PNCounter

java.lang.Object
- akka.cluster.ddata.PNCounter

All Implemented Interfaces:

RemovedNodePruning, ReplicatedData, ReplicatedDataSerialization, java.io.Serializable
```
public final class PNCounter
extends java.lang.Object
implements ReplicatedData, ReplicatedDataSerialization, RemovedNodePruning
```
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 GCounters. 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.

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor and Description

PNCounter(GCounter increments, GCounter decrements)

Constructors
Constructor and Description
`PNCounter(GCounter increments, GCounter decrements)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`static PNCounter`	`apply()`
`PNCounter`	`change(UniqueAddress key, long delta)`
`static PNCounter`	`create()` Java API
`PNCounter`	`decrement(Cluster node, long delta)` Decrement the counter with the delta specified.
`PNCounter`	`decrement(UniqueAddress key)`
`PNCounter`	`decrement(UniqueAddress key, long delta)` Decrement the counter with the delta specified.
`GCounter`	`decrements()`
`static PNCounter`	`empty()`
`boolean`	`equals(java.lang.Object o)`
`java.math.BigInteger`	`getValue()` Java API: Current total value of the counter.
`int`	`hashCode()`
`PNCounter`	`increment(Cluster node, long delta)` Increment the counter with the delta specified.
`PNCounter`	`increment(UniqueAddress key)`
`PNCounter`	`increment(UniqueAddress key, long delta)`
`GCounter`	`increments()`
`PNCounter`	`merge(PNCounter that)`
`boolean`	`needPruningFrom(UniqueAddress removedNode)` Does it have any state changes from a specific node, which has been removed from the cluster.
`PNCounter`	`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.
`PNCounter`	`pruningCleanup(UniqueAddress removedNode)` Remove data entries from a node that has been removed from the cluster and already been pruned.
`java.lang.String`	`toString()`
`static scala.Option<scala.math.BigInt>`	`unapply(PNCounter c)` Extract the `GCounter.value()`.
`scala.math.BigInt`	`value()` Scala API: Current total value of the counter.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface akka.cluster.ddata.ReplicatedData
merge

- Constructor Detail
  - PNCounter
```
public PNCounter(GCounter increments,
                 GCounter decrements)
```
- Method Detail
  - empty
```
public static PNCounter empty()
```
  - apply
```
public static PNCounter apply()
```
  - create
```
public static PNCounter create()
```
    Java API
    
    Returns:
    
    (undocumented)
  - unapply
```
public static scala.Option<scala.math.BigInt> unapply(PNCounter c)
```
    Extract the GCounter.value().
    
    Parameters:
    
    c - (undocumented)
    
    Returns:
    
    (undocumented)
  - increments
```
public GCounter increments()
```
  - decrements
```
public GCounter decrements()
```
  - value
```
public scala.math.BigInt value()
```
    Scala API: Current total value of the counter.
    
    Returns:
    
    (undocumented)
  - getValue
```
public java.math.BigInteger getValue()
```
    Java API: Current total value of the counter.
    
    Returns:
    
    (undocumented)
  - increment
```
public PNCounter increment(Cluster node,
                           long delta)
```
    Increment the counter with the delta specified. If the delta is negative then it will decrement instead of increment.
    
    Parameters:
    
    node - (undocumented)
    
    delta - (undocumented)
    
    Returns:
    
    (undocumented)
  - decrement
```
public PNCounter decrement(Cluster node,
                           long delta)
```
    Decrement the counter with the delta specified. If the delta is negative then it will increment instead of decrement.
    
    Parameters:
    
    node - (undocumented)
    
    delta - (undocumented)
    
    Returns:
    
    (undocumented)
  - increment
```
public PNCounter increment(UniqueAddress key,
                           long delta)
```
  - increment
```
public PNCounter increment(UniqueAddress key)
```
  - decrement
```
public PNCounter decrement(UniqueAddress key,
                           long delta)
```
    Decrement the counter with the delta specified. If the delta is negative then it will increment instead of decrement.
    
    Parameters:
    
    key - (undocumented)
    
    delta - (undocumented)
    
    Returns:
    
    (undocumented)
  - decrement
```
public PNCounter decrement(UniqueAddress key)
```
  - change
```
public PNCounter change(UniqueAddress key,
                        long delta)
```
  - merge
```
public PNCounter merge(PNCounter that)
```
  - needPruningFrom
```
public 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 PNCounter 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 PNCounter 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)
  - 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

Class PNCounter

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface akka.cluster.ddata.ReplicatedData

Constructor Detail

PNCounter

Method Detail

empty

apply

create

unapply

increments

decrements

value

getValue

increment

decrement

increment

increment

decrement

decrement

change

merge

needPruningFrom

prune

pruningCleanup

toString

equals

hashCode