src/main/java/org/apache/cassandra/distributed/shared/AbstractBuilder.java - cassandra-in-jvm-dtest-api - Git at Google

 /*
  * 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.distributed.shared;

 import org.apache.cassandra.distributed.api.*;

 import java.io.File;
 import java.io.IOException;
 import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;

 import static org.apache.cassandra.distributed.api.TokenSupplier.evenlyDistributedTokens;

 public abstract class AbstractBuilder<I extends IInstance, C extends ICluster, B extends AbstractBuilder<I, C, B>>
 {
     private enum VNodeState
     { SUPPORT_ALL, ONLY_SINGLE_TOKEN, ONLY_VNODE }
     public interface Factory<I extends IInstance, C extends ICluster, B extends AbstractBuilder<I, C, B>>
     {
         C newCluster(B builder);
     }

     private final Factory<I, C, B> factory;
     private int nodeCount;
     private int subnet;
     private Map<Integer, NetworkTopology.DcAndRack> nodeIdTopology;
     private TokenSupplier tokenSupplier;
     private Path rootPath;
     private File rootFile;
     private Versions.Version version;
     private Consumer<IInstanceConfig> configUpdater;
     private ClassLoader sharedClassLoader = Thread.currentThread().getContextClassLoader();
     private Predicate<String> sharedClasses = InstanceClassLoader.getDefaultLoadSharedFilter();
     private int broadcastPort = 7012;
     private IInstanceInitializer instanceInitializer = (cl, tg, num, gen) -> {};
     private IClassTransformer classTransformer;
     private int datadirCount = 3;
     private final List<Rack> racks = new ArrayList<>();
     private boolean finalised;
     private int tokenCount = getDefaultTokenCount();
     private VNodeState vnodeState = VNodeState.SUPPORT_ALL;

     protected int getDefaultTokenCount() {
         String key = "cassandra.dtest.num_tokens";
         String value = System.getProperty(key);
         if (value == null)
             value = System.getenv(key.replace(".", "_").toUpperCase());
         return value == null ? 1 : Integer.parseInt(value);
     }

     public AbstractBuilder(Factory<I, C, B> factory)
     {
         this.factory = factory;
     }

     public int getNodeCount() {
         return nodeCount;
     }

     public int getSubnet() {
         return subnet;
     }

     public Map<Integer, NetworkTopology.DcAndRack> getNodeIdTopology() {
         return nodeIdTopology;
     }

     public TokenSupplier getTokenSupplier() {
         return tokenSupplier;
     }

     public File getRoot() {
         return rootFile != null ? rootFile : rootPath.toFile();
     }

     public Path getRootPath() {
         return rootPath != null ? rootPath : rootFile.toPath();
     }

     public Versions.Version getVersion() {
         return version;
     }

     public Consumer<IInstanceConfig> getConfigUpdater() {
         return configUpdater;
     }

     public ClassLoader getSharedClassLoader() {
         return sharedClassLoader;
     }

     public Predicate<String> getSharedClasses() {
         return sharedClasses;
     }

     public int getBroadcastPort() {
         return broadcastPort;
     }

     @Deprecated
     public BiConsumer<ClassLoader, Integer> getInstanceInitializer()
     {
         return instanceInitializer::initialise;
     }

     public IInstanceInitializer getInstanceInitializer2()
     {
         return instanceInitializer;
     }

     public IClassTransformer getClassTransformer()
     {
         return classTransformer;
     }

     public int getDatadirCount()
     {
         return datadirCount;
     }

     public int getTokenCount() {
         return tokenCount;
     }

     public boolean isVNodeAllowed() {
         return vnodeState != VNodeState.ONLY_SINGLE_TOKEN;
     }

     public boolean isSingleTokenAllowed()
     {
         return vnodeState != VNodeState.ONLY_VNODE;
     }

     public C start() throws IOException
     {
         C cluster = createWithoutStarting();
         cluster.startup();
         return cluster;
     }

     public C createWithoutStarting() throws IOException
     {
         finaliseBuilder();
         if (rootFile == null && rootPath == null)
             rootPath = Files.createTempDirectory("dtests");

         if (rootFile != null) rootFile.mkdirs();
         else try { Files.createDirectories(rootPath); } catch (FileAlreadyExistsException ignore) { }

