org.apache.tinkerpop.gremlin.process.computer.clustering.connected

Class ConnectedComponentVertexProgram

java.lang.Object

org.apache.tinkerpop.gremlin.process.computer.clustering.connected.ConnectedComponentVertexProgram

All Implemented Interfaces:

Cloneable, VertexProgram<String>

public class ConnectedComponentVertexProgram
extends Object
implements VertexProgram<String>

Identifies "Connected Component" instances in a graph by assigning a component identifier (the lexicographically least string value of the vertex in the component) to each vertex.

Author:

Stephen Mallette (http://stephen.genoprime.com), Daniel Kuppitz (http://gremlin.guru)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ConnectedComponentVertexProgram.Builder

Nested classes/interfaces inherited from interface org.apache.tinkerpop.gremlin.process.computer.VertexProgram

VertexProgram.Features

Field Summary

Fields

Modifier and Type	Field and Description
static String	COMPONENT

Fields inherited from interface org.apache.tinkerpop.gremlin.process.computer.VertexProgram

VERTEX_PROGRAM

Method Summary

Modifier and Type	Method and Description
static ConnectedComponentVertexProgram.Builder	build()
ConnectedComponentVertexProgram	clone() When multiple workers on a single machine need VertexProgram instances, it is possible to use clone.
void	execute(Vertex vertex, Messenger<String> 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<MemoryComputeKey>	getMemoryComputeKeys() The Memory keys that will be used during the computation.
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()
Set<VertexComputeKey>	getVertexComputeKeys() The Element properties that will be mutated during the computation.
void	loadState(Graph graph, Configuration config) 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 config) 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.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.tinkerpop.gremlin.process.computer.VertexProgram

createVertexProgram, getMapReducers, getMessageCombiner, getTraverserRequirements, workerIterationEnd, workerIterationStart

Field Detail

COMPONENT

public static final String COMPONENT

See Also:

Constant Field Values

Method Detail

loadState

public void loadState(Graph graph,
                      Configuration config)

Description copied from interface: VertexProgram

When it is necessary to load the state of the VertexProgram, this method is called. This is typically required when the VertexProgram needs to be serialized to another machine. Note that what is loaded is simply the instance state, not any processed data.

Specified by:

loadState in interface VertexProgram<String>

Parameters:

graph - the graph that the VertexProgram will run against

config - the configuration to load the state of the VertexProgram from.

storeState

public void storeState(Configuration config)

Description copied from interface: VertexProgram

When it is necessary to store the state of the VertexProgram, this method is called. This is typically required when the VertexProgram needs to be serialized to another machine. Note that what is stored is simply the instance/configuration state, not any processed data. The default implementation provided simply stores the VertexProgram class name for reflective reconstruction. It is typically a good idea to VertexProgram.super.storeState().

Specified by:

storeState in interface VertexProgram<String>

Parameters:

config - the configuration to store the state of the VertexProgram in.

setup

public void setup(Memory memory)

Description copied from interface: VertexProgram

The method is called at the beginning of the computation. The method is global to the GraphComputer and as such, is not called for each vertex. During this stage, the Memory should be initialized to to its "start state."

Specified by:

setup in interface VertexProgram<String>

Parameters:

memory - The global memory of the GraphComputer

execute

public void execute(Vertex vertex,
                    Messenger<String> messenger,
                    Memory memory)

Description copied from interface: VertexProgram

This method denotes the main body of the computation and is executed on each vertex in the graph. This method is logically executed in parallel on all vertices in the graph. When the 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.

Specified by:

execute in interface VertexProgram<String>

Parameters:

vertex - the Vertex to execute the VertexProgram on

messenger - the messenger that moves data between vertices

memory - the shared state between all vertices in the computation

getVertexComputeKeys

public Set<VertexComputeKey> getVertexComputeKeys()

Description copied from interface: VertexProgram

The 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.

Specified by:

getVertexComputeKeys in interface VertexProgram<String>

Returns:

the set of element keys that will be mutated during the vertex program's execution

getMemoryComputeKeys

public Set<MemoryComputeKey> getMemoryComputeKeys()

Description copied from interface: VertexProgram

The 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.

Specified by:

getMemoryComputeKeys in interface VertexProgram<String>

Returns:

the set of memory keys that will be read/written

terminate

public boolean terminate(Memory memory)

Description copied from interface: VertexProgram

The method is called at the end of each iteration to determine if the computation is complete. The method is global to the GraphComputer and as such, is not called for each Vertex. The Memory maintains the aggregated data from the last execute() iteration.

Specified by:

terminate in interface VertexProgram<String>

Parameters:

memory - The global memory of the GraphComputer

Returns:

whether or not to halt the computation

getMessageScopes

public Set<MessageScope> getMessageScopes(Memory memory)

Description copied from interface: VertexProgram

This method returns all the 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.

Specified by:

getMessageScopes in interface VertexProgram<String>

Parameters:

memory - an immutable form of the Memory

Returns:

all possible message scopes during said vertex program iteration

getPreferredResultGraph

public GraphComputer.ResultGraph getPreferredResultGraph()

Specified by:

getPreferredResultGraph in interface VertexProgram<String>

getPreferredPersist

public GraphComputer.Persist getPreferredPersist()

Specified by:

getPreferredPersist in interface VertexProgram<String>

clone

public ConnectedComponentVertexProgram clone()

Description copied from interface: VertexProgram

When multiple workers on a single machine need VertexProgram instances, it is possible to use clone. This will provide a speedier way of generating instances, over the VertexProgram.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.

Specified by:

clone in interface VertexProgram<String>

Overrides:

clone in class Object

Returns:

A clone of the VertexProgram object

getFeatures

public VertexProgram.Features getFeatures()

Specified by:

getFeatures in interface VertexProgram<String>

build

public static ConnectedComponentVertexProgram.Builder build()