[SPARK-19548][SQL] Support Hive UDFs which return typed Lists/Maps

sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveInspectors.scala

@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.hive
 
+import java.lang.reflect.{ParameterizedType, Type, WildcardType}
+
 import scala.collection.JavaConverters._
 
 import org.apache.hadoop.{io => hadoopIo}
@@ -178,7 +180,7 @@ import org.apache.spark.unsafe.types.UTF8String
  */
 private[hive] trait HiveInspectors {
 
-  def javaClassToDataType(clz: Class[_]): DataType = clz match {
+  def javaTypeToDataType(clz: Type): DataType = clz match {
     // writable
     case c: Class[_] if c == classOf[hadoopIo.DoubleWritable] => DoubleType
     case c: Class[_] if c == classOf[hiveIo.DoubleWritable] => DoubleType
@@ -218,26 +220,42 @@ private[hive] trait HiveInspectors {
     case c: Class[_] if c == java.lang.Float.TYPE => FloatType
     case c: Class[_] if c == java.lang.Boolean.TYPE => BooleanType
 
-    case c: Class[_] if c.isArray => ArrayType(javaClassToDataType(c.getComponentType))
+    case c: Class[_] if c.isArray => ArrayType(javaTypeToDataType(c.getComponentType))
 
     // Hive seems to return this for struct types?
     case c: Class[_] if c == classOf[java.lang.Object] => NullType
 
-    // java list type unsupported
-    case c: Class[_] if c == classOf[java.util.List[_]] =>
+    case p: ParameterizedType if isSubClassOf(p.getRawType, classOf[java.util.List[_]]) =>
+      val Array(elementType) = p.getActualTypeArguments
+      ArrayType(javaTypeToDataType(elementType))
+
+    case p: ParameterizedType if isSubClassOf(p.getRawType, classOf[java.util.Map[_, _]]) =>
+      val Array(keyType, valueType) = p.getActualTypeArguments
+      MapType(javaTypeToDataType(keyType), javaTypeToDataType(valueType))
+
+    // raw java list type unsupported
+    case c: Class[_] if isSubClassOf(c, classOf[java.util.List[_]]) =>
       throw new AnalysisException(
-        "List type in java is unsupported because " +
-        "JVM type erasure makes spark fail to catch a component type in List<>")
+        "Raw list type in java is unsupported because Spark cannot infer the element type.")
 
-    // java map type unsupported
-    case c: Class[_] if c == classOf[java.util.Map[_, _]] =>
+    // raw java map type unsupported
+    case c: Class[_] if isSubClassOf(c, classOf[java.util.Map[_, _]]) =>
       throw new AnalysisException(
-        "Map type in java is unsupported because " +
-        "JVM type erasure makes spark fail to catch key and value types in Map<>")
+        "Raw map type in java is unsupported because Spark cannot infer key and value types.")
+
+    case _: WildcardType =>
+      throw new AnalysisException(
+        "Collection types with wildcards (e.g. List<?> or Map<?, ?>) are unsupported because " +
+          "Spark cannot infer the data type for these type parameters.")
 
     case c => throw new AnalysisException(s"Unsupported java type $c")
   }
 
+  private def isSubClassOf(t: Type, parent: Class[_]): Boolean = t match {
+    case cls: Class[_] => parent.isAssignableFrom(cls)
+    case _ => false
+  }
+
   private def withNullSafe(f: Any => Any): Any => Any = {
     input => if (input == null) null else f(input)
   }

sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala

@@ -70,7 +70,7 @@ private[hive] case class HiveSimpleUDF(
   @transient
   private lazy val conversionHelper = new ConversionHelper(method, arguments)
 
-  override lazy val dataType = javaClassToDataType(method.getReturnType)
+  override lazy val dataType = javaTypeToDataType(method.getGenericReturnType)
 
   @transient
   private lazy val wrappers = children.map(x => wrapperFor(toInspector(x), x.dataType)).toArray