         // TODO: make token allocation strategy configurable
         if (tokenSupplier == null)
             tokenSupplier = evenlyDistributedTokens(nodeCount, tokenCount);

         return factory.newCluster((B) this);
     }

     public B withSharedClassLoader(ClassLoader sharedClassLoader)
     {
         this.sharedClassLoader = Objects.requireNonNull(sharedClassLoader, "sharedClassLoader");
         return (B) this;
     }

     public B withSharedClasses(Predicate<String> sharedClasses)
     {
         this.sharedClasses = Objects.requireNonNull(sharedClasses, "sharedClasses");
         return (B) this;
     }

     public B withBroadcastPort(int broadcastPort) {
         this.broadcastPort = broadcastPort;
         return (B) this;
     }

     public B withTokenSupplier(TokenSupplier tokenSupplier)
     {
         this.tokenSupplier = tokenSupplier;
         return (B) this;
     }

     @Deprecated
     public B withTokenSupplier(SingleTokenSupplier tokenSupplier)
     {
         this.tokenSupplier = tokenSupplier;
         return (B) this;
     }

     /**
      * This class is for source backwards compatability
      */
     @Deprecated
     public interface SingleTokenSupplier extends TokenSupplier
     {
         @Override
         default Collection<String> tokens(int nodeId)
         {
             return Collections.singletonList(Long.toString(token(nodeId)));
         }

         @Override
         long token(int nodeId);
     }

     public B withSubnet(int subnet)
     {
         this.subnet = subnet;
         return (B) this;
     }

     /**
      * Start this many nodes initially
      *
      * Note that when using this in combination with withNodeIdTopology or withRacks/withDCs/... we
      * might reduce the actual number of nodes if there are not enough nodes configured in the node id
      * topology. For tests where additional nodes are started after the initial ones, it is ok to have
      * nodeCount < node id topology size
      */
     public B withNodes(int nodeCount)
     {
         this.nodeCount = nodeCount;
         return (B) this;
     }

     /**
      * Adds dcCount datacenters, splits the nodeCount over these dcs
      */
     public B withDCs(int dcCount)
     {
         return withRacks(dcCount, 1);
     }

     /**
      * Adds this many racks per datacenter
      *
      * splits nodeCount over these racks/dcs
      *
      */
     public B withRacks(int dcCount, int racksPerDC)
     {
         assert dcCount > 0 && racksPerDC > 0 : "Both dcCount and racksPerDC must be > 0";

         for (int dc = 1; dc <= dcCount; dc++)
             for (int rack = 1; rack <= racksPerDC; rack++)
                 withRack(dcName(dc), rackName(rack), -1);
         return (B) this;
     }

     /**
      * Creates a cluster with dcCount datacenters, racksPerDC racks in each dc and nodesPerRack nodes in each rack
      *
      * Note that node count must be >= dcCount * datacenters * racksPerDC, if it is smaller it will get adjusted up.
      */
     public B withRacks(int dcCount, int racksPerDC, int nodesPerRack)
     {
         assert dcCount > 0 && racksPerDC > 0 && nodesPerRack > 0 : "dcCount, racksPerDC and nodesPerRack must be > 0";
         for (int dc = 1; dc <= dcCount; dc++)
             for (int rack = 1; rack <= racksPerDC; rack++)
                 withRack(dcName(dc), rackName(rack), nodesPerRack);
         return (B) this;
     }

     /**
      * Add a dc with name dcName containing a single rack with nodeCount nodes
      */
     public B withDC(String dcName, int nodeCount)
     {
         return withRack(dcName, rackName(1), nodeCount);
     }

     /**
      * Add a rack in dcName with name rackName containing nodesInRack nodes
      */
     public B withRack(String dcName, String rackName, int nodesInRack)
     {
         racks.add(new Rack(dcName, rackName, nodesInRack));
         return (B) this;
     }

     // Map of node ids to dc and rack - must be contiguous with an entry nodeId 1 to nodeCount
     public B withNodeIdTopology(Map<Integer, NetworkTopology.DcAndRack> nodeIdTopology)
     {
         if (nodeIdTopology.isEmpty())
             throw new IllegalStateException("Topology is empty. It must have an entry for every nodeId.");

