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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.dht;
import org.apache.cassandra.config.CFMetaData;
import org.apache.cassandra.config.Schema;
import org.apache.cassandra.db.BufferDecoratedKey;
import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.BytesType;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.service.StorageService;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.Hex;
import org.apache.cassandra.utils.ObjectSizes;
import org.apache.cassandra.utils.Pair;
import org.apache.commons.lang3.ArrayUtils;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.ThreadLocalRandom;
public class ByteOrderedPartitioner implements IPartitioner
{
public static final BytesToken MINIMUM = new BytesToken(ArrayUtils.EMPTY_BYTE_ARRAY);
public static final BigInteger BYTE_MASK = new BigInteger("255");
private static final long EMPTY_SIZE = ObjectSizes.measure(MINIMUM);
public static final ByteOrderedPartitioner instance = new ByteOrderedPartitioner();
public static class BytesToken extends Token
{
static final long serialVersionUID = -2630749093733680626L;
final byte[] token;
public BytesToken(ByteBuffer token)
{
this(ByteBufferUtil.getArray(token));
}
public BytesToken(byte[] token)
{
this.token = token;
}
@Override
public String toString()
{
return Hex.bytesToHex(token);
}
public int compareTo(Token other)
{
BytesToken o = (BytesToken) other;
return FBUtilities.compareUnsigned(token, o.token, 0, 0, token.length, o.token.length);
}
@Override
public int hashCode()
{
final int prime = 31;
return prime + Arrays.hashCode(token);
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
return true;
if (!(obj instanceof BytesToken))
return false;
BytesToken other = (BytesToken) obj;
return Arrays.equals(token, other.token);
}
@Override
public IPartitioner getPartitioner()
{
return instance;
}
@Override
public long getHeapSize()
{
return EMPTY_SIZE + ObjectSizes.sizeOfArray(token);
}
@Override
public Object getTokenValue()
{
return token;
}
@Override
public double size(Token next)
{
throw new UnsupportedOperationException(String.format("Token type %s does not support token allocation.",
getClass().getSimpleName()));
}
@Override
public Token increaseSlightly()
{
throw new UnsupportedOperationException(String.format("Token type %s does not support token allocation.",
getClass().getSimpleName()));
}
}
public BytesToken getToken(ByteBuffer key)
{
if (key.remaining() == 0)
return MINIMUM;
return new BytesToken(key);
}
public DecoratedKey decorateKey(ByteBuffer key)
{
return new BufferDecoratedKey(getToken(key), key);
}
public BytesToken midpoint(Token lt, Token rt)
{
BytesToken ltoken = (BytesToken) lt;
BytesToken rtoken = (BytesToken) rt;
int sigbytes = Math.max(ltoken.token.length, rtoken.token.length);
BigInteger left = bigForBytes(ltoken.token, sigbytes);
BigInteger right = bigForBytes(rtoken.token, sigbytes);
Pair midpair = FBUtilities.midpoint(left, right, 8*sigbytes);
return new BytesToken(bytesForBig(midpair.left, sigbytes, midpair.right));
}
public Token split(Token left, Token right, double ratioToLeft)
{
throw new UnsupportedOperationException();
}
/**
* Convert a byte array containing the most significant of 'sigbytes' bytes
* representing a big-endian magnitude into a BigInteger.
*/
private BigInteger bigForBytes(byte[] bytes, int sigbytes)
{
byte[] b;
if (sigbytes != bytes.length)
{
b = new byte[sigbytes];
System.arraycopy(bytes, 0, b, 0, bytes.length);
} else
b = bytes;
return new BigInteger(1, b);
}
/**
* Convert a (positive) BigInteger into a byte array representing its magnitude.
* If remainder is true, an additional byte with the high order bit enabled
* will be added to the end of the array
*/
private byte[] bytesForBig(BigInteger big, int sigbytes, boolean remainder)
{
byte[] bytes = new byte[sigbytes + (remainder ? 1 : 0)];
if (remainder)
{
// remaining bit is the most significant in the last byte
bytes[sigbytes] |= 0x80;
}
// bitmask for a single byte
for (int i = 0; i < sigbytes; i++)
{
int maskpos = 8 * (sigbytes - (i + 1));
// apply bitmask and get byte value
bytes[i] = (byte)(big.and(BYTE_MASK.shiftLeft(maskpos)).shiftRight(maskpos).intValue() & 0xFF);
}
return bytes;
}
public BytesToken getMinimumToken()
{
return MINIMUM;
}
public BytesToken getRandomToken()
{
return getRandomToken(ThreadLocalRandom.current());
}
public BytesToken getRandomToken(Random random)
{
byte[] buffer = new byte[16];
random.nextBytes(buffer);
return new BytesToken(buffer);
}
private final Token.TokenFactory tokenFactory = new Token.TokenFactory()
{
public ByteBuffer toByteArray(Token token)
{
BytesToken bytesToken = (BytesToken) token;
return ByteBuffer.wrap(bytesToken.token);
}
public Token fromByteArray(ByteBuffer bytes)
{
return new BytesToken(bytes);
}
public String toString(Token token)
{
BytesToken bytesToken = (BytesToken) token;
return Hex.bytesToHex(bytesToken.token);
}
public void validate(String token) throws ConfigurationException
{
try
{
if (token.length() % 2 == 1)
token = "0" + token;
Hex.hexToBytes(token);
}
catch (NumberFormatException e)
{
throw new ConfigurationException("Token " + token + " contains non-hex digits");
}
}
public Token fromString(String string)
{
if (string.length() % 2 == 1)
string = "0" + string;
return new BytesToken(Hex.hexToBytes(string));
}
};
public Token.TokenFactory getTokenFactory()
{
return tokenFactory;
}
public boolean preservesOrder()
{
return true;
}
public Map describeOwnership(List sortedTokens)
{
// allTokens will contain the count and be returned, sorted_ranges is shorthand for token<->token math.
Map allTokens = new HashMap();
List> sortedRanges = new ArrayList>(sortedTokens.size());
// this initializes the counts to 0 and calcs the ranges in order.
Token lastToken = sortedTokens.get(sortedTokens.size() - 1);
for (Token node : sortedTokens)
{
allTokens.put(node, new Float(0.0));
sortedRanges.add(new Range(lastToken, node));
lastToken = node;
}
for (String ks : Schema.instance.getKeyspaces())
{
for (CFMetaData cfmd : Schema.instance.getTablesAndViews(ks))
{
for (Range r : sortedRanges)
{
// Looping over every KS:CF:Range, get the splits size and add it to the count
allTokens.put(r.right, allTokens.get(r.right) + StorageService.instance.getSplits(ks, cfmd.cfName, r, 1).size());
}
}
}
// Sum every count up and divide count/total for the fractional ownership.
Float total = new Float(0.0);
for (Float f : allTokens.values())
total += f;
for (Map.Entry row : allTokens.entrySet())
allTokens.put(row.getKey(), row.getValue() / total);
return allTokens;
}
public AbstractType getTokenValidator()
{
return BytesType.instance;
}
public AbstractType partitionOrdering()
{
return BytesType.instance;
}
}