org.apache.tinkerpop.gremlin.hadoop.process.computer

## Class AbstractHadoopGraphComputer

- java.lang.Object
- - org.apache.tinkerpop.gremlin.hadoop.process.computer.AbstractHadoopGraphComputer

- All Implemented Interfaces:
    GraphComputer
  Direct Known Subclasses:
    GiraphGraphComputer, SparkGraphComputer

      public abstract class AbstractHadoopGraphComputer
      extends Object
      implements GraphComputer

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

- - ### Nested Class Summary

    Nested Classes
    Modifier and Type | Class and Description
    --- | ---
    `class` | `AbstractHadoopGraphComputer.Features`

    - ### Nested classes/interfaces inherited from interface org.apache.tinkerpop.gremlin.process.computer.GraphComputer

      `GraphComputer.Exceptions, GraphComputer.Persist, GraphComputer.ResultGraph`

  - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected boolean` | `executed`
    `protected GraphFilter` | `graphFilter`
    `protected HadoopGraph` | `hadoopGraph`
    `protected Logger` | `logger`
    `protected Set<MapReduce>` | `mapReducers`
    `protected GraphComputer.Persist` | `persist`
    `protected GraphComputer.ResultGraph` | `resultGraph`
    `protected VertexProgram<Object>` | `vertexProgram`
    `protected int` | `workers`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `AbstractHadoopGraphComputer(HadoopGraph hadoopGraph)`

  - ### Method Summary

    All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static File` | `copyDirectoryIfNonExistent(FileSystem fileSystem, String directory)`
    `GraphComputer` | `edges(Traversal<Vertex,Edge> edgeFilter)` Add a filter that will limit which edges of the vertices are loaded from the graph source.
    `AbstractHadoopGraphComputer.Features` | `features()`
    `protected abstract void` | `loadJar(Configuration hadoopConfiguration, File file, Object... params)`
    `protected void` | `loadJars(Configuration hadoopConfiguration, Object... params)`
    `GraphComputer` | `mapReduce(MapReduce mapReduce)` Add a `MapReduce` job to the set of MapReduce jobs to be executed by the `GraphComputer`.
    `GraphComputer` | `persist(GraphComputer.Persist persist)` Set the `GraphComputer.Persist` level of the computation.
    `GraphComputer` | `program(VertexProgram vertexProgram)` Set the `VertexProgram` to be executed by the `GraphComputer`.
    `GraphComputer` | `result(GraphComputer.ResultGraph resultGraph)` Set the `GraphComputer.ResultGraph` of the computation.
    `String` | `toString()`
    `protected void` | `validateStatePriorToExecution()`
    `GraphComputer` | `vertices(Traversal<Vertex,Vertex> vertexFilter)` Add a filter that will limit which vertices are loaded from the graph source.
    `GraphComputer` | `workers(int workers)` Set the desired number of workers to execute the `VertexProgram` and `MapReduce` jobs.

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

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

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

      `configure, submit`

- - ### Field Detail

    - #### logger

          protected final Logger logger

    - #### hadoopGraph

          protected final HadoopGraph hadoopGraph

    - #### executed

          protected boolean executed

    - #### mapReducers

          protected final Set<MapReduce> mapReducers

    - #### vertexProgram

          protected VertexProgram<Object> vertexProgram

    - #### workers

          protected int workers

    - #### resultGraph

          protected GraphComputer.ResultGraph resultGraph

    - #### persist

          protected GraphComputer.Persist persist

    - #### graphFilter

          protected GraphFilter graphFilter

  - ### Constructor Detail

    - #### AbstractHadoopGraphComputer

          public AbstractHadoopGraphComputer(HadoopGraph hadoopGraph)

  - ### Method Detail

    - #### vertices

          public GraphComputer vertices(Traversal<Vertex,Vertex> vertexFilter)

      Description copied from interface: `GraphComputer`
      Add a filter that will limit which vertices are loaded from the graph source. The provided `Traversal` can only check the vertex, its vertex properties, and the vertex property properties. The loaded graph will only have those vertices that pass through the provided filter.
      Specified by:
        `vertices` in interface `GraphComputer`
      Parameters:
        `vertexFilter` - the traversal to verify whether or not to load the current vertex
      Returns:
        the updated GraphComputer with newly set vertex filter