         IntStream.rangeClosed(1, nodeIdTopology.size()).forEach(nodeId -> {
             if (nodeIdTopology.get(nodeId) == null)
                 throw new IllegalStateException("Topology is missing entry for nodeId " + nodeId);
         });

         this.nodeIdTopology = new HashMap<>(nodeIdTopology);

         return (B) this;
     }

     public B withRoot(File root)
     {
         this.rootFile = root;
         return (B) this;
     }

     public B withRoot(Path root)
     {
         this.rootPath = root;
         return (B) this;
     }

     public B withVersion(Versions.Version version)
     {
         this.version = version;
         return (B) this;
     }

     public B withConfig(Consumer<IInstanceConfig> updater)
     {
         this.configUpdater = updater;
         return (B) this;
     }

     public B appendConfig(Consumer<IInstanceConfig> updater)
     {
         Consumer<IInstanceConfig> prev = configUpdater;
         Consumer<IInstanceConfig> next = prev == null ? updater : config -> { prev.accept(config); updater.accept(config); };
         this.configUpdater = next;
         return (B) this;
     }

     public B withInstanceInitializer(BiConsumer<ClassLoader, Integer> instanceInitializer)
     {
         this.instanceInitializer = new IInstanceInitializer() {
             @Override
             public void initialise(ClassLoader classLoader, ThreadGroup threadGroup, int num, int generation) {
                 instanceInitializer.accept(classLoader, num);
             }

             @Override
             public void initialise(ClassLoader classLoader, int num) {
                 instanceInitializer.accept(classLoader, num);
             }
         };
         return (B) this;
     }

     public B withInstanceInitializer(IInstanceInitializer instanceInitializer)
     {
         this.instanceInitializer = instanceInitializer;
         return (B) this;
     }

     public B withClassTransformer(IClassTransformer classTransformer)
     {
         this.classTransformer = classTransformer;
         return (B) this;
     }

     public B withDataDirCount(int datadirCount)
     {
         assert datadirCount > 0 : "data dir count requires a positive number but given " + datadirCount;
         this.datadirCount = datadirCount;
         return (B) this;
     }

     public B withTokenCount(int tokenCount)
     {
         assert tokenCount > 0 : "Token count must be positive; given " + tokenCount;
         this.tokenCount = tokenCount;
         return (B) this;
     }

     public B withVNodes()
     {
         vnodeState = VNodeState.ONLY_VNODE;
         return (B) this;
     }

     public B withoutVNodes()
     {
         vnodeState = VNodeState.ONLY_SINGLE_TOKEN;
         return (B) this;
     }

     private void finaliseBuilder()
     {
         if (finalised)
             return;
         finalised = true;

         boolean log = logTopology();
         if (!racks.isEmpty())
         {
             setRacks();
         }
         else if (nodeIdTopology != null)
         {
             if (nodeIdTopology.size() < nodeCount)
             {
                 if (log) System.out.println("Adjusting node count since nodeIdTopology contains fewer nodes");
                 nodeCount = nodeIdTopology.size();
             }
             else if (nodeIdTopology.size() > nodeCount)
             {
                 if (nodeCount == 0)
                     nodeCount = nodeIdTopology.size();
                 else
                 if (log) System.out.printf("nodeIdTopology configured for %d nodes while nodeCount is %d%n", nodeIdTopology.size(), nodeCount);
             }
         }
         else
         {
             nodeIdTopology = IntStream.rangeClosed(1, nodeCount).boxed()
                                       .collect(Collectors.toMap(nodeId -> nodeId,
                                                                 nodeId -> NetworkTopology.dcAndRack(dcName(0), rackName(0))));
         }

         if (nodeCount <= 0)
             throw new IllegalStateException("Cluster must have at least one node");

         if (log) System.out.println("Node id topology:");
         for (int i = 1; i <= nodeIdTopology.size(); i++)
         {
             NetworkTopology.DcAndRack dcAndRack = nodeIdTopology.get(i);
             if (log) System.out.printf("node %d: dc = %s, rack = %s%n", i, dcAndRack.dc, dcAndRack.rack);
         }
         if (log) System.out.printf("Configured node count: %d, nodeIdTopology size: %d%n", nodeCount, nodeIdTopology.size());
     }

     private void setRacks()
     {
         if (nodeIdTopology == null)
             nodeIdTopology = new HashMap<>();

         boolean shouldCalculatePerRackCount = false;
         boolean hasExplicitPerRackCount = false;
         for (Rack rack : racks)
         {
             if (rack.rackNodeCount == -1)
                 shouldCalculatePerRackCount = true;
             else
                 hasExplicitPerRackCount = true;
         }

