src/java/org/apache/cassandra/dht/Murmur3Partitioner.java - cassandra - 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.dht;

 import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.nio.ByteBuffer;
 import java.util.*;
 import java.util.concurrent.ThreadLocalRandom;

 import org.apache.cassandra.db.DecoratedKey;
 import org.apache.cassandra.db.PreHashedDecoratedKey;
 import org.apache.cassandra.db.marshal.AbstractType;
 import org.apache.cassandra.db.marshal.PartitionerDefinedOrder;
 import org.apache.cassandra.db.marshal.LongType;
 import org.apache.cassandra.exceptions.ConfigurationException;
 import org.apache.cassandra.utils.ByteBufferUtil;
 import org.apache.cassandra.utils.MurmurHash;
 import org.apache.cassandra.utils.ObjectSizes;

 import com.google.common.primitives.Longs;

 /**
  * This class generates a BigIntegerToken using a Murmur3 hash.
  */
 public class Murmur3Partitioner implements IPartitioner
 {
     public static final LongToken MINIMUM = new LongToken(Long.MIN_VALUE);
     public static final long MAXIMUM = Long.MAX_VALUE;

     private static final int HEAP_SIZE = (int) ObjectSizes.measureDeep(MINIMUM);

     public static final Murmur3Partitioner instance = new Murmur3Partitioner();
     public static final AbstractType<?> partitionOrdering = new PartitionerDefinedOrder(instance);

     public DecoratedKey decorateKey(ByteBuffer key)
     {
         long[] hash = getHash(key);
         return new PreHashedDecoratedKey(getToken(key, hash), key, hash[0], hash[1]);
     }

     public Token midpoint(Token lToken, Token rToken)
     {
         // using BigInteger to avoid long overflow in intermediate operations
         BigInteger l = BigInteger.valueOf(((LongToken) lToken).token),
                    r = BigInteger.valueOf(((LongToken) rToken).token),
                    midpoint;

         if (l.compareTo(r) < 0)
         {
             BigInteger sum = l.add(r);
             midpoint = sum.shiftRight(1);
         }
         else // wrapping case
         {
             BigInteger max = BigInteger.valueOf(MAXIMUM);
             BigInteger min = BigInteger.valueOf(MINIMUM.token);
             // length of range we're bisecting is (R - min) + (max - L)
             // so we add that to L giving
             // L + ((R - min) + (max - L) / 2) = (L + R + max - min) / 2
             midpoint = (max.subtract(min).add(l).add(r)).shiftRight(1);
             if (midpoint.compareTo(max) > 0)
                 midpoint = min.add(midpoint.subtract(max));
         }

         return new LongToken(midpoint.longValue());
     }

     public LongToken getMinimumToken()
     {
         return MINIMUM;
     }

     public static class LongToken extends Token
     {
         static final long serialVersionUID = -5833580143318243006L;

         final long token;

         public LongToken(long token)
         {
             this.token = token;
         }

         public String toString()
         {
             return Long.toString(token);
         }

         public boolean equals(Object obj)
         {
             if (this == obj)
                 return true;
             if (obj == null || this.getClass() != obj.getClass())
                 return false;

             return token == (((LongToken)obj).token);
         }

         public int hashCode()
         {
             return Longs.hashCode(token);
         }

         public int compareTo(Token o)
         {
             return Long.compare(token, ((LongToken) o).token);
         }

         @Override
         public IPartitioner getPartitioner()
         {
             return instance;
         }

         @Override
         public long getHeapSize()
         {
             return HEAP_SIZE;
         }

         @Override
         public Object getTokenValue()
         {
             return token;
         }

         @Override
         public double size(Token next)
         {
             LongToken n = (LongToken) next;
             long v = n.token - token;  // Overflow acceptable and desired.
             double d = Math.scalb((double) v, -Long.SIZE); // Scale so that the full range is 1.
             return d > 0.0 ? d : (d + 1.0); // Adjust for signed long, also making sure t.size(t) == 1.
         }

         @Override
         public Token increaseSlightly()
         {
             return new LongToken(token + 1);
         }
     }

