com.bigdata.gom.om

Class ObjectMgrModel

java.lang.Object

com.bigdata.gom.om.ObjectMgrModel

All Implemented Interfaces:

INativeTransaction, IObjectManager

Direct Known Subclasses:

NanoSparqlObjectManager, ObjectManager

public abstract class ObjectMgrModel
extends Object
implements IObjectManager

Base class for IObjectManager implementations. This class handles IObjectManager protocol for maintaining an transaction edit list. Concrete implementations need to provide for communication with the database (either remote or embedded) and the DESCRIBE (aka Object) cache.

Author:

Martyn Cutcher, Bryan Thompson

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_maxDirtyListSize Default to maximum dirty list size to lock out any incremental flushing.
protected BigdataValueFactory	m_valueFactory

Constructor Summary

Constructors

Constructor and Description
ObjectMgrModel(String endpoint, BigdataValueFactory valueFactory)

Method Summary

Methods

Modifier and Type	Method and Description
void	addToDirtyList(GPO gpo) GPOs are added to the dirty list when initially modified.
int	beginNativeTransaction() Increments the native transaction counter.
<T> T	bestEffortIntern(T t) Make a best effort attempt to use the Resource associated with an IGPO in the running object table
void	clearCache()
void	close() Close the object manager, which terminates its connection with the backing store.
int	commitNativeTransaction(int expectedCounter) The native transaction is committed when the counter reaches zero.
IGPO	createGPO() The ObjectManager is able to assign automatic ids for a new object.
String	encode(org.openrdf.model.Resource v) Encode a URL, Literal, or blank node for inclusion in a SPARQL query to be sent to the remote service.
protected abstract void	flushStatements(List<org.openrdf.model.Statement> insertList, List<org.openrdf.model.Statement> removeList) Flush statements to be inserted and removed to the backing store..
IGPO	getDefaultNameMgr()
int	getDirtyObjectCount()
IGPO	getGPO(org.openrdf.model.Resource id) Return a canonical IGPO for the Resource (canonical within the scope of this object manager) and never null.
IGPO	getGPO(org.openrdf.model.Statement stmt) FIXME This is using the String representation of the Statement as the blank node ID.
Iterator<WeakReference<IGPO>>	getGPOs() An iterator that visits the weak reference values in the running object table.
UUID	getID()
Iterator<org.openrdf.model.URI>	getNames() Return the list of names that have been used to save references.
int	getNativeTransactionCounter() The current value of the native transaction counter.
BigdataValueFactory	getValueFactory() The value factory for the KB instance associated with this object manager view.
protected Map<org.openrdf.model.Resource,IGPO>	initGPO(GPO gpo, ICloseableIterator<org.openrdf.model.Statement> stmts) Initialize one or more IGPOs from a collection of statements.
Map<org.openrdf.model.Resource,IGPO>	initGPOs(ICloseableIterator<org.openrdf.model.Statement> itr) Partially materialize IGPOs from a stream of Statements.
BigdataURI	internKey(org.openrdf.model.URI aKey) Intern a predicate (internal API).
void	materialize(IGPO gpo) Ensure Statements are materialized for gpo's Resource: DESCRIBE ?s.
protected void	materializeWithDescribe(IGPO gpo)
protected void	materializeWithSelect(IGPO gpo)
org.openrdf.model.Value	recall(org.openrdf.model.URI key) Deprecated.
IGPO	recallAsGPO(org.openrdf.model.URI key) Deprecated.
void	remove(IGPO gpo) Remove all assertions involving the specified object.
void	rollbackNativeTransaction() Rollback all changes since the last time the native transaction counter was zero.
void	save(org.openrdf.model.URI key, org.openrdf.model.Value value) Deprecated.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.bigdata.gom.om.IObjectManager

evaluate, evaluateGraph, execute, isPersistent

Field Detail

m_valueFactory

protected final BigdataValueFactory m_valueFactory

m_maxDirtyListSize

protected int m_maxDirtyListSize

Default to maximum dirty list size to lock out any incremental flushing.

Note: Incremental eviction breaks the ACID contract for updates. Thus, the dirty list should not be limited in capacity.

