final class GCounter extends DeltaReplicatedData with ReplicatedDelta with ReplicatedDataSerialization with RemovedNodePruning with FastMerge

Implements a 'Growing Counter' CRDT, also called a 'G-Counter'.

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

A G-Counter is a increment-only counter (inspired by vector clocks) in which only increment and merge are possible. Incrementing the counter adds 1 to the count for the current node. Divergent histories are resolved by taking the maximum count for each node (like a vector clock merge). The value of the counter is the sum of all node counts.

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

Annotations
@SerialVersionUID()
Source
GCounter.scala
Linear Supertypes
FastMerge, RemovedNodePruning, ReplicatedDataSerialization, Serializable, ReplicatedDelta, DeltaReplicatedData, ReplicatedData, AnyRef, Any
Type Hierarchy
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Inherited
  1. GCounter
  2. FastMerge
  3. RemovedNodePruning
  4. ReplicatedDataSerialization
  5. Serializable
  6. ReplicatedDelta
  7. DeltaReplicatedData
  8. ReplicatedData
  9. AnyRef
  10. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. Protected

Type Members

  1. type D = GCounter

    The type of the delta.

    The type of the delta. To be specified by subclass. It may be the same type as T or a different type if needed. For example GSet uses the same type and ORSet uses different types.

    Definition Classes
    GCounter → DeltaReplicatedData
  2. type T = GCounter

    The type of the concrete implementation, e.g.

    The type of the concrete implementation, e.g. GSet[A]. To be specified by subclass.

    Definition Classes
    GCounter → ReplicatedData

Value Members

  1. def :+(n: Long)(implicit node: SelfUniqueAddress): GCounter

    Increment the counter with the delta n specified.

    Increment the counter with the delta n specified. The delta must be zero or positive.

  2. val delta: Option[GCounter]

    The accumulated delta of mutator operations since previous #resetDelta.

    The accumulated delta of mutator operations since previous #resetDelta. When the 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 Replicator with the #delta accessor. The modify function shall still return the full state in the same way as ReplicatedData without support for deltas.

    Definition Classes
    GCounter → DeltaReplicatedData
  3. def equals(o: Any): Boolean
    Definition Classes
    GCounter → AnyRef → Any
  4. def getValue: BigInteger

    Java API: Current total value of the counter.

  5. def hashCode(): Int
    Definition Classes
    GCounter → AnyRef → Any
  6. def increment(node: SelfUniqueAddress, n: Long): GCounter

    Increment the counter with the delta n specified.

    Increment the counter with the delta n specified. The delta n must be zero or positive.

  7. def merge(that: GCounter): GCounter

    Monotonic merge function.

    Monotonic merge function.

    Definition Classes
    GCounter → ReplicatedData
  8. def mergeDelta(thatDelta: GCounter): GCounter

    When delta is merged into the full state this method is used.

    When delta is merged into the full state this method is used. When the type D of the delta is of the same type as the full state T this method can be implemented by delegating to merge.

    Definition Classes
    GCounter → DeltaReplicatedData
  9. def modifiedByNodes: Set[UniqueAddress]

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

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

    Definition Classes
    GCounter → RemovedNodePruning
  10. def needPruningFrom(removedNode: UniqueAddress): Boolean

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

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

    Definition Classes
    GCounter → RemovedNodePruning
  11. def prune(removedNode: UniqueAddress, collapseInto: UniqueAddress): GCounter

    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.

    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.

    Definition Classes
    GCounter → RemovedNodePruning
  12. def pruningCleanup(removedNode: UniqueAddress): GCounter

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

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

    Definition Classes
    GCounter → RemovedNodePruning
  13. def resetDelta: GCounter

    Reset collection of deltas from mutator operations.

    Reset collection of deltas from mutator operations. When the 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 Replicator with the #delta accessor. When the Replicator has grabbed the delta it will invoke this method to get a clean data instance without the delta.

    Definition Classes
    GCounter → DeltaReplicatedData
  14. def toString(): String
    Definition Classes
    GCounter → AnyRef → Any
  15. def value: BigInt

    Scala API: Current total value of the counter.

  16. def zero: GCounter

    The empty full state.

    The empty full state. This is used when a delta is received and no existing full state exists on the receiving side. Then the delta is merged into the zero to create the initial full state.

    Definition Classes
    GCounter → ReplicatedDelta

Deprecated Value Members

  1. def +(n: Long)(implicit node: Cluster): GCounter
    Annotations
    @deprecated
    Deprecated

    (Since version 2.5.20) Use :+ that takes a SelfUniqueAddress parameter instead.

  2. def increment(node: Cluster, n: Long = 1): GCounter
    Annotations
    @deprecated
    Deprecated

    (Since version 2.5.20) Use increment that takes a SelfUniqueAddress parameter instead.