Github user adityakishore commented on a diff in the pull request:
https://github.com/apache/drill/pull/443#discussion_r65254353
--- Diff:
contrib/storage-hbase/src/main/java/org/apache/drill/exec/store/hbase/HBaseConnectionManager.java
---
@@ -0,0 +1,92 @@
+/**
+ * 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.hbase;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.drill.common.exceptions.UserException;
+import
org.apache.drill.exec.store.hbase.HBaseStoragePlugin.HBaseConnectionKey;
+import org.apache.hadoop.hbase.client.Connection;
+import org.apache.hadoop.hbase.client.ConnectionFactory;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.cache.RemovalListener;
+import com.google.common.cache.RemovalNotification;
+import com.google.common.util.concurrent.UncheckedExecutionException;
+
+/**
+ * <p>A singleton class which manages the lifecycle of HBase
connections.</p>
+ * <p>One connection per storage plugin instance is maintained.</p>
+ */
+public final class HBaseConnectionManager
+ extends CacheLoader<HBaseConnectionKey, Connection> implements
RemovalListener<HBaseConnectionKey, Connection> {
+ private static final org.slf4j.Logger logger =
org.slf4j.LoggerFactory.getLogger(HBaseConnectionManager.class);
+
+ public static final HBaseConnectionManager INSTANCE = new
HBaseConnectionManager();
+
+ private final LoadingCache<HBaseConnectionKey, Connection>
connectionCache;
+
+ private HBaseConnectionManager() {
+ this.connectionCache = CacheBuilder.newBuilder()
+ .expireAfterAccess(24, TimeUnit.HOURS)
+ .removalListener(this)
+ .build(this);
+ }
+
+ @Override
+ public Connection load(HBaseConnectionKey key) throws Exception {
+ Connection connection =
ConnectionFactory.createConnection(key.getHBaseConf());
+ logger.debug("HBase connection '{}' created.", connection);
+ return connection;
+ }
+
+ @Override
+ public void onRemoval(RemovalNotification<HBaseConnectionKey,
Connection> notification) {
+ try {
+ Connection conn = notification.getValue();
+ if (conn != null) {
+ conn.close();
+ }
+ logger.debug("HBase connection '{}' closed.",
notification.getValue());
+ } catch (Throwable t) {
+ logger.warn("Error while closing HBase connection.", t);
+ }
+ }
+
+ public Connection getConnection(HBaseConnectionKey key) {
+ try {
+ Connection conn = connectionCache.get(key);
+ if (conn.isAborted()
+ || conn.isClosed()) {
+ connectionCache.invalidate(key);
--- End diff --
Thanks for catching this, not sure how it slipped through my own review :(
Couldn't find a simple way to make Guava do this (validate a cached value
before returning), so will change it to do both eviction and load atomically in
this code itself.
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