cern.entwined

Class CompositeCollection

java.lang.Object

cern.entwined.SemiPersistent<CompositeCollection>

cern.entwined.CompositeCollection

public final class CompositeCollection
extends SemiPersistent<CompositeCollection>

This class is aimed at simplification of client collection and snapshot implementations. Simple adapter mapping array index to transactional collection would suffice.

DISCLAIMER This collection must never be used by clients directly! Use it only to implement custom collections and snapshots.

Author:

Ivan Koblik

Constructor Summary

Constructors

Constructor and Description
CompositeCollection(SemiPersistent... references) Creates a new CompositeCollection with given references.

Method Summary

Methods

Modifier and Type	Method and Description
CompositeCollection	cleanCopy() Creates a new transactional entity from the current one discarding all the local changes.
CompositeCollection	commit(CompositeCollection globalState)
CompositeCollection	dirtyCopy() Copies references to the source data along with local changes and read/write logs.
<T extends SemiPersistent> T	get(int idx) Returns a transactional reference or collection with the give index.
void	update(CompositeCollection changes, boolean onlyReadLogs) Updates local changes and change logs using change logs of the arguments.

Methods inherited from class java.lang.Object

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

Constructor Detail

CompositeCollection

public CompositeCollection(SemiPersistent... references)

Creates a new CompositeCollection with given references.

Parameters:

references - Transactional references or collections. Elements cannot be null.

Method Detail

cleanCopy

public final CompositeCollection cleanCopy()

Creates a new transactional entity from the current one discarding all the local changes.
Visibility is changed to public to let client collections use STM library collections through this composite, but it also means that client collection must not expose this class.

Specified by:

cleanCopy in class SemiPersistent<CompositeCollection>

Returns:

The new entity with no local changes.

dirtyCopy

public final CompositeCollection dirtyCopy()

Copies references to the source data along with local changes and read/write logs.
Note: It is very important to copy source data by reference, otherwise SemiPersistent#update(Object) will not work.
Visibility is changed to public to let client collections use STM library collections through this composite, but it also means that client collection must not expose this class.

Specified by:

dirtyCopy in class SemiPersistent<CompositeCollection>

Returns:

Dirty copy of this collection, with all the local changes and read/write logs preserved.

update

public void update(CompositeCollection changes,
          boolean onlyReadLogs)

Updates local changes and change logs using change logs of the arguments. Argument must be constructed from this using SemiPersistent.dirtyCopy().
Note: Any changes done to this collections after branching will be discarded.
Visibility is changed to public to let client collections use STM library collections through this composite, but it also means that client collection must not expose this class.

Specified by:

update in class SemiPersistent<CompositeCollection>

Parameters:

changes - The branched collection possibly with updates.

onlyReadLogs - If true only read logs are updated. Useful for read-only transactions.

commit

public final CompositeCollection commit(CompositeCollection globalState)

get

public final <T extends SemiPersistent> T get(int idx)

Returns a transactional reference or collection with the give index.

Note: Be very careful with this method! Due to the way generics are implemented in Java, no real type checking is performed. This method silently casts element to the desired type.

See the example below, both lines of code are getting element number zero from the same collection, none of them will be statically checked by the compiler , but it is certain that in runtime at least one of them is due to fail.

 TransactionalRef<Integer> ref = compositeCollection.get(0);
 TransactionalMap<Integer, Double> map = compositeCollection.get(0);
 

Type Parameters:

T - The desired type of the resulting value.

Parameters:

idx - The index.

Returns:

Requested transactional reference or collection.