[GitHub] [spark] brkyvz commented on a change in pull request #25104: [SPARK-28341][SQL] refine the v2 session catalog config

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brkyvz commented on a change in pull request #25104: [SPARK-28341][SQL] refine the v2 session catalog config
URL: https://github.com/apache/spark/pull/25104#discussion_r303023250
 
 

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 File path: sql/catalyst/src/main/scala/org/apache/spark/sql/catalog/v2/CatalogManager.scala
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+/*
+ * 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.catalog.v2
+
+import scala.collection.mutable
+import scala.util.control.NonFatal
+
+import org.apache.spark.internal.Logging
+import org.apache.spark.sql.catalyst.catalog.SessionCatalog
+import org.apache.spark.sql.internal.{SQLConf, StaticSQLConf}
+import org.apache.spark.util.Utils
+
+/**
+ * A thread-safe manager for [[CatalogPlugin]]s. It tracks all the registered catalogs, and allow
+ * the caller to look up a catalog by name.
+ */
+class CatalogManager(conf: SQLConf, val sessionCatalog: SessionCatalog) extends Logging {
+
+  /**
+   * Tracks all the registered catalogs.
+   */
+  private val catalogs = mutable.HashMap.empty[String, CatalogPlugin]
+
+  /**
+   * Looks up a catalog by name.
+   */
+  def catalog(name: String): CatalogPlugin = synchronized {
+    catalogs.getOrElseUpdate(name, Catalogs.load(name, conf))
+  }
+
+  /**
+   * Returns the default catalog specified by config.
+   */
+  // TODO(cloud-fan): This needs to be a def instead of val, because the default catalog config is
+  // a session config which can change at runtime. Shall we make it a static config instead?
+  def defaultCatalog(): Option[CatalogPlugin] = {
+    conf.defaultV2Catalog.flatMap { catalogName =>
+      try {
+        Some(catalog(catalogName))
+      } catch {
+        case NonFatal(e) =>
+          logError(s"Cannot load default v2 catalog: $catalogName", e)
+          None
+      }
+    }
+  }
+
+  /**
+   * Returns the v2 session catalog specified by config.
+   */
+  lazy val v2SessionCatalog: TableCatalog = {
+    val implClsName = conf.getConf(StaticSQLConf.V2_SESSION_CATALOG_IMPL)
 
 Review comment:
   Why does this need to be a StaticConf? Wouldn't this make it impossible to plug in your own session catalog when using the Spark Shell for example?

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