Package akka.stream

Class Materializer

  • Direct Known Subclasses:
    ActorMaterializer, SubFusingActorMaterializerImpl

    public abstract class Materializer
    extends java.lang.Object
    The Materializer is the component responsible for turning a stream blueprint into a running stream. In general the system wide materializer should be preferred over creating instances manually.

    Not for user extension

    • Constructor Summary

      Constructors 
      Constructor Description
      Materializer()  
    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      abstract ActorRef actorOf​(MaterializationContext context, Props props)
      INTERNAL API
      static Materializer apply​(ClassicActorContextProvider contextProvider)
      Scala API: Create a materializer whose lifecycle will be tied to the one of the passed actor context.
      static Materializer apply​(ClassicActorSystemProvider systemProvider)
      Scala API: Create a new materializer that will stay alive as long as the system does or until it is explicitly stopped.
      static Materializer createMaterializer​(ClassicActorContextProvider contextProvider)
      Java API: Create a materializer whose lifecycle will be tied to the one of the passed actor context.
      static Materializer createMaterializer​(ClassicActorSystemProvider systemProvider)
      Scala API: Create a new materializer that will stay alive as long as the system does or until it is explicitly stopped.
      abstract scala.concurrent.ExecutionContextExecutor executionContext()
      Running a flow graph will require execution resources, as will computations within Sources, Sinks, etc.
      abstract boolean isShutdown()
      Indicates if the materializer has been shut down.
      abstract LoggingAdapter logger()
      INTERNAL API
      abstract <Mat> Mat materialize​(Graph<ClosedShape,​Mat> runnable)
      This method interprets the given Flow description and creates the running stream.
      abstract <Mat> Mat materialize​(Graph<ClosedShape,​Mat> runnable, Attributes defaultAttributes)
      This method interprets the given Flow description and creates the running stream using an explicitly provided Attributes as top level (least specific) attributes that will be defaults for the materialized stream.
      static Materializer matFromSystem​(ClassicActorSystemProvider provider)
      Implicitly provides the system wide materializer from a classic or typed ActorSystem
      abstract Cancellable scheduleAtFixedRate​(scala.concurrent.duration.FiniteDuration initialDelay, scala.concurrent.duration.FiniteDuration interval, java.lang.Runnable task)
      Interface for operators that need timer services for their functionality.
      abstract Cancellable scheduleOnce​(scala.concurrent.duration.FiniteDuration delay, java.lang.Runnable task)
      Interface for operators that need timer services for their functionality.
      abstract Cancellable schedulePeriodically​(scala.concurrent.duration.FiniteDuration initialDelay, scala.concurrent.duration.FiniteDuration interval, java.lang.Runnable task)
      Deprecated.
      Use scheduleWithFixedDelay or scheduleAtFixedRate instead.
      abstract Cancellable scheduleWithFixedDelay​(scala.concurrent.duration.FiniteDuration initialDelay, scala.concurrent.duration.FiniteDuration delay, java.lang.Runnable task)
      Interface for operators that need timer services for their functionality.
      abstract ActorMaterializerSettings settings()
      Deprecated.
      Use attributes to access settings from stages.
      abstract void shutdown()
      Shuts down this materializer and all the operators that have been materialized through this materializer.
      abstract ActorRef supervisor()
      INTERNAL API
      abstract ActorSystem system()
      The classic actor system this materializer is backed by (and in which the streams materialized with the materializer will run)
      abstract Materializer withNamePrefix​(java.lang.String name)
      The namePrefix shall be used for deriving the names of processing entities that are created during materialization.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • Materializer

        public Materializer()
    • Method Detail

      • apply

        public static Materializer apply​(ClassicActorContextProvider contextProvider)
        Scala API: Create a materializer whose lifecycle will be tied to the one of the passed actor context. When the actor stops the materializer will stop and all streams created with it will be failed with an AbruptTerminationExeption

        You can pass either a classic actor context or a typed actor context.

      • createMaterializer

        public static Materializer createMaterializer​(ClassicActorContextProvider contextProvider)
        Java API: Create a materializer whose lifecycle will be tied to the one of the passed actor context. When the actor stops the materializer will stop and all streams created with it will be failed with an AbruptTerminationExeption

        You can pass either a classic actor context or a typed actor context.

      • apply

        public static Materializer apply​(ClassicActorSystemProvider systemProvider)
        Scala API: Create a new materializer that will stay alive as long as the system does or until it is explicitly stopped.

        *Note* prefer using the default SystemMaterializer that is implicitly available if you have an implicit ActorSystem in scope. Only create new system level materializers if you have specific needs or want to test abrupt termination of a custom graph stage. If you want to tie the lifecycle of the materializer to an actor, use the factory that takes an ActorContext instead.

      • createMaterializer

        public static Materializer createMaterializer​(ClassicActorSystemProvider systemProvider)
        Scala API: Create a new materializer that will stay alive as long as the system does or until it is explicitly stopped.

        *Note* prefer using the default SystemMaterializer by passing the ActorSystem to the various run methods on the streams. Only create new system level materializers if you have specific needs or want to test abrupt termination of a custom graph stage. If you want to tie the lifecycle of the materializer to an actor, use the factory that takes an ActorContext instead.

