952be31a7d
* fix merge issues of DataEnvelope and its pruning * simplify by removing the tombstones, which didn't work in all cases anyway * keep the PruningPerformed markers in the DataEnvelope until configured TTL has elapsed (wall clock) * simplify PruningState structure * also store the pruning markers in durable data * collect removed nodes from the data, listing on MemberRemoved is not enough * possibility to disable pruning altogether * documented caveat for durable data
108 lines
3.2 KiB
Scala
108 lines
3.2 KiB
Scala
/**
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* Copyright (C) 2009-2017 Lightbend Inc. <http://www.lightbend.com>
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*/
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package akka.cluster.ddata
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import akka.cluster.UniqueAddress
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/**
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* Interface for implementing a state based convergent
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* replicated data type (CvRDT).
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*
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* ReplicatedData types must be serializable with an Akka
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* Serializer. It is highly recommended to implement a serializer with
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* Protobuf or similar. The built in data types are marked with
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* [[ReplicatedDataSerialization]] and serialized with
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* [[akka.cluster.ddata.protobuf.ReplicatedDataSerializer]].
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*
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* Serialization of the data types are used in remote messages and also
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* for creating message digests (SHA-1) to detect changes. Therefore it is
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* important that the serialization produce the same bytes for the same content.
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* For example sets and maps should be sorted deterministically in the serialization.
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*
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* ReplicatedData types should be immutable, i.e. "modifying" methods should return
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* a new instance.
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*/
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trait ReplicatedData {
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/**
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* The type of the concrete implementation, e.g. `GSet[A]`.
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* To be specified by subclass.
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*/
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type T <: ReplicatedData
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/**
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* Monotonic merge function.
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*/
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def merge(that: T): T
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}
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/**
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* Java API: Interface for implementing a [[ReplicatedData]] in Java.
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*
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* The type parameter `D` is a self-recursive type to be defined by the
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* concrete implementation.
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* E.g. `class TwoPhaseSet extends AbstractReplicatedData<TwoPhaseSet>`
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*/
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abstract class AbstractReplicatedData[D <: AbstractReplicatedData[D]] extends ReplicatedData {
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override type T = ReplicatedData
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/**
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* Delegates to [[#mergeData]], which must be implemented by subclass.
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*/
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final override def merge(that: ReplicatedData): ReplicatedData =
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mergeData(that.asInstanceOf[D])
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/**
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* Java API: Monotonic merge function.
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*/
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def mergeData(that: D): D
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}
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/**
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* [[ReplicatedData]] that has support for pruning of data
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* belonging to a specific node may implement this interface.
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* When a node is removed from the cluster these methods will be
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* used by the [[Replicator]] to collapse data from the removed node
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* into some other node in the cluster.
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*
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* See process description in the 'CRDT Garbage' section of the [[Replicator]]
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* documentation.
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*/
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trait RemovedNodePruning extends ReplicatedData {
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/**
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* The nodes that have changed the state for this data
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* and would need pruning when such node is no longer part
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* of the cluster.
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*/
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def modifiedByNodes: Set[UniqueAddress]
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/**
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* Does it have any state changes from a specific node,
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* which has been removed from the cluster.
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*/
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def needPruningFrom(removedNode: UniqueAddress): Boolean
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/**
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* When the `removed` node has been removed from the cluster the state
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* changes from that node will be pruned by collapsing the data entries
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* to another node.
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*/
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def prune(removedNode: UniqueAddress, collapseInto: UniqueAddress): T
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/**
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* Remove data entries from a node that has been removed from the cluster
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* and already been pruned.
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*/
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def pruningCleanup(removedNode: UniqueAddress): T
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}
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/**
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* Marker trait for `ReplicatedData` serialized by
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* [[akka.cluster.ddata.protobuf.ReplicatedDataSerializer]].
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*/
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trait ReplicatedDataSerialization extends Serializable
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