public class Source$
extends java.lang.Object
| Modifier and Type | Field and Description |
|---|---|
static Source$ |
MODULE$
Static reference to the singleton instance of this Scala object.
|
| Constructor and Description |
|---|
Source$() |
| Modifier and Type | Method and Description |
|---|---|
<T> Source<T,ActorRef> |
actorPublisher(Props props)
|
<T> Source<T,ActorRef> |
actorRef(int bufferSize,
OverflowStrategy overflowStrategy)
Creates a
Source that is materialized as an ActorRef. |
<T> Source<T,NotUsed> |
apply(scala.collection.immutable.Iterable<T> iterable)
Helper to create
Source from Iterable. |
<T> Source<T,org.reactivestreams.Subscriber<T>> |
asSubscriber()
Creates a
Source that is materialized as a Subscriber |
<T,U> Source<U,NotUsed> |
combine(Source<T,?> first,
Source<T,?> second,
scala.collection.Seq<Source<T,?>> rest,
scala.Function1<java.lang.Object,Graph<UniformFanInShape<T,U>,NotUsed>> strategy)
Combines several sources with fun-in strategy like
Merge or Concat and returns Source. |
<T> Source<T,NotUsed> |
cycle(scala.Function0<scala.collection.Iterator<T>> f)
Create
Source that will continually produce given elements in specified order. |
<T> Source<T,NotUsed> |
empty()
A
Source with no elements, i.e. |
<T> Source<T,NotUsed> |
failed(java.lang.Throwable cause)
Create a
Source that immediately ends the stream with the cause error to every connected Sink. |
<T> Source<T,NotUsed> |
fromCompletionStage(java.util.concurrent.CompletionStage<T> future)
Start a new
Source from the given Future. |
<T> Source<T,NotUsed> |
fromFuture(scala.concurrent.Future<T> future)
Start a new
Source from the given Future. |
<T,M> Source<T,M> |
fromGraph(Graph<SourceShape<T>,M> g)
A graph with the shape of a source logically is a source, this method makes
it so also in type.
|
<T> Source<T,NotUsed> |
fromIterator(scala.Function0<scala.collection.Iterator<T>> f)
Helper to create
Source from Iterator. |
<T> Source<T,NotUsed> |
fromPublisher(org.reactivestreams.Publisher<T> publisher)
Helper to create
Source from Publisher. |
<T,M> Source<T,scala.concurrent.Future<M>> |
lazily(scala.Function0<Source<T,M>> create)
Creates a
Source that is not materialized until there is downstream demand, when the source gets materialized
the materialized future is completed with its value, if downstream cancels or fails without any demand the
create factory is never called and the materialized Future is failed. |
<T> Source<T,scala.concurrent.Promise<scala.Option<T>>> |
maybe()
Create a
Source which materializes a Promise which controls what element
will be emitted by the Source. |
<T> Source<T,SourceQueueWithComplete<T>> |
queue(int bufferSize,
OverflowStrategy overflowStrategy)
Creates a
Source that is materialized as an SourceQueue. |
<T> Source<T,NotUsed> |
repeat(T element)
Create a
Source that will continually emit the given element. |
<T> SourceShape<T> |
shape(java.lang.String name)
INTERNAL API
|
<T> Source<T,NotUsed> |
single(T element)
Create a
Source with one element. |
<T> Source<T,Cancellable> |
tick(scala.concurrent.duration.FiniteDuration initialDelay,
scala.concurrent.duration.FiniteDuration interval,
T tick)
Elements are emitted periodically with the specified interval.
