streams

Type Members

1. class BoundedOrdering[A, B] extends GraphStage[FlowShape[A, A]]

   

   Orders the stream within a sliding window of maxBounded elements.

   Orders the stream within a sliding window of maxBounded elements. Each element passing through the BoundedOrdering has an id. The elements can be ordered by the ordering function and the next expected id can be derived from the current id.

   It takes an element and emits downstream if the getId(elem) matches the currently stored id, if not enqueues to a priority queue. When an element is emitted, the stored id is updated by calling nextId to match the next expected element and an element is dequeued from the priority queue and emitted if it matches the updated id. If the out-of-order element arrives at a later point than maxBounded then it is emitted straight downstream.

   A

   The input and output type of this stream component.

   B

   The type of the element's id. Emits when getId(elem) matches the current state, if not enqueues it to priority queue Backpressures when downstream backpressures Completes when upstream completes Cancels when downstream cancels

2. final class Deduplicate[T, U] extends GraphStage[FlowShape[T, T]]

   

   Only pass on those elements that have not been seen so far.

   Only pass on those elements that have not been seen so far.

   Emits when the element is not a duplicate

   Backpressures when the element is not a duplicate and downstream backpressures

   Completes when upstream completes

   Cancels when downstream cancels

3. class DemandSupplyMetricsStage[T] extends GraphStage[FlowShape[T, T]]

   

   A linear GraphStage that is used to capture (downstream) demand and (upstream) supply metrics for backpressure visibility.

4. case class FlowTimeoutException(msg: String = "Flow timed out!") extends TimeoutException with Product with Serializable

   

   Exception thrown when an element times out.

   Exception thrown when an element times out.

   msg

   Defaults to "Flow timed out!"

5. case class MutableLong(value: Long = 0L) extends Product with Serializable

   

   MutableLong is used to avoid boxing/unboxing and also to avoid java.util.Map#put operation to increment the counters in the registry.

6. final class Retry[In, Out, Context] extends GraphStage[BidiShape[(In, Context), (In, Context), (Try[Out], Context), (Try[Out], Context)]]

   

   A bidi GraphStage that can be joined with flows that produce Try's to add Retry functionality when there are any failures.

   A bidi GraphStage that can be joined with flows that produce Try's to add Retry functionality when there are any failures. When the joined Flow has a failure then based on the provided max retries count, it will retry the failures.

   Emits when a Success is available from joined flow or a failure has been retried the maximum number of retries

   Backpressures when the element is not a failure and downstream backpressures or the retry buffer is full

   Completes when upstream completes

   Cancels when downstream cancels

            upstream      +------+      downstream
         (In, Context) ~> |      | ~> (In, Context)
              In1         | bidi |        Out1
   (Try[Out], Context) <~ |      | <~ (Try[Out], Context)
             Out2         +------+        In2

   In

   the type of elements pulled from the upstream along with the Context

   Out

   the type of the elements that are pushed by the joined Flow along with the Context. This then gets wrapped with a Try and pushed downstream with a Context

   Context

   the type of the context that is carried around along with the elements.

7. trait RetryMetrics extends AnyRef

   

8. case class RetryMetricsImpl extends RetryMetrics with Product with Serializable

   

9. case class RetrySettings[In, Out, Context] extends Product with Serializable

   

   A Retry Settings class for configuring a Retry

   A Retry Settings class for configuring a Retry

   Retry functionality requires each element passing through is uniquely identifiable for retrying, so it requires a Context, of any type carried along with the flow's input and output element as a Tuple2 (Scala) or Pair (Java). The requirement is that either the Context type itself or a mapping from Context should be able to uniquely identify each element passing through flow.

   Here are the ways a unique id can be provided:

   • Context itself is a type that can be used as a unique id, e.g., Int, Long, java.util.UUID
   • Context extends UniqueId.Provider and implements UniqueId.Provider.uniqueId method
   • Context is of type UniqueId.Envelope
   • Context can be mapped to a unique id by calling

   uniqueIdMapper

   In

   the type of elements pulled from upstream along with the Context

   Out

   the type of the elements that are pushed to downstream along with the Context

   Context

   the type of the context that is carried along with the elements.

   returns

   a RetrySettings with specified values

10. trait RetrySettingsMXBean extends AnyRef

    

    Annotations

    @MXBean()

11. trait RetryStateMXBean extends AnyRef

    

    Annotations

    @MXBean()

12. case class RetryStateMXBeanImpl(name: String, retryQSize: () ⇒ Int, registrySize: () ⇒ Int) extends RetryStateMXBean with Product with Serializable

    

13. final class Timeout[In, Out, Context] extends GraphStage[BidiShape[(In, Context), (In, Context), (Out, Context), (Try[Out], Context)]] with LazyLogging

    

    A bidi GraphStage that is joined with flows to add timeout functionality.

