/**
* 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 com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Multimap;
import com.google.common.collect.Sets;
import org.apache.cassandra.concurrent.JMXEnabledThreadPoolExecutor;
import org.apache.cassandra.concurrent.NamedThreadFactory;
import org.apache.cassandra.config.Schema;
import org.apache.cassandra.db.Table;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.locator.AbstractReplicationStrategy;
import org.apache.cassandra.locator.TokenMetadata;
import org.apache.cassandra.utils.Pair;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.net.InetAddress;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.*;
public class PendingRangeCalculatorService extends PendingRangeCalculatorServiceMBean
{
public static final PendingRangeCalculatorService instance = new PendingRangeCalculatorService();
private static Logger logger = LoggerFactory.getLogger(PendingRangeCalculatorService.class);
private final JMXEnabledThreadPoolExecutor executor = new JMXEnabledThreadPoolExecutor(1, Integer.MAX_VALUE, TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>(1), new NamedThreadFactory("PendingRangeCalculator"), "internal");
public PendingRangeCalculatorService()
{
executor.setRejectedExecutionHandler(new ThreadPoolExecutor.DiscardPolicy());
}
private class PendingRangeTask implements Runnable
{
public void run()
{
long start = System.currentTimeMillis();
for (String table : Schema.instance.getNonSystemTables())
{
calculatePendingRanges(Table.open(table).getReplicationStrategy(), table);
}
logger.debug("finished calculation for {} keyspaces in {}ms", Schema.instance.getNonSystemTables().size(), System.currentTimeMillis() - start);
}
}
public Future<?> update()
{
return executor.submit(new PendingRangeTask());
}
public void blockUntilFinished()
{
while (true)
{
if (executor.getActiveCount() + executor.getPendingTasks() == 0)
break;
try
{
Thread.sleep(100);
}
catch (InterruptedException e)
{
throw new RuntimeException(e);
}
}
}
/**
* Calculate pending ranges according to bootstrapping and leaving nodes. Reasoning is:
*
* (1) When in doubt, it is better to write too much to a node than too little. That is, if
* there are multiple nodes moving, calculate the biggest ranges a node could have. Cleaning
* up unneeded data afterwards is better than missing writes during movement.
* (2) When a node leaves, ranges for other nodes can only grow (a node might get additional
* ranges, but it will not lose any of its current ranges as a result of a leave). Therefore
* we will first remove _all_ leaving tokens for the sake of calculation and then check what
* ranges would go where if all nodes are to leave. This way we get the biggest possible
* ranges with regard current leave operations, covering all subsets of possible final range
* values.
* (3) When a node bootstraps, ranges of other nodes can only get smaller. Without doing
* complex calculations to see if multiple bootstraps overlap, we simply base calculations
* on the same token ring used before (reflecting situation after all leave operations have
* completed). Bootstrapping nodes will be added and removed one by one to that metadata and
* checked what their ranges would be. This will give us the biggest possible ranges the
* node could have. It might be that other bootstraps make our actual final ranges smaller,
* but it does not matter as we can clean up the data afterwards.
*
* NOTE: This is heavy and ineffective operation. This will be done only once when a node
* changes state in the cluster, so it should be manageable.
*/
// public & static for testing purposes
public static void calculatePendingRanges(AbstractReplicationStrategy strategy, String table)
{
TokenMetadata tm = StorageService.instance.getTokenMetadata();
Multimap<Range<Token>, InetAddress> pendingRanges = HashMultimap.create();
Map<Token, InetAddress> bootstrapTokens = tm.getBootstrapTokens();
Set<InetAddress> leavingEndpoints = tm.getLeavingEndpoints();
if (bootstrapTokens.isEmpty() && leavingEndpoints.isEmpty() && tm.getMovingEndpoints().isEmpty())
{
if (logger.isDebugEnabled())
logger.debug("No bootstrapping, leaving or moving nodes -> empty pending ranges for {}", table);
tm.setPendingRanges(table, pendingRanges);
return;
}
Multimap<InetAddress, Range<Token>> addressRanges = strategy.getAddressRanges();
// Copy of metadata reflecting the situation after all leave operations are finished.
TokenMetadata allLeftMetadata = tm.cloneAfterAllLeft();
// get all ranges that will be affected by leaving nodes
Set<Range<Token>> affectedRanges = new HashSet<Range<Token>>();
for (InetAddress endpoint : leavingEndpoints)
affectedRanges.addAll(addressRanges.get(endpoint));
// for each of those ranges, find what new nodes will be responsible for the range when
// all leaving nodes are gone.
for (Range<Token> range : affectedRanges)
{
Set<InetAddress> currentEndpoints = ImmutableSet.copyOf(strategy.calculateNaturalEndpoints(range.right, tm));
Set<InetAddress> newEndpoints = ImmutableSet.copyOf(strategy.calculateNaturalEndpoints(range.right, allLeftMetadata));
pendingRanges.putAll(range, Sets.difference(newEndpoints, currentEndpoints));
}
// At this stage pendingRanges has been updated according to leave operations. We can
// now continue the calculation by checking bootstrapping nodes.
// For each of the bootstrapping nodes, simply add and remove them one by one to
// allLeftMetadata and check in between what their ranges would be.
synchronized (bootstrapTokens)
{
for (Map.Entry<Token, InetAddress> entry : bootstrapTokens.entrySet())
{
InetAddress endpoint = entry.getValue();
allLeftMetadata.updateNormalToken(entry.getKey(), endpoint);
for (Range<Token> range : strategy.getAddressRanges(allLeftMetadata).get(endpoint))
pendingRanges.put(range, endpoint);
allLeftMetadata.removeEndpoint(endpoint);
}
}
// At this stage pendingRanges has been updated according to leaving and bootstrapping nodes.
// We can now finish the calculation by checking moving nodes.
// For each of the moving nodes, we do the same thing we did for bootstrapping:
// simply add and remove them one by one to allLeftMetadata and check in between what their ranges would be.
for (Pair<Token, InetAddress> moving : tm.getMovingEndpoints())
{
InetAddress endpoint = moving.right; // address of the moving node
// moving.left is a new token of the endpoint
allLeftMetadata.updateNormalToken(moving.left, endpoint);
for (Range<Token> range : strategy.getAddressRanges(allLeftMetadata).get(endpoint))
{
pendingRanges.put(range, endpoint);
}
allLeftMetadata.removeEndpoint(endpoint);
}
tm.setPendingRanges(table, pendingRanges);
if (logger.isDebugEnabled())
logger.debug("Pending ranges:\n" + (pendingRanges.isEmpty() ? "<empty>" : tm.printPendingRanges()));
}
}