Package org.nuxeo.ecm.core.storage.sql

Class Selection

java.lang.Object

org.nuxeo.ecm.core.storage.sql.Selection

public class Selection
extends Object

A Selection holds information about row ids corresponding to a fixed clause for a given table.

A clause has the form: column = fixed value. The column can be the parent id, the versionable id, the target id.

The internal state of a Selection instance reflects:

• corresponding rows known to exist in the database,
• corresponding created rows not yet flushed to database,
• corresponding rows not yet flushed to database.

Information about rows in the database may be complete, or just partial if only individual rows corresponding to the clause have been retrieved from the database.

Row ids are stored in no particular order.

When this structure holds information all flushed to the database, then it can safely be GC'ed, so it lives in a memory-sensitive map (softMap), otherwise it's moved to a normal map (hardMap).

This class is not thread-safe and should be used only from a single-threaded session.

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	complete	This is true when complete information about the existing ids is known.
protected PersistenceContext	context	The context used to fetch fragments.
protected Set<Serializable>	created	The row ids created and not yet flushed to database.
protected Set<Serializable>	deleted	The row ids deleted (or for which the clause column changed value) and not yet flushed to database.
protected Set<Serializable>	existing	The row ids known in the database and not deleted.
protected String	filterKey	The key to use to filter.

Constructor Summary

Constructors

Constructor	Description
Selection(Serializable selId, String tableName, boolean empty, String filterKey, PersistenceContext context, Map<Serializable,Selection> softMap, Map<Serializable,Selection> hardMap)	Constructs a Selection for the given selection id.

Method Summary

Modifier and Type	Method	Description
void	addCreated(Serializable id)	Adds a created row corresponding to the clause.
void	addExisting(Serializable id)	Adds a known row corresponding to the clause.
void	addExistingComplete(List<Serializable> actualExisting)	Adds ids actually read from the backend, and mark this complete.
void	flush()	Flushes to database.
protected Serializable	fragmentValue(SimpleFragment fragment)
SimpleFragment	getFragmentByValue(Serializable filter)	Gets a fragment given its filtered value.
List<SimpleFragment>	getFragmentsByValue(Serializable filter)	Gets all the fragments, if the selection is complete.
Set<Serializable>	getIds()	Gets the ids in that fragment, if complete (otherwise returns null).
boolean	isFlushed()
void	remove(Serializable id)	Removes a known child id.
void	setIncomplete()	Marks as incomplete.
protected void	warnIfBig(int added)

Methods inherited from class java.lang.Object

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

Field Detail

context

protected final PersistenceContext context

The context used to fetch fragments.

filterKey

protected final String filterKey

The key to use to filter.

For instance for a children selection this is the child name.

complete

protected boolean complete

This is true when complete information about the existing ids is known.

This is the case when a query to the database has been made to fetch all rows with the clause, or when a new value for the clause has been created (applies for instance to a new parent id appearing when a folder is created).

existing

protected Set<Serializable> existing

The row ids known in the database and not deleted.

created

protected Set<Serializable> created

The row ids created and not yet flushed to database.

deleted

protected Set<Serializable> deleted

The row ids deleted (or for which the clause column changed value) and not yet flushed to database.

Constructor Detail

Selection

public Selection(Serializable selId,
                 String tableName,
                 boolean empty,
                 String filterKey,
                 PersistenceContext context,
                 Map<Serializable,Selection> softMap,
                 Map<Serializable,Selection> hardMap)

Constructs a Selection for the given selection id.

It is automatically put in the soft map.

Parameters:

selId - the selection key (used in the soft/hard maps)

tableName - the table name to fetch fragments

empty - if the new instance is created empty

filterKey - the key to use to additionally filter on fragment values

context - the context from which to fetch fragments

softMap - the soft map, when the selection is pristine

hardMap - the hard map, when there are modifications to flush

Method Detail

getIds

public Set<Serializable> getIds()

Gets the ids in that fragment, if complete (otherwise returns null).

Since:

9.2

fragmentValue

protected Serializable fragmentValue(SimpleFragment fragment)

addExisting

public void addExisting(Serializable id)

Adds a known row corresponding to the clause.

Parameters:

id - the fragment id

addCreated

public void addCreated(Serializable id)

Adds a created row corresponding to the clause.

Parameters:

id - the fragment id

addExistingComplete

public void addExistingComplete(List<Serializable> actualExisting)

Adds ids actually read from the backend, and mark this complete.

Note that when adding a complete list of ids retrieved from the database, the deleted ids have already been removed in the result set.

Parameters:

actualExisting - the existing database ids (the list must be mutable)

setIncomplete

public void setIncomplete()

Marks as incomplete.

Called after a database operation added rows corresponding to the clause with unknown ids (restore of complex properties).

remove

public void remove(Serializable id)

Removes a known child id.

Parameters:

id - the id to remove

flush

public void flush()

Flushes to database. Clears created and deleted map.

Puts this in the soft map. Caller must remove from hard map.

warnIfBig

protected void warnIfBig(int added)

isFlushed

public boolean isFlushed()

getFragmentByValue

public SimpleFragment getFragmentByValue(Serializable filter)

Gets a fragment given its filtered value.

Returns null if there is no such fragment.

Returns SimpleFragment.UNKNOWN if there's no info about it.

Parameters:

filter - the value to filter on (cannot be null)

Returns:

the fragment, or null, or SimpleFragment.UNKNOWN

getFragmentsByValue

public List<SimpleFragment> getFragmentsByValue(Serializable filter)

Gets all the fragments, if the selection is complete.

Parameters:

filter - the value to filter on, or null for the whole selection

Returns:

the fragments, or null if the list is not known to be complete