Example #1
1
  // #timed
  // each time an event is pushed through it will trigger a period of silence
  public class TimedGate<A> extends GraphStage<FlowShape<A, A>> {

    private final FiniteDuration silencePeriod;

    public TimedGate(FiniteDuration silencePeriod) {
      this.silencePeriod = silencePeriod;
    }

    public final Inlet<A> in = Inlet.create("TimedGate.in");
    public final Outlet<A> out = Outlet.create("TimedGate.out");

    private final FlowShape<A, A> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, A> shape() {
      return shape;
    }

    @Override
    public GraphStageLogic createLogic(Attributes inheritedAttributes) {
      return new TimerGraphStageLogic(shape) {

        private boolean open = false;

        {
          setHandler(
              in,
              new AbstractInHandler() {
                @Override
                public void onPush() {
                  A elem = grab(in);
                  if (open) pull(in);
                  else {
                    push(out, elem);
                    open = true;
                    scheduleOnce("key", silencePeriod);
                  }
                }
              });
          setHandler(
              out,
              new AbstractOutHandler() {
                @Override
                public void onPull() {
                  pull(in);
                }
              });
        }

        @Override
        public void onTimer(Object key) {
          if (key.equals("key")) {
            open = false;
          }
        }
      };
    }
  }
Example #2
1
  // #materialized
  public class FirstValue<A>
      extends GraphStageWithMaterializedValue<FlowShape<A, A>, CompletionStage<A>> {

    public final Inlet<A> in = Inlet.create("FirstValue.in");
    public final Outlet<A> out = Outlet.create("FirstValue.out");

    private final FlowShape<A, A> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, A> shape() {
      return shape;
    }

    @Override
    public Tuple2<GraphStageLogic, CompletionStage<A>> createLogicAndMaterializedValue(
        Attributes inheritedAttributes) {
      Promise<A> promise = Futures.promise();

      GraphStageLogic logic =
          new GraphStageLogic(shape) {
            {
              setHandler(
                  in,
                  new AbstractInHandler() {
                    @Override
                    public void onPush() {
                      A elem = grab(in);
                      promise.success(elem);
                      push(out, elem);

                      // replace handler with one just forwarding
                      setHandler(
                          in,
                          new AbstractInHandler() {
                            @Override
                            public void onPush() {
                              push(out, grab(in));
                            }
                          });
                    }
                  });

              setHandler(
                  out,
                  new AbstractOutHandler() {
                    @Override
                    public void onPull() {
                      pull(in);
                    }
                  });
            }
          };

      return new Tuple2(logic, promise.future());
    }
  }
Example #3
0
  // #async-side-channel
  // will close upstream when the future completes
  public class KillSwitch<A> extends GraphStage<FlowShape<A, A>> {

    private final CompletionStage<Done> switchF;

    public KillSwitch(CompletionStage<Done> switchF) {
      this.switchF = switchF;
    }

    public final Inlet<A> in = Inlet.create("KillSwitch.in");
    public final Outlet<A> out = Outlet.create("KillSwitch.out");

    private final FlowShape<A, A> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, A> shape() {
      return shape;
    }

    @Override
    public GraphStageLogic createLogic(Attributes inheritedAttributes) {
      return new GraphStageLogic(shape) {

        {
          setHandler(
              in,
              new AbstractInHandler() {
                @Override
                public void onPush() {
                  push(out, grab(in));
                }
              });
          setHandler(
              out,
              new AbstractOutHandler() {
                @Override
                public void onPull() {
                  pull(in);
                }
              });
        }

        @Override
        public void preStart() {
          AsyncCallback<Done> callback =
              createAsyncCallback(
                  new Procedure<Done>() {
                    @Override
                    public void apply(Done param) throws Exception {
                      completeStage();
                    }
                  });

          ExecutionContext ec = system.dispatcher();
          switchF.thenAccept(callback::invoke);
        }
      };
    }
  }
Example #4
0
  // #one-to-many
  public class Duplicator<A> extends GraphStage<FlowShape<A, A>> {

    public final Inlet<A> in = Inlet.create("Duplicator.in");
    public final Outlet<A> out = Outlet.create("Duplicator.out");

    private final FlowShape<A, A> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, A> shape() {
      return shape;
    }

    public GraphStageLogic createLogic(Attributes inheritedAttributes) {
      return new GraphStageLogic(shape) {
        // Again: note that all mutable state
        // MUST be inside the GraphStageLogic
        Option<A> lastElem = Option.none();