|
<S,E> Source<E,NotUsed> |
unfold(S s,
scala.Function1<S,scala.Option<scala.Tuple2<S,E>>> f)
Create a
Source that will unfold a value of type S into
a pair of the next state S and output elements of type E. |
<S,E> Source<E,NotUsed> |
unfoldAsync(S s,
scala.Function1<S,scala.concurrent.Future<scala.Option<scala.Tuple2<S,E>>>> f)
Same as
unfold, but uses an async function to generate the next state-element tuple. |
<T,S> Source<T,NotUsed> |
unfoldResource(scala.Function0<S> create,
scala.Function1<S,scala.Option<T>> read,
scala.Function1<S,scala.runtime.BoxedUnit> close)
Start a new
Source from some resource which can be opened, read and closed. |
<T,S> Source<T,NotUsed> |
unfoldResourceAsync(scala.Function0<scala.concurrent.Future<S>> create,
scala.Function1<S,scala.concurrent.Future<scala.Option<T>>> read,
scala.Function1<S,scala.concurrent.Future<Done>> close)
Start a new
Source from some resource which can be opened, read and closed. |
<T> Source<scala.collection.immutable.Seq<T>,NotUsed> |
zipN(scala.collection.immutable.Seq<Source<T,?>> sources)
Combine the elements of multiple streams into a stream of sequences.
|
<T,O> Source<O,NotUsed> |
zipWithN(scala.Function1<scala.collection.immutable.Seq<T>,O> zipper,
scala.collection.immutable.Seq<Source<T,?>> sources) |
public static final Source$ MODULE$
public <T> SourceShape<T> shape(java.lang.String name)
public <T> Source<T,NotUsed> fromPublisher(org.reactivestreams.Publisher<T> publisher)
Source from Publisher.
Construct a transformation starting with given publisher. The transformation steps
are executed by a series of Processor instances
that mediate the flow of elements downstream and the propagation of
back-pressure upstream.
publisher - (undocumented)public <T> Source<T,NotUsed> fromIterator(scala.Function0<scala.collection.Iterator<T>> f)
Source from Iterator.
Example usage: Source.fromIterator(() => Iterator.from(0))
Start a new Source from the given function that produces anIterator.
The produced stream of elements will continue until the iterator runs empty
or fails during evaluation of the next() method.
Elements are pulled out of the iterator in accordance with the demand coming
from the downstream transformation steps.
f - (undocumented)public <T> Source<T,NotUsed> cycle(scala.Function0<scala.collection.Iterator<T>> f)
Source that will continually produce given elements in specified order.
Start a new 'cycled' Source from the given elements. The producer stream of elements
will continue infinitely by repeating the sequence of elements provided by function parameter.
f - (undocumented)public <T,M> Source<T,M> fromGraph(Graph<SourceShape<T>,M> g)
g - (undocumented)public <T> Source<T,NotUsed> apply(scala.collection.immutable.Iterable<T> iterable)
Source from Iterable.
Example usage: Source(Seq(1,2,3))
Starts a new Source from the given Iterable. This is like starting from an
Iterator, but every Subscriber directly attached to the Publisher of this
stream will see an individual flow of elements (always starting from the
beginning) regardless of when they subscribed.
iterable - (undocumented)public <T> Source<T,NotUsed> fromFuture(scala.concurrent.Future<T> future)
Source from the given Future. The stream will consist of
one element when the Future is completed with a successful value, which
may happen before or after materializing the Flow.
The stream terminates with a failure if the Future is completed with a failure.future - (undocumented)public <T> Source<T,NotUsed> fromCompletionStage(java.util.concurrent.CompletionStage<T> future)
Source from the given Future. The stream will consist of
one element when the Future is completed with a successful value, which
may happen before or after materializing the Flow.
The stream terminates with a failure if the Future is completed with a failure.future - (undocumented)public <T> Source<T,Cancellable> tick(scala.concurrent.duration.FiniteDuration initialDelay, scala.concurrent.duration.FiniteDuration interval, T tick)
initialDelay - (undocumented)interval - (undocumented)tick - (undocumented)public <T> Source<T,NotUsed> single(T element)
Source with one element.
Every connected Sink of this stream will see an individual stream consisting of one element.element - (undocumented)public <T> Source<T,NotUsed> repeat(T element)
Source that will continually emit the given element.element - (undocumented)public <S,E> Source<E,NotUsed> unfold(S s, scala.Function1<S,scala.Option<scala.Tuple2<S,E>>> f)
Source that will unfold a value of type S into
a pair of the next state S and output elements of type E.
