Package org.apache.ignite.internal.client.util

Class 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 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
              @Nullable Collection<N> inc,
              @Nullable
              @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.