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFRawList.java

@@ -0,0 +1,31 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.sql.hive.execution;
+
+import org.apache.hadoop.hive.ql.exec.UDF;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * UDF that returns a raw (non-parameterized) java List.
+ */
+public class UDFRawList extends UDF {
+  public List evaluate(Object o) {
+    return Collections.singletonList("data1");
+  }
+}

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFRawMap.java

@@ -0,0 +1,31 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.sql.hive.execution;
+
+import org.apache.hadoop.hive.ql.exec.UDF;
+
+import java.util.Collections;
+import java.util.Map;
+
+/**
+ * UDF that returns a raw (non-parameterized) java Map.
+ */
+public class UDFRawMap extends UDF {
+  public Map evaluate(Object o) {
+    return Collections.singletonMap("a", "1");
+  }
+}

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFToIntIntMap.java

@@ -23,13 +23,13 @@
 import java.util.Map;
 
 public class UDFToIntIntMap extends UDF {
-    public Map<Integer, Integer> evaluate(Object o) {
-        return new HashMap<Integer, Integer>() {
-            {
-                put(1, 1);
-                put(2, 1);
-                put(3, 1);
-            }
-        };
-    }
+  public Map<Integer, Integer> evaluate(Object o) {
+    return new HashMap<Integer, Integer>() {
+      {
+        put(1, 1);
+        put(2, 1);
+        put(3, 1);
+      }
+    };
+  }
 }

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFToListInt.java

@@ -19,11 +19,11 @@
 
 import org.apache.hadoop.hive.ql.exec.UDF;
 
+import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.List;
 
 public class UDFToListInt extends UDF {
-    public List<Integer> evaluate(Object o) {
-        return Arrays.asList(1, 2, 3);
-    }
+  public ArrayList<Integer> evaluate(Object o) {
+    return new ArrayList<>(Arrays.asList(1, 2, 3));
+  }
 }

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFToListMapStringListInt.java

@@ -0,0 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.sql.hive.execution;
+
+import org.apache.hadoop.hive.ql.exec.UDF;
+
+import java.util.*;
+
+/**
+ * UDF that returns a nested list of maps that uses a string as its key and a list of ints as its
+ * values.
+ */
+public class UDFToListMapStringListInt extends UDF {
+  public List<Map<String, List<Integer>>> evaluate(Object o) {
+    final Map<String, List<Integer>> map = new HashMap<>();
+    map.put("a", Arrays.asList(1, 2));
+    map.put("b", Arrays.asList(3, 4));
+    return Collections.singletonList(map);
+  }
+}

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFToListString.java

@@ -23,7 +23,7 @@
 import java.util.List;
 
 public class UDFToListString extends UDF {
-    public List<String> evaluate(Object o) {
-        return Arrays.asList("data1", "data2", "data3");
-    }
+  public List<String> evaluate(Object o) {
+    return Arrays.asList("data1", "data2", "data3");
+  }
 }

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFToStringIntMap.java

@@ -20,16 +20,15 @@
 import org.apache.hadoop.hive.ql.exec.UDF;
 
 import java.util.HashMap;
-import java.util.Map;
 
 public class UDFToStringIntMap extends UDF {
-    public Map<String, Integer> evaluate(Object o) {
-        return new HashMap<String, Integer>() {
-            {
-                put("key1", 1);
-                put("key2", 2);
-                put("key3", 3);
-            }
-        };
-    }
+  public HashMap<String, Integer> evaluate(Object o) {
+    return new HashMap<String, Integer>() {
+      {
+        put("key1", 1);
+        put("key2", 2);
+        put("key3", 3);
+      }
+    };
+  }
 }

sql/hive/src/test/java/org/apache/spark/sql/hive/execution/UDFWildcardList.java

@@ -0,0 +1,31 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.spark.sql.hive.execution;
+
+import org.apache.hadoop.hive.ql.exec.UDF;
+
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * UDF that returns a raw (non-parameterized) java List.
+ */
+public class UDFWildcardList extends UDF {
+  public List<?> evaluate(Object o) {
+    return Collections.singletonList("data1");
+  }
+}