Package org.apache.pekko.stream

Class Attributes

  • All Implemented Interfaces:
    java.io.Serializable, scala.Equals, scala.Product
    public final class Attributes
extends java.lang.Object
implements scala.Product, java.io.Serializable
    Holds attributes which can be used to alter pekko.stream.scaladsl.Flow / pekko.stream.javadsl.Flow or pekko.stream.scaladsl.GraphDSL / pekko.stream.javadsl.GraphDSL materialization.

    Note that more attributes for the Materializer are defined in ActorAttributes.

    The attributeList is ordered with the most specific attribute first, least specific last. Note that the order was the opposite in Akka 2.4.x.

    Operators should in general not access the attributeList but instead use get to get the expected value of an attribute.

    See Also:
    Serialized Form

    • Constructor Detail

      • Attributes

        public Attributes​(scala.collection.immutable.List<Attributes.Attribute> attributeList)

    • Method Detail

      • $lessinit$greater$default$1

        public static scala.collection.immutable.List<Attributes.Attribute> $lessinit$greater$default$1()

      • cancellationStrategyCompleteState

        public static org.apache.pekko.stream.Attributes.CancellationStrategy.Strategy cancellationStrategyCompleteState()
        Java API

        Strategy that treats cancelStage the same as completeStage, i.e. all inlets are cancelled (propagating the cancellation cause) and all outlets are regularly completed.

        This used to be the default behavior before Akka 2.6.

        This behavior can be problematic in stacks of BidiFlows where different layers of the stack are both connected through inputs and outputs. In this case, an error in a doubly connected component triggers both a cancellation going upstream and an error going downstream. Since the stack might be connected to those components with inlets and outlets, a race starts whether the cancellation or the error arrives first. If the error arrives first, that's usually good because then the error can be propagated both on inlets and outlets. However, if the cancellation arrives first, the previous default behavior to complete the stage will lead other outputs to be completed regularly. The error which arrive late at the other hand will just be ignored (that connection will have been cancelled already and also the paths through which the error could propagates are already shut down).

      • cancellationStrategyFailStage

        public static org.apache.pekko.stream.Attributes.CancellationStrategy.Strategy cancellationStrategyFailStage()
        Java API

        Strategy that treats cancelStage the same as failStage, i.e. all inlets are cancelled (propagating the cancellation cause) and all outlets are failed propagating the cause from cancellation.

      • cancellationStrategyPropagateFailure

        public static org.apache.pekko.stream.Attributes.CancellationStrategy.Strategy cancellationStrategyPropagateFailure()
        Java API

        Strategy that treats cancelStage in different ways depending on the cause that was given to the cancellation.

        If the cause was a regular, active cancellation (SubscriptionWithCancelException.NoMoreElementsNeeded), the stage receiving this cancellation is completed regularly.

        If another cause was given, this is treated as an error and the behavior is the same as with failStage.

        This is a good default strategy.

      • cancellationStrategyAfterDelay

        public static org.apache.pekko.stream.Attributes.CancellationStrategy.Strategy cancellationStrategyAfterDelay​(scala.concurrent.duration.FiniteDuration delay,
                                                                                                              org.apache.pekko.stream.Attributes.CancellationStrategy.Strategy strategy)
        Java API

        Strategy that allows to delay any action when cancelStage is invoked.

        The idea of this strategy is to delay any action on cancellation because it is expected that the stage is completed through another path in the meantime. The downside is that a stage and a stream may live longer than expected if no such signal is received and cancellation is invoked later on. In streams with many stages that all apply this strategy, this strategy might significantly delay the propagation of a cancellation signal because each upstream stage might impose such a delay. During this time, the stream will be mostly "silent", i.e. it cannot make progress because of backpressure, but you might still be able observe a long delay at the ultimate source.

      • nestedMaterializationCancellationPolicyEagerCancellation

        public static Attributes.NestedMaterializationCancellationPolicy nestedMaterializationCancellationPolicyEagerCancellation()
        JAVA API A Attributes.NestedMaterializationCancellationPolicy that configures graph stages delaying nested flow materialization to cancel immediately when downstream cancels before nested flow materialization. This applies to pekko.stream.scaladsl.FlowOps.flatMapPrefix, pekko.stream.scaladsl.Flow.futureFlow and derived operators.

