Github user arina-ielchiieva commented on a diff in the pull request:
https://github.com/apache/drill/pull/1163#discussion_r174432531
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/sys/store/VersionedDelegatingStore.java
---
@@ -0,0 +1,118 @@
+/*
+ * 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.sys.store;
+
+import java.util.Iterator;
+import java.util.Map;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
+import org.apache.drill.common.AutoCloseables.Closeable;
+import org.apache.drill.common.concurrent.AutoCloseableLock;
+import org.apache.drill.exec.exception.VersionMismatchException;
+import org.apache.drill.exec.store.sys.PersistentStore;
+import org.apache.drill.exec.store.sys.PersistentStoreMode;
+import org.apache.drill.exec.store.sys.VersionedPersistentStore;
+
+public class VersionedDelegatingStore<V> implements
VersionedPersistentStore<V>
+{
+ private final PersistentStore<V> store;
+ private final ReadWriteLock readWriteLock;
+ private final AutoCloseableLock readLock;
+ private final AutoCloseableLock writeLock;
+ private int version;
+
+ public VersionedDelegatingStore(PersistentStore<V> store) {
+ this.store = store;
+ readWriteLock = new ReentrantReadWriteLock();
+ readLock = new AutoCloseableLock(readWriteLock.readLock());
+ writeLock = new AutoCloseableLock(readWriteLock.writeLock());
+ version = -1;
+ }
+
+ @Override
+ public PersistentStoreMode getMode()
+ {
--- End diff --
Please move to the upper line.
---