For example, all the Fibonacci numbers under 10M:
Source.unfold(0 → 1) {
case (a, _) if a > 10000000 ⇒ None
case (a, b) ⇒ Some((b → (a + b)) → a)
}
s - (undocumented)f - (undocumented)public <S,E> Source<E,NotUsed> unfoldAsync(S s, scala.Function1<S,scala.concurrent.Future<scala.Option<scala.Tuple2<S,E>>>> f)
unfold, but uses an async function to generate the next state-element tuple.
async fibonacci example:
Source.unfoldAsync(0 → 1) {
case (a, _) if a > 10000000 ⇒ Future.successful(None)
case (a, b) ⇒ Future{
Thread.sleep(1000)
Some((b → (a + b)) → a)
}
}
s - (undocumented)f - (undocumented)public <T> Source<T,NotUsed> empty()
Source with no elements, i.e. an empty stream that is completed immediately for every connected Sink.public <T> Source<T,scala.concurrent.Promise<scala.Option<T>>> maybe()
Source which materializes a Promise which controls what element
will be emitted by the Source.
If the materialized promise is completed with a Some, that value will be produced downstream,
followed by completion.
If the materialized promise is completed with a None, no value will be produced downstream and completion will
be signalled immediately.
If the materialized promise is completed with a failure, then the returned source will terminate with that error.
If the downstream of this source cancels before the promise has been completed, then the promise will be completed
with None.public <T> Source<T,NotUsed> failed(java.lang.Throwable cause)
Source that immediately ends the stream with the cause error to every connected Sink.cause - (undocumented)public <T,M> Source<T,scala.concurrent.Future<M>> lazily(scala.Function0<Source<T,M>> create)
Source that is not materialized until there is downstream demand, when the source gets materialized
the materialized future is completed with its value, if downstream cancels or fails without any demand the
create factory is never called and the materialized Future is failed.create - (undocumented)public <T> Source<T,org.reactivestreams.Subscriber<T>> asSubscriber()
Source that is materialized as a Subscriberpublic <T> Source<T,ActorRef> actorPublisher(Props props)
Source that is materialized to an ActorRef which points to an Actor
created according to the passed in Props. Actor created by the props must
be ActorPublisher.props - (undocumented)public <T> Source<T,ActorRef> actorRef(int bufferSize, OverflowStrategy overflowStrategy)
Source that is materialized as an ActorRef.
Messages sent to this actor will be emitted to the stream if there is demand from downstream,
otherwise they will be buffered until request for demand is received.
Depending on the defined OverflowStrategy it might drop elements if
there is no space available in the buffer.
The strategy akka.stream.OverflowStrategy.backpressure is not supported, and an
IllegalArgument("Backpressure overflowStrategy not supported") will be thrown if it is passed as argument.
The buffer can be disabled by using bufferSize of 0 and then received messages are dropped if there is no demand
from downstream. When bufferSize is 0 the overflowStrategy does not matter. An async boundary is added after
this Source; as such, it is never safe to assume the downstream will always generate demand.
The stream can be completed successfully by sending the actor reference a Status.Success
(whose content will be ignored) in which case already buffered elements will be signaled before signaling
completion, or by sending PoisonPill in which case completion will be signaled immediately.
The stream can be completed with failure by sending a Status.Failure to the
actor reference. In case the Actor is still draining its internal buffer (after having received
a Status.Success) before signaling completion and it receives a Status.Failure,
the failure will be signaled downstream immediately (instead of the completion signal).
The actor will be stopped when the stream is completed, failed or canceled from downstream, i.e. you can watch it to get notified when that happens.
