Package akka.stream.scaladsl

Class Flow$

  • public class Flow$
extends java.lang.Object

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static Flow$ MODULE$
      Static reference to the singleton instance of this Scala object.

    • Constructor Summary

      Constructors 
      Constructor Description
      Flow$()  

    • Method Summary

      All Methods Instance Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      <T> Flow<T,​T,​NotUsed> apply()
      Returns a Flow which outputs all its inputs.
      <A,​B>
      Flow<A,​B,​NotUsed>      		 fromFunction​(scala.Function1<A,​B> f)
      Creates a [Flow] which will use the given function to transform its inputs to outputs.
      <I,​O,​M>
      Flow<I,​O,​M>      		 fromGraph​(Graph<FlowShape<I,​O>,​M> g)
      A graph with the shape of a flow logically is a flow, this method makes it so also in type.
      <T,​U,​M>
      Flow<T,​U,​scala.concurrent.Future<M>>      		 fromMaterializer​(scala.Function2<Materializer,​Attributes,​Flow<T,​U,​M>> factory)
      Defers the creation of a Flow until materialization.
      <I,​O>
      Flow<I,​O,​NotUsed>      		 fromProcessor​(scala.Function0<org.reactivestreams.Processor<I,​O>> processorFactory)
      Creates a Flow from a Reactive Streams Processor
      <I,​O,​M>
      Flow<I,​O,​M>      		 fromProcessorMat​(scala.Function0<scala.Tuple2<org.reactivestreams.Processor<I,​O>,​M>> processorFactory)
      Creates a Flow from a Reactive Streams Processor and returns a materialized value.
      <I,​O>
      Flow<I,​O,​NotUsed>      		 fromSinkAndSource​(Graph<SinkShape<I>,​?> sink, Graph<SourceShape<O>,​?> source)
      Creates a Flow from a Sink and a Source where the Flow's input will be sent to the Sink and the Flow's output will come from the Source.
      <I,​O>
      Flow<I,​O,​NotUsed>      		 fromSinkAndSourceCoupled​(Graph<SinkShape<I>,​?> sink, Graph<SourceShape<O>,​?> source)
      Allows coupling termination (cancellation, completion, erroring) of Sinks and Sources while creating a Flow from them.
      <I,​O,​M1,​M2,​M>
      Flow<I,​O,​M>      		 fromSinkAndSourceCoupledMat​(Graph<SinkShape<I>,​M1> sink, Graph<SourceShape<O>,​M2> source, scala.Function2<M1,​M2,​M> combine)
      Allows coupling termination (cancellation, completion, erroring) of Sinks and Sources while creating a Flow from them.
      <I,​O,​M1,​M2,​M>
      Flow<I,​O,​M>      		 fromSinkAndSourceMat​(Graph<SinkShape<I>,​M1> sink, Graph<SourceShape<O>,​M2> source, scala.Function2<M1,​M2,​M> combine)
      Creates a Flow from a Sink and a Source where the Flow's input will be sent to the Sink and the Flow's output will come from the Source.
      <I,​O,​M>
      Flow<I,​O,​scala.concurrent.Future<M>>      		 futureFlow​(scala.concurrent.Future<Flow<I,​O,​M>> flow)
      Turn a Future[Flow] into a flow that will consume the values of the source when the future completes successfully.
      <I,​O,​M>
      Flow<I,​O,​scala.concurrent.Future<M>>      		 lazyFlow​(scala.Function0<Flow<I,​O,​M>> create)
      Defers invoking the create function to create a future flow until there is downstream demand and passing that downstream demand upstream triggers the first element.
      <I,​O,​M>
      Flow<I,​O,​scala.concurrent.Future<M>>      		 lazyFutureFlow​(scala.Function0<scala.concurrent.Future<Flow<I,​O,​M>>> create)
      Defers invoking the create function to create a future flow until there downstream demand has caused upstream to send a first element.
      <I,​O,​M>
      Flow<I,​O,​M>      		 lazyInit​(scala.Function1<I,​scala.concurrent.Future<Flow<I,​O,​M>>> flowFactory, scala.Function0<M> fallback)
      Deprecated.
      Use 'Flow.futureFlow' in combination with prefixAndTail(1) instead, see `futureFlow` operator docs for details.
      <I,​O,​M>
      Flow<I,​O,​scala.concurrent.Future<scala.Option<M>>>      		 lazyInitAsync​(scala.Function0<scala.concurrent.Future<Flow<I,​O,​M>>> flowFactory)
      Deprecated.
      Use 'Flow.lazyFutureFlow' instead.
      <T,​U,​M>
      Flow<T,​U,​scala.concurrent.Future<M>>      		 setup​(scala.Function2<ActorMaterializer,​Attributes,​Flow<T,​U,​M>> factory)
      Deprecated.
      Use 'fromMaterializer' instead.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • MODULE$

        public static final Flow$ MODULE$
        Static reference to the singleton instance of this Scala object.

