Class ORSet<A>
- java.lang.Object
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- akka.persistence.typed.crdt.ORSet<A>
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- All Implemented Interfaces:
OpCrdt<ORSet.DeltaOp>
public final class ORSet<A> extends java.lang.Object implements OpCrdt<ORSet.DeltaOp>
Implements a 'Observed Remove Set' operation based CRDT, also called a 'OR-Set'. Elements can be added and removed any number of times. Concurrent add wins over remove.It is not implemented as in the paper A comprehensive study of Convergent and Commutative Replicated Data Types. This is more space efficient and doesn't accumulate garbage for removed elements. It is described in the paper An optimized conflict-free replicated set The implementation is inspired by the Riak DT riak_dt_orswot.
The ORSet has a version vector that is incremented when an element is added to the set. The
DC -> count
pair for that increment is stored against the element as its "birth dot". Every time the element is re-added to the set, its "birth dot" is updated to that of theDC -> count
version vector entry resulting from the add. When an element is removed, we simply drop it, no tombstones.When an element exists in replica A and not replica B, is it because A added it and B has not yet seen that, or that B removed it and A has not yet seen that? In this implementation we compare the
dot
of the present element to the version vector in the Set it is absent from. If the element dot is not "seen" by the Set version vector, that means the other set has yet to see this add, and the item is in the merged Set. If the Set version vector dominates the dot, that means the other Set has removed this element already, and the item is not in the merged Set.This class is immutable, i.e. "modifying" methods return a new instance.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
ORSet.AddDeltaOp$
static class
ORSet.DeltaGroup$
static interface
ORSet.DeltaOp
static class
ORSet.FullStateDeltaOp$
static class
ORSet.RemoveDeltaOp$
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description ORSet.DeltaOp
$minus(A element)
Removes an element from the set.ORSet.DeltaOp
$plus(A element)
Adds an element to the setORSet.DeltaOp
add(A element)
Adds an element to the setORSet.DeltaOp
addAll(java.util.Set<A> elems)
Java API: Add several elements to the set.ORSet.DeltaOp
addAll(scala.collection.immutable.Set<A> elems)
Scala API: Add several elements to the set.static <A> ORSet<A>
apply(ReplicaId originReplica)
ORSet<A>
applyOperation(ORSet.DeltaOp thatDelta)
ORSet.DeltaOp
clear()
Removes all elements from the set, but keeps the history.boolean
contains(A a)
static <A> ORSet<A>
create(ReplicaId originReplica)
Java APIscala.collection.immutable.Set<A>
elements()
Scala APIstatic <A> ORSet<A>
empty(ReplicaId originReplica)
boolean
equals(java.lang.Object o)
java.util.Set<A>
getElements()
Java APIint
hashCode()
boolean
isEmpty()
java.lang.String
originReplica()
ORSet.DeltaOp
remove(A element)
Removes an element from the set.ORSet.DeltaOp
removeAll(java.util.Set<A> elems)
Java API: Remove several elements from the set.ORSet.DeltaOp
removeAll(scala.collection.immutable.Set<A> elems)
Scala API: Remove several elements from the set.int
size()
java.lang.String
toString()
static <A> scala.Option<scala.collection.immutable.Set<A>>
unapply(ORSet<A> s)
Extract theelements()
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Method Detail
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unapply
public static <A> scala.Option<scala.collection.immutable.Set<A>> unapply(ORSet<A> s)
Extract theelements()
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originReplica
public java.lang.String originReplica()
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elements
public scala.collection.immutable.Set<A> elements()
Scala API
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getElements
public java.util.Set<A> getElements()
Java API
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contains
public boolean contains(A a)
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isEmpty
public boolean isEmpty()
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size
public int size()
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$plus
public ORSet.DeltaOp $plus(A element)
Adds an element to the set
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add
public ORSet.DeltaOp add(A element)
Adds an element to the set
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addAll
public ORSet.DeltaOp addAll(java.util.Set<A> elems)
Java API: Add several elements to the set.elems
must not be empty.
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addAll
public ORSet.DeltaOp addAll(scala.collection.immutable.Set<A> elems)
Scala API: Add several elements to the set.elems
must not be empty.
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$minus
public ORSet.DeltaOp $minus(A element)
Removes an element from the set.
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remove
public ORSet.DeltaOp remove(A element)
Removes an element from the set.
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removeAll
public ORSet.DeltaOp removeAll(java.util.Set<A> elems)
Java API: Remove several elements from the set.elems
must not be empty.
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removeAll
public ORSet.DeltaOp removeAll(scala.collection.immutable.Set<A> elems)
Scala API: Remove several elements from the set.elems
must not be empty.
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clear
public ORSet.DeltaOp clear()
Removes all elements from the set, but keeps the history. This has the same result as usingremove(A)
for each element, but it is more efficient.
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applyOperation
public ORSet<A> applyOperation(ORSet.DeltaOp thatDelta)
- Specified by:
applyOperation
in interfaceOpCrdt<A>
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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equals
public boolean equals(java.lang.Object o)
- Overrides:
equals
in classjava.lang.Object
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hashCode
public int hashCode()
- Overrides:
hashCode
in classjava.lang.Object
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