Constructor Detail

ObjectMgrModel

public ObjectMgrModel(String endpoint,
              BigdataValueFactory valueFactory)

Parameters:

endpoint - The SPARQL endpoint that can be used to communicate with the database.

valueFactory - The value factory.

Method Detail

getDefaultNameMgr

public IGPO getDefaultNameMgr()

getID

public UUID getID()

Specified by:

getID in interface IObjectManager

Returns:

the UUID that identifies this ObjectManager

getValueFactory

public final BigdataValueFactory getValueFactory()

Description copied from interface: IObjectManager

The value factory for the KB instance associated with this object manager view.

Specified by:

getValueFactory in interface IObjectManager

internKey

public BigdataURI internKey(org.openrdf.model.URI aKey)

Intern a predicate (internal API). This provides the guarantee that we can use reference tests (==) for URIs within the scope of a given object manager.

Parameters:

key - The predicate.

Returns:

The interned version of the predicate.

bestEffortIntern

public <T> T bestEffortIntern(T t)

Make a best effort attempt to use the Resource associated with an IGPO in the running object table

Parameters:

t - Some identifier.

Returns:

Either the same reference or one that will be canonical as long as that IGPO remains pinned in the running object table.

addToDirtyList

public void addToDirtyList(GPO gpo)

GPOs are added to the dirty list when initially modified. The dirty list is not bounded. Large updates should be done using the RDF and SPARQL layer which do not have this implicit scaling limit.

Note: We can not do incremental eviction unless we are holding open a connection to the database that will isolate those edits. This could be done in principle with either full read/write transactions or with the unisolated connection (if embedded) but we do not yet support remove create/run/commit for full read/write transactions in the NSS REST API. The problem with holding the unisolated connection across incremental updates is that it will lock out any other updates against the backing store for the life cycle of the object manager.

getDirtyObjectCount

public int getDirtyObjectCount()

Returns:

size of dirty list

flushStatements

protected abstract void flushStatements(List<org.openrdf.model.Statement> insertList,
                   List<org.openrdf.model.Statement> removeList)

Flush statements to be inserted and removed to the backing store..

Parameters:

insertList - The list of statements to be added.

removeList - The list of statements to be removed.

getGPO

public IGPO getGPO(org.openrdf.model.Resource id)

Description copied from interface: IObjectManager

Return a canonical IGPO for the Resource (canonical within the scope of this object manager) and never null.

Specified by:

getGPO in interface IObjectManager

Parameters:

id - The Resource.

Returns:

The IGPO.

See Also:

IGPO.getId()

getGPO

public IGPO getGPO(org.openrdf.model.Statement stmt)

FIXME This is using the String representation of the Statement as the blank node ID. It needs to work with the stable IVs as assigned by the lexicon. However, we need to ensure that the IVs are being reported through to the object manager in the various interchange formats that it uses and work through how we will provide that information in the SELECT query as well as CONSTRUCT and DESCRIBE (basically, we need to conneg for a MIME Type that supports it).

Specified by:

getGPO in interface IObjectManager

getGPOs

public Iterator<WeakReference<IGPO>> getGPOs()

Description copied from interface: IObjectManager

An iterator that visits the weak reference values in the running object table. You must test each weak reference in order to determine whether its value has been cleared as of the moment that you request that value. The entries visited by the iterator are not "touched" so the use of the iterator will not cause them to be retained any longer than they otherwise would have been retained. TODO We could do one-step look ahead and buffer a hard reference to the next IGPO to be visited. That would allow us to eliminate the WeakReference from this method signature.

Specified by:

getGPOs in interface IObjectManager

materialize

public void materialize(IGPO gpo)

Description copied from interface: IObjectManager

Ensure Statements are materialized for gpo's Resource: DESCRIBE ?s.

Specified by:

materialize in interface IObjectManager

materializeWithDescribe

protected void materializeWithDescribe(IGPO gpo)

materializeWithSelect

protected void materializeWithSelect(IGPO gpo)

initGPOs

public Map<org.openrdf.model.Resource,IGPO> initGPOs(ICloseableIterator<org.openrdf.model.Statement> itr)

Description copied from interface: IObjectManager

Partially materialize IGPOs from a stream of Statements.