      • nestedMaterializationCancellationPolicyPropagateToNested

        public static Attributes.NestedMaterializationCancellationPolicy nestedMaterializationCancellationPolicyPropagateToNested()
        JAVA API A Attributes.NestedMaterializationCancellationPolicy that configures graph stages delaying nested flow materialization to delay cancellation when downstream cancels before nested flow materialization. Once the nested flow is materialized it will be cancelled immediately. This applies to pekko.stream.scaladsl.FlowOps.flatMapPrefix, pekko.stream.scaladsl.Flow.futureFlow and derived operators.

      • apply$default$1

        public static scala.collection.immutable.List<Attributes.Attribute> apply$default$1()

      • none

        public static Attributes none()
        INTERNAL API

      • asyncBoundary

        public static Attributes asyncBoundary()

      • name

        public static Attributes name​(java.lang.String name)
        Specifies the name of the operation. If the name is null or empty the name is ignored, i.e. none() is returned.

      • inputBuffer

        public static Attributes inputBuffer​(int initial,
                                     int max)
        Each asynchronous piece of a materialized stream topology is executed by one Actor that manages an input buffer for all inlets of its shape. This attribute configures the initial and maximal input buffer in number of elements for each inlet.

      • createLogLevels

        public static Attributes createLogLevels​(Logging.LogLevel onElement)
        Java API

        Configures log() operator log-levels to be used when logging onElement. Logging a certain operation can be completely disabled by using logLevelOff().

      • logLevels

        public static Attributes logLevels​(Logging.LogLevel onElement,
                                   Logging.LogLevel onFinish,
                                   Logging.LogLevel onFailure)
        Configures log() operator log-levels to be used when logging. Logging a certain operation can be completely disabled by using LogLevels.Off.

        See Attributes.createLogLevels for Java API

      • extractName

        public static java.lang.String extractName​(org.apache.pekko.stream.impl.TraversalBuilder builder,
                                           java.lang.String default_)
        Compute a name by concatenating all Name attributes that the given module has, returning the given default value if none are found.

      • getAttribute

        public <T extends Attributes.Attribute> T getAttribute​(java.lang.Class<T> c,
                                                       T default_)
        Java API: Get the most specific attribute value for a given Attribute type or subclass thereof. If no such attribute exists, return a default value.

        The most specific value is the value that was added closest to the graph or operator itself or if the same attribute was added multiple times to the same graph, the last to be added.

        This is the expected way for operators to access attributes.

      • getAttribute

        public <T extends Attributes.Attribute> java.util.Optional<T> getAttribute​(java.lang.Class<T> c)
        Java API: Get the most specific attribute value for a given Attribute type or subclass thereof.

        The most specific value is the value that was added closest to the graph or operator itself or if the same attribute was added multiple times to the same graph, the last to be added.

        This is the expected way for operators to access attributes.

      • get

        public <T extends Attributes.Attribute> T get​(T default_,
                                              scala.reflect.ClassTag<T> evidence$1)
        Scala API: Get the most specific attribute value for a given Attribute type or subclass thereof or if no such attribute exists, return a default value.

        The most specific value is the value that was added closest to the graph or operator itself or if the same attribute was added multiple times to the same graph, the last to be added.

        This is the expected way for operators to access attributes.

      • get

        public <T extends Attributes.Attribute> scala.Option<T> get​(scala.reflect.ClassTag<T> evidence$2)
        Scala API: Get the most specific attribute value for a given Attribute type or subclass thereof.

        The most specific value is the value that was added closest to the graph or operator itself or if the same attribute was added multiple times to the same graph, the last to be added.

        This is the expected way for operators to access attributes.

      • mandatoryAttribute

        public <T extends Attributes.MandatoryAttribute> T mandatoryAttribute​(scala.reflect.ClassTag<T> evidence$3)
        Scala API: Get the most specific of one of the mandatory attributes. Mandatory attributes are guaranteed to always be among the attributes when the attributes are coming from a materialization.

      • getMandatoryAttribute

        public <T extends Attributes.MandatoryAttribute> T getMandatoryAttribute​(java.lang.Class<T> c)
        Java API: Get the most specific of one of the mandatory attributes. Mandatory attributes are guaranteed to always be among the attributes when the attributes are coming from a materialization.

