Package org.apache.pekko.stream.javadsl

Class FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat>

  • All Implemented Interfaces:
    Graph<FlowShape<Pair<In,​CtxIn>,​Pair<Out,​CtxOut>>,​Mat>
    public final class FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat>
extends org.apache.pekko.stream.GraphDelegate<FlowShape<Pair<In,​CtxIn>,​Pair<Out,​CtxOut>>,​Mat>
    A flow that provides operations which automatically propagate the context of an element. Only a subset of common operations from Flow is supported. As an escape hatch you can use FlowWithContext.via to manually provide the context propagation for otherwise unsupported operations.

    An "empty" flow can be created by calling FlowWithContext[Ctx, T].

    • Method Detail

      • fromPairs

        public static <In,​CtxIn,​Out,​CtxOut,​Mat> FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> fromPairs​(Flow<Pair<In,​CtxIn>,​Pair<Out,​CtxOut>,​Mat> under)
        Creates a FlowWithContext from a regular flow that operates on Pair elements.

      • unsafeOptionalDataVia

        public static <FIn,​FOut,​FViaOut,​Ctx,​FMat,​FViaMat,​Mat> FlowWithContext<FIn,​Ctx,​java.util.Optional<FViaOut>,​Ctx,​Mat> unsafeOptionalDataVia​(FlowWithContext<FIn,​Ctx,​java.util.Optional<FOut>,​Ctx,​FMat> flow,
                                                                                                                                                                                                     Flow<FOut,​FViaOut,​FViaMat> viaFlow,
                                                                                                                                                                                                     Function2<FMat,​FViaMat,​Mat> combine)
        Creates a FlowWithContext from an existing base FlowWithContext outputting an optional element and applying an additional viaFlow only if the element in the stream is defined.

        '''Emits when''' the provided viaFlow runs with defined elements

        '''Backpressures when''' the viaFlow runs for the defined elements and downstream backpressures

        '''Completes when''' upstream completes

        '''Cancels when''' downstream cancels

        Parameters:
        flow - The base flow that outputs an optional element
        viaFlow - The flow that gets used if the optional element in is defined. This flow only works on the data portion of flow and ignores the context so this flow *must* not re-order, drop or emit multiple elements for one incoming element
        combine - How to combine the materialized values of flow and viaFlow
        Returns:
        a FlowWithContext with the viaFlow applied onto defined elements of the flow. The output value is contained within an Optional which indicates whether the original flow's element had viaFlow applied.
        Since:
        1.1.0

      • via

        public <Out2,​CtxOut2,​Mat2> FlowWithContext<In,​CtxIn,​Out2,​CtxOut2,​Mat> via​(Graph<FlowShape<Pair<Out,​CtxOut>,​Pair<Out2,​CtxOut2>>,​Mat2> viaFlow)
        Transform this flow by the regular flow. The given flow must support manual context propagation by taking and producing tuples of (data, context).

        It is up to the implementer to ensure the inner flow does not exhibit any behavior that is not expected by the downstream elements, such as reordering. For more background on these requirements see https://pekko.apache.org/docs/pekko/current/stream/stream-context.html.

        This can be used as an escape hatch for operations that are not (yet) provided with automatic context propagation here.

        See Also:
        pekko.stream.javadsl.Flow.via

      • unsafeDataVia

        public <Out2,​Mat2> FlowWithContext<In,​CtxIn,​Out2,​CtxOut,​Mat> unsafeDataVia​(Graph<FlowShape<Out,​Out2>,​Mat2> viaFlow)
        Transform this flow by the regular flow. The given flow works on the data portion of the stream and ignores the context.

        The given flow *must* not re-order, drop or emit multiple elements for one incoming element, the sequence of incoming contexts is re-combined with the outgoing elements of the stream. If a flow not fulfilling this requirement is used the stream will not fail but continue running in a corrupt state and re-combine incorrect pairs of elements and contexts or deadlock.

        For more background on these requirements see https://pekko.apache.org/docs/pekko/current/stream/stream-context.html.

      • withAttributes

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> withAttributes​(Attributes attr)
        Context-preserving variant of pekko.stream.javadsl.Flow.withAttributes.

        See Also:
        pekko.stream.javadsl.Flow.withAttributes

      • mapError

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> mapError​(scala.PartialFunction<java.lang.Throwable,​java.lang.Throwable> pf)
        Context-preserving variant of pekko.stream.javadsl.Flow.mapError.

        See Also:
        pekko.stream.javadsl.Flow.mapError

      • mapMaterializedValue

        public <Mat2> FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat2> mapMaterializedValue​(Function<Mat,​Mat2> f)
        Context-preserving variant of pekko.stream.javadsl.Flow.mapMaterializedValue.

        See Also:
        pekko.stream.javadsl.Flow.mapMaterializedValue

      • collect

        public <Out2> FlowWithContext<In,​CtxIn,​Out2,​CtxOut,​Mat> collect​(scala.PartialFunction<Out,​Out2> pf)
        Context-preserving variant of pekko.stream.javadsl.Flow.collect.

        Note, that the context of elements that are filtered out is skipped as well.

        See Also:
        pekko.stream.javadsl.Flow.collect

      • filter

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> filter​(Predicate<Out> p)
        Context-preserving variant of pekko.stream.javadsl.Flow.filter.

        Note, that the context of elements that are filtered out is skipped as well.

        See Also:
        pekko.stream.javadsl.Flow.filter

      • filterNot

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> filterNot​(Predicate<Out> p)
        Context-preserving variant of pekko.stream.javadsl.Flow.filterNot.

