org.apache.cassandra.db.memtable

Class ShardBoundaries

java.lang.Object

org.apache.cassandra.db.memtable.ShardBoundaries

public class ShardBoundaries
extends java.lang.Object

Holds boundaries (tokens) used to map a particular token (so partition key) to a shard id. In practice, each keyspace has its associated boundaries, see Keyspace.

Technically, if we use n shards, this is a list of n-1 tokens and each token tk gets assigned to the shard ID corresponding to the slot of the smallest token in the list that is greater to tk, or n if tk is bigger than any token in the list.

Field Summary

Fields

Modifier and Type	Field and Description
static ShardBoundaries	NONE
long	ringVersion

Constructor Summary

Constructors

Constructor and Description
ShardBoundaries(java.util.List<Token> boundaries, long ringVersion)
ShardBoundaries(Token[] boundaries, long ringVersion)

Method Summary

Modifier and Type	Method and Description
boolean	equals(java.lang.Object o)
int	getShardForKey(PartitionPosition key) Computes the shard to use for the provided key.
int	getShardForToken(Token tk) Computes the shard to use for the provided token.
int	hashCode()
int	shardCount() The number of shards that this boundaries support, that is how many different shard ids getShardForToken(org.apache.cassandra.dht.Token) might possibly return.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

NONE

public static final ShardBoundaries NONE

ringVersion

public final long ringVersion

Constructor Detail

ShardBoundaries

public ShardBoundaries(Token[] boundaries,
                       long ringVersion)

ShardBoundaries

public ShardBoundaries(java.util.List<Token> boundaries,
                       long ringVersion)

Method Detail

getShardForToken

public int getShardForToken(Token tk)

Computes the shard to use for the provided token.

getShardForKey

public int getShardForKey(PartitionPosition key)

Computes the shard to use for the provided key.

shardCount

public int shardCount()

The number of shards that this boundaries support, that is how many different shard ids getShardForToken(org.apache.cassandra.dht.Token) might possibly return.

Returns:

the number of shards supported by theses boundaries.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object