      • withNamePrefix

        public abstract Materializer withNamePrefix​(java.lang.String name)
        The namePrefix shall be used for deriving the names of processing entities that are created during materialization. This is meant to aid logging and failure reporting both during materialization and while the stream is running.
      • materialize

        public abstract <Mat> Mat materialize​(Graph<ClosedShape,​Mat> runnable)
        This method interprets the given Flow description and creates the running stream. The result can be highly implementation specific, ranging from local actor chains to remote-deployed processing networks.
      • materialize

        public abstract <Mat> Mat materialize​(Graph<ClosedShape,​Mat> runnable,
                                              Attributes defaultAttributes)
        This method interprets the given Flow description and creates the running stream using an explicitly provided Attributes as top level (least specific) attributes that will be defaults for the materialized stream. The result can be highly implementation specific, ranging from local actor chains to remote-deployed processing networks.
      • executionContext

        public abstract scala.concurrent.ExecutionContextExecutor executionContext()
        Running a flow graph will require execution resources, as will computations within Sources, Sinks, etc. This ExecutionContextExecutor can be used by parts of the flow to submit processing jobs for execution, run Future callbacks, etc.

        Note that this is not necessarily the same execution context the stream operator itself is running on.

      • scheduleOnce

        public abstract Cancellable scheduleOnce​(scala.concurrent.duration.FiniteDuration delay,
                                                 java.lang.Runnable task)
        Interface for operators that need timer services for their functionality. Schedules a single task with the given delay.

        Returns:
        A Cancellable that allows cancelling the timer. Cancelling is best effort, if the event has been already enqueued it will not have an effect.
      • scheduleWithFixedDelay

        public abstract Cancellable scheduleWithFixedDelay​(scala.concurrent.duration.FiniteDuration initialDelay,
                                                           scala.concurrent.duration.FiniteDuration delay,
                                                           java.lang.Runnable task)
        Interface for operators that need timer services for their functionality.

        Schedules a Runnable to be run repeatedly with an initial delay and a fixed delay between subsequent executions.

        It will not compensate the delay between tasks if the execution takes a long time or if scheduling is delayed longer than specified for some reason. The delay between subsequent execution will always be (at least) the given delay. In the long run, the frequency of execution will generally be slightly lower than the reciprocal of the specified delay.

        If the Runnable throws an exception the repeated scheduling is aborted, i.e. the function will not be invoked any more.

        Returns:
        A Cancellable that allows cancelling the timer. Cancelling is best effort, if the event has been already enqueued it will not have an effect.
        Throws:
        java.lang.IllegalArgumentException - if the given delays exceed the maximum supported by the Scheduler.

      • scheduleAtFixedRate

        public abstract Cancellable scheduleAtFixedRate​(scala.concurrent.duration.FiniteDuration initialDelay,
                                                        scala.concurrent.duration.FiniteDuration interval,
                                                        java.lang.Runnable task)
        Interface for operators that need timer services for their functionality.

        Schedules a Runnable to be run repeatedly with an initial delay and a frequency. E.g. if you would like the function to be run after 2 seconds and thereafter every 100ms you would set delay=Duration(2, TimeUnit.SECONDS) and interval=Duration(100, TimeUnit.MILLISECONDS).

        It will compensate the delay for a subsequent task if the previous tasks took too long to execute. In such cases, the actual execution interval will differ from the interval passed to the method.

        If the execution of the tasks takes longer than the interval, the subsequent execution will start immediately after the prior one completes (there will be no overlap of executions). This also has the consequence that after long garbage collection pauses or other reasons when the JVM was suspended all "missed" tasks will execute when the process wakes up again.

        In the long run, the frequency of execution will be exactly the reciprocal of the specified interval.

        Warning: scheduleAtFixedRate can result in bursts of scheduled tasks after long garbage collection pauses, which may in worst case cause undesired load on the system. Therefore scheduleWithFixedDelay is often preferred.

        If the Runnable throws an exception the repeated scheduling is aborted, i.e. the function will not be invoked any more.

        Returns:
        A Cancellable that allows cancelling the timer. Cancelling is best effort, if the event has been already enqueued it will not have an effect.
        Throws:
        java.lang.IllegalArgumentException - if the given delays exceed the maximum supported by the Scheduler.

      • schedulePeriodically

        public abstract Cancellable schedulePeriodically​(scala.concurrent.duration.FiniteDuration initialDelay,
                                                         scala.concurrent.duration.FiniteDuration interval,
                                                         java.lang.Runnable task)
        Deprecated.
        Use scheduleWithFixedDelay or scheduleAtFixedRate instead. This has the same semantics as scheduleAtFixedRate, but scheduleWithFixedDelay is often preferred. Since 2.6.0.
        Interface for operators that need timer services for their functionality. Schedules a repeated task with the given interval between invocations.

        Returns:
        A Cancellable that allows cancelling the timer. Cancelling is best effort, if the event has been already enqueued it will not have an effect.
      • shutdown

        public abstract void shutdown()
        Shuts down this materializer and all the operators that have been materialized through this materializer. After having shut down, this materializer cannot be used again. Any attempt to materialize operators after having shut down will result in an IllegalStateException being thrown at materialization time.
      • isShutdown

        public abstract boolean isShutdown()
        Indicates if the materializer has been shut down.
      • system

        public abstract ActorSystem system()
        The classic actor system this materializer is backed by (and in which the streams materialized with the materializer will run)
      • supervisor

        public abstract ActorRef supervisor()
        INTERNAL API
      • settings

        public abstract ActorMaterializerSettings settings()
        Deprecated.
        Use attributes to access settings from stages. Since 2.6.0.