    A bidi GraphStage that is joined with flows to add timeout functionality. This bidi stage is used with flows that do not guarantee the message ordering. So, it requires a context to be carried along with the elements to uniquely identify each element.

    Emits when an element is available from the joined Flow or an element has already timed out

    Backpressures when the downstream backpressures

    Completes when upstream completes

    Cancels when downstream cancels

                           +------+
          (In, Context) ~> |      | ~> (In, Context)
                           | bidi |
    (Try[Out], Context) <~ |      | <~ (Out, Context)
                           +------+

    In

    the type of the elements pulled from the upstream along with the Context

    Out

    the type of the elements that are pushed by the joined Flow along with the Context. This then gets wrapped with a Try and pushed downstream with a Context

    Context

    the type of the context that is carried around along with the elements.

14. abstract class TimeoutGraphStageLogic[In, FromWrapped, Out] extends TimerGraphStageLogic

    

    A bidi GraphStageLogic that is used by TimeoutOrdered and Timeout to wrap flows to add timeout functionality.

    A bidi GraphStageLogic that is used by TimeoutOrdered and Timeout to wrap flows to add timeout functionality.

    Once an element is pushed from the wrapped flow (from fromWrapped), it first checks if the element is already timed out. If a timeout message has already been sent for that element to downstream, then the element from the wrapped flow is dropped.

    A timer gets scheduled when there is a downstream demand that's not immediately addressed. This is to make sure that a timeout response is sent to the downstream when upstream cannot address the demand on time.

    Timer precision is at best 10ms to avoid unnecessary timer scheduling cycles

           +------+
     In ~> |      | ~> In
           | bidi |
    Out <~ |      | <~ FromWrapped
           +------+

    In

    the type of the elements that gets forwarded to the wrapped flow

    FromWrapped

    the type of the elements that the wrapped flow sends back

    Out

    the type of the elements that are pushed to downstream

15. final class TimeoutOrdered[In, Out] extends GraphStage[BidiShape[In, In, Out, Try[Out]]]

    

    A bidi GraphStage that is joined with flows to add timeout functionality.

    A bidi GraphStage that is joined with flows to add timeout functionality. This bidi stage is used with flows that guarantee the message ordering.

    Emits when an element is available from the wrapped flow or an element has already timed out

    Backpressures when the downstream backpressures

    Completes when upstream completes

    Cancels when downstream cancels

                +------+
          In ~> |      | ~> In
                | bidi |
    Try[Out] <~ |      | <~ Out
                +------+

    In

    the type of the elements pulled from the upstream and pushed down to joined flow

    Out

    the type of the elements that are pushed to downstream

16. case class TimeoutSettings[In, Out, Context] extends Product with Serializable

    

    Timeout functionality requires each element to be uniquely identified, so it requires a Context, of any type defined by the application, to be carried along with the flow's input and output as a Tuple2 (Scala) or Pair (Java).

    Timeout functionality requires each element to be uniquely identified, so it requires a Context, of any type defined by the application, to be carried along with the flow's input and output as a Tuple2 (Scala) or Pair (Java). The requirement is that either the Context itself or a mapping from Context should be able to uniquely identify an element. Here is the ways how a unique id can be retrieved:

    • Context itself is a type that can be used as a unique id, e.g., Int, Long, java.util.UUID
    • Context extends UniqueId.Provider and implements UniqueId.Provider.uniqueId method
    • Context is of type UniqueId.Envelope
    • Context can be mapped to a unique id by calling

    uniqueIdMapper

    In

    the type of the elements pulled from the upstream along with the Context

    Out

    the type of the elements that are pushed to downstream along with the Context

    Context

    the type of the context that is carried around along with the elements.

    returns

    a BidiFlow with timeout functionality