com.bigdata.rdf.graph.impl.bd

Class BigdataGASState<VS,ES,ST>

java.lang.Object

com.bigdata.rdf.graph.impl.GASState<VS,ES,ST>

com.bigdata.rdf.graph.impl.bd.BigdataGASState<VS,ES,ST>

All Implemented Interfaces:

IGASState<VS,ES,ST>

public class BigdataGASState<VS,ES,ST>
extends GASState<VS,ES,ST>

Field Summary

Fields inherited from class com.bigdata.rdf.graph.impl.GASState

edgeState, vertexState

Constructor Summary

Constructors

Constructor and Description
BigdataGASState(IGASEngine gasEngine, BigdataGASEngine.BigdataGraphAccessor graphAccessor, IStaticFrontier frontier, IGASSchedulerImpl gasScheduler, IGASProgram<VS,ES,ST> gasProgram)

Method Summary

Methods

Modifier and Type	Method and Description
int	compareTo(org.openrdf.model.Value u, org.openrdf.model.Value v) Return -1, o, or 1 if u is LT, EQ, or GT v.
org.openrdf.model.Statement	decodeStatement(org.openrdf.model.Value v) If the vertex is actually an edge, then return the decoded edge.
protected BigdataGASEngine.BigdataGraphAccessor	getGraphAccessor() Provides access to the backing graph.
org.openrdf.model.Literal	getLinkAttr(org.openrdf.model.Value u, org.openrdf.model.Statement e) This will only work for the BigdataGASState.
org.openrdf.model.Value	getOtherVertex(org.openrdf.model.Value u, org.openrdf.model.Statement e) Return the other end of a link.
boolean	isAttrib(org.openrdf.model.Statement e) Return true iff the given Statement models an property value for a vertex of the graph (Statements also model edges).
boolean	isEdge(org.openrdf.model.Statement e) Return true iff the given Statement models an edge that connects two vertices (Statements also model property values).
boolean	isLinkAttrib(org.openrdf.model.Statement e, org.openrdf.model.URI linkAttribType) Return true iff the statement models a link attribute having the specified link type.
String	toString(org.openrdf.model.Statement e) Return a useful representation of an edge (non-batch API, debug only).
void	traceState() Conditionally log various interesting information about the state of the computation.

Methods inherited from class com.bigdata.rdf.graph.impl.GASState

asValue, endRound, frontier, getScheduler, getState, getState, isVisited, isVisited, reduce, reset, retainAll, round, setFrontier

Methods inherited from class java.lang.Object

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

Constructor Detail

BigdataGASState

public BigdataGASState(IGASEngine gasEngine,
               BigdataGASEngine.BigdataGraphAccessor graphAccessor,
               IStaticFrontier frontier,
               IGASSchedulerImpl gasScheduler,
               IGASProgram<VS,ES,ST> gasProgram)

Method Detail

getGraphAccessor

protected BigdataGASEngine.BigdataGraphAccessor getGraphAccessor()

Description copied from class: GASState

Provides access to the backing graph. Used to decode vertices and edges for GASState.traceState().

Overrides:

getGraphAccessor in class GASState<VS,ES,ST>

traceState

public void traceState()

Conditionally log various interesting information about the state of the computation. TODO EDGE STATE: edge state should be traced out also.

Specified by:

traceState in interface IGASState<VS,ES,ST>

Overrides:

traceState in class GASState<VS,ES,ST>

toString

public String toString(org.openrdf.model.Statement e)

Description copied from interface: IGASState

Return a useful representation of an edge (non-batch API, debug only). This method is only required when the edge objects are internal database objects lacking fully materialized RDF Values. In this case, it will materialize the RDF Values and present a pleasant view of the edge. The materialization step is a random access, which is why this method is for debug only. Efficient, vectored mechanisms exist to materialize RDF Values for other purposes, e.g., when exporting a set of edges as as graph in a standard interchange syntax.

Specified by:

toString in interface IGASState<VS,ES,ST>

Overrides:

toString in class GASState<VS,ES,ST>

Parameters:

e - The edge.

Returns:

The representation of that edge.

isEdge

public boolean isEdge(org.openrdf.model.Statement e)

Return true iff the given Statement models an edge that connects two vertices (Statements also model property values).

