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The Apache Cassandra Project develops a highly scalable second-generation distributed database, bringing together Dynamo's fully distributed design and Bigtable's ColumnFamily-based data model.
/*
* 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.locator;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.net.InetAddress;
import java.util.*;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.atomic.AtomicReference;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.Multimap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.db.ConsistencyLevel;
import org.apache.cassandra.db.Keyspace;
import org.apache.cassandra.db.WriteType;
import org.apache.cassandra.dht.Range;
import org.apache.cassandra.dht.RingPosition;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.service.AbstractWriteResponseHandler;
import org.apache.cassandra.service.DatacenterSyncWriteResponseHandler;
import org.apache.cassandra.service.DatacenterWriteResponseHandler;
import org.apache.cassandra.service.WriteResponseHandler;
import org.apache.cassandra.utils.FBUtilities;
import org.cliffc.high_scale_lib.NonBlockingHashMap;
/**
* A abstract parent for all replication strategies.
*/
public abstract class AbstractReplicationStrategy
{
private static final Logger logger = LoggerFactory.getLogger(AbstractReplicationStrategy.class);
@VisibleForTesting
final String keyspaceName;
private Keyspace keyspace;
public final Map configOptions;
private final TokenMetadata tokenMetadata;
private final ReplicaCache> replicas = new ReplicaCache<>();
public IEndpointSnitch snitch;
protected AbstractReplicationStrategy(String keyspaceName, TokenMetadata tokenMetadata, IEndpointSnitch snitch, Map configOptions)
{
assert keyspaceName != null;
assert snitch != null;
assert tokenMetadata != null;
this.tokenMetadata = tokenMetadata;
this.snitch = snitch;
this.configOptions = configOptions == null ? Collections.emptyMap() : configOptions;
this.keyspaceName = keyspaceName;
// lazy-initialize keyspace itself since we don't create them until after the replication strategies
}
private ArrayList getCachedEndpoints(long ringVersion, Token t)
{
return replicas.get(ringVersion, t);
}
/**
* get the (possibly cached) endpoints that should store the given Token.
* Note that while the endpoints are conceptually a Set (no duplicates will be included),
* we return a List to avoid an extra allocation when sorting by proximity later
* @param searchPosition the position the natural endpoints are requested for
* @return a copy of the natural endpoints for the given token
*/
public ArrayList getNaturalEndpoints(RingPosition searchPosition)
{
Token searchToken = searchPosition.getToken();
long currentRingVersion = tokenMetadata.getRingVersion();
Token keyToken = TokenMetadata.firstToken(tokenMetadata.sortedTokens(), searchToken);
ArrayList endpoints = getCachedEndpoints(currentRingVersion, keyToken);
if (endpoints == null)
{
TokenMetadata tm = tokenMetadata.cachedOnlyTokenMap();
// if our cache got invalidated, it's possible there is a new token to account for too
keyToken = TokenMetadata.firstToken(tm.sortedTokens(), searchToken);
endpoints = new ArrayList(calculateNaturalEndpoints(searchToken, tm));
replicas.put(tm.getRingVersion(), keyToken, endpoints);
}
return new ArrayList<>(endpoints);
}
/**
* calculate the natural endpoints for the given token
*
* @see #getNaturalEndpoints(org.apache.cassandra.dht.RingPosition)
*
* @param searchToken the token the natural endpoints are requested for
* @return a copy of the natural endpoints for the given token
*/
public abstract List calculateNaturalEndpoints(Token searchToken, TokenMetadata tokenMetadata);
public AbstractWriteResponseHandler getWriteResponseHandler(Collection naturalEndpoints,
Collection pendingEndpoints,
ConsistencyLevel consistency_level,
Runnable callback,
WriteType writeType,
long queryStartNanoTime)
{
if (consistency_level.isDatacenterLocal())
{
// block for in this context will be localnodes block.