         if (shouldCalculatePerRackCount && hasExplicitPerRackCount)
             throw new IllegalStateException("Can't mix explicit and implicit per rack counts");

         int nodeId = nodeIdTopology.isEmpty() ? 1 : Collections.max(nodeIdTopology.keySet()) + 1;
         if (shouldCalculatePerRackCount)
         {
             if (nodeCount == 0)
                 throw new IllegalStateException("Node count must be set when not setting per rack counts");
             int totalRacks = racks.size();
             int nodesPerRack = (nodeCount + totalRacks - 1) / totalRacks;

             for (Rack rack : racks)
                 for (int i = 1; i <= nodesPerRack; i++)
                     nodeIdTopology.put(nodeId++, NetworkTopology.dcAndRack(rack.dcName, rack.rackName));
         }
         else
         {
             for (Rack rack : racks)
                 for (int i = 1; i <= rack.rackNodeCount; i++)
                     nodeIdTopology.put(nodeId++, NetworkTopology.dcAndRack(rack.dcName, rack.rackName));
         }

         if (nodeCount != nodeIdTopology.size())
         {
             assert nodeIdTopology.size() > nodeCount : "withRacks should only ever increase the node count";
             if (nodeCount == 0)
                 nodeCount =  nodeIdTopology.size();
             else if (logTopology())
                 System.out.printf("Network topology of %s requires more nodes, only starting %s out of %s configured nodes%n", nodeIdTopology, nodeCount, nodeIdTopology.size());
         }
     }

     static String dcName(int index)
     {
         return "datacenter" + index;
     }

     static String rackName(int index)
     {
         return "rack" + index;
     }

     private static class Rack
     {
         final String dcName;
         final String rackName;
         final int rackNodeCount;

         private Rack(String dcName, String rackName, int rackNodeCount)
         {
             this.dcName = dcName;
             this.rackName = rackName;
             this.rackNodeCount = rackNodeCount;
         }
     }

     private static boolean logTopology()
     {
         return !System.getProperty("cassandra.dtest.api.log.topology", "").equals("false");
     }
 }
	/*
	* 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.distributed.shared;

	import org.apache.cassandra.distributed.api.*;

	import java.io.File;
	import java.io.IOException;
	import java.nio.file.FileAlreadyExistsException;
	import java.nio.file.Files;
	import java.nio.file.Path;
	import java.util.ArrayList;
	import java.util.Collection;
	import java.util.Collections;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.Objects;
	import java.util.function.BiConsumer;
	import java.util.function.Consumer;
	import java.util.function.Predicate;
	import java.util.stream.Collectors;
	import java.util.stream.IntStream;

	import static org.apache.cassandra.distributed.api.TokenSupplier.evenlyDistributedTokens;

	public abstract class AbstractBuilder<I extends IInstance, C extends ICluster, B extends AbstractBuilder<I, C, B>>
	{
	private enum VNodeState
	{ SUPPORT_ALL, ONLY_SINGLE_TOKEN, ONLY_VNODE }
	public interface Factory<I extends IInstance, C extends ICluster, B extends AbstractBuilder<I, C, B>>
	{
	C newCluster(B builder);
	}

	private final Factory<I, C, B> factory;
	private int nodeCount;
	private int subnet;
	private Map<Integer, NetworkTopology.DcAndRack> nodeIdTopology;
	private TokenSupplier tokenSupplier;
	private Path rootPath;
	private File rootFile;
	private Versions.Version version;
	private Consumer<IInstanceConfig> configUpdater;
	private ClassLoader sharedClassLoader = Thread.currentThread().getContextClassLoader();
	private Predicate<String> sharedClasses = InstanceClassLoader.getDefaultLoadSharedFilter();
	private int broadcastPort = 7012;
	private IInstanceInitializer instanceInitializer = (cl, tg, num, gen) -> {};
	private IClassTransformer classTransformer;
	private int datadirCount = 3;
	private final List<Rack> racks = new ArrayList<>();
	private boolean finalised;
	private int tokenCount = getDefaultTokenCount();
	private VNodeState vnodeState = VNodeState.SUPPORT_ALL;

	protected int getDefaultTokenCount() {
	String key = "cassandra.dtest.num_tokens";
	String value = System.getProperty(key);
	if (value == null)
	value = System.getenv(key.replace(".", "_").toUpperCase());
	return value == null ? 1 : Integer.parseInt(value);
	}

