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https://issues.apache.org/jira/browse/OMID-102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16565493#comment-16565493
]
ASF GitHub Bot commented on OMID-102:
-------------------------------------
Github user JamesRTaylor commented on a diff in the pull request:
https://github.com/apache/incubator-omid/pull/41#discussion_r206927180
--- Diff:
hbase-coprocessor/src/main/java/org/apache/omid/transaction/TransactionVisibilityFilter.java
---
@@ -0,0 +1,248 @@
+/*
+ * 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.omid.transaction;
+
+import com.google.common.base.Optional;
+import com.sun.istack.Nullable;
+import org.apache.hadoop.hbase.Cell;
+import org.apache.hadoop.hbase.CellUtil;
+import org.apache.hadoop.hbase.KeyValue;
+import org.apache.hadoop.hbase.client.Get;
+import org.apache.hadoop.hbase.client.Result;
+import org.apache.hadoop.hbase.filter.Filter;
+import org.apache.hadoop.hbase.filter.FilterBase;
+import org.apache.hadoop.hbase.util.Bytes;
+
+import java.io.IOException;
+import java.util.*;
+
+public class TransactionVisibilityFilter extends FilterBase {
+
+ // optional sub-filter to apply to visible cells
+ private final Filter userFilter;
+ private final SnapshotFilterImpl snapshotFilter;
+ private final Map<Long ,Long> shadowCellCache;
+ private final HBaseTransaction hbaseTransaction;
+ private final Map<String, Long> familyDeletionCache;
+
+ public SnapshotFilter getSnapshotFilter() {
+ return snapshotFilter;
+ }
+
+ public TransactionVisibilityFilter(@Nullable Filter cellFilter,
+ SnapshotFilterImpl snapshotFilter,
+ HBaseTransaction hbaseTransaction) {
+ this.userFilter = cellFilter;
+ this.snapshotFilter = snapshotFilter;
+ shadowCellCache = new HashMap<>();
+ this.hbaseTransaction = hbaseTransaction;
+ familyDeletionCache = new HashMap<String, Long>();
+ }
+
+ @Override
+ public ReturnCode filterKeyValue(Cell v) throws IOException {
+ if (CellUtils.isShadowCell(v)) {
+ Long commitTs = Bytes.toLong(CellUtil.cloneValue(v));
+ shadowCellCache.put(v.getTimestamp(), commitTs);
+ // Continue getting shadow cells until one of them fits this
transaction
+ if (hbaseTransaction.getStartTimestamp() >= commitTs) {
+ return ReturnCode.NEXT_COL;
+ } else {
+ return ReturnCode.SKIP;
+ }
+ } else if (CellUtils.isFamilyDeleteCell(v)) {
+ //Delete is part of this transaction
+ if (snapshotFilter.getTSIfInTransaction(v,
hbaseTransaction).isPresent()) {
+
familyDeletionCache.put(Bytes.toString(CellUtil.cloneFamily(v)),
v.getTimestamp());
+ return ReturnCode.NEXT_COL;
+ }
+
+ if (shadowCellCache.containsKey(v.getTimestamp()) &&
+ hbaseTransaction.getStartTimestamp() >=
shadowCellCache.get(v.getTimestamp())) {
+
familyDeletionCache.put(Bytes.toString(CellUtil.cloneFamily(v)),
shadowCellCache.get(v.getTimestamp()));
--- End diff --
Avoid allocating memory within this call. Either use TreeMap<byte[],Cell>
and don't do the copy or use HashMap<ImmutableBytesPtr,Cell>. You can
copy/paste ImmutableBytesPtr from Phoenix - it's a wrapper around byte[] that
handles equality and hashcode without doing any copying.
> Implement visibility filter as pure HBase Filter
> ------------------------------------------------
>
> Key: OMID-102
> URL: https://issues.apache.org/jira/browse/OMID-102
> Project: Apache Omid
> Issue Type: Sub-task
> Reporter: James Taylor
> Assignee: Yonatan Gottesman
> Priority: Major
>
> The way Omid currently filters through it's own RegionScanner won't work the
> way it's implemented (i.e. the way the filtering is done *after* the next
> call). The reason is that the state of HBase filters get messed up since
> these filters will start to see cells that it shouldn't (i.e. cells that
> would be filtered based on snapshot isolation). It cannot be worked around by
> manually running filters afterwards because filters may issue seek calls
> which are handled during the running of scans by HBase.
>
> Instead, the filtering needs to be implemented as a pure HBase filter and
> that filter needs to delegate to the other, delegate filter once it's
> determined that the cell is visible. See Tephra's TransactionVisibilityFilter
> and they way it calls the delegate filter (cellFilters) only after it's
> determined that the cell is visible. You may run into TEPHRA-169 without
> including the CellSkipFilter too.
> Because it'll be easier if you see shadow cells *before* their corresponding
> real cells you can prefix instead of suffix the column qualifiers to
> guarantee that you'd see the shadow cells prior to the actual cells. Or you
> could buffer cells in your filter prior to omitting them. Another issue would
> be if the shadow cells aren't found and you need to consult the commit table
> - I suppose if the shadow cells are first, this logic would be easier to know
> when it needs to be called.
>
> To reproduce, see the Phoenix unit tests
> FlappingTransactionIT.testInflightUpdateNotSeen() and
> testInflightDeleteNotSeen().
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