How to use org.apache.tinkerpop.gremlin.process.computer

@Override
public boolean terminate(Memory memory)
{
  return memory.getIteration() > 1;
}

@Override
public boolean doStage(final Stage stage) {
  return stage.equals(Stage.MAP);
}

@Override
public void removeRelation(InternalRelation e) {
  throw GraphComputer.Exceptions.adjacentVertexPropertiesCanNotBeReadOrUpdated();
}

public FulgoraMemory(final VertexProgram<?> vertexProgram, final Set<MapReduce> mapReducers) {
  this.currentMap = new ConcurrentHashMap<>();
  this.previousMap = new ConcurrentHashMap<>();
  if (null != vertexProgram) {
    for (final MemoryComputeKey key : vertexProgram.getMemoryComputeKeys()) {
      this.memoryKeys.put(key.getKey(), key);
    }
  }
  for (final MapReduce mapReduce : mapReducers) {
    this.memoryKeys.put(mapReduce.getMemoryKey(), MemoryComputeKey.of(mapReduce.getMemoryKey(), Operator.assign, false, false));
  }
}

@Override
public <R> R get(final String key) throws IllegalArgumentException {
  final R r = (R) this.previousMap.get(key);
  if (null == r)
    throw Memory.Exceptions.memoryDoesNotExist(key);
  else if (this.inExecute && !this.memoryKeys.get(key).isBroadcast())
    throw Memory.Exceptions.memoryDoesNotExist(key);
  else
    return r;
}

@Override
public <R> R get(final String key) throws IllegalArgumentException {
  final R r = (R) this.previousMap.get(key);
  if (null == r)
    throw Memory.Exceptions.memoryDoesNotExist(key);
  else
    return r;
}

@Override
public GraphComputer edges(final Traversal<Vertex, Edge> edgeFilter) {
  this.graphFilter.setEdgeFilter(edgeFilter);
  return this;
}

@Override
public GraphComputer vertices(final Traversal<Vertex, Vertex> vertexFilter) {
  this.graphFilter.setVertexFilter(vertexFilter);
  return this;
}

@Override
public TitanEdge addEdge(String s, Vertex vertex, Object... keyValues) {
  throw GraphComputer.Exceptions.adjacentVertexEdgesAndVerticesCanNotBeReadOrUpdated();
}

@Override
public final void accessEdges() {
  throw GraphComputer.Exceptions.incidentAndAdjacentElementsCanNotBeAccessedInMapReduce();
}

@Override
public void accessSetProperty() {
  throw GraphComputer.Exceptions.vertexPropertiesCanNotBeUpdatedInMapReduce();
}

@Override
public boolean terminate(Memory memory) {
  return memory.getIteration() >= maxIterations;
}

@Override
public final void accessProperties() {
  throw GraphComputer.Exceptions.adjacentVertexPropertiesCanNotBeReadOrUpdated();
}

@Override
public boolean doStage(final Stage stage) {
  return stage.equals(Stage.MAP);
}

@Override
public boolean terminate(Memory memory) {
  return memory.getIteration()>=length;
}

@Override
public boolean addRelation(InternalRelation e) {
  throw GraphComputer.Exceptions.adjacentVertexPropertiesCanNotBeReadOrUpdated();
}

@Override
public boolean terminate(final Memory memory) {
  return memory.getIteration() >= this.maxDepth;
}

@Override
public final void accessEdges() {
  throw GraphComputer.Exceptions.adjacentVertexPropertiesCanNotBeReadOrUpdated();
}

@Override
public boolean terminate(Memory memory)
{
  return memory.getIteration() > 1;
}

@Override
public void accessSetProperty() {
  throw GraphComputer.Exceptions.adjacentVertexPropertiesCanNotBeReadOrUpdated();
}