Making tableRelationCache private and updating the comments.

Author: Reza Safi

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -126,51 +126,41 @@ class SessionCatalog(
     if (conf.caseSensitiveAnalysis) name else name.toLowerCase(Locale.ROOT)
   }
 
-  /**
-    * A cache of qualified table names to table relation plans.
-    * Accessing tableRelationCache directly is not recommended,
-    * since it will introduce exposures to guava libraries.
-    */
-  val tableRelationCache: Cache[QualifiedTableName, LogicalPlan] = {
+  private val tableRelationCache: Cache[QualifiedTableName, LogicalPlan] = {
     val cacheSize = conf.tableRelationCacheSize
     CacheBuilder.newBuilder().maximumSize(cacheSize).build[QualifiedTableName, LogicalPlan]()
   }
 
   /**
-    * This method provides a way to get a cached plan
-    * without exposing components to Guava library.
+    * This method provides a way to get a cached plan.
     */
   def getCachedPlan(t: QualifiedTableName, c: Callable[LogicalPlan]): LogicalPlan = {
     tableRelationCache.get(t, c)
   }
 
   /**
-    * This method provides a way to get a cached plan if the key exists
-    * without exposing components to Guava library.
+    * This method provides a way to get a cached plan if the key exists.
     */
   def getCachedTableIfPresent(key: QualifiedTableName): LogicalPlan = {
     tableRelationCache.getIfPresent(key)
   }
 
   /**
-    * This method provides a way to cache a plan
-    * without exposing components to Guava library.
+    * This method provides a way to cache a plan.
     */
   def putTableInCache(t: QualifiedTableName, l: LogicalPlan): Unit = {
     tableRelationCache.put(t, l)
   }
 
   /**
-    * This method provides a way to invalidate a cached plan
-    * without exposing components to Guava library.
+    * This method provides a way to invalidate a cached plan.
     */
   def invalidateCachedTable(key: QualifiedTableName): Unit = {
     tableRelationCache.invalidate(key)
   }
 
   /**
-    * This method provides a way to invalidate all the cached plans
-    * without exposing components to Guava library.
+    * This method provides a way to invalidate all the cached plans.
     */
   def invalidateAllCachedTables(): Unit = {
     tableRelationCache.invalidateAll()