Class PNCounter

Implements a 'Increment/Decrement Counter' CRDT, also called a 'PN-Counter'.

It is described in the paper A comprehensive study of Convergent and Commutative Replicated Data Types.

PN-Counters allow the counter to be incremented by tracking the increments (P) separate from the decrements (N). Both P and N are represented as two internal [[GCounter]]s. Merge is handled by merging the internal P and N counters. The value of the counter is the value of the P _counter minus the value of the N counter.

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

Inheritance

object

PNCounter

Implements

IDeltaReplicatedData<PNCounter, PNCounter>

IDeltaReplicatedData

IRemovedNodePruning<PNCounter>

IRemovedNodePruning

IReplicatedData<PNCounter>

IReplicatedDataSerialization

IEquatable<PNCounter>

IReplicatedDelta

IReplicatedData

Inherited Members

object.Equals(object, object)

object.GetType()

object.ReferenceEquals(object, object)

Namespace: Akka.DistributedData

Assembly: Akka.DistributedData.dll

Syntax

[Serializable]
public sealed class PNCounter : IDeltaReplicatedData<PNCounter, PNCounter>, IDeltaReplicatedData, IRemovedNodePruning<PNCounter>, IRemovedNodePruning, IReplicatedData<PNCounter>, IReplicatedDataSerialization, IEquatable<PNCounter>, IReplicatedDelta, IReplicatedData

Constructors

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PNCounter()

Declaration

public PNCounter()

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PNCounter(GCounter, GCounter)

Declaration

public PNCounter(GCounter increments, GCounter decrements)

Parameters

Type	Name	Description
GCounter	increments
GCounter	decrements

Fields

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Empty

Declaration

public static readonly PNCounter Empty

Field Value

Type	Description
PNCounter

Properties

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Decrements

Declaration

public GCounter Decrements { get; }

Property Value

Type	Description
GCounter

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Delta

The accumulated delta of mutator operations since previous ResetDelta(). When the Akka.DistributedData.Replicator invokes the modify function of the Update message and the user code is invoking one or more mutator operations the data is collecting the delta of the operations and makes it available for the Akka.DistributedData.Replicator with the Delta accessor. The modify function shall still return the full state in the same way as IReplicatedData<T> without support for deltas.

Declaration

public PNCounter Delta { get; }

Property Value

Type	Description
PNCounter

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Increments

Declaration

public GCounter Increments { get; }

Property Value

Type	Description
GCounter

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ModifiedByNodes

The nodes that have changed the state for this data and would need pruning when such node is no longer part of the cluster.

Declaration

public ImmutableHashSet<UniqueAddress> ModifiedByNodes { get; }

Property Value

Type	Description
ImmutableHashSet<UniqueAddress>

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Value

Declaration

public BigInteger Value { get; }

Property Value

Type	Description
BigInteger

Methods

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Decrement(Cluster, long)

Decrement the counter with the delta specified. If the delta is negative then it will increment instead of decrement.

Declaration

public PNCounter Decrement(Cluster node, long delta = 1)

Parameters

Type	Name	Description
Cluster	node
long	delta

Returns

Type	Description
PNCounter

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Decrement(UniqueAddress, long)

Decrement the counter with the delta specified. If the delta is negative then it will increment instead of decrement.

Declaration

public PNCounter Decrement(UniqueAddress address, long delta = 1)

Parameters

Type	Name	Description
UniqueAddress	address
long	delta

Returns

Type	Description
PNCounter

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Equals(PNCounter)

Declaration

public bool Equals(PNCounter other)

Parameters

Type	Name	Description
PNCounter	other

Returns

Type	Description
bool

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Equals(object)

Declaration

public override bool Equals(object obj)

Parameters

Type	Name	Description
object	obj

Returns

Type	Description
bool

Overrides

object.Equals(object)

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GetHashCode()

Declaration

public override int GetHashCode()

Returns

Type	Description
int

Overrides

object.GetHashCode()

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Increment(Cluster, long)

Increment the counter with the delta specified. If the delta is negative then it will decrement instead of increment.

Declaration

public PNCounter Increment(Cluster node, long delta = 1)

Parameters

Type	Name	Description
Cluster	node
long	delta

Returns

Type	Description
PNCounter

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Increment(UniqueAddress, long)

Increment the counter with the delta specified. If the delta is negative then it will decrement instead of increment.

Declaration

public PNCounter Increment(UniqueAddress address, long delta = 1)

Parameters

Type	Name	Description
UniqueAddress	address
long	delta

Returns

Type	Description
PNCounter

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Merge(IReplicatedData)

Declaration

public IReplicatedData Merge(IReplicatedData other)

Parameters

Type	Name	Description
IReplicatedData	other

Returns

Type	Description
IReplicatedData

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Merge(PNCounter)

Monotonic merge method.

Declaration

public PNCounter Merge(PNCounter other)

Parameters

Type	Name	Description
PNCounter	other

Returns

Type	Description
PNCounter

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MergeDelta(PNCounter)

When delta is merged into the full state this method is used. When the type PNCounter of the delta is of the same type as the full state PNCounter this method can be implemented by delegating to Merge(T).

Declaration

public PNCounter MergeDelta(PNCounter delta)

Parameters

Type	Name	Description
PNCounter	delta

Returns

Type	Description
PNCounter

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NeedPruningFrom(UniqueAddress)

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

Declaration

public bool NeedPruningFrom(UniqueAddress removedNode)

Parameters

Type	Name	Description
UniqueAddress	removedNode

Returns

Type	Description
bool

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Prune(UniqueAddress, UniqueAddress)

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

Declaration

public PNCounter Prune(UniqueAddress removedNode, UniqueAddress collapseInto)

Parameters

Type	Name	Description
UniqueAddress	removedNode
UniqueAddress	collapseInto

Returns

Type	Description
PNCounter

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PruningCleanup(UniqueAddress)

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

Declaration

public PNCounter PruningCleanup(UniqueAddress removedNode)

Parameters

Type	Name	Description
UniqueAddress	removedNode

Returns

Type	Description
PNCounter

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ResetDelta()

Reset collection of deltas from mutator operations. When the Akka.DistributedData.Replicator invokes the modify function of the Update message the delta is always "reset" and when the user code is invoking one or more mutator operations the data is collecting the delta of the operations and makes it available for the Akka.DistributedData.Replicator with the Delta accessor. When the Akka.DistributedData.Replicator has grabbed the Delta it will invoke this method to get a clean data instance without the delta.

Declaration

public PNCounter ResetDelta()

Returns

Type	Description
PNCounter

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ToString()

Declaration

public override string ToString()

Returns

Type	Description
string