return new DatacenterWriteResponseHandler(naturalEndpoints, pendingEndpoints, consistency_level, getKeyspace(), callback, writeType, queryStartNanoTime);
}
else if (consistency_level == ConsistencyLevel.EACH_QUORUM && (this instanceof NetworkTopologyStrategy))
{
return new DatacenterSyncWriteResponseHandler(naturalEndpoints, pendingEndpoints, consistency_level, getKeyspace(), callback, writeType, queryStartNanoTime);
}
return new WriteResponseHandler(naturalEndpoints, pendingEndpoints, consistency_level, getKeyspace(), callback, writeType, queryStartNanoTime);
}
private Keyspace getKeyspace()
{
if (keyspace == null)
keyspace = Keyspace.open(keyspaceName);
return keyspace;
}
/**
* calculate the RF based on strategy_options. When overwriting, ensure that this get()
* is FAST, as this is called often.
*
* @return the replication factor
*/
public abstract int getReplicationFactor();
/*
* NOTE: this is pretty inefficient. also the inverse (getRangeAddresses) below.
* this is fine as long as we don't use this on any critical path.
* (fixing this would probably require merging tokenmetadata into replicationstrategy,
* so we could cache/invalidate cleanly.)
*/
public Multimap> getAddressRanges(TokenMetadata metadata)
{
Multimap> map = HashMultimap.create();
for (Token token : metadata.sortedTokens())
{
Range range = metadata.getPrimaryRangeFor(token);
for (InetAddress ep : calculateNaturalEndpoints(token, metadata))
{
map.put(ep, range);
}
}
return map;
}
public Multimap, InetAddress> getRangeAddresses(TokenMetadata metadata)
{
Multimap, InetAddress> map = HashMultimap.create();
for (Token token : metadata.sortedTokens())
{
Range range = metadata.getPrimaryRangeFor(token);
for (InetAddress ep : calculateNaturalEndpoints(token, metadata))
{
map.put(range, ep);
}
}
return map;
}
public Multimap> getAddressRanges()
{
return getAddressRanges(tokenMetadata.cloneOnlyTokenMap());
}
public Collection> getPendingAddressRanges(TokenMetadata metadata, Token pendingToken, InetAddress pendingAddress)
{
return getPendingAddressRanges(metadata, Arrays.asList(pendingToken), pendingAddress);
}
public Collection> getPendingAddressRanges(TokenMetadata metadata, Collection pendingTokens, InetAddress pendingAddress)
{
TokenMetadata temp = metadata.cloneOnlyTokenMap();
temp.updateNormalTokens(pendingTokens, pendingAddress);
return getAddressRanges(temp).get(pendingAddress);
}
public abstract void validateOptions() throws ConfigurationException;
public abstract void maybeWarnOnOptions();
/*
* The options recognized by the strategy.
* The empty collection means that no options are accepted, but null means
* that any option is accepted.
*/
public Collection recognizedOptions()
{
// We default to null for backward compatibility sake
return null;
}
private static AbstractReplicationStrategy createInternal(String keyspaceName,
Class strategyClass,
TokenMetadata tokenMetadata,
IEndpointSnitch snitch,
Map strategyOptions)
throws ConfigurationException
{
AbstractReplicationStrategy strategy;
Class [] parameterTypes = new Class[] {String.class, TokenMetadata.class, IEndpointSnitch.class, Map.class};
try
{
Constructor constructor = strategyClass.getConstructor(parameterTypes);
strategy = constructor.newInstance(keyspaceName, tokenMetadata, snitch, strategyOptions);
}
catch (InvocationTargetException e)
{
Throwable targetException = e.getTargetException();
throw new ConfigurationException(targetException.getMessage(), targetException);
}
catch (Exception e)
{
throw new ConfigurationException("Error constructing replication strategy class", e);
}
return strategy;
}
public static AbstractReplicationStrategy createReplicationStrategy(String keyspaceName,
Class strategyClass,
TokenMetadata tokenMetadata,
IEndpointSnitch snitch,
Map strategyOptions)
{
AbstractReplicationStrategy strategy = createInternal(keyspaceName, strategyClass, tokenMetadata, snitch, strategyOptions);
// Because we used to not properly validate unrecognized options, we only log a warning if we find one.
