public final class TraversalVertexProgram extends Object implements VertexProgram<TraverserSet<Object>>
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<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<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() |
static Traversal.Admin<?,?> |
getTraversal(Graph graph,
Configuration configuration)
|
Set<VertexComputeKey> |
getVertexComputeKeys()
The
Element properties that will be mutated during the computation. |
void |
loadState(Graph graph,
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.
|
void |
storeState(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() |
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitcreateVertexProgram, workerIterationEnd, workerIterationStartpublic static final String TRAVERSAL
public static final String HALTED_TRAVERSERS
public static final String ACTIVE_TRAVERSERS
protected static final String MUTATED_MEMORY_KEYS
public static Traversal.Admin<?,?> getTraversal(Graph graph, Configuration configuration)
graph - the graph that the traversal will run againstconfiguration - The configuration containing the TRAVERSAL key.public void loadState(Graph graph, Configuration configuration)
VertexProgramloadState in interface VertexProgram<TraverserSet<Object>>graph - the graph that the VertexProgram will run againstconfiguration - the configuration to load the state of the VertexProgram from.public void storeState(Configuration configuration)
VertexProgramstoreState in interface VertexProgram<TraverserSet<Object>>configuration - the configuration to store the state of the VertexProgram in.public void setup(Memory memory)
VertexProgramGraphComputer 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<TraverserSet<Object>>memory - The global memory of the GraphComputerpublic Set<MessageScope> getMessageScopes(Memory memory)
VertexProgramMessageScope 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<TraverserSet<Object>>memory - an immutable form of the Memorypublic void execute(Vertex vertex, Messenger<TraverserSet<Object>> messenger, Memory memory)
VertexProgramMemory 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<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)
VertexProgramGraphComputer and as such, is not called for each Vertex.
The Memory maintains the aggregated data from the last execute() iteration.terminate in interface VertexProgram<TraverserSet<Object>>memory - The global memory of the GraphComputerpublic Set<VertexComputeKey> getVertexComputeKeys()
VertexProgramElement 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<TraverserSet<Object>>public Set<MemoryComputeKey> getMemoryComputeKeys()
VertexProgramMemory 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<TraverserSet<Object>>public Set<MapReduce> getMapReducers()
VertexProgramMapReduce 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<TraverserSet<Object>>MapReduce jobs associated with this VertexProgrampublic Optional<MessageCombiner<TraverserSet<Object>>> getMessageCombiner()
VertexProgramgetMessageCombiner in interface VertexProgram<TraverserSet<Object>>public TraversalVertexProgram clone()
VertexProgramVertexProgram.storeState(Configuration) and VertexProgram.loadState(org.apache.tinkerpop.gremlin.structure.Graph, Configuration) model.
The default implementation simply returns the object as it assumes that the VertexProgram instance is a stateless singleton.clone in interface VertexProgram<TraverserSet<Object>>clone in class Objectpublic GraphComputer.ResultGraph getPreferredResultGraph()
getPreferredResultGraph in interface VertexProgram<TraverserSet<Object>>public GraphComputer.Persist getPreferredPersist()
getPreferredPersist in interface VertexProgram<TraverserSet<Object>>public VertexProgram.Features getFeatures()
getFeatures in interface VertexProgram<TraverserSet<Object>>public static TraversalVertexProgram.Builder build()
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