org.apache.cassandra.dht.Token Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of cassandra-all Show documentation
Show all versions of cassandra-all Show documentation
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 java.io.DataInput;
import java.io.IOException;
import java.io.Serializable;
import java.nio.ByteBuffer;
import org.apache.cassandra.db.RowPosition;
import org.apache.cassandra.db.TypeSizes;
import org.apache.cassandra.exceptions.ConfigurationException;
import org.apache.cassandra.io.util.DataOutputPlus;
import org.apache.cassandra.utils.ByteBufferUtil;
public abstract class Token implements RingPosition, Serializable
{
private static final long serialVersionUID = 1L;
public static final TokenSerializer serializer = new TokenSerializer();
public static abstract class TokenFactory
{
public abstract ByteBuffer toByteArray(Token token);
public abstract Token fromByteArray(ByteBuffer bytes);
public abstract String toString(Token token); // serialize as string, not necessarily human-readable
public abstract Token fromString(String string); // deserialize
public abstract void validate(String token) throws ConfigurationException;
}
public static class TokenSerializer implements IPartitionerDependentSerializer
{
public void serialize(Token token, DataOutputPlus out, int version) throws IOException
{
IPartitioner p = token.getPartitioner();
ByteBuffer b = p.getTokenFactory().toByteArray(token);
ByteBufferUtil.writeWithLength(b, out);
}
public Token deserialize(DataInput in, IPartitioner p, int version) throws IOException
{
int size = in.readInt();
byte[] bytes = new byte[size];
in.readFully(bytes);
return p.getTokenFactory().fromByteArray(ByteBuffer.wrap(bytes));
}
public long serializedSize(Token object, int version)
{
IPartitioner p = object.getPartitioner();
ByteBuffer b = p.getTokenFactory().toByteArray(object);
return TypeSizes.NATIVE.sizeof(b.remaining()) + b.remaining();
}
}
abstract public IPartitioner getPartitioner();
abstract public long getHeapSize();
abstract public Object getTokenValue();
public Token getToken()
{
return this;
}
public Token minValue()
{
return getPartitioner().getMinimumToken();
}
public boolean isMinimum()
{
return this.equals(minValue());
}
/*
* A token corresponds to the range of all the keys having this token.
* A token is thus no comparable directly to a key. But to be able to select
* keys given tokens, we introduce two "fake" keys for each token T:
* - lowerBoundKey: a "fake" key representing the lower bound T represents.
* In other words, lowerBoundKey is the smallest key that
* have token T.
* - upperBoundKey: a "fake" key representing the upper bound T represents.
* In other words, upperBoundKey is the largest key that
* have token T.
*
* Note that those are "fake" keys and should only be used for comparison
* of other keys, for selection of keys when only a token is known.
*/
public KeyBound minKeyBound()
{
return new KeyBound(this, true);
}
public KeyBound maxKeyBound()
{
/*
* For each token, we needs both minKeyBound and maxKeyBound
* because a token corresponds to a range of keys. But the minimun
* token corresponds to no key, so it is valid and actually much
* simpler to associate the same value for minKeyBound and
* maxKeyBound for the minimun token.
*/
if (isMinimum())
return minKeyBound();
return new KeyBound(this, false);
}
@SuppressWarnings("unchecked")
public > R upperBound(Class klass)
{
if (klass.equals(getClass()))
return (R)this;
else
return (R)maxKeyBound();
}
public static class KeyBound implements RowPosition
{
private final Token token;
public final boolean isMinimumBound;
private KeyBound(Token t, boolean isMinimumBound)
{
this.token = t;
this.isMinimumBound = isMinimumBound;
}
public Token getToken()
{
return token;
}
public int compareTo(RowPosition pos)
{
if (this == pos)
return 0;
int cmp = getToken().compareTo(pos.getToken());
if (cmp != 0)
return cmp;
if (isMinimumBound)
return ((pos instanceof KeyBound) && ((KeyBound)pos).isMinimumBound) ? 0 : -1;
else
return ((pos instanceof KeyBound) && !((KeyBound)pos).isMinimumBound) ? 0 : 1;
}
public IPartitioner getPartitioner()
{
return getToken().getPartitioner();
}
public KeyBound minValue()
{
return getPartitioner().getMinimumToken().minKeyBound();
}
public boolean isMinimum()
{
return getToken().isMinimum();
}
public RowPosition.Kind kind()
{
return isMinimumBound ? RowPosition.Kind.MIN_BOUND : RowPosition.Kind.MAX_BOUND;
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
return true;
if (obj == null || this.getClass() != obj.getClass())
return false;
KeyBound other = (KeyBound)obj;
return token.equals(other.token) && isMinimumBound == other.isMinimumBound;
}
@Override
public int hashCode()
{
return getToken().hashCode() + (isMinimumBound ? 0 : 1);
}
@Override
public String toString()
{
return String.format("%s(%s)", isMinimumBound ? "min" : "max", getToken().toString());
}
}
}