com.bigdata.rdf.graph

Interface IGASContext<VS,ES,ST>

Type Parameters:

VS - The generic type for the per-vertex state. This is scoped to the computation of the IGASProgram.

ES - The generic type for the per-edge state. This is scoped to the computation of the IGASProgram.

ST - The generic type for the SUM. This is often directly related to the generic type for the per-edge state, but that is not always true. The SUM type is scoped to the GATHER + SUM operation (NOT the computation). TODO Add option to order the vertices to provide a serializable execution plan (like GraphChi). I believe that this reduces to computing a DAG over the frontier before executing the GATHER and then executing the frontier such that the parallel execution is constrained by arcs in the DAG that do not have mutual dependencies. This would have to place a partial ordering over the vertices in the frontier and then process the frontier with limited parallelism based on that partial ordering.

All Superinterfaces:

Callable<IGASStats>

All Known Implementing Classes:

GASContext

public interface IGASContext<VS,ES,ST>
extends Callable<IGASStats>

Execution context for an IGASProgram. This is distinct from the IGASEngine so we can support distributed evaluation and concurrent evaluation of multiple IGASPrograms.

Author:

Bryan Thompson

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.
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.
void	setLinkAttributeType(org.openrdf.model.URI linkType) 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.

Method Detail

getGASProgram

IGASProgram<VS,ES,ST> getGASProgram()

Return the program that is being evaluated.

getGASState

IGASState<VS,ES,ST> getGASState()

The computation state.

getGraphAccessor

IGraphAccessor getGraphAccessor()

The graph access object.

setTraversalDirection

void setTraversalDirection(TraversalDirectionEnum newVal)

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.

See Also:

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

getTraversalDirection

TraversalDirectionEnum getTraversalDirection()

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

setMaxIterations

void setMaxIterations(int newValue)

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

Parameters:

newValue - The maximum number of iterations.

Throws:

IllegalArgumentException - if the new value is non-positive.

getMaxIterations

int getMaxIterations()

Return the maximum number iterations for the algorithm.

setMaxVisited

void setMaxVisited(int newValue)

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

Parameters:

newValue - The maximum number of vertices in the frontier.

Throws:

IllegalArgumentException - if the new value is non-positive.

getMaxVisited

int getMaxVisited()

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

getLinkType

org.openrdf.model.URI getLinkType()

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.

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

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

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).

Parameters:

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

getLinkAttributeType

org.openrdf.model.URI getLinkAttributeType()

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.

Returns:

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

See Also:

setLinkType(URI)

setLinkAttributeType

void setLinkAttributeType(org.openrdf.model.URI linkType)

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.

Parameters:

linkAttributeType - The link attribute type to visit (optional). When null, the link attributes for the visited links are NOT visited (the topology of the graph is visited, but not the attributes for the edges).

setRunAfterOp

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

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

Parameters:

afterOp - The IReducer.

getRunAfterOp

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

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

doRound

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

Execute one iteration.

Parameters:

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

Returns:

true iff the new frontier is empty.

Throws:

Exception

ExecutionException

InterruptedException

call

IGASStats call()
               throws Exception

Execute the associated IGASProgram.

Specified by:

call in interface Callable<IGASStats>

Throws:

Exception

setTargetVertices

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

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

getTargetVertices

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

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

Returns:

setMaxIterationsAfterTargets

void setMaxIterationsAfterTargets(int newValue)

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.

Parameters:

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

getMaxIterationsAfterTargets

int getMaxIterationsAfterTargets()

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