     /**
      * Generate the token of a key.
      * Note that we need to ensure all generated token are strictly bigger than MINIMUM.
      * In particular we don't want MINIMUM to correspond to any key because the range (MINIMUM, X] doesn't
      * include MINIMUM but we use such range to select all data whose token is smaller than X.
      */
     public LongToken getToken(ByteBuffer key)
     {
         return getToken(key, getHash(key));
     }

     private LongToken getToken(ByteBuffer key, long[] hash)
     {
         if (key.remaining() == 0)
             return MINIMUM;

         return new LongToken(normalize(hash[0]));
     }

     private long[] getHash(ByteBuffer key)
     {
         long[] hash = new long[2];
         MurmurHash.hash3_x64_128(key, key.position(), key.remaining(), 0, hash);
         return hash;
     }

     public LongToken getRandomToken()
     {
         return getRandomToken(ThreadLocalRandom.current());
     }

     public LongToken getRandomToken(Random r)
     {
         return new LongToken(normalize(r.nextLong()));
     }

     private long normalize(long v)
     {
         // We exclude the MINIMUM value; see getToken()
         return v == Long.MIN_VALUE ? Long.MAX_VALUE : v;
     }

     public boolean preservesOrder()
     {
         return false;
     }

     public Map<Token, Float> describeOwnership(List<Token> sortedTokens)
     {
         Map<Token, Float> ownerships = new HashMap<Token, Float>();
         Iterator<Token> i = sortedTokens.iterator();

         // 0-case
         if (!i.hasNext())
             throw new RuntimeException("No nodes present in the cluster. Has this node finished starting up?");
         // 1-case
         if (sortedTokens.size() == 1)
             ownerships.put(i.next(), new Float(1.0));
         // n-case
         else
         {
             final BigInteger ri = BigInteger.valueOf(MAXIMUM).subtract(BigInteger.valueOf(MINIMUM.token + 1));  //  (used for addition later)
             final BigDecimal r  = new BigDecimal(ri);
             Token start = i.next();BigInteger ti = BigInteger.valueOf(((LongToken)start).token);  // The first token and its value
             Token t; BigInteger tim1 = ti;                                                                // The last token and its value (after loop)

             while (i.hasNext())
             {
                 t = i.next(); ti = BigInteger.valueOf(((LongToken) t).token); // The next token and its value
                 float age = new BigDecimal(ti.subtract(tim1).add(ri).mod(ri)).divide(r, 6, BigDecimal.ROUND_HALF_EVEN).floatValue(); // %age = ((T(i) - T(i-1) + R) % R) / R
                 ownerships.put(t, age);                           // save (T(i) -> %age)
                 tim1 = ti;                                        // -> advance loop
             }

             // The start token's range extends backward to the last token, which is why both were saved above.
             float x = new BigDecimal(BigInteger.valueOf(((LongToken)start).token).subtract(ti).add(ri).mod(ri)).divide(r, 6, BigDecimal.ROUND_HALF_EVEN).floatValue();
             ownerships.put(start, x);
         }

         return ownerships;
     }

     public Token.TokenFactory getTokenFactory()
     {
         return tokenFactory;
     }

     private final Token.TokenFactory tokenFactory = new Token.TokenFactory()
     {
         public ByteBuffer toByteArray(Token token)
         {
             LongToken longToken = (LongToken) token;
             return ByteBufferUtil.bytes(longToken.token);
         }

         public Token fromByteArray(ByteBuffer bytes)
         {
             return new LongToken(ByteBufferUtil.toLong(bytes));
         }

         public String toString(Token token)
         {
             return token.toString();
         }

         public void validate(String token) throws ConfigurationException
         {
             try
             {
                 Long.valueOf(token);
             }
             catch (NumberFormatException e)
             {
                 throw new ConfigurationException(e.getMessage());
             }
         }

         public Token fromString(String string)
         {
             try
             {
                 return new LongToken(Long.parseLong(string));
             }
             catch (NumberFormatException e)
             {
                 throw new IllegalArgumentException(String.format("Invalid token for Murmur3Partitioner. Got %s but expected a long value (unsigned 8 bytes integer).", string));
             }
         }
     };

     public AbstractType<?> getTokenValidator()
     {
         return LongType.instance;
     }

     public AbstractType<?> partitionOrdering()
     {
         return partitionOrdering;
     }
 }
	/**
	* 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.dht;

