abstract static class Example1 {
// #first-sample
// #materializer-setup
final ActorSystem system = ActorSystem.create("reactive-tweets");
final Materializer mat = ActorMaterializer.create(system);
// #first-sample
// #materializer-setup
}
public class RecipeWorkerPool extends RecipeTest {
static ActorSystem system;
@BeforeClass
public static void setup() {
system = ActorSystem.create("RecipeWorkerPool");
}
@AfterClass
public static void tearDown() {
JavaTestKit.shutdownActorSystem(system);
system = null;
}
final Materializer mat = ActorMaterializer.create(system);
// #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());
}));
}
// #worker-pool
@Test
public void workForVersion1() throws Exception {
new JavaTestKit(system) {
{
Source<Message, BoxedUnit> data =
Source.from(Arrays.asList("1", "2", "3", "4", "5")).map(t -> new Message(t));
Flow<Message, Message, BoxedUnit> worker =
Flow.of(Message.class).map(m -> new Message(m.msg + " done"));
// #worker-pool2
Flow<Message, Message, BoxedUnit> balancer = balancer(worker, 3);
Source<Message, BoxedUnit> processedJobs = data.via(balancer);
// #worker-pool2
FiniteDuration timeout = FiniteDuration.create(200, TimeUnit.MILLISECONDS);
Future<List<String>> future =
processedJobs.map(m -> m.msg).grouped(10).runWith(Sink.head(), mat);
List<String> got = Await.result(future, timeout);
assertTrue(got.contains("1 done"));
assertTrue(got.contains("2 done"));
assertTrue(got.contains("3 done"));
assertTrue(got.contains("4 done"));
assertTrue(got.contains("5 done"));
}
};
}
}
public class GraphStageDocTest {
static ActorSystem system;
@BeforeClass
public static void setup() {
system = ActorSystem.create("FlowGraphDocTest");
}
@AfterClass
public static void tearDown() {
JavaTestKit.shutdownActorSystem(system);
system = null;
}
final Materializer mat = ActorMaterializer.create(system);
// #simple-source
public class NumbersSource extends GraphStage<SourceShape<Integer>> {
// Define the (sole) output port of this stage
public final Outlet<Integer> out = Outlet.create("NumbersSource.out");
// Define the shape of this stage, which is SourceShape with the port we defined above
private final SourceShape<Integer> shape = SourceShape.of(out);
@Override
public SourceShape<Integer> shape() {
return shape;
}
// This is where the actual (possibly stateful) logic is created
@Override
public GraphStageLogic createLogic(Attributes inheritedAttributes) {
return new GraphStageLogic(shape()) {
// All state MUST be inside the GraphStageLogic,
// never inside the enclosing GraphStage.
// This state is safe to access and modify from all the
// callbacks that are provided by GraphStageLogic and the
// registered handlers.
private int counter = 1;
{
setHandler(
out,
new AbstractOutHandler() {
@Override
public void onPull() {
push(out, counter);
counter += 1;
}
});
}
};
}
}
// #simple-source
@Test
public void demonstrateCustomSourceUsage() throws Exception {
// #simple-source-usage
// A GraphStage is a proper Graph, just like what GraphDSL.create would return
Graph<SourceShape<Integer>, NotUsed> sourceGraph = new NumbersSource();
// Create a Source from the Graph to access the DSL
Source<Integer, NotUsed> mySource = Source.fromGraph(sourceGraph);
// Returns 55
CompletionStage<Integer> result1 = mySource.take(10).runFold(0, (sum, next) -> sum + next, mat);
// The source is reusable. This returns 5050
CompletionStage<Integer> result2 =
mySource.take(100).runFold(0, (sum, next) -> sum + next, mat);
// #simple-source-usage
assertEquals(result1.toCompletableFuture().get(3, TimeUnit.SECONDS), (Integer) 55);
assertEquals(result2.toCompletableFuture().get(3, TimeUnit.SECONDS), (Integer) 5050);
}
// #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);
}
});
}
};
}
}
// #one-to-one
@Test
public void demonstrateOneToOne() throws Exception {
// tests:
final Graph<FlowShape<String, Integer>, NotUsed> stringLength =
Flow.fromGraph(
new Map<String, Integer>(
new Function<String, Integer>() {
@Override
public Integer apply(String str) {
return str.length();
}
}));
CompletionStage<Integer> result =
Source.from(Arrays.asList("one", "two", "three"))
.via(stringLength)
.runFold(0, (sum, n) -> sum + n, mat);
assertEquals(new Integer(11), result.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
// #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);
}
});
}
};
}
}
// #many-to-one
@Test
public void demonstrateAManyToOneElementGraphStage() throws Exception {
// tests:
Graph<FlowShape<Integer, Integer>, NotUsed> evenFilter =
Flow.fromGraph(new Filter<Integer>(n -> n % 2 == 0));
CompletionStage<Integer> result =
Source.from(Arrays.asList(1, 2, 3, 4, 5, 6))
