/*
* 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.net.InetAddress;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.concurrent.Stage;
import org.apache.cassandra.concurrent.StageManager;
import org.apache.cassandra.config.DatabaseDescriptor;
import org.apache.cassandra.db.ReadCommand;
import org.apache.cassandra.db.Keyspace;
import org.apache.cassandra.exceptions.ReadTimeoutException;
import org.apache.cassandra.exceptions.UnavailableException;
import org.apache.cassandra.metrics.ReadRepairMetrics;
import org.apache.cassandra.net.IAsyncCallback;
import org.apache.cassandra.net.MessageIn;
import org.apache.cassandra.net.MessageOut;
import org.apache.cassandra.net.MessagingService;
import org.apache.cassandra.db.ConsistencyLevel;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.SimpleCondition;
public class ReadCallback<TMessage, TResolved> implements IAsyncCallback<TMessage>
{
protected static final Logger logger = LoggerFactory.getLogger( ReadCallback.class );
public final IResponseResolver<TMessage, TResolved> resolver;
private final SimpleCondition condition = new SimpleCondition();
final long start;
final int blockfor;
final List<InetAddress> endpoints;
private final IReadCommand command;
private final ConsistencyLevel consistencyLevel;
private final AtomicInteger received = new AtomicInteger(0);
private final Keyspace keyspace; // TODO push this into ConsistencyLevel?
/**
* Constructor when response count has to be calculated and blocked for.
*/
public ReadCallback(IResponseResolver<TMessage, TResolved> resolver, ConsistencyLevel consistencyLevel, IReadCommand command, List<InetAddress> filteredEndpoints)
{
this(resolver, consistencyLevel, consistencyLevel.blockFor(Keyspace.open(command.getKeyspace())), command, Keyspace.open(command.getKeyspace()), filteredEndpoints);
if (logger.isTraceEnabled())
logger.trace(String.format("Blockfor is %s; setting up requests to %s", blockfor, StringUtils.join(this.endpoints, ",")));
}
public ReadCallback(IResponseResolver<TMessage, TResolved> resolver, ConsistencyLevel consistencyLevel, int blockfor, IReadCommand command, Keyspace keyspace, List<InetAddress> endpoints)
{
this.command = command;
this.keyspace = keyspace;
this.blockfor = blockfor;
this.consistencyLevel = consistencyLevel;
this.resolver = resolver;
this.start = System.nanoTime();
this.endpoints = endpoints;
// we don't support read repair (or rapid read protection) for range scans yet (CASSANDRA-6897)
assert !(resolver instanceof RangeSliceResponseResolver) || blockfor >= endpoints.size();
}
public boolean await(long timePastStart, TimeUnit unit)
{
long time = unit.toNanos(timePastStart) - (System.nanoTime() - start);
try
{
return condition.await(time, TimeUnit.NANOSECONDS);
}
catch (InterruptedException ex)
{
throw new AssertionError(ex);
}
}
public TResolved get() throws ReadTimeoutException, DigestMismatchException
{
if (!await(command.getTimeout(), TimeUnit.MILLISECONDS))
{
// Same as for writes, see AbstractWriteResponseHandler
ReadTimeoutException ex = new ReadTimeoutException(consistencyLevel, received.get(), blockfor, resolver.isDataPresent());
if (logger.isDebugEnabled())
logger.debug("Read timeout: {}", ex.toString());
throw ex;
}
return blockfor == 1 ? resolver.getData() : resolver.resolve();
}
public void response(MessageIn<TMessage> message)
{
resolver.preprocess(message);
int n = waitingFor(message)
? received.incrementAndGet()
: received.get();
if (n >= blockfor && resolver.isDataPresent())
{
condition.signalAll();
// kick off a background digest comparison if this is a result that (may have) arrived after
// the original resolve that get() kicks off as soon as the condition is signaled
if (blockfor < endpoints.size() && n == endpoints.size())
StageManager.getStage(Stage.READ_REPAIR).execute(new AsyncRepairRunner());
}
}
/**
* @return true if the message counts towards the blockfor threshold
*/
private boolean waitingFor(MessageIn message)
{
return consistencyLevel.isDatacenterLocal()
? DatabaseDescriptor.getLocalDataCenter().equals(DatabaseDescriptor.getEndpointSnitch().getDatacenter(message.from))
: true;
}
/**
* @return the current number of received responses
*/
public int getReceivedCount()
{
return received.get();
}
public void response(TMessage result)
{
MessageIn<TMessage> message = MessageIn.create(FBUtilities.getBroadcastAddress(),
result,
Collections.<String, byte[]>emptyMap(),
MessagingService.Verb.INTERNAL_RESPONSE,
MessagingService.current_version);
response(message);
}
public void assureSufficientLiveNodes() throws UnavailableException
{
consistencyLevel.assureSufficientLiveNodes(keyspace, endpoints);
}
public boolean isLatencyForSnitch()
{
return true;
}
private class AsyncRepairRunner implements Runnable
{
public void run()
{
// If the resolver is a RowDigestResolver, we need to do a full data read if there is a mismatch.
// Otherwise, resolve will send the repairs directly if needs be (and in that case we should never
// get a digest mismatch)
try
{
resolver.resolve();
}
catch (DigestMismatchException e)
{
assert resolver instanceof RowDigestResolver;
if (logger.isDebugEnabled())
logger.debug("Digest mismatch:", e);
ReadRepairMetrics.repairedBackground.mark();
ReadCommand readCommand = (ReadCommand) command;
final RowDataResolver repairResolver = new RowDataResolver(readCommand.ksName, readCommand.key, readCommand.filter(), readCommand.timestamp);
AsyncRepairCallback repairHandler = new AsyncRepairCallback(repairResolver, endpoints.size());
MessageOut<ReadCommand> message = ((ReadCommand) command).createMessage();
for (InetAddress endpoint : endpoints)
MessagingService.instance().sendRR(message, endpoint, repairHandler);
}
}
}
}