	import java.math.BigDecimal;
	import java.math.BigInteger;
	import java.nio.ByteBuffer;
	import java.util.*;
	import java.util.concurrent.ThreadLocalRandom;

	import org.apache.cassandra.db.DecoratedKey;
	import org.apache.cassandra.db.PreHashedDecoratedKey;
	import org.apache.cassandra.db.marshal.AbstractType;
	import org.apache.cassandra.db.marshal.PartitionerDefinedOrder;
	import org.apache.cassandra.db.marshal.LongType;
	import org.apache.cassandra.exceptions.ConfigurationException;
	import org.apache.cassandra.utils.ByteBufferUtil;
	import org.apache.cassandra.utils.MurmurHash;
	import org.apache.cassandra.utils.ObjectSizes;

	import com.google.common.primitives.Longs;

	/**
	* This class generates a BigIntegerToken using a Murmur3 hash.
	*/
	public class Murmur3Partitioner implements IPartitioner
	{
	public static final LongToken MINIMUM = new LongToken(Long.MIN_VALUE);
	public static final long MAXIMUM = Long.MAX_VALUE;

	private static final int HEAP_SIZE = (int) ObjectSizes.measureDeep(MINIMUM);

	public static final Murmur3Partitioner instance = new Murmur3Partitioner();
	public static final AbstractType<?> partitionOrdering = new PartitionerDefinedOrder(instance);

	public DecoratedKey decorateKey(ByteBuffer key)
	{
	long[] hash = getHash(key);
	return new PreHashedDecoratedKey(getToken(key, hash), key, hash[0], hash[1]);
	}

	public Token midpoint(Token lToken, Token rToken)
	{
	// using BigInteger to avoid long overflow in intermediate operations
	BigInteger l = BigInteger.valueOf(((LongToken) lToken).token),
	r = BigInteger.valueOf(((LongToken) rToken).token),
	midpoint;

	if (l.compareTo(r) < 0)
	{
	BigInteger sum = l.add(r);
	midpoint = sum.shiftRight(1);
	}
	else // wrapping case
	{
	BigInteger max = BigInteger.valueOf(MAXIMUM);
	BigInteger min = BigInteger.valueOf(MINIMUM.token);
	// length of range we're bisecting is (R - min) + (max - L)
	// so we add that to L giving
	// L + ((R - min) + (max - L) / 2) = (L + R + max - min) / 2
	midpoint = (max.subtract(min).add(l).add(r)).shiftRight(1);
	if (midpoint.compareTo(max) > 0)
	midpoint = min.add(midpoint.subtract(max));
	}

	return new LongToken(midpoint.longValue());
	}

	public LongToken getMinimumToken()
	{
	return MINIMUM;
	}

	public static class LongToken extends Token
	{
	static final long serialVersionUID = -5833580143318243006L;

	final long token;

	public LongToken(long token)
	{
	this.token = token;
	}

	public String toString()
	{
	return Long.toString(token);
	}

	public boolean equals(Object obj)
	{
	if (this == obj)
	return true;
	if (obj == null \|\| this.getClass() != obj.getClass())
	return false;

	return token == (((LongToken)obj).token);
	}

	public int hashCode()
	{
	return Longs.hashCode(token);
	}

	public int compareTo(Token o)
	{
	return Long.compare(token, ((LongToken) o).token);
	}

	@Override
	public IPartitioner getPartitioner()
	{
	return instance;
	}

	@Override
	public long getHeapSize()
	{
	return HEAP_SIZE;
	}

	@Override
	public Object getTokenValue()
	{
	return token;
	}

	@Override
	public double size(Token next)
	{
	LongToken n = (LongToken) next;
	long v = n.token - token; // Overflow acceptable and desired.
	double d = Math.scalb((double) v, -Long.SIZE); // Scale so that the full range is 1.
	return d > 0.0 ? d : (d + 1.0); // Adjust for signed long, also making sure t.size(t) == 1.
	}

	@Override
	public Token increaseSlightly()
	{
	return new LongToken(token + 1);
	}
	}