.via(evenFilter)
.runFold(0, (elem, sum) -> sum + elem, mat);
assertEquals(new Integer(12), result.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
// #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);
}
}
});
}
};
}
}
// #one-to-many
@Test
public void demonstrateAOneToManyElementGraphStage() throws Exception {
// tests:
Graph<FlowShape<Integer, Integer>, NotUsed> duplicator =
Flow.fromGraph(new Duplicator<Integer>());
CompletionStage<Integer> result =
Source.from(Arrays.asList(1, 2, 3)).via(duplicator).runFold(0, (n, sum) -> n + sum, mat);
assertEquals(new Integer(12), result.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
// #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);
}
});
}
};
}
}
// #simpler-one-to-many
@Test
public void demonstrateASimplerOneToManyStage() throws Exception {
// tests:
Graph<FlowShape<Integer, Integer>, NotUsed> duplicator =
Flow.fromGraph(new Duplicator2<Integer>());
CompletionStage<Integer> result =
Source.from(Arrays.asList(1, 2, 3)).via(duplicator).runFold(0, (n, sum) -> n + sum, mat);
assertEquals(new Integer(12), result.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
@Test
public void demonstrateChainingOfGraphStages() throws Exception {
Graph<SinkShape<Integer>, CompletionStage<String>> sink =
Sink.fold("", (acc, n) -> acc + n.toString());
// #graph-stage-chain
CompletionStage<String> resultFuture =
Source.from(Arrays.asList(1, 2, 3, 4, 5))
.via(new Filter<Integer>((n) -> n % 2 == 0))
.via(new Duplicator<Integer>())
.via(new Map<Integer, Integer>((n) -> n / 2))
.runWith(sink, mat);
// #graph-stage-chain
assertEquals("1122", resultFuture.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
// #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);
}
};
}
}
// #async-side-channel
@Test
public void demonstrateAnAsynchronousSideChannel() throws Exception {
// tests:
CompletableFuture<Done> switchF = new CompletableFuture<>();
Graph<FlowShape<Integer, Integer>, NotUsed> killSwitch =
Flow.fromGraph(new KillSwitch<>(switchF));
ExecutionContext ec = system.dispatcher();
CompletionStage<Integer> valueAfterKill = switchF.thenApply(in -> 4);
CompletionStage<Integer> result =
Source.from(Arrays.asList(1, 2, 3))
.concat(Source.fromCompletionStage(valueAfterKill))
.via(killSwitch)
.runFold(0, (n, sum) -> n + sum, mat);
switchF.complete(Done.getInstance());
assertEquals(new Integer(6), result.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
// #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;
}
}
};
}
}
// #timed
public void demonstrateAGraphStageWithATimer() throws Exception {
// tests:
CompletionStage<Integer> result =
Source.from(Arrays.asList(1, 2, 3))
.via(new TimedGate<>(Duration.create(2, "seconds")))
.takeWithin(Duration.create(250, "millis"))
.runFold(0, (n, sum) -> n + sum, mat);
assertEquals(new Integer(1), result.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
// #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());
}
}
// #materialized
public void demonstrateACustomMaterializedValue() throws Exception {
// tests:
RunnableGraph<CompletionStage<Integer>> flow =
Source.from(Arrays.asList(1, 2, 3))
.viaMat(new FirstValue(), Keep.right())
.to(Sink.ignore());
CompletionStage<Integer> result = flow.run(mat);
assertEquals(new Integer(1), result.toCompletableFuture().get(3, TimeUnit.SECONDS));
}
// #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);
}
}
});
}
};
}
}
// #detached
public void demonstrateADetachedGraphStage() throws Exception {
// tests:
CompletionStage<Integer> result1 =
Source.from(Arrays.asList(1, 2, 3))
.via(new TwoBuffer<>())
.runFold(0, (acc, n) -> acc + n, mat);
assertEquals(new Integer(6), result1.toCompletableFuture().get(3, TimeUnit.SECONDS));
TestSubscriber.ManualProbe<Integer> subscriber = TestSubscriber.manualProbe(system);
TestPublisher.Probe<Integer> publisher = TestPublisher.probe(0, system);
RunnableGraph<NotUsed> flow2 =
Source.fromPublisher(publisher).via(new TwoBuffer<>()).to(Sink.fromSubscriber(subscriber));
flow2.run(mat);
Subscription sub = subscriber.expectSubscription();
// this happens even though the subscriber has not signalled any demand
publisher.sendNext(1);
publisher.sendNext(2);
sub.cancel();
}
}
@SuppressWarnings("unused")
public class TwitterStreamQuickstartDocTest {
static ActorSystem system;
@BeforeClass
public static void setup() {
system = ActorSystem.create("SampleActorTest");
}
@AfterClass
public static void tearDown() {
JavaTestKit.shutdownActorSystem(system);
system = null;
}
abstract static class Model {
// #model
public static class Author {
public final String handle;
public Author(String handle) {
this.handle = handle;
}
// ...