	public AbstractBuilder(Factory<I, C, B> factory)
	{
	this.factory = factory;
	}

	public int getNodeCount() {
	return nodeCount;
	}

	public int getSubnet() {
	return subnet;
	}

	public Map<Integer, NetworkTopology.DcAndRack> getNodeIdTopology() {
	return nodeIdTopology;
	}

	public TokenSupplier getTokenSupplier() {
	return tokenSupplier;
	}

	public File getRoot() {
	return rootFile != null ? rootFile : rootPath.toFile();
	}

	public Path getRootPath() {
	return rootPath != null ? rootPath : rootFile.toPath();
	}

	public Versions.Version getVersion() {
	return version;
	}

	public Consumer<IInstanceConfig> getConfigUpdater() {
	return configUpdater;
	}

	public ClassLoader getSharedClassLoader() {
	return sharedClassLoader;
	}

	public Predicate<String> getSharedClasses() {
	return sharedClasses;
	}

	public int getBroadcastPort() {
	return broadcastPort;
	}

	@Deprecated
	public BiConsumer<ClassLoader, Integer> getInstanceInitializer()
	{
	return instanceInitializer::initialise;
	}

	public IInstanceInitializer getInstanceInitializer2()
	{
	return instanceInitializer;
	}

	public IClassTransformer getClassTransformer()
	{
	return classTransformer;
	}

	public int getDatadirCount()
	{
	return datadirCount;
	}

	public int getTokenCount() {
	return tokenCount;
	}

	public boolean isVNodeAllowed() {
	return vnodeState != VNodeState.ONLY_SINGLE_TOKEN;
	}

	public boolean isSingleTokenAllowed()
	{
	return vnodeState != VNodeState.ONLY_VNODE;
	}

	public C start() throws IOException
	{
	C cluster = createWithoutStarting();
	cluster.startup();
	return cluster;
	}

	public C createWithoutStarting() throws IOException
	{
	finaliseBuilder();
	if (rootFile == null && rootPath == null)
	rootPath = Files.createTempDirectory("dtests");

	if (rootFile != null) rootFile.mkdirs();
	else try { Files.createDirectories(rootPath); } catch (FileAlreadyExistsException ignore) { }

	// TODO: make token allocation strategy configurable
	if (tokenSupplier == null)
	tokenSupplier = evenlyDistributedTokens(nodeCount, tokenCount);

	return factory.newCluster((B) this);
	}

	public B withSharedClassLoader(ClassLoader sharedClassLoader)
	{
	this.sharedClassLoader = Objects.requireNonNull(sharedClassLoader, "sharedClassLoader");
	return (B) this;
	}

	public B withSharedClasses(Predicate<String> sharedClasses)
	{
	this.sharedClasses = Objects.requireNonNull(sharedClasses, "sharedClasses");
	return (B) this;
	}

	public B withBroadcastPort(int broadcastPort) {
	this.broadcastPort = broadcastPort;
	return (B) this;
	}

	public B withTokenSupplier(TokenSupplier tokenSupplier)
	{
	this.tokenSupplier = tokenSupplier;
	return (B) this;
	}

	@Deprecated
	public B withTokenSupplier(SingleTokenSupplier tokenSupplier)
	{
	this.tokenSupplier = tokenSupplier;
	return (B) this;
	}

	/**
	* This class is for source backwards compatability
	*/
	@Deprecated
	public interface SingleTokenSupplier extends TokenSupplier
	{
	@Override
	default Collection<String> tokens(int nodeId)
	{
	return Collections.singletonList(Long.toString(token(nodeId)));
	}

	@Override
	long token(int nodeId);
	}

	public B withSubnet(int subnet)
	{
	this.subnet = subnet;
	return (B) this;
	}

	/**
	* Start this many nodes initially
	*
	* Note that when using this in combination with withNodeIdTopology or withRacks/withDCs/... we
	* might reduce the actual number of nodes if there are not enough nodes configured in the node id
	* topology. For tests where additional nodes are started after the initial ones, it is ok to have
	* nodeCount < node id topology size
	*/
	public B withNodes(int nodeCount)
	{
	this.nodeCount = nodeCount;
	return (B) this;
	}

	/**
	* Adds dcCount datacenters, splits the nodeCount over these dcs
	*/
	public B withDCs(int dcCount)
	{
	return withRacks(dcCount, 1);
	}

