[SPARK-14013][SQL] Proper temp function support in catalog

## What changes were proposed in this pull request?

Session catalog was added in #11750. However, it doesn't really support temporary functions properly; right now we only store the metadata in the form of `CatalogFunction`, but this doesn't make sense for temporary functions because there is no class name.

This patch moves the `FunctionRegistry` into the `SessionCatalog`. With this, the user can call `catalog.createTempFunction` and `catalog.lookupFunction` to use the function they registered previously. This is currently still dead code, however.

## How was this patch tested?

`SessionCatalogSuite`.

Author: Andrew Or <andrew@databricks.com>

Closes #11972 from andrewor14/temp-functions.

3 files changed, 20 insertions, 8 deletions

diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
index ec7bf61be1..ff12245e8d 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionCatalog.scala
@@ -18,6 +18,7 @@
 package org.apache.spark.sql.hive
 
 import org.apache.spark.sql.catalyst.TableIdentifier
+import org.apache.spark.sql.catalyst.analysis.FunctionRegistry
 import org.apache.spark.sql.catalyst.catalog.SessionCatalog
 import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, SubqueryAlias}
 import org.apache.spark.sql.catalyst.rules.Rule
@@ -31,8 +32,9 @@ class HiveSessionCatalog(
     externalCatalog: HiveExternalCatalog,
     client: HiveClient,
     context: HiveContext,
+    functionRegistry: FunctionRegistry,
     conf: SQLConf)
-  extends SessionCatalog(externalCatalog, conf) {
+  extends SessionCatalog(externalCatalog, functionRegistry, conf) {
 
   override def setCurrentDatabase(db: String): Unit = {
     super.setCurrentDatabase(db)
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionState.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionState.scala
index caa7f296ed..c9b6b1dfb6 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionState.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveSessionState.scala
@@ -35,13 +35,6 @@ private[hive] class HiveSessionState(ctx: HiveContext) extends SessionState(ctx)
   }
 
   /**
-   * Internal catalog for managing table and database states.
-   */
-  override lazy val catalog = {
-    new HiveSessionCatalog(ctx.hiveCatalog, ctx.metadataHive, ctx, conf)
-  }
-
-  /**
    * Internal catalog for managing functions registered by the user.
    * Note that HiveUDFs will be overridden by functions registered in this context.
    */
@@ -50,6 +43,13 @@ private[hive] class HiveSessionState(ctx: HiveContext) extends SessionState(ctx)
   }
 
   /**
+   * Internal catalog for managing table and database states.
+   */
+  override lazy val catalog = {
+    new HiveSessionCatalog(ctx.hiveCatalog, ctx.metadataHive, ctx, functionRegistry, conf)
+  }
+
+  /**
    * An analyzer that uses the Hive metastore.
    */
   override lazy val analyzer: Analyzer = {
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala
index efaa052370..c07c428895 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala
@@ -141,6 +141,16 @@ private[hive] class HiveFunctionRegistry(
       }
     }.getOrElse(None))
   }
+
+  override def lookupFunctionBuilder(name: String): Option[FunctionBuilder] = {
+    underlying.lookupFunctionBuilder(name)
+  }
+
+  // Note: This does not drop functions stored in the metastore
+  override def dropFunction(name: String): Boolean = {
+    underlying.dropFunction(name)
+  }
+
 }
 
 private[hive] case class HiveSimpleUDF(