com.bigdata.rdf.graph.impl

Class GASContext<VS,ES,ST>

java.lang.Object

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

All Implemented Interfaces:

IGASContext<VS,ES,ST>, Callable<IGASStats>

public class GASContext<VS,ES,ST>
extends Object
implements IGASContext<VS,ES,ST>

Constructor Summary

Constructors

Constructor and Description
GASContext(GASEngine gasEngine, IGraphAccessor graphAccessor, IGASState<VS,ES,ST> gasState, IGASProgram<VS,ES,ST> gasProgram)

Method Summary

Methods

Modifier and Type	Method and Description
IGASStats	call() Execute the associated IGASProgram.
boolean	doRound(IGASStats stats) Execute one iteration.
IGASProgram<VS,ES,ST>	getGASProgram() Return the program that is being evaluated.
IGASState<VS,ES,ST>	getGASState() The computation state.
IGraphAccessor	getGraphAccessor() The graph access object.
protected IFilter	getLinkAttribFilter(IGASContext<VS,ES,ST> ctx, org.openrdf.model.URI linkAttribType) Return a filter that only visits the edges of graph that are instances of the specified link attribute type.
org.openrdf.model.URI	getLinkAttributeType() Return non-null iff there is a single link attribute type to be visited.
org.openrdf.model.URI	getLinkType() Return non-null iff there is a single link type to be visited.
int	getMaxIterations() Return the maximum number iterations for the algorithm.
int	getMaxIterationsAfterTargets() Return the maximum number iterations for the algorithm to continue once all the target vertices have been reached.
int	getMaxVisited() Return the maximum number of vertices that may be visited.
<T> IReducer<VS,ES,ST,T>	getRunAfterOp() Return an optional IReducer that will run after the IGASProgram is terminated.
Set<org.openrdf.model.Value>	getTargetVertices() Get the target vertices for the program (if any).
TraversalDirectionEnum	getTraversalDirection() Return a type safe value indicating the traversal direction for the IGASProgram.
<T> T	reduceOverFrontier(IStaticFrontier f, IReducer<VS,ES,ST,T> op) Reduce over the frontier (used for apply()).
void	setLinkAttributeType(org.openrdf.model.URI linkAttributeType) Imposes an optional restriction on which link attributes are considered by the algorithm.
void	setLinkType(org.openrdf.model.URI linkType) Set an optional restriction on the type of the visited links.
void	setMaxIterations(int newValue) Specify the maximum number of iterations for the algorithm.
void	setMaxIterationsAfterTargets(int newValue) Specify the maximum number of iterations for the algorithm to continue once all the target vertices have been reached.
void	setMaxVisited(int newValue) Specify the maximum number of vertices that may be visited.
<T> void	setRunAfterOp(IReducer<VS,ES,ST,T> afterOp) Set an optional IReducer that will run after the IGASProgram is terminated.
void	setTargetVertices(org.openrdf.model.Value[] targetVertices) Set the target vertices for the program (if any).
void	setTraversalDirection(TraversalDirectionEnum newVal) Specify the traversal direction for the IGASProgram.

Methods inherited from class java.lang.Object

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

Constructor Detail

GASContext

public GASContext(GASEngine gasEngine,
          IGraphAccessor graphAccessor,
          IGASState<VS,ES,ST> gasState,
          IGASProgram<VS,ES,ST> gasProgram)

Parameters:

namespace - The namespace of the graph (KB instance).

timestamp - The timestamp of the graph view (this should be a read-only view for non-blocking index reads).

gasProgram - The program to execute against that graph.

Method Detail

getGASState

public IGASState<VS,ES,ST> getGASState()

Description copied from interface: IGASContext

The computation state.

Specified by:

getGASState in interface IGASContext<VS,ES,ST>

getGASProgram

public IGASProgram<VS,ES,ST> getGASProgram()

Description copied from interface: IGASContext

Return the program that is being evaluated.

Specified by:

getGASProgram in interface IGASContext<VS,ES,ST>

getGraphAccessor

public IGraphAccessor getGraphAccessor()

Description copied from interface: IGASContext

The graph access object.