See also akka.stream.scaladsl.Source.queue.
bufferSize - The size of the buffer in element countoverflowStrategy - Strategy that is used when incoming elements cannot fit inside the bufferpublic <T,U> Source<U,NotUsed> combine(Source<T,?> first, Source<T,?> second, scala.collection.Seq<Source<T,?>> rest, scala.Function1<java.lang.Object,Graph<UniformFanInShape<T,U>,NotUsed>> strategy)
Merge or Concat and returns Source.first - (undocumented)second - (undocumented)rest - (undocumented)strategy - (undocumented)public <T> Source<scala.collection.immutable.Seq<T>,NotUsed> zipN(scala.collection.immutable.Seq<Source<T,?>> sources)
sources - (undocumented)public <T,O> Source<O,NotUsed> zipWithN(scala.Function1<scala.collection.immutable.Seq<T>,O> zipper, scala.collection.immutable.Seq<Source<T,?>> sources)
public <T> Source<T,SourceQueueWithComplete<T>> queue(int bufferSize, OverflowStrategy overflowStrategy)
Source that is materialized as an SourceQueue.
You can push elements to the queue and they will be emitted to the stream if there is demand from downstream,
otherwise they will be buffered until request for demand is received. Elements in the buffer will be discarded
if downstream is terminated.
Depending on the defined OverflowStrategy it might drop elements if
there is no space available in the buffer.
Acknowledgement mechanism is available.
akka.stream.scaladsl.SourceQueue.offer returns Future[QueueOfferResult] which completes with
QueueOfferResult.Enqueued if element was added to buffer or sent downstream. It completes with
QueueOfferResult.Dropped if element was dropped. Can also complete with QueueOfferResult.Failure -
when stream failed or QueueOfferResult.QueueClosed when downstream is completed.
The strategy akka.stream.OverflowStrategy.backpressure will not complete last offer():Future
call when buffer is full.
You can watch accessibility of stream with akka.stream.scaladsl.SourceQueue.watchCompletion.
It returns future that completes with success when stream is completed or fail when stream is failed.
The buffer can be disabled by using bufferSize of 0 and then received message will wait
for downstream demand unless there is another message waiting for downstream demand, in that case
offer result will be completed according to the overflow strategy.
SourceQueue that current source is materialized to is for single thread usage only.
bufferSize - size of buffer in element countoverflowStrategy - Strategy that is used when incoming elements cannot fit inside the bufferpublic <T,S> Source<T,NotUsed> unfoldResource(scala.Function0<S> create, scala.Function1<S,scala.Option<T>> read, scala.Function1<S,scala.runtime.BoxedUnit> close)
Source from some resource which can be opened, read and closed.
Interaction with resource happens in a blocking way.
Example:
Source.unfoldResource(
() => new BufferedReader(new FileReader("...")),
reader => Option(reader.readLine()),
reader => reader.close())
You can use the supervision strategy to handle exceptions for read function. All exceptions thrown by create
or close will fail the stream.
Restart supervision strategy will close and create blocking IO again. Default strategy is Stop which means
that stream will be terminated on error in read function by default.
You can configure the default dispatcher for this Source by changing the akka.stream.blocking-io-dispatcher or
set it for a given Source by using ActorAttributes.
create - - function that is called on stream start and creates/opens resource.read - - function that reads data from opened resource. It is called each time backpressure signal
is received. Stream calls close and completes when read returns None.close - - function that closes resourcepublic <T,S> Source<T,NotUsed> unfoldResourceAsync(scala.Function0<scala.concurrent.Future<S>> create, scala.Function1<S,scala.concurrent.Future<scala.Option<T>>> read, scala.Function1<S,scala.concurrent.Future<Done>> close)
Source from some resource which can be opened, read and closed.
It's similar to unfoldResource but takes functions that return Futures instead of plain values.
You can use the supervision strategy to handle exceptions for read function or failures of produced Futures.
All exceptions thrown by create or close as well as fails of returned futures will fail the stream.
Restart supervision strategy will close and create resource. Default strategy is Stop which means
that stream will be terminated on error in read function (or future) by default.
You can configure the default dispatcher for this Source by changing the akka.stream.blocking-io-dispatcher or
set it for a given Source by using ActorAttributes.
create - - function that is called on stream start and creates/opens resource.read - - function that reads data from opened resource. It is called each time backpressure signal
is received. Stream calls close and completes when Future from read function returns None.close - - function that closes resource