cats-effect-std/cats.effect.std/Dispatcher

Dispatcher

cats.effect.std.Dispatcher

See theDispatcher companion trait

object Dispatcher

Attributes

Companion: trait
Source: Dispatcher.scala
Graph
Supertypes: class Object

trait Matchable

class Any
Self type: Dispatcher.type

Members list

Value members

Concrete methods

Create a Dispatcher that can be used within a resource scope.

Create a Dispatcher that can be used within a resource scope. Once the resource scope exits, all active effects will be canceled, and attempts to submit new effects will throw an exception.

Attributes

Source: Dispatcher.scala

Create a Dispatcher that can be used within a resource scope.

Create a Dispatcher that can be used within a resource scope. Once the resource scope exits, depending on the termination policy all active effects will be canceled or awaited, and attempts to submit new effects will throw an exception.

This corresponds to a pattern in which a single Dispatcher is being used by multiple calling threads simultaneously, with complex (potentially long-running) actions submitted for evaluation. In this mode, order of operation is not in any way guaranteed, and execution of each submitted action has some unavoidable overhead due to the forking of a new fiber for each action. This mode is most appropriate for scenarios in which a single Dispatcher is being widely shared across the application, and where sequencing is not assumed.

The lifecycle of spawned fibers is managed by Supervisor. The termination policy can be configured by the await parameter.

Value parameters

await

the termination policy of the internal Supervisor.

true - wait for the completion of the active fibers
false - cancel the active fibers

Attributes

See also

Supervisor for the termination policy details

Note

if an effect that never completes, is evaluating by a Dispatcher with awaiting termination policy, the termination of the Dispatcher is indefinitely suspended

val io: IO[Unit] = // never completes
  Dispatcher.parallel[F](await = true).use { dispatcher =>
    dispatcher.unsafeRunAndForget(Concurrent[F].never)
    Concurrent[F].unit
  }

Source

Dispatcher.scala

Create a Dispatcher that can be used within a resource scope.

Create a Dispatcher that can be used within a resource scope. Once the resource scope exits, all active effects will be canceled, and attempts to submit new effects will throw an exception.

Attributes

Source: Dispatcher.scala

Create a Dispatcher that can be used within a resource scope.

This corresponds to a Dispatcher mode in which submitted actions are evaluated strictly in sequence (FIFO). In this mode, any actions submitted to Dispatcher.unsafeRunAndForget are guaranteed to run in exactly the order submitted, and subsequent actions will not start evaluation until previous actions are completed. This avoids a significant amount of overhead associated with the Parallel mode and allows callers to make assumptions around ordering, but the downside is that long-running actions will starve subsequent actions, and all submitters must contend for a singular coordination resource. Thus, this mode is most appropriate for cases where the actions are relatively trivial (such as Queue.offer) and the Dispatcher in question is not shared across multiple producers. To be clear, shared dispatchers in sequential mode will still function correctly, but performance will be suboptimal due to single-point contention.

Value parameters

await

the termination policy.

true - wait for the completion of the active fiber
false - cancel the active fiber

Attributes

Note

if an effect that never completes, is evaluating by a Dispatcher with awaiting termination policy, the termination of the Dispatcher is indefinitely suspended

val io: IO[Unit] = // never completes
  Dispatcher.sequential[IO](await = true).use { dispatcher =>
    dispatcher.unsafeRunAndForget(IO.never)
    IO.unit
  }

Source

Dispatcher.scala

Deprecated methods

Attributes

Deprecated: [Since version 3.4.0] use \'.parallel\' or \'.sequential\' instead; the former corresponds to the current semantics of \'.apply\'
Source: Dispatcher.scala

In this article

Generated with