        {
          setHandler(
              in,
              new AbstractInHandler() {
                @Override
                public void onPush() {
                  A elem = grab(in);
                  lastElem = Option.some(elem);
                  push(out, elem);
                }

                @Override
                public void onUpstreamFinish() {
                  if (lastElem.isDefined()) {
                    emit(out, lastElem.get());
                  }
                  complete(out);
                }
              });

          setHandler(
              out,
              new AbstractOutHandler() {
                @Override
                public void onPull() {
                  if (lastElem.isDefined()) {
                    push(out, lastElem.get());
                    lastElem = Option.none();
                  } else {
                    pull(in);
                  }
                }
              });
        }
      };
    }
  }
Example #5
0
  // #many-to-one
  public final class Filter<A> extends GraphStage<FlowShape<A, A>> {

    private final Predicate<A> p;

    public Filter(Predicate<A> p) {
      this.p = p;
    }

    public final Inlet<A> in = Inlet.create("Filter.in");
    public final Outlet<A> out = Outlet.create("Filter.out");

    private final FlowShape<A, A> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, A> shape() {
      return shape;
    }

    public GraphStageLogic createLogic(Attributes inheritedAttributes) {
      return new GraphStageLogic(shape) {
        {
          setHandler(
              in,
              new AbstractInHandler() {
                @Override
                public void onPush() {
                  A elem = grab(in);
                  if (p.test(elem)) {
                    push(out, elem);
                  } else {
                    pull(in);
                  }
                }
              });

          setHandler(
              out,
              new AbstractOutHandler() {
                @Override
                public void onPull() {
                  pull(in);
                }
              });
        }
      };
    }
  }
Example #6
0
  // #one-to-one
  public class Map<A, B> extends GraphStage<FlowShape<A, B>> {

    private final Function<A, B> f;

    public Map(Function<A, B> f) {
      this.f = f;
    }

    public final Inlet<A> in = Inlet.create("Map.in");
    public final Outlet<B> out = Outlet.create("Map.out");

    private final FlowShape<A, B> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, B> shape() {
      return shape;
    }

    @Override
    public GraphStageLogic createLogic(Attributes inheritedAttributes) {
      return new GraphStageLogic(shape) {

        {
          setHandler(
              in,
              new AbstractInHandler() {
                @Override
                public void onPush() {
                  try {
                    push(out, f.apply(grab(in)));
                  } catch (Exception ex) {
                    failStage(ex);
                  }
                }
              });
          setHandler(
              out,
              new AbstractOutHandler() {
                @Override
                public void onPull() {
                  pull(in);
                }
              });
        }
      };
    }
  }
Example #7
0
  // #worker-pool
  public static <In, Out> Flow<In, Out, BoxedUnit> balancer(
      Flow<In, Out, BoxedUnit> worker, int workerCount) {
    return Flow.fromGraph(
        GraphDSL.create(
            b -> {
              boolean waitForAllDownstreams = true;
              final UniformFanOutShape<In, In> balance =
                  b.add(Balance.<In>create(workerCount, waitForAllDownstreams));
              final UniformFanInShape<Out, Out> merge = b.add(Merge.<Out>create(workerCount));

              for (int i = 0; i < workerCount; i++) {
                b.from(balance.out(i)).via(b.add(worker)).toInlet(merge.in(i));
              }

              return FlowShape.of(balance.in(), merge.out());
            }));
  }
Example #8
0
  // #simpler-one-to-many
  public class Duplicator2<A> extends GraphStage<FlowShape<A, A>> {

    public final Inlet<A> in = Inlet.create("Duplicator.in");
    public final Outlet<A> out = Outlet.create("Duplicator.out");

    private final FlowShape<A, A> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, A> shape() {
      return shape;
    }

    @Override
    public GraphStageLogic createLogic(Attributes inheritedAttributes) {
      return new GraphStageLogic(shape) {

        {
          setHandler(
              in,
              new AbstractInHandler() {
                @Override
                public void onPush() {
                  A elem = grab(in);
                  // this will temporarily suspend this handler until the two elems
                  // are emitted and then reinstates it
                  emitMultiple(out, Arrays.asList(elem, elem).iterator());
                }
              });

          setHandler(
              out,
              new AbstractOutHandler() {
                @Override
                public void onPull() {
                  pull(in);
                }
              });
        }
      };
    }
  }
Example #9
0
  // #detached
  public class TwoBuffer<A> extends GraphStage<FlowShape<A, A>> {

    public final Inlet<A> in = Inlet.create("TwoBuffer.in");
    public final Outlet<A> out = Outlet.create("TwoBuffer.out");

    private final FlowShape<A, A> shape = FlowShape.of(in, out);

