org.janusgraph.diskstorage

Class Mutation<E,K>

java.lang.Object

org.janusgraph.diskstorage.Mutation<E,K>

Direct Known Subclasses:

IndexMutation, KCVEntryMutation, KCVMutation, KVMutation

public abstract class Mutation<E,K>
extends Object

Container for collection mutations against a data store. Mutations are either additions or deletions.

Author:

Matthias Broecheler (me@matthiasb.com)

Constructor Summary

Constructors

Constructor and Description
Mutation()
Mutation(List<E> additions, List<K> deletions)

Method Summary

Modifier and Type	Method and Description
void	addition(E entry) Adds a new entry as an addition to this mutation
abstract void	consolidate()
<V> void	consolidate(com.google.common.base.Function<E,V> convertAdditions, com.google.common.base.Function<K,V> convertDeletions) Consolidates this mutation by removing redundant deletions.
void	deletion(K key) Adds a new key as a deletion to this mutation
List<E>	getAdditions() Returns the list of additions in this mutation
List<K>	getDeletions() Returns the list of deletions in this mutation.
int	getTotalMutations()
boolean	hasAdditions() Whether this mutation has additions
boolean	hasDeletions() Whether this mutation has deletions
abstract boolean	isConsolidated()
<V> boolean	isConsolidated(com.google.common.base.Function<E,V> convertAdditions, com.google.common.base.Function<K,V> convertDeletions) Checks whether this mutation is consolidated in the sense of consolidate(com.google.common.base.Function, com.google.common.base.Function).
boolean	isEmpty()
void	merge(Mutation<E,K> m) Merges another mutation into this mutation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Mutation

public Mutation(List<E> additions,
                List<K> deletions)

Mutation

public Mutation()

Method Detail

hasAdditions

public boolean hasAdditions()

Whether this mutation has additions

Returns:

hasDeletions

public boolean hasDeletions()

Whether this mutation has deletions

Returns:

getAdditions

public List<E> getAdditions()

Returns the list of additions in this mutation

Returns:

getDeletions

public List<K> getDeletions()

Returns the list of deletions in this mutation.

Returns:

addition

public void addition(E entry)

Adds a new entry as an addition to this mutation

Parameters:

entry -

deletion

public void deletion(K key)

Adds a new key as a deletion to this mutation

Parameters:

key -

merge

public void merge(Mutation<E,K> m)

Merges another mutation into this mutation. Ensures that all additions and deletions are added to this mutation. Does not remove duplicates if such exist - this needs to be ensured by the caller.

Parameters:

m -

isEmpty

public boolean isEmpty()

getTotalMutations

public int getTotalMutations()

consolidate

public <V> void consolidate(com.google.common.base.Function<E,V> convertAdditions,
                            com.google.common.base.Function<K,V> convertDeletions)

Consolidates this mutation by removing redundant deletions. A deletion is considered redundant if it is identical to some addition under the provided conversion functions since we consider additions to apply logically after deletions. Hence, such a deletion would be applied and immediately overwritten by an addition. To avoid this inefficiency, consolidation should be called.

The provided conversion functions map additions and deletions into some object space V for comparison. An addition is considered identical to a deletion if both map to the same object (i.e. equals=true) with the respective conversion functions.

It needs to be ensured that V objects have valid hashCode() and equals() implementations.

Parameters:

convertAdditions - Function which maps additions onto comparison objects.

convertDeletions - Function which maps deletions onto comparison objects.

consolidate

public abstract void consolidate()

isConsolidated

public <V> boolean isConsolidated(com.google.common.base.Function<E,V> convertAdditions,
                                  com.google.common.base.Function<K,V> convertDeletions)

Checks whether this mutation is consolidated in the sense of consolidate(com.google.common.base.Function, com.google.common.base.Function). This should only be used in assertions and tests due to the performance penalty.

Type Parameters:

V -

Parameters:

convertAdditions -

convertDeletions -

Returns:

isConsolidated

public abstract boolean isConsolidated()