Specified by:

initGPOs in interface IObjectManager

Parameters:

itr - The Statements.

Returns:

A hard reference collection that will keep the any materialized IGPOs from being finalized before the caller has a chance to do something with them.

initGPO

protected Map<org.openrdf.model.Resource,IGPO> initGPO(GPO gpo,
                                           ICloseableIterator<org.openrdf.model.Statement> stmts)

Initialize one or more IGPOs from a collection of statements.

Parameters:

gpo - The gpo (optional). When given, only the specified IGPO will be initialized. When not provided, all Resources in the subject and object position of the visited Statements will be resolved to IGPOs and the corresponding properties and/or links initialized from the Statements.

stmts - The statements.

Returns:

A hard reference collection that will keep the any materialized IGPOs from being finalized before the caller has a chance to do something with them.

beginNativeTransaction

public int beginNativeTransaction()

Description copied from interface: INativeTransaction

Increments the native transaction counter. When this counter reaches zero, the transaction will be committed.

Specified by:

beginNativeTransaction in interface INativeTransaction

Returns:

The new value of the native transaction counter, i.e., after it was incremented.

commitNativeTransaction

public int commitNativeTransaction(int expectedCounter)

Description copied from interface: INativeTransaction

The native transaction is committed when the counter reaches zero. This method accepts the value returned by INativeTransaction.beginNativeTransaction() and throws an exception if expectedCounter is not equal to the internal counter. This provides an eager search for un-matched native transactions.

Specified by:

commitNativeTransaction in interface INativeTransaction

Returns:

The value of the counter after it has been decremented. If the returned value is zero, then the native transaction was committed.

getNativeTransactionCounter

public int getNativeTransactionCounter()

Description copied from interface: INativeTransaction

The current value of the native transaction counter.

Specified by:

getNativeTransactionCounter in interface INativeTransaction

rollbackNativeTransaction

public void rollbackNativeTransaction()

Description copied from interface: INativeTransaction

Rollback all changes since the last time the native transaction counter was zero.

Specified by:

rollbackNativeTransaction in interface INativeTransaction

createGPO

public IGPO createGPO()

Description copied from interface: IObjectManager

The ObjectManager is able to assign automatic ids for a new object. These will be of the form "gpo:#[genid]"

Specified by:

createGPO in interface IObjectManager

Returns:

a new GPO

remove

public final void remove(IGPO gpo)

Description copied from interface: IObjectManager

Remove all assertions involving the specified object.

Specified by:

remove in interface IObjectManager

save

@Deprecated
public void save(org.openrdf.model.URI key,
                   org.openrdf.model.Value value)

Deprecated.

Simple save/recall interface that the ObjectManager provides to simplify other pattern implementations. Internally it uses a NameManager GPO

Specified by:

save in interface IObjectManager

recall

@Deprecated
public org.openrdf.model.Value recall(org.openrdf.model.URI key)

Deprecated.

Simple save/recall interface that the ObjectManager provides to simplify other pattern implementations. Internally it uses a NameManager GPO

Specified by:

recall in interface IObjectManager

recallAsGPO

@Deprecated
public IGPO recallAsGPO(org.openrdf.model.URI key)

Deprecated.

Specified by:

recallAsGPO in interface IObjectManager

getNames

public Iterator<org.openrdf.model.URI> getNames()

Return the list of names that have been used to save references. These are the properties of the internal NameManager.

Specified by:

getNames in interface IObjectManager

close

public void close()

Description copied from interface: IObjectManager

Close the object manager, which terminates its connection with the backing store. Any open concurrent or nested/native transactions are flushed to the store. The object manager can not be used after it has been closed.

Specified by:

close in interface IObjectManager

clearCache

public final void clearCache()

encode

public String encode(org.openrdf.model.Resource v)

Encode a URL, Literal, or blank node for inclusion in a SPARQL query to be sent to the remote service.

Parameters:

v - The resource.

Returns:

The encoded representation of the resource. TODO This must correctly encode a URL, Literal, or blank node for inclusion in a SPARQL query to be sent to the remote service.