Resilient.pudu

Pudu47 lines2.2 KB

Copy pathGitHub ↗

1/** @Mediator.Behaviors.Resilient.Module — requests run through a resilience pipeline */2module PuduLangMediator.Behaviors.Resilient34import PuduLangMediator.Context as Context5import PuduLangMediator as Messaging6import PuduLangMediator.Registration as Registration7import PuduLangMediator.Request as Request8import PuduLangResilience.Context as Guard9import PuduLangResilience.Pipeline as Pipeline10import PuduLangResilience as Resilience1112/// A behavior running the rest of the pipeline under `pipeline`'s retry, timeout, circuit, rate,13/// hedging, and fallback policies. Each attempt observes the strategies' token through its14/// context; a failure of the rest of the pipeline reaches the strategies as `Raised`, except a15/// cancellation, which stays one.16export fn behavior[Q, R, E](pipeline: Pipeline.Pipeline[R, Messaging.Failure[E]]) -> Request.Behavior[Q, R, E] {17  fn(_request: Q, context: Context.Context, next: Request.Next[R, E]) -> Messaging.Outcome[R, E] {18    let outcome = Pipeline.executeWith(&pipeline, Guard.cancellable(context.token), fn(attempt: Guard.Context) -> Resilience.Outcome[R, Messaging.Failure[E]] {19        match next(Context.withToken(&context, attempt.token)) {20          case Ok(value) => Ok(value)21          case Err(Messaging.Cancelled(reason)) => Err(Resilience.Cancelled(reason))22          case Err(failure) => Err(Resilience.Raised(failure))23        }24      })25    match outcome {26      case Ok(value) => Ok(value)27      case Err(failure) => Err(translated(&failure))28    }29  }30}3132/// The resilience behavior of one request kind.33export fn register[Q, R, E](subject: &Request.Kind[Q, R, E], pipeline: Pipeline.Pipeline[R, Messaging.Failure[E]]) -> Registration.Registration {34  Registration.behavior(subject, behavior(pipeline))35}3637/// A resilience failure as a mediator failure: the pipeline's own failure unchanged, a38/// cancellation or crash as one, and a strategy's rejection refused with its description.39export fn translated[E](failure: &Resilience.Failure[Messaging.Failure[E]]) -> Messaging.Failure[E] {40  match failure {41    case Resilience.Raised(inner) => inner42    case Resilience.Cancelled(reason) => Messaging.Cancelled(reason)43    case Resilience.Crashed(reason) => Messaging.Crashed(reason)44    case rejection => Messaging.Refused(Resilience.describe(&rejection))45  }46}47