From cd308f38adf44af72a254c4706abd0dfbef1a887 Mon Sep 17 00:00:00 2001
From: Min Zhao <zhaomin1423@163.com>
Date: Mon, 19 Jul 2021 18:16:38 +0800
Subject: [PATCH] [KYUUBI #758] [KYUUBI 661] Add UDF system_user

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### _Why are the changes needed?_
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  1. If you add a feature, you can talk about the use case of it.
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add udf system_user.

### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible

- [ ] Add screenshots for manual tests if appropriate

- [ ] [Run test](https://kyuubi.readthedocs.io/en/latest/tools/testing.html#running-tests) locally before make a pull request

Closes #758 from zhaomin1423/661_add-system_user.

Closes #758

70eba56a [Min Zhao] update system user name
f5edc621 [Min Zhao] [KYUUBI 661] Add UDF system_user

Authored-by: Min Zhao <zhaomin1423@163.com>
Signed-off-by: Kent Yao <yao@apache.org>
---
 docs/sql/functions.md                                     | 1 +
 .../org/apache/kyuubi/engine/spark/udf/KDFRegistry.scala  | 7 +++++++
 .../scala/org/apache/kyuubi/operation/JDBCTests.scala     | 8 ++++++++
 3 files changed, 16 insertions(+)

diff --git a/docs/sql/functions.md b/docs/sql/functions.md
index 90a09e503..0415e7b83 100644
--- a/docs/sql/functions.md
+++ b/docs/sql/functions.md
@@ -13,4 +13,5 @@ Kyuubi provides several auxiliary SQL functions as supplement to Spark's [Built-
 Name | Description | Return Type | Since
 --- | --- | --- | ---
 kyuubi_version | Return the version of Kyuubi Server | string | 1.3.0
+system_user | Return the system user name for the associated query engine | string | 1.3.0
 
diff --git a/externals/kyuubi-spark-sql-engine/src/main/scala/org/apache/kyuubi/engine/spark/udf/KDFRegistry.scala b/externals/kyuubi-spark-sql-engine/src/main/scala/org/apache/kyuubi/engine/spark/udf/KDFRegistry.scala
index 98c4077fd..14c837af8 100644
--- a/externals/kyuubi-spark-sql-engine/src/main/scala/org/apache/kyuubi/engine/spark/udf/KDFRegistry.scala
+++ b/externals/kyuubi-spark-sql-engine/src/main/scala/org/apache/kyuubi/engine/spark/udf/KDFRegistry.scala
@@ -36,6 +36,13 @@ object KDFRegistry {
     "string",
     "1.3.0")
 
+  val system_user: KyuubiDefinedFunction = create(
+    "system_user",
+    udf(() => System.getProperty("user.name")).asNonNullable(),
+    "Return the system user name for the associated query engine",
+    "string",
+    "1.3.0")
+
   def create(
     name: String,
     udf: UserDefinedFunction,
diff --git a/kyuubi-common/src/test/scala/org/apache/kyuubi/operation/JDBCTests.scala b/kyuubi-common/src/test/scala/org/apache/kyuubi/operation/JDBCTests.scala
index 660a1f046..fa0ed60bb 100644
--- a/kyuubi-common/src/test/scala/org/apache/kyuubi/operation/JDBCTests.scala
+++ b/kyuubi-common/src/test/scala/org/apache/kyuubi/operation/JDBCTests.scala
@@ -359,4 +359,12 @@ trait JDBCTests extends BasicJDBCTests {
       assert(rs.getString(1) == KYUUBI_VERSION)
     }
   }
+
+  test("kyuubi defined function - system_user") {
+    withJdbcStatement() { statement =>
+      val rs = statement.executeQuery("SELECT system_user()")
+      assert(rs.next())
+      assert(rs.getString(1) == System.getProperty("user.name"))
+    }
+  }
 }