public final class TraversalVertexProgram extends Object implements VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
TraversalVertexProgram
enables the evaluation of a Traversal
on a GraphComputer
.
At the start of the computation, each Vertex
(or Edge
) is assigned a single Traverser
.
For each traverser that is local to the vertex, the vertex looks up its current location in the traversal and
processes that step. If the outputted traverser of the step references a local structure on the vertex (e.g. the
vertex, an incident edge, its properties, or an arbitrary object), then the vertex continues to compute the next
traverser. If the traverser references another location in the graph, then the traverser is sent to that location
in the graph via a message. The messages of TraversalVertexProgram are traversers. This continues until all
traversers in the computation have halted.Modifier and Type | Class and Description |
---|---|
static class |
TraversalVertexProgram.Builder |
VertexProgram.Features
Modifier and Type | Field and Description |
---|---|
static String |
ACTIVE_TRAVERSERS |
static String |
HALTED_TRAVERSERS |
protected static String |
MUTATED_MEMORY_KEYS |
static String |
TRAVERSAL |
VERTEX_PROGRAM
Modifier and Type | Method and Description |
---|---|
static TraversalVertexProgram.Builder |
build() |
TraversalVertexProgram |
clone()
When multiple workers on a single machine need VertexProgram instances, it is possible to use clone.
|
void |
execute(Vertex vertex,
Messenger<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>> messenger,
Memory memory)
This method denotes the main body of the computation and is executed on each vertex in the graph.
|
VertexProgram.Features |
getFeatures() |
Set<MapReduce> |
getMapReducers()
The set of
MapReduce jobs that are associated with the VertexProgram . |
Set<MemoryComputeKey> |
getMemoryComputeKeys()
The
Memory keys that will be used during the computation. |
Optional<MessageCombiner<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>> |
getMessageCombiner()
Combine the messages in route to a particular vertex.
|
Set<MessageScope> |
getMessageScopes(Memory memory)
This method returns all the
MessageScope possibilities for a particular iteration of the vertex program. |
GraphComputer.Persist |
getPreferredPersist() |
GraphComputer.ResultGraph |
getPreferredResultGraph() |
org.apache.tinkerpop.gremlin.process.traversal.util.PureTraversal<?,?> |
getTraversal()
Get the
PureTraversal associated with the current instance of the TraversalVertexProgram . |
Set<VertexComputeKey> |
getVertexComputeKeys()
The
Element properties that will be mutated during the computation. |
static <R> org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<R> |
loadHaltedTraversers(org.apache.commons.configuration.Configuration configuration) |
void |
loadState(Graph graph,
org.apache.commons.configuration.Configuration configuration)
When it is necessary to load the state of the VertexProgram, this method is called.
|
void |
setup(Memory memory)
The method is called at the beginning of the computation.
|
static <R> void |
storeHaltedTraversers(org.apache.commons.configuration.Configuration configuration,
org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<R> haltedTraversers) |
void |
storeState(org.apache.commons.configuration.Configuration configuration)
When it is necessary to store the state of the VertexProgram, this method is called.
|
boolean |
terminate(Memory memory)
The method is called at the end of each iteration to determine if the computation is complete.
|
String |
toString() |
void |
workerIterationEnd(Memory memory)
This method is called at the end of each iteration of each "computational chunk."
The set of vertices in the graph are typically not processed with full parallelism.
|
void |
workerIterationStart(Memory memory)
This method is called at the start of each iteration of each "computational chunk."
The set of vertices in the graph are typically not processed with full parallelism.
|
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
createVertexProgram, getTraverserRequirements
public static final String TRAVERSAL
public static final String HALTED_TRAVERSERS
public static final String ACTIVE_TRAVERSERS
protected static final String MUTATED_MEMORY_KEYS
public org.apache.tinkerpop.gremlin.process.traversal.util.PureTraversal<?,?> getTraversal()
PureTraversal
associated with the current instance of the TraversalVertexProgram
.public static <R> org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<R> loadHaltedTraversers(org.apache.commons.configuration.Configuration configuration)
public static <R> void storeHaltedTraversers(org.apache.commons.configuration.Configuration configuration, org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<R> haltedTraversers)
public void loadState(Graph graph, org.apache.commons.configuration.Configuration configuration)
VertexProgram
loadState
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
graph
- the graph that the VertexProgram will run againstconfiguration
- the configuration to load the state of the VertexProgram from.public void storeState(org.apache.commons.configuration.Configuration configuration)
VertexProgram
storeState
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
configuration
- the configuration to store the state of the VertexProgram in.public void setup(Memory memory)
VertexProgram
GraphComputer
and as such, is not called for each vertex.