        Note, that the context of elements that are filtered out is skipped as well.

        See Also:
        pekko.stream.javadsl.Flow.filterNot

      • grouped

        public FlowWithContext<In,​CtxIn,​java.util.List<Out>,​java.util.List<CtxOut>,​Mat> grouped​(int n)
        Context-preserving variant of pekko.stream.javadsl.Flow.grouped.

        Each output group will be associated with a Seq of corresponding context elements.

        See Also:
        pekko.stream.javadsl.Flow.grouped

      • map

        public <Out2> FlowWithContext<In,​CtxIn,​Out2,​CtxOut,​Mat> map​(Function<Out,​Out2> f)
        Context-preserving variant of pekko.stream.javadsl.Flow.map.

        See Also:
        pekko.stream.javadsl.Flow.map

      • mapAsync

        public <Out2> FlowWithContext<In,​CtxIn,​Out2,​CtxOut,​Mat> mapAsync​(int parallelism,
                                                                                         Function<Out,​java.util.concurrent.CompletionStage<Out2>> f)
        Context-preserving variant of pekko.stream.javadsl.Flow.mapAsync.

        See Also:
        pekko.stream.javadsl.Flow.mapAsync

      • mapAsyncPartitioned

        public <Out2,​P> FlowWithContext<In,​CtxIn,​Out2,​CtxOut,​Mat> mapAsyncPartitioned​(int parallelism,
                                                                                                            Function<Out,​P> partitioner,
                                                                                                            Function2<Out,​P,​java.util.concurrent.CompletionStage<Out2>> f)
        Context-preserving variant of pekko.stream.javadsl.Flow.mapAsyncPartitioned.

        Since:
        1.1.0
        See Also:
        pekko.stream.javadsl.Flow.mapAsyncPartitioned

      • mapAsyncPartitionedUnordered

        public <Out2,​P> FlowWithContext<In,​CtxIn,​Out2,​CtxOut,​Mat> mapAsyncPartitionedUnordered​(int parallelism,
                                                                                                                     Function<Out,​P> partitioner,
                                                                                                                     Function2<Out,​P,​java.util.concurrent.CompletionStage<Out2>> f)
        Context-preserving variant of pekko.stream.javadsl.Flow.mapAsyncPartitionedUnordered.

        Since:
        1.1.0
        See Also:
        pekko.stream.javadsl.Flow.mapAsyncPartitionedUnordered

      • mapConcat

        public <Out2> FlowWithContext<In,​CtxIn,​Out2,​CtxOut,​Mat> mapConcat​(Function<Out,​? extends java.lang.Iterable<Out2>> f)
        Context-preserving variant of pekko.stream.javadsl.Flow.mapConcat.

        The context of the input element will be associated with each of the output elements calculated from this input element.

        Example:

        def dup(element: String) = Seq(element, element)

        Input:

        ("a", 1) ("b", 2)

        inputElements.mapConcat(dup)

        Output:

        ("a", 1) ("a", 1) ("b", 2) ("b", 2)

        See Also:
        pekko.stream.javadsl.Flow.mapConcat

      • mapContext

        public <CtxOut2> FlowWithContext<In,​CtxIn,​Out,​CtxOut2,​Mat> mapContext​(Function<CtxOut,​CtxOut2> extractContext)
        Apply the given function to each context element (leaving the data elements unchanged).

      • sliding

        public FlowWithContext<In,​CtxIn,​java.util.List<Out>,​java.util.List<CtxOut>,​Mat> sliding​(int n,
                                                                                                                int step)
        Context-preserving variant of pekko.stream.javadsl.Flow.sliding.

        Each output group will be associated with a Seq of corresponding context elements.

        See Also:
        pekko.stream.javadsl.Flow.sliding

      • sliding$default$2

        public int sliding$default$2()

      • log

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> log​(java.lang.String name,
                                                                            Function<Out,​java.lang.Object> extract)
        Context-preserving variant of pekko.stream.javadsl.Flow.log.

        See Also:
        pekko.stream.javadsl.Flow.log

      • log

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> log​(java.lang.String name)
        Context-preserving variant of pekko.stream.javadsl.Flow.log.

        See Also:
        pekko.stream.javadsl.Flow.log

      • throttle

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> throttle​(int elements,
                                                                                 java.time.Duration per)
        Context-preserving variant of pekko.stream.javadsl.Flow.throttle.

        See Also:
        pekko.stream.javadsl.Flow.throttle

      • throttle

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> throttle​(int elements,
                                                                                 java.time.Duration per,
                                                                                 int maximumBurst,
                                                                                 ThrottleMode mode)
        Context-preserving variant of pekko.stream.javadsl.Flow.throttle.

        See Also:
        pekko.stream.javadsl.Flow.throttle

      • throttle

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> throttle​(int cost,
                                                                                 java.time.Duration per,
                                                                                 Function<Out,​java.lang.Integer> costCalculation)
        Context-preserving variant of pekko.stream.javadsl.Flow.throttle.

        See Also:
        pekko.stream.javadsl.Flow.throttle

      • throttle

        public FlowWithContext<In,​CtxIn,​Out,​CtxOut,​Mat> throttle​(int cost,
                                                                                 java.time.Duration per,
                                                                                 int maximumBurst,
                                                                                 Function<Out,​java.lang.Integer> costCalculation,
                                                                                 ThrottleMode mode)
        Context-preserving variant of pekko.stream.javadsl.Flow.throttle.

        See Also:
        pekko.stream.javadsl.Flow.throttle