue();
/* 039 */         }
/* 040 */
/* 041 */       }
/* 042 */       serializefromobject_rowWriter.zeroOutNullBytes();
/* 043 */
/* 044 */       if (serializefromobject_isNull) {
/* 045 */         serializefromobject_rowWriter.setNullAt(0);
/* 046 */       } else {
/* 047 */         serializefromobject_rowWriter.write(0, serializefromobject_value);
/* 048 */       }
/* 049 */       append(serializefromobject_result);
/* 050 */       if (shouldStop()) return;
/* 051 */     }
/* 052 */   }
/* 053 */ }
```

## How was this patch tested?

Added new test suites in `DataFrameSuites`

Author: Kazuaki Ishizaki <ishizaki@jp.ibm.com>

Closes #17302 from kiszk/SPARK-19959.

1 files changed, 11 insertions, 0 deletions

diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameImplicitsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameImplicitsSuite.scala
index 094efbaead..63094d1b61 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameImplicitsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameImplicitsSuite.scala
@@ -51,4 +51,15 @@ class DataFrameImplicitsSuite extends QueryTest with SharedSQLContext {
       sparkContext.parallelize(1 to 10).map(_.toString).toDF("stringCol"),
       (1 to 10).map(i => Row(i.toString)))
   }
+
+  test("SPARK-19959: df[java.lang.Long].collect includes null throws NullPointerException") {
+    checkAnswer(sparkContext.parallelize(Seq[java.lang.Integer](0, null, 2), 1).toDF,
+      Seq(Row(0), Row(null), Row(2)))
+    checkAnswer(sparkContext.parallelize(Seq[java.lang.Long](0L, null, 2L), 1).toDF,
+      Seq(Row(0L), Row(null), Row(2L)))
+    checkAnswer(sparkContext.parallelize(Seq[java.lang.Float](0.0F, null, 2.0F), 1).toDF,
+      Seq(Row(0.0F), Row(null), Row(2.0F)))
+    checkAnswer(sparkContext.parallelize(Seq[java.lang.Double](0.0D, null, 2.0D), 1).toDF,
+      Seq(Row(0.0D), Row(null), Row(2.0D)))
+  }
 }