Github user poornachandra commented on a diff in the pull request:
https://github.com/apache/incubator-tephra/pull/67#discussion_r160402855
--- Diff:
tephra-hbase-compat-2.0/src/main/java/org/apache/tephra/hbase/coprocessor/TransactionProcessor.java
---
@@ -0,0 +1,583 @@
+/*
+ * 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.tephra.hbase.coprocessor;
+
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.Cell;
+import org.apache.hadoop.hbase.CellUtil;
+import org.apache.hadoop.hbase.CoprocessorEnvironment;
+import org.apache.hadoop.hbase.DoNotRetryIOException;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.ColumnFamilyDescriptor;
+import org.apache.hadoop.hbase.client.Delete;
+import org.apache.hadoop.hbase.client.Durability;
+import org.apache.hadoop.hbase.client.Get;
+import org.apache.hadoop.hbase.client.OperationWithAttributes;
+import org.apache.hadoop.hbase.client.Put;
+import org.apache.hadoop.hbase.client.Scan;
+import org.apache.hadoop.hbase.client.TableDescriptor;
+import org.apache.hadoop.hbase.coprocessor.ObserverContext;
+import org.apache.hadoop.hbase.coprocessor.RegionCoprocessor;
+import org.apache.hadoop.hbase.coprocessor.RegionCoprocessorEnvironment;
+import org.apache.hadoop.hbase.coprocessor.RegionObserver;
+import org.apache.hadoop.hbase.filter.Filter;
+import org.apache.hadoop.hbase.filter.FilterBase;
+import org.apache.hadoop.hbase.regionserver.HStore;
+import org.apache.hadoop.hbase.regionserver.InternalScanner;
+import org.apache.hadoop.hbase.regionserver.Region;
+import org.apache.hadoop.hbase.regionserver.ScanOptions;
+import org.apache.hadoop.hbase.regionserver.ScanType;
+import org.apache.hadoop.hbase.regionserver.Store;
+import org.apache.hadoop.hbase.regionserver.StoreFile;
+import
org.apache.hadoop.hbase.regionserver.compactions.CompactionLifeCycleTracker;
+import org.apache.hadoop.hbase.regionserver.compactions.CompactionRequest;
+import org.apache.hadoop.hbase.util.Bytes;
+import org.apache.hadoop.hbase.wal.WALEdit;
+import org.apache.tephra.Transaction;
+import org.apache.tephra.TransactionCodec;
+import org.apache.tephra.TxConstants;
+import org.apache.tephra.coprocessor.CacheSupplier;
+import org.apache.tephra.coprocessor.TransactionStateCache;
+import org.apache.tephra.coprocessor.TransactionStateCacheSupplier;
+import org.apache.tephra.hbase.txprune.CompactionState;
+import org.apache.tephra.persist.TransactionVisibilityState;
+import org.apache.tephra.util.TxUtils;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.NavigableSet;
+import java.util.Optional;
+import java.util.Set;
+import java.util.concurrent.TimeUnit;
+
+import javax.annotation.Nullable;
+
+/**
+ * {@code org.apache.hadoop.hbase.coprocessor.RegionObserver} coprocessor
that handles server-side processing
+ * for transactions:
+ * <ul>
+ * <li>applies filtering to exclude data from invalid and in-progress
transactions</li>
+ * <li>overrides the scanner returned for flush and compaction to drop
data written by invalidated transactions,
+ * or expired due to TTL.</li>
+ * </ul>
+ *
+ * <p>In order to use this coprocessor for transactions, configure the
class on any table involved in transactions,
+ * or on all user tables by adding the following to hbase-site.xml:
+ * {@code
+ * <property>
+ * <name>hbase.coprocessor.region.classes</name>
+ *
<value>org.apache.tephra.hbase.coprocessor.TransactionProcessor</value>
+ * </property>
+ * }
+ * </p>
+ *
+ * <p>HBase {@code Get} and {@code Scan} operations should have the
current transaction serialized on to the operation
+ * as an attribute:
+ * {@code
+ * Transaction t = ...;
+ * Get get = new Get(...);
+ * TransactionCodec codec = new TransactionCodec();
+ * codec.addToOperation(get, t);
+ * }
+ * </p>
+ */
+public class TransactionProcessor implements RegionObserver,
RegionCoprocessor {
+ private static final Log LOG =
LogFactory.getLog(TransactionProcessor.class);
--- End diff --
This file also needs to use 2 spaces for indentation
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