	/**
	* Generate the token of a key.
	* Note that we need to ensure all generated token are strictly bigger than MINIMUM.
	* In particular we don't want MINIMUM to correspond to any key because the range (MINIMUM, X] doesn't
	* include MINIMUM but we use such range to select all data whose token is smaller than X.
	*/
	public LongToken getToken(ByteBuffer key)
	{
	return getToken(key, getHash(key));
	}

	private LongToken getToken(ByteBuffer key, long[] hash)
	{
	if (key.remaining() == 0)
	return MINIMUM;

	return new LongToken(normalize(hash[0]));
	}

	private long[] getHash(ByteBuffer key)
	{
	long[] hash = new long[2];
	MurmurHash.hash3_x64_128(key, key.position(), key.remaining(), 0, hash);
	return hash;
	}

	public LongToken getRandomToken()
	{
	return getRandomToken(ThreadLocalRandom.current());
	}

	public LongToken getRandomToken(Random r)
	{
	return new LongToken(normalize(r.nextLong()));
	}

	private long normalize(long v)
	{
	// We exclude the MINIMUM value; see getToken()
	return v == Long.MIN_VALUE ? Long.MAX_VALUE : v;
	}

	public boolean preservesOrder()
	{
	return false;
	}

	public Map<Token, Float> describeOwnership(List<Token> sortedTokens)
	{
	Map<Token, Float> ownerships = new HashMap<Token, Float>();
	Iterator<Token> i = sortedTokens.iterator();

	// 0-case
	if (!i.hasNext())
	throw new RuntimeException("No nodes present in the cluster. Has this node finished starting up?");
	// 1-case
	if (sortedTokens.size() == 1)
	ownerships.put(i.next(), new Float(1.0));
	// n-case
	else
	{
	final BigInteger ri = BigInteger.valueOf(MAXIMUM).subtract(BigInteger.valueOf(MINIMUM.token + 1)); // (used for addition later)
	final BigDecimal r = new BigDecimal(ri);
	Token start = i.next();BigInteger ti = BigInteger.valueOf(((LongToken)start).token); // The first token and its value
	Token t; BigInteger tim1 = ti; // The last token and its value (after loop)

	while (i.hasNext())
	{
	t = i.next(); ti = BigInteger.valueOf(((LongToken) t).token); // The next token and its value
	float age = new BigDecimal(ti.subtract(tim1).add(ri).mod(ri)).divide(r, 6, BigDecimal.ROUND_HALF_EVEN).floatValue(); // %age = ((T(i) - T(i-1) + R) % R) / R
	ownerships.put(t, age); // save (T(i) -> %age)
	tim1 = ti; // -> advance loop
	}

	// The start token's range extends backward to the last token, which is why both were saved above.
	float x = new BigDecimal(BigInteger.valueOf(((LongToken)start).token).subtract(ti).add(ri).mod(ri)).divide(r, 6, BigDecimal.ROUND_HALF_EVEN).floatValue();
	ownerships.put(start, x);
	}

	return ownerships;
	}

	public Token.TokenFactory getTokenFactory()
	{
	return tokenFactory;
	}

	private final Token.TokenFactory tokenFactory = new Token.TokenFactory()
	{
	public ByteBuffer toByteArray(Token token)
	{
	LongToken longToken = (LongToken) token;
	return ByteBufferUtil.bytes(longToken.token);
	}

	public Token fromByteArray(ByteBuffer bytes)
	{
	return new LongToken(ByteBufferUtil.toLong(bytes));
	}

	public String toString(Token token)
	{
	return token.toString();
	}

	public void validate(String token) throws ConfigurationException
	{
	try
	{
	Long.valueOf(token);
	}
	catch (NumberFormatException e)
	{
	throw new ConfigurationException(e.getMessage());
	}
	}

	public Token fromString(String string)
	{
	try
	{
	return new LongToken(Long.parseLong(string));
	}
	catch (NumberFormatException e)
	{
	throw new IllegalArgumentException(String.format("Invalid token for Murmur3Partitioner. Got %s but expected a long value (unsigned 8 bytes integer).", string));
	}
	}
	};

	public AbstractType<?> getTokenValidator()
	{
	return LongType.instance;
	}

	public AbstractType<?> partitionOrdering()
	{
	return partitionOrdering;
	}
	}