    • Constructor Detail

      • Flow$

        public Flow$()

    • Method Detail

      • fromProcessor

        public <I,​O> Flow<I,​O,​NotUsed> fromProcessor​(scala.Function0<org.reactivestreams.Processor<I,​O>> processorFactory)
        Creates a Flow from a Reactive Streams Processor

      • fromProcessorMat

        public <I,​O,​M> Flow<I,​O,​M> fromProcessorMat​(scala.Function0<scala.Tuple2<org.reactivestreams.Processor<I,​O>,​M>> processorFactory)
        Creates a Flow from a Reactive Streams Processor and returns a materialized value.

      • apply

        public <T> Flow<T,​T,​NotUsed> apply()
        Returns a Flow which outputs all its inputs.

      • fromFunction

        public <A,​B> Flow<A,​B,​NotUsed> fromFunction​(scala.Function1<A,​B> f)
        Creates a [Flow] which will use the given function to transform its inputs to outputs. It is equivalent to Flow[T].map(f)

      • fromGraph

        public <I,​O,​M> Flow<I,​O,​M> fromGraph​(Graph<FlowShape<I,​O>,​M> g)
        A graph with the shape of a flow logically is a flow, this method makes it so also in type.

      • fromMaterializer

        public <T,​U,​M> Flow<T,​U,​scala.concurrent.Future<M>> fromMaterializer​(scala.Function2<Materializer,​Attributes,​Flow<T,​U,​M>> factory)
        Defers the creation of a Flow until materialization. The factory function exposes Materializer which is going to be used during materialization and Attributes of the Flow returned by this method.

      • setup

        public <T,​U,​M> Flow<T,​U,​scala.concurrent.Future<M>> setup​(scala.Function2<ActorMaterializer,​Attributes,​Flow<T,​U,​M>> factory)
        Deprecated.
        Use 'fromMaterializer' instead. Since 2.6.0.
        Defers the creation of a Flow until materialization. The factory function exposes ActorMaterializer which is going to be used during materialization and Attributes of the Flow returned by this method.

      • fromSinkAndSource

        public <I,​O> Flow<I,​O,​NotUsed> fromSinkAndSource​(Graph<SinkShape<I>,​?> sink,
                                                                   Graph<SourceShape<O>,​?> source)
        Creates a Flow from a Sink and a Source where the Flow's input will be sent to the Sink and the Flow's output will come from the Source.

        The resulting flow can be visualized as: 

        
     +----------------------------------------------+
     | Resulting Flow[I, O, NotUsed]                |
     |                                              |
     |  +---------+                  +-----------+  |
     |  |         |                  |           |  |
 I  ~~> | Sink[I] | [no-connection!] | Source[O] | ~~> O
     |  |         |                  |           |  |
     |  +---------+                  +-----------+  |
     +----------------------------------------------+

        The completion of the Sink and Source sides of a Flow constructed using this method are independent. So if the Sink receives a completion signal, the Source side will remain unaware of that. If you are looking to couple the termination signals of the two sides use Flow.fromSinkAndSourceCoupled instead.

        See also <I,O,M1,M2,M>fromSinkAndSourceMat(akka.stream.Graph<akka.stream.SinkShape<I>,M1>,akka.stream.Graph<akka.stream.SourceShape<O>,M2>,scala.Function2<M1,M2,M>) when access to materialized values of the parameters is needed.

      • fromSinkAndSourceMat

        public <I,​O,​M1,​M2,​M> Flow<I,​O,​M> fromSinkAndSourceMat​(Graph<SinkShape<I>,​M1> sink,
                                                                                          Graph<SourceShape<O>,​M2> source,
                                                                                          scala.Function2<M1,​M2,​M> combine)
        Creates a Flow from a Sink and a Source where the Flow's input will be sent to the Sink and the Flow's output will come from the Source.

        The resulting flow can be visualized as: 

        
     +-------------------------------------------------------+
     | Resulting Flow[I, O, M]                              |
     |                                                      |
     |  +-------------+                  +---------------+  |
     |  |             |                  |               |  |
 I  ~~> | Sink[I, M1] | [no-connection!] | Source[O, M2] | ~~> O
     |  |             |                  |               |  |
     |  +-------------+                  +---------------+  |
     +------------------------------------------------------+

        The completion of the Sink and Source sides of a Flow constructed using this method are independent. So if the Sink receives a completion signal, the Source side will remain unaware of that. If you are looking to couple the termination signals of the two sides use Flow.fromSinkAndSourceCoupledMat instead.