	/**
	* Adds this many racks per datacenter
	*
	* splits nodeCount over these racks/dcs
	*
	*/
	public B withRacks(int dcCount, int racksPerDC)
	{
	assert dcCount > 0 && racksPerDC > 0 : "Both dcCount and racksPerDC must be > 0";

	for (int dc = 1; dc <= dcCount; dc++)
	for (int rack = 1; rack <= racksPerDC; rack++)
	withRack(dcName(dc), rackName(rack), -1);
	return (B) this;
	}

	/**
	* Creates a cluster with dcCount datacenters, racksPerDC racks in each dc and nodesPerRack nodes in each rack
	*
	* Note that node count must be >= dcCount * datacenters * racksPerDC, if it is smaller it will get adjusted up.
	*/
	public B withRacks(int dcCount, int racksPerDC, int nodesPerRack)
	{
	assert dcCount > 0 && racksPerDC > 0 && nodesPerRack > 0 : "dcCount, racksPerDC and nodesPerRack must be > 0";
	for (int dc = 1; dc <= dcCount; dc++)
	for (int rack = 1; rack <= racksPerDC; rack++)
	withRack(dcName(dc), rackName(rack), nodesPerRack);
	return (B) this;
	}

	/**
	* Add a dc with name dcName containing a single rack with nodeCount nodes
	*/
	public B withDC(String dcName, int nodeCount)
	{
	return withRack(dcName, rackName(1), nodeCount);
	}

	/**
	* Add a rack in dcName with name rackName containing nodesInRack nodes
	*/
	public B withRack(String dcName, String rackName, int nodesInRack)
	{
	racks.add(new Rack(dcName, rackName, nodesInRack));
	return (B) this;
	}

	// Map of node ids to dc and rack - must be contiguous with an entry nodeId 1 to nodeCount
	public B withNodeIdTopology(Map<Integer, NetworkTopology.DcAndRack> nodeIdTopology)
	{
	if (nodeIdTopology.isEmpty())
	throw new IllegalStateException("Topology is empty. It must have an entry for every nodeId.");

	IntStream.rangeClosed(1, nodeIdTopology.size()).forEach(nodeId -> {
	if (nodeIdTopology.get(nodeId) == null)
	throw new IllegalStateException("Topology is missing entry for nodeId " + nodeId);
	});

	this.nodeIdTopology = new HashMap<>(nodeIdTopology);

	return (B) this;
	}

	public B withRoot(File root)
	{
	this.rootFile = root;
	return (B) this;
	}

	public B withRoot(Path root)
	{
	this.rootPath = root;
	return (B) this;
	}

	public B withVersion(Versions.Version version)
	{
	this.version = version;
	return (B) this;
	}

	public B withConfig(Consumer<IInstanceConfig> updater)
	{
	this.configUpdater = updater;
	return (B) this;
	}

	public B appendConfig(Consumer<IInstanceConfig> updater)
	{
	Consumer<IInstanceConfig> prev = configUpdater;
	Consumer<IInstanceConfig> next = prev == null ? updater : config -> { prev.accept(config); updater.accept(config); };
	this.configUpdater = next;
	return (B) this;
	}

	public B withInstanceInitializer(BiConsumer<ClassLoader, Integer> instanceInitializer)
	{
	this.instanceInitializer = new IInstanceInitializer() {
	@Override
	public void initialise(ClassLoader classLoader, ThreadGroup threadGroup, int num, int generation) {
	instanceInitializer.accept(classLoader, num);
	}

	@Override
	public void initialise(ClassLoader classLoader, int num) {
	instanceInitializer.accept(classLoader, num);
	}
	};
	return (B) this;
	}

	public B withInstanceInitializer(IInstanceInitializer instanceInitializer)
	{
	this.instanceInitializer = instanceInitializer;
	return (B) this;
	}

	public B withClassTransformer(IClassTransformer classTransformer)
	{
	this.classTransformer = classTransformer;
	return (B) this;
	}

	public B withDataDirCount(int datadirCount)
	{
	assert datadirCount > 0 : "data dir count requires a positive number but given " + datadirCount;
	this.datadirCount = datadirCount;
	return (B) this;
	}

	public B withTokenCount(int tokenCount)
	{
	assert tokenCount > 0 : "Token count must be positive; given " + tokenCount;
	this.tokenCount = tokenCount;
	return (B) this;
	}