// #model
@Override
public String toString() {
return "Author(" + handle + ")";
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
Author author = (Author) o;
if (handle != null ? !handle.equals(author.handle) : author.handle != null) {
return false;
}
return true;
}
@Override
public int hashCode() {
return handle != null ? handle.hashCode() : 0;
}
// #model
}
// #model
// #model
public static class Hashtag {
public final String name;
public Hashtag(String name) {
this.name = name;
}
// ...
// #model
@Override
public int hashCode() {
return name.hashCode();
}
@Override
public boolean equals(Object obj) {
if (this == obj) return true;
if (obj == null) return false;
if (getClass() != obj.getClass()) return false;
Hashtag other = (Hashtag) obj;
return name.equals(other.name);
}
@Override
public String toString() {
return "Hashtag(" + name + ")";
}
// #model
}
// #model
// #model
public static class Tweet {
public final Author author;
public final long timestamp;
public final String body;
public Tweet(Author author, long timestamp, String body) {
this.author = author;
this.timestamp = timestamp;
this.body = body;
}
public Set<Hashtag> hashtags() {
return Arrays.asList(body.split(" "))
.stream()
.filter(a -> a.startsWith("#"))
.map(a -> new Hashtag(a))
.collect(Collectors.toSet());
}
// ...
// #model
@Override
public String toString() {
return "Tweet(" + author + "," + timestamp + "," + body + ")";
}
// #model
}
// #model
// #model
public static final Hashtag AKKA = new Hashtag("#akka");
// #model
public static final Source<Tweet, NotUsed> tweets =
Source.from(
Arrays.asList(
new Tweet[] {
new Tweet(new Author("rolandkuhn"), System.currentTimeMillis(), "#akka rocks!"),
new Tweet(new Author("patriknw"), System.currentTimeMillis(), "#akka !"),
new Tweet(new Author("bantonsson"), System.currentTimeMillis(), "#akka !"),
new Tweet(new Author("drewhk"), System.currentTimeMillis(), "#akka !"),
new Tweet(
new Author("ktosopl"), System.currentTimeMillis(), "#akka on the rocks!"),
new Tweet(new Author("mmartynas"), System.currentTimeMillis(), "wow #akka !"),
new Tweet(new Author("akkateam"), System.currentTimeMillis(), "#akka rocks!"),
new Tweet(new Author("bananaman"), System.currentTimeMillis(), "#bananas rock!"),
new Tweet(new Author("appleman"), System.currentTimeMillis(), "#apples rock!"),
new Tweet(
new Author("drama"),
System.currentTimeMillis(),
"we compared #apples to #oranges!")