        The combine function is used to compose the materialized values of the sink and source into the materialized value of the resulting Flow.

      • fromSinkAndSourceCoupled

        public <I,​O> Flow<I,​O,​NotUsed> fromSinkAndSourceCoupled​(Graph<SinkShape<I>,​?> sink,
                                                                          Graph<SourceShape<O>,​?> source)
        Allows coupling termination (cancellation, completion, erroring) of Sinks and Sources while creating a Flow from them. Similar to Flow.fromSinkAndSource however couples the termination of these two operators.

        The resulting flow can be visualized as: 

        
     +---------------------------------------------+
     | Resulting Flow[I, O, NotUsed]               |
     |                                             |
     |  +---------+                 +-----------+  |
     |  |         |                 |           |  |
 I  ~~> | Sink[I] | ~~~(coupled)~~~ | Source[O] | ~~> O
     |  |         |                 |           |  |
     |  +---------+                 +-----------+  |
     +---------------------------------------------+

        E.g. if the emitted Flow gets a cancellation, the Source of course is cancelled, however the Sink will also be completed. The table below illustrates the effects in detail:

        Returned Flow Sink (in) Source (out)
        cause: upstream (sink-side) receives completion effect: receives completion effect: receives cancel
        cause: upstream (sink-side) receives error effect: receives error effect: receives cancel
        cause: downstream (source-side) receives cancel effect: completes effect: receives cancel
        effect: cancels upstream, completes downstream effect: completes cause: signals complete
        effect: cancels upstream, errors downstream effect: receives error cause: signals error or throws
        effect: cancels upstream, completes downstream cause: cancels effect: receives cancel

        See also <I,O,M1,M2,M>fromSinkAndSourceCoupledMat(akka.stream.Graph<akka.stream.SinkShape<I>,M1>,akka.stream.Graph<akka.stream.SourceShape<O>,M2>,scala.Function2<M1,M2,M>) when access to materialized values of the parameters is needed.

      • fromSinkAndSourceCoupledMat

        public <I,​O,​M1,​M2,​M> Flow<I,​O,​M> fromSinkAndSourceCoupledMat​(Graph<SinkShape<I>,​M1> sink,
                                                                                                 Graph<SourceShape<O>,​M2> source,
                                                                                                 scala.Function2<M1,​M2,​M> combine)
        Allows coupling termination (cancellation, completion, erroring) of Sinks and Sources while creating a Flow from them. Similar to Flow.fromSinkAndSource however couples the termination of these two operators.

        The resulting flow can be visualized as: 

        
     +-----------------------------------------------------+
     | Resulting Flow[I, O, M]                             |
     |                                                     |
     |  +-------------+                 +---------------+  |
     |  |             |                 |               |  |
 I  ~~> | Sink[I, M1] | ~~~(coupled)~~~ | Source[O, M2] | ~~> O
     |  |             |                 |               |  |
     |  +-------------+                 +---------------+  |
     +-----------------------------------------------------+

        E.g. if the emitted Flow gets a cancellation, the Source of course is cancelled, however the Sink will also be completed. The table on Flow.fromSinkAndSourceCoupled illustrates the effects in detail.

        The combine function is used to compose the materialized values of the sink and source into the materialized value of the resulting Flow.

      • lazyInit

        public <I,​O,​M> Flow<I,​O,​M> lazyInit​(scala.Function1<I,​scala.concurrent.Future<Flow<I,​O,​M>>> flowFactory,
                                                            scala.Function0<M> fallback)
        Deprecated.
        Use 'Flow.futureFlow' in combination with prefixAndTail(1) instead, see `futureFlow` operator docs for details. Since 2.6.0.
        Creates a real Flow upon receiving the first element. Internal Flow will not be created if there are no elements, because of completion, cancellation, or error.

        The materialized value of the Flow is the value that is created by the fallback function.

        '''Emits when''' the internal flow is successfully created and it emits

        '''Backpressures when''' the internal flow is successfully created and it backpressures

        '''Completes when''' upstream completes and all elements have been emitted from the internal flow

        '''Cancels when''' downstream cancels (see below)

        The operator's default behaviour in case of downstream cancellation before nested flow materialization (future completion) is to cancel immediately. This behaviour can be controlled by setting the akka.stream.Attributes.NestedMaterializationCancellationPolicy.PropagateToNested attribute, this will delay downstream cancellation until nested flow's materialization which is then immediately cancelled (with the original cancellation cause).

