/**
* 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.cassandra.service;
import java.io.IOError;
import java.io.IOException;
import java.net.InetAddress;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import org.apache.commons.collections.iterators.CollatingIterator;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.columniterator.IdentityQueryFilter;
import org.apache.cassandra.db.filter.QueryFilter;
import org.apache.cassandra.db.filter.QueryPath;
import org.apache.cassandra.gms.Gossiper;
import org.apache.cassandra.net.Message;
import org.apache.cassandra.net.MessagingService;
public class RowRepairResolver extends AbstractRowResolver
{
public RowRepairResolver(String table, ByteBuffer key)
{
super(key, table);
}
/*
* This method handles the following scenario:
*
* there was a mismatch on the initial read (1a or 1b), so we redid the digest requests
* as full data reads. In this case we need to compute the most recent version
* of each column, and send diffs to out-of-date replicas.
*/
public Row resolve() throws DigestMismatchException, IOException
{
if (logger.isDebugEnabled())
logger.debug("resolving " + replies.size() + " responses");
long startTime = System.currentTimeMillis();
List<ColumnFamily> versions = new ArrayList<ColumnFamily>();
List<InetAddress> endpoints = new ArrayList<InetAddress>();
// case 1: validate digests against each other; throw immediately on mismatch.
// also, collects data results into versions/endpoints lists.
//
// results are cleared as we process them, to avoid unnecessary duplication of work
// when resolve() is called a second time for read repair on responses that were not
// necessary to satisfy ConsistencyLevel.
for (Map.Entry<Message, ReadResponse> entry : replies.entrySet())
{
Message message = entry.getKey();
ReadResponse response = entry.getValue();
assert !response.isDigestQuery();
versions.add(response.row().cf);
endpoints.add(message.getFrom());
}
ColumnFamily resolved;
if (versions.size() > 1)
{
resolved = resolveSuperset(versions);
if (logger.isDebugEnabled())
logger.debug("versions merged");
maybeScheduleRepairs(resolved, table, key, versions, endpoints);
}
else
{
resolved = versions.get(0);
}
if (logger.isDebugEnabled())
logger.debug("resolve: " + (System.currentTimeMillis() - startTime) + " ms.");
return new Row(key, resolved);
}
/**
* For each row version, compare with resolved (the superset of all row versions);
* if it is missing anything, send a mutation to the endpoint it come from.
*/
public static void maybeScheduleRepairs(ColumnFamily resolved, String table, DecoratedKey key, List<ColumnFamily> versions, List<InetAddress> endpoints)
{
for (int i = 0; i < versions.size(); i++)
{
ColumnFamily diffCf = ColumnFamily.diff(versions.get(i), resolved);
if (diffCf == null) // no repair needs to happen
continue;
// create and send the row mutation message based on the diff
RowMutation rowMutation = new RowMutation(table, key.key);
rowMutation.add(diffCf);
Message repairMessage;
try
{
repairMessage = rowMutation.getMessage(Gossiper.instance.getVersion(endpoints.get(i)));
}
catch (IOException e)
{
throw new IOError(e);
}
MessagingService.instance().sendOneWay(repairMessage, endpoints.get(i));
}
}
static ColumnFamily resolveSuperset(List<ColumnFamily> versions)
{
assert versions.size() > 0;
ColumnFamily resolved = null;
for (ColumnFamily cf : versions)
{
if (cf == null)
continue;
if (resolved == null)
resolved = cf.cloneMeShallow();
else
resolved.delete(cf);
}
if (resolved == null)
return null;
// mimic the collectCollatedColumn + removeDeleted path that getColumnFamily takes.
// this will handle removing columns and subcolumns that are supressed by a row or
// supercolumn tombstone.
QueryFilter filter = new QueryFilter(null, new QueryPath(resolved.metadata().cfName), new IdentityQueryFilter());
CollatingIterator iter = new CollatingIterator(resolved.metadata().comparator.columnComparator);
for (ColumnFamily version : versions)
{
if (version == null)
continue;
iter.addIterator(version.getColumnsMap().values().iterator());
}
filter.collectCollatedColumns(resolved, iter, Integer.MIN_VALUE);
return ColumnFamilyStore.removeDeleted(resolved, Integer.MIN_VALUE);
}
public Row getData() throws IOException
{
throw new UnsupportedOperationException();
}
public boolean isDataPresent()
{
throw new UnsupportedOperationException();
}
}