	public B withVNodes()
	{
	vnodeState = VNodeState.ONLY_VNODE;
	return (B) this;
	}

	public B withoutVNodes()
	{
	vnodeState = VNodeState.ONLY_SINGLE_TOKEN;
	return (B) this;
	}

	private void finaliseBuilder()
	{
	if (finalised)
	return;
	finalised = true;

	boolean log = logTopology();
	if (!racks.isEmpty())
	{
	setRacks();
	}
	else if (nodeIdTopology != null)
	{
	if (nodeIdTopology.size() < nodeCount)
	{
	if (log) System.out.println("Adjusting node count since nodeIdTopology contains fewer nodes");
	nodeCount = nodeIdTopology.size();
	}
	else if (nodeIdTopology.size() > nodeCount)
	{
	if (nodeCount == 0)
	nodeCount = nodeIdTopology.size();
	else
	if (log) System.out.printf("nodeIdTopology configured for %d nodes while nodeCount is %d%n", nodeIdTopology.size(), nodeCount);
	}
	}
	else
	{
	nodeIdTopology = IntStream.rangeClosed(1, nodeCount).boxed()
	.collect(Collectors.toMap(nodeId -> nodeId,
	nodeId -> NetworkTopology.dcAndRack(dcName(0), rackName(0))));
	}

	if (nodeCount <= 0)
	throw new IllegalStateException("Cluster must have at least one node");

	if (log) System.out.println("Node id topology:");
	for (int i = 1; i <= nodeIdTopology.size(); i++)
	{
	NetworkTopology.DcAndRack dcAndRack = nodeIdTopology.get(i);
	if (log) System.out.printf("node %d: dc = %s, rack = %s%n", i, dcAndRack.dc, dcAndRack.rack);
	}
	if (log) System.out.printf("Configured node count: %d, nodeIdTopology size: %d%n", nodeCount, nodeIdTopology.size());
	}

	private void setRacks()
	{
	if (nodeIdTopology == null)
	nodeIdTopology = new HashMap<>();

	boolean shouldCalculatePerRackCount = false;
	boolean hasExplicitPerRackCount = false;
	for (Rack rack : racks)
	{
	if (rack.rackNodeCount == -1)
	shouldCalculatePerRackCount = true;
	else
	hasExplicitPerRackCount = true;
	}

	if (shouldCalculatePerRackCount && hasExplicitPerRackCount)
	throw new IllegalStateException("Can't mix explicit and implicit per rack counts");

	int nodeId = nodeIdTopology.isEmpty() ? 1 : Collections.max(nodeIdTopology.keySet()) + 1;
	if (shouldCalculatePerRackCount)
	{
	if (nodeCount == 0)
	throw new IllegalStateException("Node count must be set when not setting per rack counts");
	int totalRacks = racks.size();
	int nodesPerRack = (nodeCount + totalRacks - 1) / totalRacks;

	for (Rack rack : racks)
	for (int i = 1; i <= nodesPerRack; i++)
	nodeIdTopology.put(nodeId++, NetworkTopology.dcAndRack(rack.dcName, rack.rackName));
	}
	else
	{
	for (Rack rack : racks)
	for (int i = 1; i <= rack.rackNodeCount; i++)
	nodeIdTopology.put(nodeId++, NetworkTopology.dcAndRack(rack.dcName, rack.rackName));
	}

	if (nodeCount != nodeIdTopology.size())
	{
	assert nodeIdTopology.size() > nodeCount : "withRacks should only ever increase the node count";
	if (nodeCount == 0)
	nodeCount = nodeIdTopology.size();
	else if (logTopology())
	System.out.printf("Network topology of %s requires more nodes, only starting %s out of %s configured nodes%n", nodeIdTopology, nodeCount, nodeIdTopology.size());
	}
	}

	static String dcName(int index)
	{
	return "datacenter" + index;
	}

	static String rackName(int index)
	{
	return "rack" + index;
	}

	private static class Rack
	{
	final String dcName;
	final String rackName;
	final int rackNodeCount;

	private Rack(String dcName, String rackName, int rackNodeCount)
	{
	this.dcName = dcName;
	this.rackName = rackName;
	this.rackNodeCount = rackNodeCount;
	}
	}

	private static boolean logTopology()
	{
	return !System.getProperty("cassandra.dtest.api.log.topology", "").equals("false");
	}
	}