org.gridgain.client.util

Class GridClientConsistentHash<N>

java.lang.Object

org.gridgain.client.util.GridClientConsistentHash<N>

public class GridClientConsistentHash<N>
extends Object

Controls key to node affinity using consistent hash algorithm. This class is thread-safe and does not have to be externally synchronized.

For a good explanation of what consistent hashing is, you can refer to Tom White's Blog.

Constructor Summary

Constructors

Constructor and Description
GridClientConsistentHash() Constructs consistent hash using empty affinity seed and MD5 hasher function.
GridClientConsistentHash(Comparator<N> nodesComp, Object affSeed) Constructs consistent hash using given affinity seed and hasher function.
GridClientConsistentHash(Object affSeed) Constructs consistent hash using given affinity seed and MD5 hasher function.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	addNode(N node, int replicas) Adds a node to consistent hash algorithm.
void	addNodes(Collection<N> nodes, int replicas) Adds nodes to consistent hash algorithm (if nodes are null or empty, then no-op).
int	count() Gets number of distinct nodes, excluding replicas, in consistent hash.
static int	hash(Object o) Gets hash code for a given object.
boolean	isEmpty() Checks if consistent hash has nodes added to it.
N	node(Object key) Gets node for a key.
N	node(Object key, Collection<N> inc) Gets node for a given key.
N	node(Object key, Collection<N> inc, Collection<N> exc) Gets node for a given key.
N	node(Object key, GridClientPredicate<N>... p) Gets node for a given key.
Set<N>	nodes() Gets set of all distinct nodes in the consistent hash (in no particular order).
N	random() Picks a random node from consistent hash.
boolean	removeNode(N node) Removes a node and all of its replicas.
int	size() Gets size of all nodes (including replicas) in consistent hash.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

GridClientConsistentHash

public GridClientConsistentHash()

Constructs consistent hash using empty affinity seed and MD5 hasher function.

GridClientConsistentHash

public GridClientConsistentHash(Object affSeed)

Constructs consistent hash using given affinity seed and MD5 hasher function.

Parameters:

affSeed - Affinity seed (will be used as key prefix for hashing).

GridClientConsistentHash

public GridClientConsistentHash(Comparator<N> nodesComp,
                        Object affSeed)

Constructs consistent hash using given affinity seed and hasher function.

Parameters:

nodesComp - Nodes comparator to resolve hash codes collisions. If null natural order will be used.

affSeed - Affinity seed (will be used as key prefix for hashing).

Method Detail

addNodes

public void addNodes(Collection<N> nodes,
            int replicas)

Adds nodes to consistent hash algorithm (if nodes are null or empty, then no-op).

Parameters:

nodes - Nodes to add.

replicas - Number of replicas for every node.

addNode

public boolean addNode(N node,
              int replicas)

Adds a node to consistent hash algorithm.

Parameters:

node - New node (if null then no-op).

replicas - Number of replicas for the node.

Returns:

True if node was added, false if it is null or is already contained in the hash.

removeNode

public boolean removeNode(N node)

Removes a node and all of its replicas.

Parameters:

node - Node to remove (if null, then no-op).

Returns:

True if node was removed, false if node is null or not present in hash.

count

public int count()

Gets number of distinct nodes, excluding replicas, in consistent hash.

Returns:

Number of distinct nodes, excluding replicas, in consistent hash.

size

public int size()

Gets size of all nodes (including replicas) in consistent hash.

Returns:

Size of all nodes (including replicas) in consistent hash.

isEmpty

public boolean isEmpty()

Checks if consistent hash has nodes added to it.

Returns:

True if consistent hash is empty, false otherwise.

nodes

public Set<N> nodes()

Gets set of all distinct nodes in the consistent hash (in no particular order).

Returns:

Set of all distinct nodes in the consistent hash.

random

public N random()

Picks a random node from consistent hash.

Returns:

Random node from consistent hash or null if there are no nodes.

node

public N node(Object key)

Gets node for a key.

Parameters:

key - Key.

Returns:

Node.

node

public N node(Object key,
     Collection<N> inc)

Gets node for a given key.

Parameters:

key - Key to get node for.

inc - Optional inclusion set. Only nodes contained in this set may be returned. If null, then all nodes may be included.

Returns:

Node for key, or null if node was not found.

node

public N node(Object key,
     @Nullable
     Collection<N> inc,
     @Nullable
     Collection<N> exc)

Gets node for a given key.

Parameters:

key - Key to get node for.

inc - Optional inclusion set. Only nodes contained in this set may be returned. If null, then all nodes may be included.

exc - Optional exclusion set. Only nodes not contained in this set may be returned. If null, then all nodes may be returned.

Returns:

Node for key, or null if node was not found.

node

public N node(Object key,
     GridClientPredicate<N>... p)

Gets node for a given key.

Parameters:

key - Key to get node for.

p - Optional predicate for node filtering.

Returns:

Node for key, or null if node was not found.

hash

public static int hash(Object o)

Gets hash code for a given object.

Parameters:

o - Object to get hash code for.

Returns:

Hash code.

toString

public String toString()

Overrides:

toString in class Object