Packages

  • package root
    Definition Classes
    root
  • package com
    Definition Classes
    root
  • package twitter

    Start with com.twitter.finagle.

    Definition Classes
    com
  • package finagle

    Finagle is an extensible RPC system.

    Finagle is an extensible RPC system.

    Services are represented by class com.twitter.finagle.Service. Clients make use of com.twitter.finagle.Service objects while servers implement them.

    Finagle contains a number of protocol implementations; each of these implement Client and/or com.twitter.finagle.Server. For example, Finagle's HTTP implementation, com.twitter.finagle.Http (in package finagle-http), exposes both.

    Thus a simple HTTP server is built like this:

    import com.twitter.finagle.{Http, Service}
    import com.twitter.finagle.http.{Request, Response}
    import com.twitter.util.{Await, Future}
    
    val service = new Service[Request, Response] {
      def apply(req: Request): Future[Response] =
        Future.value(Response())
    }
    val server = Http.server.serve(":8080", service)
    Await.ready(server)

    We first define a service to which requests are dispatched. In this case, the service returns immediately with a HTTP 200 OK response, and with no content.

    This service is then served via the Http protocol on TCP port 8080. Finally we wait for the server to stop serving.

    We can now query our web server:

    % curl -D - localhost:8080
    HTTP/1.1 200 OK

    Building an HTTP client is also simple. (Note that type annotations are added for illustration.)

    import com.twitter.finagle.{Http, Service}
    import com.twitter.finagle.http.{Request, Response}
    import com.twitter.util.{Future, Return, Throw}
    
    val client: Service[Request, Response] = Http.client.newService("localhost:8080")
    val f: Future[Response] = client(Request()).respond {
      case Return(rep) =>
        printf("Got HTTP response %s\n", rep)
      case Throw(exc) =>
        printf("Got error %s\n", exc)
    }

    Http.client.newService("localhost:8080") constructs a new com.twitter.finagle.Service instance connected to localhost TCP port 8080. We then issue a HTTP/1.1 GET request to URI "/". The service returns a com.twitter.util.Future representing the result of the operation. We listen to this future, printing an appropriate message when the response arrives.

    The Finagle homepage contains useful documentation and resources for using Finagle.

    Definition Classes
    twitter
  • package exp

    Package exp contains experimental code.

    Package exp contains experimental code. This can be removed or stabilized (moved elsewhere) at any time.

    Definition Classes
    finagle
  • package pushsession
    Definition Classes
    exp
  • AbstractDarkTrafficFilter
  • Address
  • BackupRequestFilter
  • DarkTrafficFilter
  • ForwardingWarmUpFilter
  • ThriftForwardingWarmUpFilter
  • scheduler

class BackupRequestFilter[Req, Rep] extends SimpleFilter[Req, Rep]

Issue a backup request after a threshold time has elapsed, useful for curtailing tail latencies in distributed systems. See [1] for details.

Several stats are exported through the given stats receiver exposing the filter's operating behavior:

  • counter timeouts indicates the number of original requests that timed out and subsequently caused a backup request to be issued;
  • counter won indicates the number of original requests that won, including those that didn't actually race with a backup;
  • counter lost indicates the number of original requests that lost a race with their corresponding backup request, and finally
  • gauge cutoff_ms indicates the current backup request cutoff value in milliseconds.

[1]: Dean, J. and Barroso, L.A. (2013), The Tail at Scale, Communications of the ACM, Vol. 56 No. 2, Pages 74-80, http://cacm.acm.org/magazines/2013/2/160173-the-tail-at-scale/fulltext

Note

A filter alone cannot guarantee that a request is dispatched onto a different endpoint from the original. Eventually, this should be implemented as a sort of queueing policy.

,

Care must be taken to ensure that application of this filter preserves semantics since a request may be issued twice (ie. they are idempotent).

Linear Supertypes
SimpleFilter[Req, Rep], Filter[Req, Rep, Req, Rep], (Req, Service[Req, Rep]) ⇒ Future[Rep], AnyRef, Any
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. BackupRequestFilter
  2. SimpleFilter
  3. Filter
  4. Function2
  5. AnyRef
  6. Any
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new BackupRequestFilter(quantile: Int, clipDuration: Duration, timer: Timer, statsReceiver: StatsReceiver, history: Duration)

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def agnosticAndThen(next: TypeAgnostic): Filter[Req, Rep, Req, Rep]

    Convert the Filter.TypeAgnostic filter to a Filter and chain it with andThen.

    Convert the Filter.TypeAgnostic filter to a Filter and chain it with andThen.

    Definition Classes
    Filter
  5. def andThen(factory: ServiceFactory[Req, Rep]): ServiceFactory[Req, Rep]

    Terminates a filter chain in a ServiceFactory.

    Terminates a filter chain in a ServiceFactory. For example,

    myFilter.andThen(myServiceFactory)
    factory

    a service factory that takes the output request type and the input response type.

    Definition Classes
    Filter
  6. def andThen(service: Service[Req, Rep]): Service[Req, Rep]

    Terminates a filter chain in a Service.

    Terminates a filter chain in a Service. For example,

    myFilter.andThen(myService)
    service

    a service that takes the output request type and the input response type.

    Definition Classes
    Filter
  7. def andThen[Req2, Rep2](next: Filter[Req, Rep, Req2, Rep2]): Filter[Req, Rep, Req2, Rep2]

    Chains a series of filters together:

    Chains a series of filters together:

    myModularService = handleExceptions.andThen(thrift2Pojo.andThen(parseString))
    next

    another filter to follow after this one

    Definition Classes
    Filter
    Note

    synchronously thrown exceptions in the underlying service are automatically lifted into Future.exception.

  8. def andThenIf[Req2 >: Req, Rep2 <: Rep](condAndFilter: (Boolean, Filter[Req, Rep, Req2, Rep2])): Filter[Req, Rep, Req2, Rep2]

    Conditionally propagates requests down the filter chain.

    Conditionally propagates requests down the filter chain. This may useful if you are statically wiring together filter chains based on a configuration file, for instance.

    condAndFilter

    a tuple of boolean and filter.

    Definition Classes
    Filter
  9. def apply(req: Req, service: Service[Req, Rep]): Future[Rep]

    This is the method to override/implement to create your own Filter.

    This is the method to override/implement to create your own Filter.

    service

    a service that takes the output request type and the input response type

    Definition Classes
    BackupRequestFilterFilter → Function2
  10. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  11. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  12. def curried: (Req) ⇒ (Service[Req, Rep]) ⇒ Future[Rep]
    Definition Classes
    Function2
    Annotations
    @unspecialized()
  13. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  15. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  16. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  17. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  18. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  19. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  20. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  21. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  22. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  23. def toString(): String
    Definition Classes
    Function2 → AnyRef → Any
  24. def tupled: ((Req, Service[Req, Rep])) ⇒ Future[Rep]
    Definition Classes
    Function2
    Annotations
    @unspecialized()
  25. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  26. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  27. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )

Inherited from SimpleFilter[Req, Rep]

Inherited from Filter[Req, Rep, Req, Rep]

Inherited from (Req, Service[Req, Rep]) ⇒ Future[Rep]

Inherited from AnyRef

Inherited from Any

Ungrouped