During this stage, the Memory
should be initialized to to its "start state."setup
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
memory
- The global memory of the GraphComputerpublic Set<MessageScope> getMessageScopes(Memory memory)
VertexProgram
MessageScope
possibilities for a particular iteration of the vertex program.
The returned messages scopes are the scopes that will be used to send messages during the stated iteration.
It is not a requirement that all stated messages scopes be used, just that it is possible that they be used during the iteration.getMessageScopes
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
memory
- an immutable form of the Memory
public void execute(Vertex vertex, Messenger<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>> messenger, Memory memory)
VertexProgram
Memory
is read, it is according to the aggregated state yielded in the previous iteration.
When the Memory
is written, the data will be aggregated at the end of the iteration for reading in the next iteration.execute
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
vertex
- the Vertex
to execute the VertexProgram
onmessenger
- the messenger that moves data between verticesmemory
- the shared state between all vertices in the computationpublic boolean terminate(Memory memory)
VertexProgram
GraphComputer
and as such, is not called for each Vertex
.
The Memory
maintains the aggregated data from the last execute() iteration.terminate
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
memory
- The global memory of the GraphComputer
public void workerIterationStart(Memory memory)
VertexProgram
VertexProgram.execute(org.apache.tinkerpop.gremlin.structure.Vertex, org.apache.tinkerpop.gremlin.process.computer.Messenger<M>, org.apache.tinkerpop.gremlin.process.computer.Memory)
method.
The default implementation is a no-op.workerIterationStart
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
memory
- The memory at the start of the iteration.public void workerIterationEnd(Memory memory)
VertexProgram
VertexProgram.execute(org.apache.tinkerpop.gremlin.structure.Vertex, org.apache.tinkerpop.gremlin.process.computer.Messenger<M>, org.apache.tinkerpop.gremlin.process.computer.Memory)
method.
The default implementation is a no-op.workerIterationEnd
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
memory
- The memory at the end of the iteration.public Set<VertexComputeKey> getVertexComputeKeys()
VertexProgram
Element
properties that will be mutated during the computation. All properties in the graph are
readable, but only the keys specified here are writable. The default is an empty set.getVertexComputeKeys
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
public Set<MemoryComputeKey> getMemoryComputeKeys()
VertexProgram
Memory
keys that will be used during the computation.
These are the only keys that can be read or written throughout the life of the GraphComputer
.
The default is an empty set.getMemoryComputeKeys
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
public Set<MapReduce> getMapReducers()
VertexProgram
MapReduce
jobs that are associated with the VertexProgram
.
This is not necessarily the exhaustive list over the life of the GraphComputer
.
If MapReduce jobs are declared by GraphComputer.mapReduce(), they are not contained in this set.
The default is an empty set.getMapReducers
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
MapReduce
jobs associated with this VertexProgram
public Optional<MessageCombiner<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>> getMessageCombiner()
VertexProgram
getMessageCombiner
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
public TraversalVertexProgram clone()
VertexProgram
VertexProgram.storeState(org.apache.commons.configuration.Configuration)
and VertexProgram.loadState(org.apache.tinkerpop.gremlin.structure.Graph, org.apache.commons.configuration.Configuration)
model.
The default implementation simply returns the object as it assumes that the VertexProgram instance is a stateless singleton.clone
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
clone
in class Object
public GraphComputer.ResultGraph getPreferredResultGraph()
getPreferredResultGraph
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
public GraphComputer.Persist getPreferredPersist()
getPreferredPersist
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
public VertexProgram.Features getFeatures()
getFeatures
in interface VertexProgram<org.apache.tinkerpop.gremlin.process.traversal.traverser.util.TraverserSet<Object>>
public static TraversalVertexProgram.Builder build()
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