Specified by:

getGraphAccessor in interface IGASContext<VS,ES,ST>

call

public IGASStats call()
               throws Exception

Description copied from interface: IGASContext

Execute the associated IGASProgram.

Specified by:

call in interface IGASContext<VS,ES,ST>

Specified by:

call in interface Callable<IGASStats>

Throws:

Exception

doRound

public boolean doRound(IGASStats stats)
                throws InterruptedException,
                       ExecutionException,
                       Exception

Execute one iteration. TODO This is an Asynchronous implementation. Further, it does not attempt to race ahead to accelerate convergence (unlike an asynchronous neural network). TODO There should be an option for property value access during the APPLY (either no property values are required, or some (or all) are required and must optionally be materialized. Likewise, there could be an option to force the materialization of the URIs for the (s,p,o).

Property value access is on the SPO index. If we are doing a reverse gather (out-edges) then it will be right there and the Apply should be pushed into the Gather. If we are doing a forward gather (in-edges), then we are reading on OSP and will need to do a separate read on SPO.

Specified by:

doRound in interface IGASContext<VS,ES,ST>

Parameters:

stats - Used to report statistics about the execution of the algorithm.

Returns:

true iff the new frontier is empty.

Throws:

InterruptedException

ExecutionException

Exception

reduceOverFrontier

public <T> T reduceOverFrontier(IStaticFrontier f,
                       IReducer<VS,ES,ST,T> op)
                     throws Exception

Reduce over the frontier (used for apply()).

Parameters:

f - The frontier.

op - The IReducer.

Returns:

The result.

Throws:

Exception

setMaxIterations

public void setMaxIterations(int newValue)

Description copied from interface: IGASContext

Specify the maximum number of iterations for the algorithm. A value of ONE means that the algorithm will halt after the first round.

Specified by:

setMaxIterations in interface IGASContext<VS,ES,ST>

Parameters:

newValue - The maximum number of iterations.

getTraversalDirection

public TraversalDirectionEnum getTraversalDirection()

Description copied from interface: IGASContext

Return a type safe value indicating the traversal direction for the IGASProgram.

Specified by:

getTraversalDirection in interface IGASContext<VS,ES,ST>

setTraversalDirection

public void setTraversalDirection(TraversalDirectionEnum newVal)

Description copied from interface: IGASContext

Specify the traversal direction for the IGASProgram.

The value specified here is used to determine how the EdgesEnum will be interpreted for the GATHER and SCATTER phases. The default is TraversalDirectionEnum.Forward.

Specified by:

setTraversalDirection in interface IGASContext<VS,ES,ST>

See Also:

TraversalDirectionEnum.asTraversed(EdgesEnum), EdgesEnum.asUndirectedTraversal()

getMaxIterations

public int getMaxIterations()

Description copied from interface: IGASContext

Return the maximum number iterations for the algorithm.

Specified by:

getMaxIterations in interface IGASContext<VS,ES,ST>

setMaxVisited

public void setMaxVisited(int newValue)

Description copied from interface: IGASContext

Specify the maximum number of vertices that may be visited. The algorithm will halt if this value is exceeded.

Specified by:

setMaxVisited in interface IGASContext<VS,ES,ST>

Parameters:

newValue - The maximum number of vertices in the frontier.

getMaxVisited

public int getMaxVisited()

Description copied from interface: IGASContext

Return the maximum number of vertices that may be visited. The algorithm will halt if this value is exceeded.

Specified by:

getMaxVisited in interface IGASContext<VS,ES,ST>

getLinkType

public org.openrdf.model.URI getLinkType()

Description copied from interface: IGASContext

Return non-null iff there is a single link type to be visited. This corresponds to a view of the graph as sparse connectivity matrix. The IGASEngine can optimize traversal patterns using the POS index.

Note: When this option is used, the scatter and gather will not visit the property set for the vertex. Instead, the graph is treated as if it were an unattributed graph and only mined for the connectivity data.