    - #### edges

          public GraphComputer edges(Traversal<Vertex,Edge> edgeFilter)

      Description copied from interface: `GraphComputer`
      Add a filter that will limit which edges of the vertices are loaded from the graph source. The provided `Traversal` can only check the local star graph of the vertex and thus, can not access properties/labels of the adjacent vertices. The vertices of the loaded graph will only have those edges that pass through the provided filter.
      Specified by:
        `edges` in interface `GraphComputer`
      Parameters:
        `edgeFilter` - the traversal that determines which edges are loaded for each vertex
      Returns:
        the updated GraphComputer with newly set edge filter

    - #### result

          public GraphComputer result(GraphComputer.ResultGraph resultGraph)

      Description copied from interface: `GraphComputer`
      Set the `GraphComputer.ResultGraph` of the computation. If this is not set explicitly by the user, then the `VertexProgram` can choose the most efficient result for its intended use. If there is no declared vertex program, then the `GraphComputer` defaults to `GraphComputer.ResultGraph.ORIGINAL`.
      Specified by:
        `result` in interface `GraphComputer`
      Parameters:
        `resultGraph` - the type of graph to be returned by `ComputerResult.graph()`
      Returns:
        the updated GraphComputer with newly set result graph

    - #### persist

          public GraphComputer persist(GraphComputer.Persist persist)

      Description copied from interface: `GraphComputer`
      Set the `GraphComputer.Persist` level of the computation. If this is not set explicitly by the user, then the `VertexProgram` can choose the most efficient persist for the its intended use. If there is no declared vertex program, then the `GraphComputer` defaults to `GraphComputer.Persist.NOTHING`.
      Specified by:
        `persist` in interface `GraphComputer`
      Parameters:
        `persist` - the persistence level of the resultant computation
      Returns:
        the updated GraphComputer with newly set persist

    - #### program

          public GraphComputer program(VertexProgram vertexProgram)

      Description copied from interface: `GraphComputer`
      Set the `VertexProgram` to be executed by the `GraphComputer`. There can only be one VertexProgram for the GraphComputer.
      Specified by:
        `program` in interface `GraphComputer`
      Parameters:
        `vertexProgram` - the VertexProgram to be executed
      Returns:
        the updated GraphComputer with newly set VertexProgram

    - #### mapReduce

          public GraphComputer mapReduce(MapReduce mapReduce)

      Description copied from interface: `GraphComputer`
      Add a `MapReduce` job to the set of MapReduce jobs to be executed by the `GraphComputer`. There can be any number of MapReduce jobs.
      Specified by:
        `mapReduce` in interface `GraphComputer`
      Parameters:
        `mapReduce` - the MapReduce job to add to the computation
      Returns:
        the updated GraphComputer with newly added MapReduce job

    - #### workers

          public GraphComputer workers(int workers)

      Description copied from interface: `GraphComputer`
      Set the desired number of workers to execute the `VertexProgram` and `MapReduce` jobs. This is a recommendation to the underlying `GraphComputer` implementation and is allowed to deviate accordingly by the implementation.
      Specified by:
        `workers` in interface `GraphComputer`
      Parameters:
        `workers` - the number of workers to execute the submission
      Returns:
        the updated GraphComputer with newly set worker count

    - #### toString

          public String toString()

      Overrides:
        `toString` in class `Object`

    - #### validateStatePriorToExecution

          protected void validateStatePriorToExecution()

    - #### loadJars

          protected void loadJars(Configuration hadoopConfiguration,
                                  Object... params)

    - #### loadJar

          protected abstract void loadJar(Configuration hadoopConfiguration,
                                          File file,
                                          Object... params)
                                   throws IOException

      Throws:
        `IOException`

    - #### features

          public AbstractHadoopGraphComputer.Features features()

      Specified by:
        `features` in interface `GraphComputer`

    - #### copyDirectoryIfNonExistent

          public static File copyDirectoryIfNonExistent(FileSystem fileSystem,
                                                        String directory)

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