}));
}
abstract static class Example0 {
// #tweet-source
Source<Tweet, NotUsed> tweets;
// #tweet-source
}
abstract static class Example1 {
// #first-sample
// #materializer-setup
final ActorSystem system = ActorSystem.create("reactive-tweets");
final Materializer mat = ActorMaterializer.create(system);
// #first-sample
// #materializer-setup
}
static class Example2 {
public void run(final Materializer mat)
throws TimeoutException, InterruptedException, ExecutionException {
// #backpressure-by-readline
final CompletionStage<Done> completion =
Source.from(Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10))
.map(
i -> {
System.out.println("map => " + i);
return i;
})
.runForeach(
i ->
System.console()
.readLine("Element = %s continue reading? [press enter]\n", i),
mat);
completion.toCompletableFuture().get(1, TimeUnit.SECONDS);
// #backpressure-by-readline
}
}
final Materializer mat = ActorMaterializer.create(system);
@Test
public void demonstrateFilterAndMap() {
final SilenceSystemOut.System System = SilenceSystemOut.get();
// #first-sample
// #authors-filter-map
final Source<Author, NotUsed> authors =
tweets.filter(t -> t.hashtags().contains(AKKA)).map(t -> t.author);
// #first-sample
// #authors-filter-map
new Object() {
// #authors-collect
JavaPartialFunction<Tweet, Author> collectFunction =
new JavaPartialFunction<Tweet, Author>() {
public Author apply(Tweet t, boolean isCheck) {
if (t.hashtags().contains(AKKA)) {
if (isCheck) return null; // to spare the expensive or side-effecting code
return t.author;
} else {
throw noMatch();
}
}
};
final Source<Author, NotUsed> authors = tweets.collect(collectFunction);
// #authors-collect
};
// #first-sample
// #authors-foreachsink-println
authors.runWith(Sink.foreach(a -> System.out.println(a)), mat);
// #first-sample
// #authors-foreachsink-println
// #authors-foreach-println
authors.runForeach(a -> System.out.println(a), mat);
// #authors-foreach-println
}
@Test
public void demonstrateMapConcat() {
// #hashtags-mapConcat
final Source<Hashtag, NotUsed> hashtags =
tweets.mapConcat(t -> new ArrayList<Hashtag>(t.hashtags()));
// #hashtags-mapConcat
}
abstract static class HiddenDefinitions {
// #flow-graph-broadcast
Sink<Author, NotUsed> writeAuthors;
Sink<Hashtag, NotUsed> writeHashtags;
// #flow-graph-broadcast
}
@Test
public void demonstrateBroadcast() {
final Sink<Author, CompletionStage<Done>> writeAuthors = Sink.ignore();
final Sink<Hashtag, CompletionStage<Done>> writeHashtags = Sink.ignore();
// #flow-graph-broadcast
RunnableGraph.fromGraph(
GraphDSL.create(
b -> {
final UniformFanOutShape<Tweet, Tweet> bcast = b.add(Broadcast.create(2));
final FlowShape<Tweet, Author> toAuthor =
b.add(Flow.of(Tweet.class).map(t -> t.author));
final FlowShape<Tweet, Hashtag> toTags =
b.add(
Flow.of(Tweet.class)
.mapConcat(t -> new ArrayList<Hashtag>(t.hashtags())));
final SinkShape<Author> authors = b.add(writeAuthors);
final SinkShape<Hashtag> hashtags = b.add(writeHashtags);
b.from(b.add(tweets)).viaFanOut(bcast).via(toAuthor).to(authors);
b.from(bcast).via(toTags).to(hashtags);
return ClosedShape.getInstance();
}))
.run(mat);
// #flow-graph-broadcast
}
long slowComputation(Tweet t) {
try {
// act as if performing some heavy computation
Thread.sleep(500);
} catch (InterruptedException e) {
}
return 42;
}
@Test
public void demonstrateSlowProcessing() {
// #tweets-slow-consumption-dropHead
tweets
.buffer(10, OverflowStrategy.dropHead())
.map(t -> slowComputation(t))
.runWith(Sink.ignore(), mat);
// #tweets-slow-consumption-dropHead
}
@Test
public void demonstrateCountOnFiniteStream() {
// #tweets-fold-count
final Sink<Integer, CompletionStage<Integer>> sumSink =
Sink.<Integer, Integer>fold(0, (acc, elem) -> acc + elem);
final RunnableGraph<CompletionStage<Integer>> counter =
tweets.map(t -> 1).toMat(sumSink, Keep.right());
final CompletionStage<Integer> sum = counter.run(mat);
sum.thenAcceptAsync(
c -> System.out.println("Total tweets processed: " + c), system.dispatcher());
// #tweets-fold-count
new Object() {
// #tweets-fold-count-oneline
final CompletionStage<Integer> sum = tweets.map(t -> 1).runWith(sumSink, mat);
// #tweets-fold-count-oneline
};
}
@Test
public void demonstrateMaterializeMultipleTimes() {
final Source<Tweet, NotUsed> tweetsInMinuteFromNow =
tweets; // not really in second, just acting as if
// #tweets-runnable-flow-materialized-twice
final Sink<Integer, CompletionStage<Integer>> sumSink =
Sink.<Integer, Integer>fold(0, (acc, elem) -> acc + elem);
final RunnableGraph<CompletionStage<Integer>> counterRunnableGraph =
tweetsInMinuteFromNow
.filter(t -> t.hashtags().contains(AKKA))
.map(t -> 1)
.toMat(sumSink, Keep.right());
// materialize the stream once in the morning
final CompletionStage<Integer> morningTweetsCount = counterRunnableGraph.run(mat);
// and once in the evening, reusing the blueprint
final CompletionStage<Integer> eveningTweetsCount = counterRunnableGraph.run(mat);
// #tweets-runnable-flow-materialized-twice
}
}
@BeforeClass
public static void setup() {
system = ActorSystem.create("CompositionDocTest");
mat = ActorMaterializer.create(system);
}