    @Override
    public FlowShape<A, A> shape() {
      return shape;
    }

    @Override
    public GraphStageLogic createLogic(Attributes inheritedAttributes) {
      return new GraphStageLogic(shape) {

        private final int SIZE = 2;
        private Queue<A> buffer = new ArrayDeque<>(SIZE);
        private boolean downstreamWaiting = false;

        private boolean isBufferFull() {
          return buffer.size() == SIZE;
        }

        @Override
        public void preStart() {
          // a detached stage needs to start upstream demand
          // itself as it is not triggered by downstream demand
          pull(in);
        }

        {
          setHandler(
              in,
              new AbstractInHandler() {
                @Override
                public void onPush() {
                  A elem = grab(in);
                  buffer.add(elem);
                  if (downstreamWaiting) {
                    downstreamWaiting = false;
                    A bufferedElem = buffer.poll();
                    push(out, bufferedElem);
                  }
                  if (!isBufferFull()) {
                    pull(in);
                  }
                }

                @Override
                public void onUpstreamFinish() {
                  if (!buffer.isEmpty()) {
                    // emit the rest if possible
                    emitMultiple(out, buffer.iterator());
                  }
                  completeStage();
                }
              });

          setHandler(
              out,
              new AbstractOutHandler() {
                @Override
                public void onPull() {
                  if (buffer.isEmpty()) {
                    downstreamWaiting = true;
                  } else {
                    A elem = buffer.poll();
                    push(out, elem);
                  }
                  if (!isBufferFull() && !hasBeenPulled(in)) {
                    pull(in);
                  }
                }
              });
        }
      };
    }
  }
Example #10
0
  public static void main(String[] args) {

    Outlet<Integer> outlet = null;

    Outlet<Integer> outlet1 = null;
    Outlet<Integer> outlet2 = null;

    Inlet<Integer> inlet = null;

    Inlet<Integer> inlet1 = null;
    Inlet<Integer> inlet2 = null;

    Flow<Integer, Integer, BoxedUnit> flow = Flow.of(Integer.class);
    Flow<Integer, Integer, BoxedUnit> flow1 = Flow.of(Integer.class);
    Flow<Integer, Integer, BoxedUnit> flow2 = Flow.of(Integer.class);

    Promise<Option<Integer>> promise = null;

    {
      Graph<SourceShape<Integer>, BoxedUnit> graphSource = null;
      Graph<SinkShape<Integer>, BoxedUnit> graphSink = null;
      Graph<FlowShape<Integer, Integer>, BoxedUnit> graphFlow = null;

      // #flow-wrap
      Source<Integer, BoxedUnit> source = Source.fromGraph(graphSource);
      Sink<Integer, BoxedUnit> sink = Sink.fromGraph(graphSink);
      Flow<Integer, Integer, BoxedUnit> aflow = Flow.fromGraph(graphFlow);
      Flow.fromSinkAndSource(Sink.<Integer>head(), Source.single(0));
      Flow.fromSinkAndSourceMat(Sink.<Integer>head(), Source.single(0), Keep.left());
      // #flow-wrap

      Graph<BidiShape<Integer, Integer, Integer, Integer>, BoxedUnit> bidiGraph = null;

      // #bidi-wrap
      BidiFlow<Integer, Integer, Integer, Integer, BoxedUnit> bidiFlow =
          BidiFlow.fromGraph(bidiGraph);
      BidiFlow.fromFlows(flow1, flow2);
      BidiFlow.fromFlowsMat(flow1, flow2, Keep.both());
      // #bidi-wrap

    }

    {
      // #graph-create
      GraphDSL.create(
          builder -> {
            // ...
            return ClosedShape.getInstance();
          });

      GraphDSL.create(
          builder -> {
            // ...
            return new FlowShape<>(inlet, outlet);
          });
      // #graph-create
    }

    {
      // #graph-create-2
      GraphDSL.create(
          builder -> {
            // ...
            return SourceShape.of(outlet);
          });

      GraphDSL.create(
          builder -> {
            // ...
            return SinkShape.of(inlet);
          });

      GraphDSL.create(
          builder -> {
            // ...
            return FlowShape.of(inlet, outlet);
          });

