org.apache.cassandra.db.DecoratedKey Maven / Gradle / Ivy
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* to you under the Apache License, Version 2.0 (the
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*
* http://www.apache.org/licenses/LICENSE-2.0
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*/
package org.apache.cassandra.db;
import java.nio.ByteBuffer;
import java.util.Comparator;
import org.apache.cassandra.dht.IPartitioner;
import org.apache.cassandra.dht.Token;
import org.apache.cassandra.dht.Token.KeyBound;
import org.apache.cassandra.utils.ByteBufferUtil;
import org.apache.cassandra.utils.MurmurHash;
import org.apache.cassandra.utils.IFilter.FilterKey;
/**
* Represents a decorated key, handy for certain operations
* where just working with strings gets slow.
*
* We do a lot of sorting of DecoratedKeys, so for speed, we assume that tokens correspond one-to-one with keys.
* This is not quite correct in the case of RandomPartitioner (which uses MD5 to hash keys to tokens);
* if this matters, you can subclass RP to use a stronger hash, or use a non-lossy tokenization scheme (as in the
* OrderPreservingPartitioner classes).
*/
public abstract class DecoratedKey implements PartitionPosition, FilterKey
{
public static final Comparator comparator = new Comparator()
{
public int compare(DecoratedKey o1, DecoratedKey o2)
{
return o1.compareTo(o2);
}
};
private final Token token;
public DecoratedKey(Token token)
{
assert token != null;
this.token = token;
}
@Override
public int hashCode()
{
return getKey().hashCode(); // hash of key is enough
}
@Override
public boolean equals(Object obj)
{
if (this == obj)
return true;
if (obj == null || !(obj instanceof DecoratedKey))
return false;
DecoratedKey other = (DecoratedKey)obj;
return ByteBufferUtil.compareUnsigned(getKey(), other.getKey()) == 0; // we compare faster than BB.equals for array backed BB
}
public int compareTo(PartitionPosition pos)
{
if (this == pos)
return 0;
// delegate to Token.KeyBound if needed
if (!(pos instanceof DecoratedKey))
return -pos.compareTo(this);
DecoratedKey otherKey = (DecoratedKey) pos;
int cmp = getToken().compareTo(otherKey.getToken());
return cmp == 0 ? ByteBufferUtil.compareUnsigned(getKey(), otherKey.getKey()) : cmp;
}
public static int compareTo(IPartitioner partitioner, ByteBuffer key, PartitionPosition position)
{
// delegate to Token.KeyBound if needed
if (!(position instanceof DecoratedKey))
return -position.compareTo(partitioner.decorateKey(key));
DecoratedKey otherKey = (DecoratedKey) position;
int cmp = partitioner.getToken(key).compareTo(otherKey.getToken());
return cmp == 0 ? ByteBufferUtil.compareUnsigned(key, otherKey.getKey()) : cmp;
}
public IPartitioner getPartitioner()
{
return getToken().getPartitioner();
}
public KeyBound minValue()
{
return getPartitioner().getMinimumToken().minKeyBound();
}
public boolean isMinimum()
{
// A DecoratedKey can never be the minimum position on the ring
return false;
}
public PartitionPosition.Kind kind()
{
return PartitionPosition.Kind.ROW_KEY;
}
@Override
public String toString()
{
String keystring = getKey() == null ? "null" : ByteBufferUtil.bytesToHex(getKey());
return "DecoratedKey(" + getToken() + ", " + keystring + ")";
}
public Token getToken()
{
return token;
}
public abstract ByteBuffer getKey();
public void filterHash(long[] dest)
{
ByteBuffer key = getKey();
MurmurHash.hash3_x64_128(key, key.position(), key.remaining(), 0, dest);
}
}