Package org.apache.tinkerpop.gremlin.process.computer

Class GraphComputerTest.MapReduceB

java.lang.Object
org.apache.tinkerpop.gremlin.process.computer.util.StaticMapReduce<Integer,Integer,Integer,Integer,List<Integer>>
org.apache.tinkerpop.gremlin.process.computer.GraphComputerTest.MapReduceB
All Implemented Interfaces:
Cloneable, MapReduce<Integer,Integer,Integer,Integer,List<Integer>>
Enclosing class:
GraphComputerTest
public static class GraphComputerTest.MapReduceB extends StaticMapReduce<Integer,Integer,Integer,Integer,List<Integer>>

  • Constructor Details

    • MapReduceB

      public MapReduceB()

  • Method Details

    • doStage

      public boolean doStage(MapReduce.Stage stage)
      Description copied from interface: MapReduce
      A MapReduce job can be map-only, map-reduce-only, or map-combine-reduce. Before executing the particular stage, this method is called to determine if the respective stage is defined. This method should return true if the respective stage as a non-default method implementation.
      Parameters:
      stage - the stage to check for definition.
      Returns:
      whether that stage should be executed.

    • map

      public void map(Vertex vertex, MapReduce.MapEmitter<Integer,Integer> emitter)
      Description copied from interface: MapReduce
      The map() method is logically executed at all vertices in the graph in parallel. The map() method emits key/value pairs given some analysis of the data in the vertices (and/or its incident edges). All MapReduce classes must at least provide an implementation of MapReduce#map(Vertex, MapEmitter).
      Parameters:
      vertex - the current vertex being map() processed.
      emitter - the component that allows for key/value pairs to be emitted to the next stage.

    • reduce

      public void reduce(Integer key, Iterator<Integer> values, MapReduce.ReduceEmitter<Integer,Integer> emitter)
      Description copied from interface: MapReduce
      The reduce() method is logically on the "machine" the respective key hashes to. The reduce() method combines all the values associated with the key and emits key/value pairs.
      Parameters:
      key - the key that has aggregated values
      values - the aggregated values associated with the key
      emitter - the component that allows for key/value pairs to be emitted as the final result.

    • getReduceKeySort

      public Optional<Comparator<Integer>> getReduceKeySort()
      Description copied from interface: MapReduce
      If a Comparator is provided, then all pairs leaving the MapReduce.ReduceEmitter are sorted. If sorting is not required, then Optional.empty() should be returned as sorting is computationally expensive. The default implementation returns Optional.empty().
      Returns:
      an Optional of a comparator for sorting the reduce output.

    • getMemoryKey

      public String getMemoryKey()
      Description copied from interface: MapReduce
      The results of the MapReduce job are associated with a memory-key to ultimately be stored in Memory.
      Returns:
      the memory key of the generated result object.

    • generateFinalResult

      public List<Integer> generateFinalResult(Iterator<KeyValue<Integer,Integer>> keyValues)
      Description copied from interface: MapReduce
      The key/value pairs emitted by reduce() (or map() in a map-only job) can be iterated to generate a local JVM Java object.
      Parameters:
      keyValues - the key/value pairs that were emitted from reduce() (or map() in a map-only job)
      Returns:
      the resultant object formed from the emitted key/values.