[GitHub] [drill] ihuzenko commented on a change in pull request #1706: DRILL-7115: Improve Hive schema show tables performance

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ihuzenko commented on a change in pull request #1706: DRILL-7115: Improve Hive schema show tables performance
URL: https://github.com/apache/drill/pull/1706#discussion_r271203347
 
 

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 File path: contrib/storage-hive/core/src/main/java/org/apache/drill/exec/store/hive/client/TableEntryCacheLoader.java
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 @@ -0,0 +1,106 @@
+/*
+ * 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.drill.exec.store.hive.client;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.apache.drill.common.AutoCloseables;
+import org.apache.drill.exec.store.hive.ColumnListsCache;
+import org.apache.drill.exec.store.hive.HiveReadEntry;
+import org.apache.drill.exec.store.hive.HiveTableWithColumnCache;
+import org.apache.drill.exec.store.hive.HiveTableWrapper;
+import org.apache.drill.exec.store.hive.HiveUtilities;
+import org.apache.drill.shaded.guava.com.google.common.cache.CacheLoader;
+import org.apache.hadoop.hive.metastore.api.MetaException;
+import org.apache.hadoop.hive.metastore.api.NoSuchObjectException;
+import org.apache.hadoop.hive.metastore.api.Partition;
+import org.apache.hadoop.hive.metastore.api.Table;
+import org.apache.hadoop.hive.metastore.api.UnknownTableException;
+import org.apache.thrift.TException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * CacheLoader that synchronized on client and tries to reconnect when
+ * client fails. Used by {@link HiveMetadataCache}.
+ */
+final class TableEntryCacheLoader extends CacheLoader<TableName, HiveReadEntry> {
+
+  private static final Logger logger = LoggerFactory.getLogger(TableNameLoader.class);
+
+  private final DrillHiveMetaStoreClient client;
+
+  TableEntryCacheLoader(DrillHiveMetaStoreClient client) {
+    this.client = client;
+  }
+
+
+  @Override
+  @SuppressWarnings("NullableProblems")
+  public HiveReadEntry load(TableName key) throws Exception {
+    Table table;
+    List<Partition> partitions;
+    synchronized (client) {
+      table = getTable(key);
+      partitions = getPartitions(key);
+    }
+    HiveTableWithColumnCache hiveTable = new HiveTableWithColumnCache(table, new ColumnListsCache(table));
+    List<HiveTableWrapper.HivePartitionWrapper> partitionWrappers = partitions.isEmpty()
+        ? null
 
 Review comment:
   Good catch, the logic was here previously since the class was static nested. So I extracted it and preserved existing logic, but I'll try to use empty list and maybe somewhere else redundant null check will be removed too.  

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