akka.cluster.ddata

Class VersionVector

java.lang.Object

akka.cluster.ddata.VersionVector

All Implemented Interfaces:

RemovedNodePruning, ReplicatedData, ReplicatedDataSerialization, java.io.Serializable

Direct Known Subclasses:

ManyVersionVector, OneVersionVector

public abstract class VersionVector
extends java.lang.Object
implements ReplicatedData, ReplicatedDataSerialization, RemovedNodePruning

Representation of a Vector-based clock (counting clock), inspired by Lamport logical clocks.

 Reference:
    1) Leslie Lamport (1978). "Time, clocks, and the ordering of events in a distributed system". Communications of the ACM 21 (7): 558-565.
    2) Friedemann Mattern (1988). "Virtual Time and Global States of Distributed Systems". Workshop on Parallel and Distributed Algorithms: pp. 215-226
 

Based on code from akka.cluster.VectorClock.

This class is immutable, i.e. "modifying" methods return a new instance.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	VersionVector.After$
static class	VersionVector.Before$
static class	VersionVector.Concurrent$
static interface	VersionVector.Ordering
static class	VersionVector.Same$
static class	VersionVector.Timestamp$ INTERNAL API

Constructor Summary

Constructors

Constructor and Description
VersionVector()

Method Summary

Modifier and Type	Method and Description
static VersionVector.After$	AfterInstance() Java API: The VersionVector.After instance
static VersionVector	apply()
static VersionVector	apply(scala.collection.immutable.List<scala.Tuple2<UniqueAddress,java.lang.Object>> versions) INTERNAL API
static VersionVector	apply(scala.collection.immutable.TreeMap<UniqueAddress,java.lang.Object> versions)
static VersionVector	apply(UniqueAddress node, long version)
static VersionVector.Before$	BeforeInstance() Java API: The VersionVector.Before instance
VersionVector.Ordering	compareTo(VersionVector that) Compare two version vectors.
static VersionVector.Concurrent$	ConcurrentInstance() Java API: The VersionVector.Concurrent instance
abstract boolean	contains(UniqueAddress node) INTERNAL API
static VersionVector	create() Java API
static VersionVector	empty()
VersionVector	increment(Cluster node) Increment the version for the node passed as argument.
abstract VersionVector	increment(UniqueAddress node) INTERNAL API Increment the version for the node passed as argument.
abstract boolean	isEmpty()
abstract VersionVector	merge(VersionVector that) Merges this VersionVector with another VersionVector.
abstract boolean	needPruningFrom(UniqueAddress removedNode) Does it have any state changes from a specific node, which has been removed from the cluster.
abstract VersionVector	prune(UniqueAddress removedNode, UniqueAddress collapseInto) When the removed node has been removed from the cluster the state changes from that node will be pruned by collapsing the data entries to another node.
abstract VersionVector	pruningCleanup(UniqueAddress removedNode) Remove data entries from a node that has been removed from the cluster and already been pruned.
static VersionVector.Same$	SameInstance() Java API: The VersionVector.Same instance
abstract int	size() INTERNAL API
abstract long	versionAt(UniqueAddress node) INTERNAL API
abstract scala.collection.Iterator<scala.Tuple2<UniqueAddress,java.lang.Object>>	versionsIterator() INTERNAL API

Methods inherited from class java.lang.Object

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

Methods inherited from interface akka.cluster.ddata.ReplicatedData

merge

Constructor Detail

VersionVector

public VersionVector()

Method Detail

empty

public static VersionVector empty()

apply

public static VersionVector apply()

apply

public static VersionVector apply(scala.collection.immutable.TreeMap<UniqueAddress,java.lang.Object> versions)

apply

public static VersionVector apply(UniqueAddress node,
                                  long version)

apply

public static VersionVector apply(scala.collection.immutable.List<scala.Tuple2<UniqueAddress,java.lang.Object>> versions)

INTERNAL API

create

public static VersionVector create()

Java API

Returns:

(undocumented)

AfterInstance

public static VersionVector.After$ AfterInstance()

Java API: The VersionVector.After instance

Returns:

(undocumented)

BeforeInstance

public static VersionVector.Before$ BeforeInstance()

Java API: The VersionVector.Before instance

Returns:

(undocumented)

SameInstance

public static VersionVector.Same$ SameInstance()

Java API: The VersionVector.Same instance

Returns:

(undocumented)

ConcurrentInstance

public static VersionVector.Concurrent$ ConcurrentInstance()

Java API: The VersionVector.Concurrent instance

Returns:

(undocumented)

increment

public VersionVector increment(Cluster node)

Increment the version for the node passed as argument. Returns a new VersionVector.

Parameters:

node - (undocumented)

Returns:

(undocumented)

isEmpty

public abstract boolean isEmpty()

size

public abstract int size()

INTERNAL API

Returns:

(undocumented)

increment

public abstract VersionVector increment(UniqueAddress node)

INTERNAL API Increment the version for the node passed as argument. Returns a new VersionVector.

Parameters:

node - (undocumented)

Returns:

(undocumented)

versionAt

public abstract long versionAt(UniqueAddress node)

INTERNAL API

Parameters:

node - (undocumented)

Returns:

(undocumented)

contains

public abstract boolean contains(UniqueAddress node)

INTERNAL API

Parameters:

node - (undocumented)

Returns:

(undocumented)

versionsIterator

public abstract scala.collection.Iterator<scala.Tuple2<UniqueAddress,java.lang.Object>> versionsIterator()

INTERNAL API

Returns:

(undocumented)

compareTo

public VersionVector.Ordering compareTo(VersionVector that)

Compare two version vectors. The outcome will be one of the following:

   1. Version 1 is SAME (==)       as Version 2 iff for all i c1(i) == c2(i)
   2. Version 1 is BEFORE (<)      Version 2 iff for all i c1(i) <= c2(i) and there exist a j such that c1(j) < c2(j)
   3. Version 1 is AFTER (>)       Version 2 iff for all i c1(i) >= c2(i) and there exist a j such that c1(j) > c2(j).
   4. Version 1 is CONCURRENT (<>) to Version 2 otherwise.
 

Parameters:

that - (undocumented)

Returns:

(undocumented)

merge

public abstract VersionVector merge(VersionVector that)

Merges this VersionVector with another VersionVector. E.g. merges its versioned history.

Parameters:

that - (undocumented)

Returns:

(undocumented)

needPruningFrom

public abstract boolean needPruningFrom(UniqueAddress removedNode)

Description copied from interface: RemovedNodePruning

Does it have any state changes from a specific node, which has been removed from the cluster.

Specified by:

needPruningFrom in interface RemovedNodePruning

Parameters:

removedNode - (undocumented)

Returns:

(undocumented)

prune

public abstract VersionVector prune(UniqueAddress removedNode,
                                    UniqueAddress collapseInto)

Description copied from interface: RemovedNodePruning

When the removed node has been removed from the cluster the state changes from that node will be pruned by collapsing the data entries to another node.

Specified by:

prune in interface RemovedNodePruning

Parameters:

removedNode - (undocumented)

collapseInto - (undocumented)

Returns:

(undocumented)

pruningCleanup

public abstract VersionVector pruningCleanup(UniqueAddress removedNode)

Description copied from interface: RemovedNodePruning

Remove data entries from a node that has been removed from the cluster and already been pruned.

Specified by:

pruningCleanup in interface RemovedNodePruning

Parameters:

removedNode - (undocumented)

Returns:

(undocumented)