        Parameters:
        c - A class that is a subtype of Attributes.MandatoryAttribute

      • and

        public Attributes and​(Attributes other)
        Adds given attributes. Added attributes are considered more specific than already existing attributes of the same type.

      • and

        public Attributes and​(Attributes.Attribute other)
        Adds given attribute. Added attribute is considered more specific than already existing attributes of the same type.

      • nameLifted

        public scala.Option<java.lang.String> nameLifted()
        Extracts Name attributes and concatenates them.

      • nameOrDefault

        public java.lang.String nameOrDefault​(java.lang.String default_)

      • nameOrDefault$default$1

        public java.lang.String nameOrDefault$default$1()

      • contains

        public boolean contains​(Attributes.Attribute attr)
        Test whether the given attribute is contained within this attributes list.

        Note that operators in general should not inspect the whole hierarchy but instead use get to get the most specific attribute value.

      • getAttributeList

        public java.util.List<Attributes.Attribute> getAttributeList()
        Java API

        The list is ordered with the most specific attribute first, least specific last. Note that the order was the opposite in Akka 2.4.x.

        Note that operators in general should not inspect the whole hierarchy but instead use get to get the most specific attribute value.

      • getAttributeList

        public <T extends Attributes.Attribute> java.util.List<T> getAttributeList​(java.lang.Class<T> c)
        Java API: Get all attributes of a given Class or subclass thereof.

        The list is ordered with the most specific attribute first, least specific last. Note that the order was the opposite in Akka 2.4.x.

        Note that operators in general should not inspect the whole hierarchy but instead use get to get the most specific attribute value.

      • filtered

        public <T extends Attributes.Attribute> scala.collection.immutable.List<T> filtered​(scala.reflect.ClassTag<T> evidence$4)
        Scala API: Get all attributes of a given type (or subtypes thereof).

        Note that operators in general should not inspect the whole hierarchy but instead use get to get the most specific attribute value.

        The list is ordered with the most specific attribute first, least specific last. Note that the order was the opposite in Akka 2.4.x.

      • getFirstAttribute

        public <T extends Attributes.Attribute> T getFirstAttribute​(java.lang.Class<T> c,
                                                            T default_)
        Deprecated.
        Attributes should always be most specific, use getAttribute[T]. Since Akka 2.5.7.
        Java API: Get the least specific attribute (added first) of a given Class or subclass thereof. If no such attribute exists the default value is returned.

      • getFirstAttribute

        public <T extends Attributes.Attribute> java.util.Optional<T> getFirstAttribute​(java.lang.Class<T> c)
        Deprecated.
        Attributes should always be most specific, use get[T]. Since Akka 2.5.7.
        Java API: Get the least specific attribute (added first) of a given Class or subclass thereof.

      • getFirst

        public <T extends Attributes.Attribute> T getFirst​(T default_,
                                                   scala.reflect.ClassTag<T> evidence$5)
        Deprecated.
        Attributes should always be most specific, use get[T]. Since Akka 2.5.7.
        Scala API: Get the least specific attribute (added first) of a given type parameter T Class or subclass thereof. If no such attribute exists the default value is returned.

      • getFirst

        public <T extends Attributes.Attribute> scala.Option<T> getFirst​(scala.reflect.ClassTag<T> evidence$6)
        Deprecated.
        Attributes should always be most specific, use get[T]. Since Akka 2.5.7.
        Scala API: Get the least specific attribute (added first) of a given type parameter T Class or subclass thereof.

      • productPrefix

        public java.lang.String productPrefix()
        Specified by:
        productPrefix in interface scala.Product

      • productArity

        public int productArity()
        Specified by:
        productArity in interface scala.Product

      • productElement

        public java.lang.Object productElement​(int x$1)
        Specified by:
        productElement in interface scala.Product

      • productIterator

        public scala.collection.Iterator<java.lang.Object> productIterator()
        Specified by:
        productIterator in interface scala.Product

      • canEqual

        public boolean canEqual​(java.lang.Object x$1)
        Specified by:
        canEqual in interface scala.Equals

      • productElementName

        public java.lang.String productElementName​(int x$1)
        Specified by:
        productElementName in interface scala.Product

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class java.lang.Object

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • equals

        public boolean equals​(java.lang.Object x$1)
        Specified by:
        equals in interface scala.Equals
        Overrides:
        equals in class java.lang.Object