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/*
* 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.hints;
import java.net.InetAddress;
import java.util.UUID;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.db.partitions.PartitionUpdate;
import org.apache.cassandra.net.IVerbHandler;
import org.apache.cassandra.net.MessageIn;
import org.apache.cassandra.net.MessagingService;
import org.apache.cassandra.serializers.MarshalException;
import org.apache.cassandra.service.StorageProxy;
import org.apache.cassandra.service.StorageService;
/**
* Verb handler used both for hint dispatch and streaming.
*
* With the non-sstable format, we cannot just stream hint sstables on node decommission. So sometimes, at decommission
* time, we might have to stream hints to a non-owning host (say, if the owning host B is down during decommission of host A).
* In that case the handler just stores the received hint in its local hint store.
*/
public final class HintVerbHandler implements IVerbHandler
{
private static final Logger logger = LoggerFactory.getLogger(HintVerbHandler.class);
public void doVerb(MessageIn message, int id)
{
UUID hostId = message.payload.hostId;
Hint hint = message.payload.hint;
InetAddress address = StorageService.instance.getEndpointForHostId(hostId);
// If we see an unknown table id, it means the table, or one of the tables in the mutation, had been dropped.
// In that case there is nothing we can really do, or should do, other than log it go on.
// This will *not* happen due to a not-yet-seen table, because we don't transfer hints unless there
// is schema agreement between the sender and the receiver.
if (hint == null)
{
logger.trace("Failed to decode and apply a hint for {}: {} - table with id {} is unknown",
address,
hostId,
message.payload.unknownTableID);
reply(id, message.from);
return;
}
// We must perform validation before applying the hint, and there is no other place to do it other than here.
try
{
hint.mutation.getPartitionUpdates().forEach(PartitionUpdate::validate);
}
catch (MarshalException e)
{
logger.warn("Failed to validate a hint for {}: {} - skipped", address, hostId);
reply(id, message.from);
return;
}
if (!hostId.equals(StorageService.instance.getLocalHostUUID()))
{
// the node is not the final destination of the hint (must have gotten it from a decommissioning node),
// so just store it locally, to be delivered later.
HintsService.instance.write(hostId, hint);
reply(id, message.from);
}
else if (!StorageProxy.instance.appliesLocally(hint.mutation))
{
// the topology has changed, and we are no longer a replica of the mutation - since we don't know which node(s)
// it has been handed over to, re-address the hint to all replicas; see CASSANDRA-5902.
HintsService.instance.writeForAllReplicas(hint);
reply(id, message.from);
}
else
{
// the common path - the node is both the destination and a valid replica for the hint.
hint.applyFuture().thenAccept(o -> reply(id, message.from)).exceptionally(e -> {logger.debug("Failed to apply hint", e); return null;});
}
}
private static void reply(int id, InetAddress to)
{
MessagingService.instance().sendReply(HintResponse.message, id, to);
}
}