Github user denalex commented on a diff in the pull request:
https://github.com/apache/incubator-hawq/pull/1379#discussion_r202126694
--- Diff:
pxf/pxf-service/src/main/java/org/apache/hawq/pxf/service/UGICache.java ---
@@ -0,0 +1,318 @@
+package org.apache.hawq.pxf.service;
+
+/*
+ * 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.
+ */
+
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.DelayQueue;
+import java.util.concurrent.Delayed;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import com.google.common.base.Ticker;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.security.UserGroupInformation;
+
+/**
+ * Stores UserGroupInformation instances for each active session. The UGIs
are cleaned up if they
+ * have not been accessed for 15 minutes.
+ * <p>
+ * The motivation for caching is that destroying UGIs is slow. The
alternative, creating and
+ * destroying a UGI per-request, is wasteful.
+ */
+public class UGICache {
+
+ private static final Log LOG = LogFactory.getLog(UGICache.class);
+ private Map<SessionId, Entry> cache = new ConcurrentHashMap<>();
+ @SuppressWarnings("unchecked")
--- End diff --
do you still need this ? that was needed for arrays, should be ok for maps ?
---
