add tests and codegen

Author: adrian-wang

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala

@@ -158,7 +158,11 @@ object FunctionRegistry {
     expression[Substring]("substring"),
     expression[Upper]("ucase"),
     expression[UnHex]("unhex"),
-    expression[Upper]("upper")
+    expression[Upper]("upper"),
+
+    //datetime functions
+    expression[CurrentDate]("current_date"),
+    expression[CurrentTimestamp]("current_timestamp")
   )
 
   val builtin: FunctionRegistry = {

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

@@ -17,37 +17,52 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
+import org.apache.spark.sql.catalyst.expressions.codegen.{CodeGenContext, GeneratedExpressionCode}
 import org.apache.spark.sql.catalyst.util.DateTimeUtils
 import org.apache.spark.sql.types._
 
 /**
- * Adds a number of days to startdate: date_add('2008-12-31', 1) = '2009-01-01'.
+ * Returns the current date at the start of query evaluation.
+ * All calls of current_date within the same query return the same value.
  */
-case class CurrentTimestamp() extends Expression {
-  override def children: Seq[Expression] = Nil
-
+case class CurrentDate() extends LeafExpression {
   override def foldable: Boolean = true
   override def nullable: Boolean = false
 
-  override def dataType: DataType = TimestampType
+  override def dataType: DataType = DateType
 
   override def eval(input: InternalRow): Any = {
-    (new java.util.Date()).getTime * 10000L
+    DateTimeUtils.millisToDays(System.currentTimeMillis())
+  }
+
+  override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode): String = {
+    val datetimeUtils = "org.apache.spark.sql.catalyst.util.DateTimeUtils"
+    s"""
+      boolean ${ev.isNull} = false;
+      ${ctx.javaType(dataType)} ${ev.primitive} =
+        $datetimeUtils.millisToDays(System.currentTimeMillis());
+    """
   }
 }
 
 /**
- * Subtracts a number of days to startdate: date_sub('2008-12-31', 1) = '2008-12-30'.
+ * Returns the current timestamp at the start of query evaluation.
+ * All calls of current_timestamp within the same query return the same value.
  */
-case class CurrentDate() extends Expression {
-  override def children: Seq[Expression] = Nil
-
+case class CurrentTimestamp() extends LeafExpression {
   override def foldable: Boolean = true
   override def nullable: Boolean = false
 
-  override def dataType: DataType = DateType
+  override def dataType: DataType = TimestampType
 
   override def eval(input: InternalRow): Any = {
-    DateTimeUtils.millisToDays((new java.util.Date()).getTime)
+    System.currentTimeMillis() * 10000L
+  }
+
+  override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode): String = {
+    s"""
+      boolean ${ev.isNull} = false;
+      ${ctx.javaType(dataType)} ${ev.primitive} = System.currentTimeMillis() * 10000L;
+    """
   }
 }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/DatetimeFunctionsSuite.scala

@@ -0,0 +1,40 @@
+/*
+ * 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.catalyst.expressions
+
+import java.sql.Date
+
+import org.apache.spark.SparkFunSuite
+import org.apache.spark.sql.types.DateType
+
+class DatetimeFunctionsSuite extends SparkFunSuite with ExpressionEvalHelper {
+  test("datetime function current_date") {
+    checkEvaluation(
+      CurrentDate(),
+      new Date(System.currentTimeMillis), EmptyRow)
+  }
+
+  test("datetime function current_timestamp") {
+    // By the time we run check, current timestamp has been different.
+    // So we just check the date part.
+    checkEvaluation(
+      Cast(CurrentTimestamp(), DateType),
+      new Date(System.currentTimeMillis), EmptyRow)
+  }
+
+}

sql/core/src/test/scala/org/apache/spark/sql/DatetimeExpressionsSuite.scala

@@ -0,0 +1,46 @@
+/*
+ * 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
+
+import java.sql.Date
+
+import org.apache.spark.sql.catalyst.util.DateTimeUtils
+import org.scalatest.BeforeAndAfterAll
+
+class DatetimeExpressionsSuite extends QueryTest with BeforeAndAfterAll {
+  private lazy val ctx = org.apache.spark.sql.test.TestSQLContext
+
+  test("function current_date") {
+    // Date constructor would keep the original millis, we need to align it with begin of day.
+    checkAnswer(ctx.sql("""SELECT CURRENT_DATE()"""),
+      Row(new Date(DateTimeUtils.daysToMillis(
+        DateTimeUtils.millisToDays(System.currentTimeMillis())))))
+  }
+
+  test("function current_timestamp") {
+    // Execution in one query should return the same value
+    checkAnswer(ctx.sql("""SELECT CURRENT_TIMESTAMP() = CURRENT_TIMESTAMP()"""),
+      Row(true))
+    // By the time we run check, current timestamp has been different.
+    // So we just check the date part.
+    checkAnswer(ctx.sql("""SELECT CAST(CURRENT_TIMESTAMP() AS DATE)"""),
+      Row(new Date(DateTimeUtils.daysToMillis(
+        DateTimeUtils.millisToDays(System.currentTimeMillis())))))
+  }
+
+}