try
{
strategy.validateExpectedOptions();
}
catch (ConfigurationException e)
{
logger.warn("Ignoring {}", e.getMessage());
}
strategy.validateOptions();
return strategy;
}
public static void validateReplicationStrategy(String keyspaceName,
Class strategyClass,
TokenMetadata tokenMetadata,
IEndpointSnitch snitch,
Map strategyOptions) throws ConfigurationException
{
AbstractReplicationStrategy strategy = createInternal(keyspaceName, strategyClass, tokenMetadata, snitch, strategyOptions);
strategy.validateExpectedOptions();
strategy.validateOptions();
strategy.maybeWarnOnOptions();
}
public static Class getClass(String cls) throws ConfigurationException
{
String className = cls.contains(".") ? cls : "org.apache.cassandra.locator." + cls;
Class strategyClass = FBUtilities.classForName(className, "replication strategy");
if (!AbstractReplicationStrategy.class.isAssignableFrom(strategyClass))
{
throw new ConfigurationException(String.format("Specified replication strategy class (%s) is not derived from AbstractReplicationStrategy", className));
}
return strategyClass;
}
public boolean hasSameSettings(AbstractReplicationStrategy other)
{
return getClass().equals(other.getClass()) && getReplicationFactor() == other.getReplicationFactor();
}
protected void validateReplicationFactor(String rf) throws ConfigurationException
{
try
{
if (Integer.parseInt(rf) < 0)
{
throw new ConfigurationException("Replication factor must be non-negative; found " + rf);
}
}
catch (NumberFormatException e2)
{
throw new ConfigurationException("Replication factor must be numeric; found " + rf);
}
}
private void validateExpectedOptions() throws ConfigurationException
{
Collection expectedOptions = recognizedOptions();
if (expectedOptions == null)
return;
for (String key : configOptions.keySet())
{
if (!expectedOptions.contains(key))
throw new ConfigurationException(String.format("Unrecognized strategy option {%s} passed to %s for keyspace %s", key, getClass().getSimpleName(), keyspaceName));
}
}
@VisibleForTesting
public static class ReplicaCache
{
private final AtomicReference> cachedReplicas = new AtomicReference<>(new ReplicaHolder<>(0, 4));
V get(long ringVersion, K keyToken)
{
ReplicaHolder replicaHolder = maybeClearAndGet(ringVersion);
if (replicaHolder == null)
return null;
return replicaHolder.replicas.get(keyToken);
}
void put(long ringVersion, K keyToken, V endpoints)
{
ReplicaHolder current = maybeClearAndGet(ringVersion);
if (current != null)
{
// if we have the same ringVersion, but already know about the keyToken the endpoints should be the same
current.replicas.putIfAbsent(keyToken, endpoints);
}
}
ReplicaHolder maybeClearAndGet(long ringVersion)
{
ReplicaHolder current = cachedReplicas.get();
if (ringVersion == current.ringVersion)
return current;
else if (ringVersion < current.ringVersion) // things have already moved on
return null;
// If ring version has changed, create a fresh replica holder and try to replace the current one.
// This may race with other threads that have the same new ring version and one will win and the loosers
// will be garbage collected
ReplicaHolder cleaned = new ReplicaHolder<>(ringVersion, current.replicas.size());
cachedReplicas.compareAndSet(current, cleaned);
// A new ring version may have come along while making the new holder, so re-check the
// reference and return the ring version if the same, otherwise return null as there is no point
// in using it.
current = cachedReplicas.get();
if (ringVersion == current.ringVersion)
return current;
else
return null;
}
}
static class ReplicaHolder
{
private final long ringVersion;
private final NonBlockingHashMap replicas;
ReplicaHolder(long ringVersion, int expectedEntries)
{
this.ringVersion = ringVersion;
this.replicas = new NonBlockingHashMap<>(expectedEntries);
}
}
}
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