      • lazyInitAsync

        public <I,​O,​M> Flow<I,​O,​scala.concurrent.Future<scala.Option<M>>> lazyInitAsync​(scala.Function0<scala.concurrent.Future<Flow<I,​O,​M>>> flowFactory)
        Deprecated.
        Use 'Flow.lazyFutureFlow' instead. Since 2.6.0.
        Creates a real Flow upon receiving the first element. Internal Flow will not be created if there are no elements, because of completion, cancellation, or error.

        The materialized value of the Flow is a Future[Option[M} that is completed with Some(mat) when the internal flow gets materialized or with None when there where no elements. If the flow materialization (including the call of the flowFactory) fails then the future is completed with a failure.

        '''Emits when''' the internal flow is successfully created and it emits

        '''Backpressures when''' the internal flow is successfully created and it backpressures

        '''Completes when''' upstream completes and all elements have been emitted from the internal flow

        '''Cancels when''' downstream cancels (see below)

        The operator's default behaviour in case of downstream cancellation before nested flow materialization (future completion) is to cancel immediately. This behaviour can be controlled by setting the akka.stream.Attributes.NestedMaterializationCancellationPolicy.PropagateToNested attribute, this will delay downstream cancellation until nested flow's materialization which is then immediately cancelled (with the original cancellation cause).

      • futureFlow

        public <I,​O,​M> Flow<I,​O,​scala.concurrent.Future<M>> futureFlow​(scala.concurrent.Future<Flow<I,​O,​M>> flow)
        Turn a Future[Flow] into a flow that will consume the values of the source when the future completes successfully. If the Future is completed with a failure the stream is failed.

        The materialized future value is completed with the materialized value of the future flow or failed with a NeverMaterializedException if upstream fails or downstream cancels before the future has completed.

        The operator's default behaviour in case of downstream cancellation before nested flow materialization (future completion) is to cancel immediately. This behaviour can be controlled by setting the akka.stream.Attributes.NestedMaterializationCancellationPolicy.PropagateToNested attribute, this will delay downstream cancellation until nested flow's materialization which is then immediately cancelled (with the original cancellation cause).

      • lazyFlow

        public <I,​O,​M> Flow<I,​O,​scala.concurrent.Future<M>> lazyFlow​(scala.Function0<Flow<I,​O,​M>> create)
        Defers invoking the create function to create a future flow until there is downstream demand and passing that downstream demand upstream triggers the first element.

        The materialized future value is completed with the materialized value of the created flow when that has successfully been materialized.

        If the create function throws or returns a future that fails the stream is failed, in this case the materialized future value is failed with a NeverMaterializedException.

        Note that asynchronous boundaries (and other operators) in the stream may do pre-fetching which counter acts the laziness and can trigger the factory earlier than expected.

        '''Emits when''' the internal flow is successfully created and it emits

        '''Backpressures when''' the internal flow is successfully created and it backpressures or downstream backpressures

        '''Completes when''' upstream completes and all elements have been emitted from the internal flow

        '''Cancels when''' downstream cancels (see below)

        The operator's default behaviour in case of downstream cancellation before nested flow materialization (future completion) is to cancel immediately. This behaviour can be controlled by setting the akka.stream.Attributes.NestedMaterializationCancellationPolicy.PropagateToNested attribute, this will delay downstream cancellation until nested flow's materialization which is then immediately cancelled (with the original cancellation cause).

      • lazyFutureFlow

        public <I,​O,​M> Flow<I,​O,​scala.concurrent.Future<M>> lazyFutureFlow​(scala.Function0<scala.concurrent.Future<Flow<I,​O,​M>>> create)
        Defers invoking the create function to create a future flow until there downstream demand has caused upstream to send a first element.

        The materialized future value is completed with the materialized value of the created flow when that has successfully been materialized.

        If the create function throws or returns a future that fails the stream is failed, in this case the materialized future value is failed with a NeverMaterializedException.

        Note that asynchronous boundaries (and other operators) in the stream may do pre-fetching which counter acts the laziness and can trigger the factory earlier than expected.

        '''Emits when''' the internal flow is successfully created and it emits

        '''Backpressures when''' the internal flow is successfully created and it backpressures or downstream backpressures

        '''Completes when''' upstream completes and all elements have been emitted from the internal flow

        '''Cancels when''' downstream cancels (see below)

        The operator's default behaviour in case of downstream cancellation before nested flow materialization (future completion) is to cancel immediately. This behaviour can be controlled by setting the akka.stream.Attributes.NestedMaterializationCancellationPolicy.PropagateToNested attribute, this will delay downstream cancellation until nested flow's materialization which is then immediately cancelled (with the original cancellation cause).