[SPARK-6429] Implement hashCode and equals together

## What changes were proposed in this pull request?

Implement some `hashCode` and `equals` together in order to enable the scalastyle.
This is a first batch, I will continue to implement them but I wanted to know your thoughts.

Author: Joan <joan@goyeau.com>

Closes #12157 from joan38/SPARK-6429-HashCode-Equals.

13 files changed, 57 insertions, 18 deletions

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/AttributeSet.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/AttributeSet.scala
index 8bdf9b29c9..b77f93373e 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/AttributeSet.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/AttributeSet.scala
@@ -60,6 +60,8 @@ object AttributeSet {
 class AttributeSet private (val baseSet: Set[AttributeEquals])
   extends Traversable[Attribute] with Serializable {
 
+  override def hashCode: Int = baseSet.hashCode()
+
   /** Returns true if the members of this AttributeSet and other are the same. */
   override def equals(other: Any): Boolean = other match {
     case otherSet: AttributeSet =>
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/EquivalentExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/EquivalentExpressions.scala
index 607c7c877c..d0ad7a05a0 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/EquivalentExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/EquivalentExpressions.scala
@@ -35,7 +35,8 @@ class EquivalentExpressions {
       case other: Expr => e.semanticEquals(other.e)
       case _ => false
     }
-    override val hashCode: Int = e.semanticHash()
+
+    override def hashCode: Int = e.semanticHash()
   }
 
   // For each expression, the set of equivalent expressions.
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
index e9dda588de..7e3683e482 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/literals.scala
@@ -19,6 +19,7 @@ package org.apache.spark.sql.catalyst.expressions
 
 import java.nio.charset.StandardCharsets
 import java.sql.{Date, Timestamp}
+import java.util.Objects
 
 import org.json4s.JsonAST._
 
@@ -170,6 +171,8 @@ case class Literal protected (value: Any, dataType: DataType)
 
   override def toString: String = if (value != null) value.toString else "null"
 
+  override def hashCode(): Int = 31 * (31 * Objects.hashCode(dataType)) + Objects.hashCode(value)
+
   override def equals(other: Any): Boolean = other match {
     case o: Literal =>
       dataType.equals(o.dataType) &&
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
index c083f12724..8b38838537 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/namedExpressions.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
-import java.util.UUID
+import java.util.{Objects, UUID}
 
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
@@ -175,6 +175,11 @@ case class Alias(child: Expression, name: String)(
     exprId :: qualifier :: explicitMetadata :: isGenerated :: Nil
   }
 
+  override def hashCode(): Int = {
+    val state = Seq(name, exprId, child, qualifier, explicitMetadata)
+    state.map(Objects.hashCode).foldLeft(0)((a, b) => 31 * a + b)
+  }
+
   override def equals(other: Any): Boolean = other match {
     case a: Alias =>
       name == a.name && exprId == a.exprId && child == a.child && qualifier == a.qualifier &&
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala
index fb7251d71b..71a9b9f808 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/types/UserDefinedType.scala
@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.types
 
+import java.util.Objects
+
 import org.json4s.JsonAST.JValue
 import org.json4s.JsonDSL._
 
@@ -83,6 +85,8 @@ abstract class UserDefinedType[UserType >: Null] extends DataType with Serializa
 
   override def sql: String = sqlType.sql
 
+  override def hashCode(): Int = getClass.hashCode()
+
   override def equals(other: Any): Boolean = other match {
     case that: UserDefinedType[_] => this.acceptsType(that)
     case _ => false
@@ -115,7 +119,9 @@ private[sql] class PythonUserDefinedType(
   }
 
   override def equals(other: Any): Boolean = other match {
-    case that: PythonUserDefinedType => this.pyUDT.equals(that.pyUDT)
+    case that: PythonUserDefinedType => pyUDT == that.pyUDT
     case _ => false
   }
+
+  override def hashCode(): Int = Objects.hashCode(pyUDT)
 }
diff --git a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoderSuite.scala b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoderSuite.scala
index 18752014ea..c3b20e2cc0 100644
--- a/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoderSuite.scala
+++ b/sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoderSuite.scala
@@ -35,6 +35,9 @@ import org.apache.spark.sql.types.{ArrayType, Decimal, ObjectType, StructType}
 case class RepeatedStruct(s: Seq[PrimitiveData])
 
 case class NestedArray(a: Array[Array[Int]]) {
+  override def hashCode(): Int =
+    java.util.Arrays.deepHashCode(a.asInstanceOf[Array[AnyRef]])
+
   override def equals(other: Any): Boolean = other match {
     case NestedArray(otherArray) =>
       java.util.Arrays.deepEquals(
@@ -64,15 +67,21 @@ case class SpecificCollection(l: List[Int])
 
 /** For testing Kryo serialization based encoder. */
 class KryoSerializable(val value: Int) {
-  override def equals(other: Any): Boolean = {
-    this.value == other.asInstanceOf[KryoSerializable].value
+  override def hashCode(): Int = value
+
+  override def equals(other: Any): Boolean = other match {
+    case that: KryoSerializable => this.value == that.value
+    case _ => false
   }
 }
 