Specified by:

getLinkType in interface IGASContext<VS,ES,ST>

Returns:

The Value for the predicate that identifies the desired link type (there can be many types of links - the return value specifies which attribute is of interest).

setLinkType

public void setLinkType(org.openrdf.model.URI linkType)

Description copied from interface: IGASContext

Set an optional restriction on the type of the visited links.

Note: When this option is used, the scatter and gather will not visit the property set for the vertex. Instead, the graph is treated as if it were an unattributed graph and only mined for the connectivity data (which may include a link weight).

Specified by:

setLinkType in interface IGASContext<VS,ES,ST>

Parameters:

linkType - The link type to visit (optional). When null, all link types are visited.

getLinkAttributeType

public org.openrdf.model.URI getLinkAttributeType()

Description copied from interface: IGASContext

Return non-null iff there is a single link attribute type to be visited. This imposes a restriction on which link attributes are considered by the algorithm. The link attribute type restriction may be (and often is) paired with a link type restriction.

Specified by:

getLinkAttributeType in interface IGASContext<VS,ES,ST>

Returns:

The Value for the predicate that identifies the desired link attribute type.

See Also:

IGASContext.setLinkType(URI)

setLinkAttributeType

public void setLinkAttributeType(org.openrdf.model.URI linkAttributeType)

Description copied from interface: IGASContext

Imposes an optional restriction on which link attributes are considered by the algorithm. The link attribute type restriction may be (and often is) paired with a link type restriction.

Specified by:

setLinkAttributeType in interface IGASContext<VS,ES,ST>

setTargetVertices

public void setTargetVertices(org.openrdf.model.Value[] targetVertices)

Description copied from interface: IGASContext

Set the target vertices for the program (if any).

Specified by:

setTargetVertices in interface IGASContext<VS,ES,ST>

getTargetVertices

public Set<org.openrdf.model.Value> getTargetVertices()

Description copied from interface: IGASContext

Get the target vertices for the program (if any).

Specified by:

getTargetVertices in interface IGASContext<VS,ES,ST>

Returns:

setMaxIterationsAfterTargets

public void setMaxIterationsAfterTargets(int newValue)

Description copied from interface: IGASContext

Specify the maximum number of iterations for the algorithm to continue once all the target vertices have been reached. Default is for the program to run until completion without regard to whether the target vertices have been reached or not. A value of ZERO will stop the program exactly when all target vertices are found in the frontier.

Specified by:

setMaxIterationsAfterTargets in interface IGASContext<VS,ES,ST>

Parameters:

newValue - The maximum number of iterations past the target vertices.

getMaxIterationsAfterTargets

public int getMaxIterationsAfterTargets()

Description copied from interface: IGASContext

Return the maximum number iterations for the algorithm to continue once all the target vertices have been reached.

Specified by:

getMaxIterationsAfterTargets in interface IGASContext<VS,ES,ST>

getLinkAttribFilter

protected IFilter getLinkAttribFilter(IGASContext<VS,ES,ST> ctx,
                          org.openrdf.model.URI linkAttribType)

Return a filter that only visits the edges of graph that are instances of the specified link attribute type.

Note: For bigdata, the visited edges can be decoded to recover the original link as well.

See Also:

IGASState.isLinkAttrib(Statement, URI), IGASState.decodeStatement(Value)

setRunAfterOp

public <T> void setRunAfterOp(IReducer<VS,ES,ST,T> afterOp)

Description copied from interface: IGASContext

Set an optional IReducer that will run after the IGASProgram is terminated. This may be used to extract results from the visited vertices.

Specified by:

setRunAfterOp in interface IGASContext<VS,ES,ST>

Parameters:

afterOp - The IReducer.

getRunAfterOp

public <T> IReducer<VS,ES,ST,T> getRunAfterOp()

Description copied from interface: IGASContext

Return an optional IReducer that will run after the IGASProgram is terminated. This may be used to extract results from the visited vertices.

Specified by:

getRunAfterOp in interface IGASContext<VS,ES,ST>