      GraphDSL.create(
          builder -> {
            // ...
            return BidiShape.of(inlet1, outlet1, inlet2, outlet2);
          });
      // #graph-create-2
    }

    {
      // #graph-builder
      GraphDSL.create(
          builder -> {
            builder.from(outlet).toInlet(inlet);
            builder.from(outlet).via(builder.add(flow)).toInlet(inlet);
            builder.from(builder.add(Source.single(0))).to(builder.add(Sink.head()));
            // ...
            return ClosedShape.getInstance();
          });
      // #graph-builder
    }

    // #source-creators
    Source<Integer, Promise<Option<Integer>>> src = Source.<Integer>maybe();
    // Complete the promise with an empty option to emulate the old lazyEmpty
    promise.trySuccess(scala.Option.empty());

    final Source<String, Cancellable> ticks =
        Source.tick(
            FiniteDuration.create(0, TimeUnit.MILLISECONDS),
            FiniteDuration.create(200, TimeUnit.MILLISECONDS),
            "tick");

    final Source<Integer, BoxedUnit> pubSource =
        Source.fromPublisher(TestPublisher.<Integer>manualProbe(true, sys));

    final Source<Integer, BoxedUnit> futSource = Source.fromFuture(Futures.successful(42));

    final Source<Integer, Subscriber<Integer>> subSource = Source.<Integer>asSubscriber();
    // #source-creators

    // #sink-creators
    final Sink<Integer, BoxedUnit> subSink =
        Sink.fromSubscriber(TestSubscriber.<Integer>manualProbe(sys));
    // #sink-creators

    // #sink-as-publisher
    final Sink<Integer, Publisher<Integer>> pubSink = Sink.<Integer>asPublisher(false);

    final Sink<Integer, Publisher<Integer>> pubSinkFanout = Sink.<Integer>asPublisher(true);
    // #sink-as-publisher

    // #empty-flow
    Flow<Integer, Integer, BoxedUnit> emptyFlow = Flow.<Integer>create();
    // or
    Flow<Integer, Integer, BoxedUnit> emptyFlow2 = Flow.of(Integer.class);
    // #empty-flow

    // #flatMapConcat
    Flow.<Source<Integer, BoxedUnit>>create()
        .<Integer, BoxedUnit>flatMapConcat(
            new Function<Source<Integer, BoxedUnit>, Source<Integer, BoxedUnit>>() {
              @Override
              public Source<Integer, BoxedUnit> apply(Source<Integer, BoxedUnit> param)
                  throws Exception {
                return param;
              }
            });
    // #flatMapConcat

    Uri uri = null;
    // #raw-query
    final akka.japi.Option<String> theRawQueryString = uri.rawQueryString();
    // #raw-query

    // #query-param
    final akka.japi.Option<String> aQueryParam = uri.query().get("a");
    // #query-param

    // #file-source-sink
    final Source<ByteString, Future<Long>> fileSrc = FileIO.fromFile(new File("."));

    final Source<ByteString, Future<Long>> otherFileSrc = FileIO.fromFile(new File("."), 1024);

    final Sink<ByteString, Future<Long>> fileSink = FileIO.toFile(new File("."));
    // #file-source-sink

    // #input-output-stream-source-sink
    final Source<ByteString, Future<java.lang.Long>> inputStreamSrc =
        StreamConverters.fromInputStream(
            new Creator<InputStream>() {
              public InputStream create() {
                return new SomeInputStream();
              }
            });

    final Source<ByteString, Future<java.lang.Long>> otherInputStreamSrc =
        StreamConverters.fromInputStream(
            new Creator<InputStream>() {
              public InputStream create() {
                return new SomeInputStream();
              }
            },
            1024);

    final Sink<ByteString, Future<java.lang.Long>> outputStreamSink =
        StreamConverters.fromOutputStream(
            new Creator<OutputStream>() {
              public OutputStream create() {
                return new SomeOutputStream();
              }
            });
    // #input-output-stream-source-sink

    // #output-input-stream-source-sink
    final FiniteDuration timeout = FiniteDuration.Zero();

    final Source<ByteString, OutputStream> outputStreamSrc = StreamConverters.asOutputStream();

    final Source<ByteString, OutputStream> otherOutputStreamSrc =
        StreamConverters.asOutputStream(timeout);

    final Sink<ByteString, InputStream> someInputStreamSink = StreamConverters.asInputStream();

    final Sink<ByteString, InputStream> someOtherInputStreamSink =
        StreamConverters.asInputStream(timeout);
    // #output-input-stream-source-sink

  }