 /** For testing Java serialization based encoder. */
 class JavaSerializable(val value: Int) extends Serializable {
-  override def equals(other: Any): Boolean = {
-    this.value == other.asInstanceOf[JavaSerializable].value
+  override def hashCode(): Int = value
+
+  override def equals(other: Any): Boolean = other match {
+    case that: JavaSerializable => this.value == that.value
+    case _ => false
   }
 }
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/ShuffledRowRDD.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/ShuffledRowRDD.scala
index 42891287a3..e81cd28ea3 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/ShuffledRowRDD.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/ShuffledRowRDD.scala
@@ -33,7 +33,10 @@ private final class ShuffledRowRDDPartition(
     val startPreShufflePartitionIndex: Int,
     val endPreShufflePartitionIndex: Int) extends Partition {
   override val index: Int = postShufflePartitionIndex
+
   override def hashCode(): Int = postShufflePartitionIndex
+
+  override def equals(other: Any): Boolean = super.equals(other)
 }
 
 /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/DefaultSource.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/DefaultSource.scala
index 34db10f822..61ec7ed2b1 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/DefaultSource.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/csv/DefaultSource.scala
@@ -44,6 +44,8 @@ class DefaultSource extends FileFormat with DataSourceRegister {
 
   override def toString: String = "CSV"
 
+  override def hashCode(): Int = getClass.hashCode()
+
   override def equals(other: Any): Boolean = other.isInstanceOf[DefaultSource]
 
   override def inferSchema(
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/json/JSONRelation.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/json/JSONRelation.scala
index 7364a1dc06..7773ff550f 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/json/JSONRelation.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/json/JSONRelation.scala
@@ -154,6 +154,9 @@ class DefaultSource extends FileFormat with DataSourceRegister {
   }
 
   override def toString: String = "JSON"
+
+  override def hashCode(): Int = getClass.hashCode()
+
   override def equals(other: Any): Boolean = other.isInstanceOf[DefaultSource]
 }
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
index bfe7aefe41..38c0084952 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
@@ -60,6 +60,8 @@ private[sql] class DefaultSource
 
   override def toString: String = "ParquetFormat"
 
+  override def hashCode(): Int = getClass.hashCode()
+
   override def equals(other: Any): Boolean = other.isInstanceOf[DefaultSource]
 
   override def prepareWrite(
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/metric/SQLMetrics.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/metric/SQLMetrics.scala
index 92c31eac95..930adabc48 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/metric/SQLMetrics.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/metric/SQLMetrics.scala
@@ -82,12 +82,12 @@ private[sql] class LongSQLMetricValue(private var _value : Long) extends SQLMetr
   override def value: Long = _value
 
   // Needed for SQLListenerSuite
-  override def equals(other: Any): Boolean = {
-    other match {
-      case o: LongSQLMetricValue => value == o.value
-      case _ => false
-    }
+  override def equals(other: Any): Boolean = other match {
+    case o: LongSQLMetricValue => value == o.value
+    case _ => false
   }
+
+  override def hashCode(): Int = _value.hashCode()
 }
 
 /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/test/ExamplePointUDT.scala b/sql/core/src/main/scala/org/apache/spark/sql/test/ExamplePointUDT.scala
index 695a5ad78a..a73e427295 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/test/ExamplePointUDT.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/test/ExamplePointUDT.scala
@@ -27,6 +27,9 @@ import org.apache.spark.sql.types._
  */
 @SQLUserDefinedType(udt = classOf[ExamplePointUDT])
 private[sql] class ExamplePoint(val x: Double, val y: Double) extends Serializable {
+
+  override def hashCode(): Int = 31 * (31 * x.hashCode()) + y.hashCode()
+
   override def equals(other: Any): Boolean = other match {
     case that: ExamplePoint => this.x == that.x && this.y == that.y
     case _ => false
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/UserDefinedTypeSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/UserDefinedTypeSuite.scala
index acc9f48d7e..a49aaa8b73 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/UserDefinedTypeSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/UserDefinedTypeSuite.scala
@@ -37,9 +37,10 @@ object UDT {
 
   @SQLUserDefinedType(udt = classOf[MyDenseVectorUDT])
   private[sql] class MyDenseVector(val data: Array[Double]) extends Serializable {
+    override def hashCode(): Int = java.util.Arrays.hashCode(data)
+
     override def equals(other: Any): Boolean = other match {
-      case v: MyDenseVector =>
-        java.util.Arrays.equals(this.data, v.data)
+      case v: MyDenseVector => java.util.Arrays.equals(this.data, v.data)
       case _ => false
     }
   }
@@ -63,10 +64,9 @@ object UDT {
 
     private[spark] override def asNullable: MyDenseVectorUDT = this
 
-    override def equals(other: Any): Boolean = other match {
-      case _: MyDenseVectorUDT => true
-      case _ => false
-    }
+    override def hashCode(): Int = getClass.hashCode()
+
+    override def equals(other: Any): Boolean = other.isInstanceOf[MyDenseVectorUDT]
   }
 
 }