Note: The IV classes sometimes implement more than one kind of Value. E.g., TermId can be a BNode, URI, or Literal and implements ALL of those interfaces. So we have to make an IV-specific check here. TODO This is visiting all edges, including link attributes (aka hyperedges or statements about statements). Should we further restrict traversal to only simple edges (by checking that the source and target vertices are not SidIVs).

Specified by:

isEdge in interface IGASState<VS,ES,ST>

Overrides:

isEdge in class GASState<VS,ES,ST>

Parameters:

e - The statement.

Returns:

true iff that Statement is an edge of the graph.

isAttrib

public boolean isAttrib(org.openrdf.model.Statement e)

Description copied from interface: IGASState

Return true iff the given Statement models an property value for a vertex of the graph (Statements also model edges).

Specified by:

isAttrib in interface IGASState<VS,ES,ST>

Overrides:

isAttrib in class GASState<VS,ES,ST>

Parameters:

e - The statement.

Returns:

true iff that Statement is an edge of the graph.

isLinkAttrib

public boolean isLinkAttrib(org.openrdf.model.Statement e,
                   org.openrdf.model.URI linkAttribType)

Description copied from class: GASState

Return true iff the statement models a link attribute having the specified link type. When this method returns true, the Statement.getSubject() may be decoded to obtain the link described by that link attribute using IGASState.decodeStatement(Value).

The openrdf implementation does not support link attributes and this method always returns false.

Specified by:

isLinkAttrib in interface IGASState<VS,ES,ST>

Overrides:

isLinkAttrib in class GASState<VS,ES,ST>

Parameters:

e - The statement.

linkAttribType - The type for the link attribute.

Returns:

false

decodeStatement

public org.openrdf.model.Statement decodeStatement(org.openrdf.model.Value v)

Description copied from class: GASState

If the vertex is actually an edge, then return the decoded edge.

Note: A vertex may be an edge. A link attribute is modeled by treating the link as a vertex and then asserting a property value about that "link vertex". For bigdata, this is handled efficiently as inline statements about statements. This approach subsumes the property graph model (property graphs do not permit recursive nesting of these relationships) and is 100% consistent with RDF reification, except that the link attributes are modeled efficiently inline with the links. This is what we call Reification Done Right .

The openrdf implementation does not support link attributes and this method always returns null.

Specified by:

decodeStatement in interface IGASState<VS,ES,ST>

Overrides:

decodeStatement in class GASState<VS,ES,ST>

Parameters:

v - The vertex.

Returns:

null

See Also:

Reification Done Right , RDF GAS API

compareTo

public int compareTo(org.openrdf.model.Value u,
            org.openrdf.model.Value v)

Description copied from interface: IGASState

Return -1, o, or 1 if u is LT, EQ, or GT v. A number of GAS programs depend on the ability to place an order over the vertex identifiers, as does 2D partitioning. The ordering provided by this method MAY be arbitrary, but it MUST be total and stable across the life-cycle of the GAS program evaluation.

Specified by:

compareTo in interface IGASState<VS,ES,ST>

Overrides:

compareTo in class GASState<VS,ES,ST>

Parameters:

u - A vertex.

v - Another vertex.

getOtherVertex

public org.openrdf.model.Value getOtherVertex(org.openrdf.model.Value u,
                                     org.openrdf.model.Statement e)

Description copied from class: GASState

Return the other end of a link.

FIXME We can optimize this to use reference testing if we are careful in the GATHER and SCATTER implementations to impose a canonical mapping over the vertex objects for the edges that are exposed to the IGASProgram during a single round.

Specified by:

getOtherVertex in interface IGASState<VS,ES,ST>

Overrides:

getOtherVertex in class GASState<VS,ES,ST>

Parameters:

u - One end of the link.

e - The link.

Returns:

The other end of the link.

getLinkAttr

public org.openrdf.model.Literal getLinkAttr(org.openrdf.model.Value u,
                                    org.openrdf.model.Statement e)

This will only work for the BigdataGASState.

Specified by:

getLinkAttr in interface IGASState<VS,ES,ST>

Overrides:

getLinkAttr in class GASState<VS,ES,ST>

Parameters:

u - One end of the link.

e - The link.

Returns:

The other end of the link.