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

## Class PeerPressureVertexProgram

- java.lang.Object
- - org.apache.tinkerpop.gremlin.process.computer.util.StaticVertexProgram<<any>>
  - - org.apache.tinkerpop.gremlin.process.computer.clustering.peerpressure.PeerPressureVertexProgram

- All Implemented Interfaces:
    Cloneable, VertexProgram<<any>>

      public class PeerPressureVertexProgram
      extends StaticVertexProgram<<any>>

  Author:
    Marko A. Rodriguez (http://markorodriguez.com)

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `static class` | `PeerPressureVertexProgram.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` | `CLUSTER`

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

      `VERTEX_PROGRAM`

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static PeerPressureVertexProgram.Builder` | `build()`
    `void` | `execute(Vertex vertex, Messenger<<any>> 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 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()`

    - ### Methods inherited from class org.apache.tinkerpop.gremlin.process.computer.util.StaticVertexProgram

      `clone`

    - ### Methods inherited from class java.lang.Object

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

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

      `createVertexProgram, getMapReducers, getMessageCombiner, getTraverserRequirements, workerIterationEnd, workerIterationStart`

- - ### Field Detail

    - #### CLUSTER

          public static final String CLUSTER

      See Also:
        Constant Field Values

  - ### Method Detail

    - #### loadState

          public void loadState(Graph graph,
                                Configuration configuration)

      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.
      Parameters:
        `graph` - the graph that the VertexProgram will run against
        `configuration` - the configuration to load the state of the VertexProgram from.

    - #### storeState

          public void storeState(Configuration configuration)

      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<<any>>`
      Overrides:
        `storeState` in class `StaticVertexProgram<<any>>`
      Parameters:
        `configuration` - the configuration to store the state of the VertexProgram in.

    - #### 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.
      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.
      Returns:
        the set of memory keys that will be read/written

    - #### 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.
      Parameters:
        `memory` - an immutable form of the `Memory`
      Returns:
        all possible message scopes during said vertex program iteration

    - #### getPreferredResultGraph

          public GraphComputer.ResultGraph getPreferredResultGraph()

    - #### getPreferredPersist

          public GraphComputer.Persist getPreferredPersist()

    - #### 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."
      Parameters:
        `memory` - The global memory of the GraphComputer

    - #### execute

          public void execute(Vertex vertex,
                              Messenger<<any>> 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.
      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

    - #### 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.
      Parameters:
        `memory` - The global memory of the `GraphComputer`
      Returns:
        whether or not to halt the computation

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`

    - #### build

          public static PeerPressureVertexProgram.Builder build()

    - #### getFeatures

          public VertexProgram.Features getFeatures()

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