Logging.pudu

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1/** @Mediator.Behaviors.Logging.Module — structured events for every request, stream, and notification */2module PuduLangMediator.Behaviors.Logging34import Std.Time as Time5import PuduLangLog.Logger as Logger6import PuduLangLog.Value as Value7import PuduLangMediator.Context as Context8import PuduLangMediator.Message as Message9import PuduLangMediator as Messaging10import PuduLangMediator.Open as Open11import PuduLangMediator.Request as Request12import PuduLangMediator.Stream as Stream13import PuduLangMediator.Utils.Shared as Shared1415/** @Mediator.Behaviors.Logging.Recorder — writes one event per message start and end */16export type Recorder = { logger: Logger.Logger }1718/// The event written when a message starts; its properties are the kind's name and shape.19export const STARTED: Str = "Handling \{MessageName\} (\{MessageShape\})"2021/// The event written when a message succeeds; its properties are the name and elapsed milliseconds.22export const SUCCEEDED: Str = "Handled \{MessageName\} in \{Elapsed\} ms"2324/// The event written when a stream ends; its properties are the name, item count, and elapsed milliseconds.25export const STREAMED: Str = "Streamed \{MessageName\}: \{Items\} items in \{Elapsed\} ms"2627/// The event written when a message fails; its properties are the name, elapsed milliseconds, and failure.28export const FAILED: Str = "\{MessageName\} failed in \{Elapsed\} ms: \{Failure\}"2930/// The event written when a notification is heard; its property is the kind's name.31export const HEARD: Str = "Published \{MessageName\}"3233/// A recorder writing to `logger` under the source `PuduLangMediator`.34export fn of(logger: Logger.Logger) -> Recorder { Recorder{logger: logger.forSource("PuduLangMediator")} }3536impl Open.Behavior for Recorder {37  /// Writes a debug event before the request and an information or warning event after it.38  fn handleRequest[Q, R, E](self: &Self, request: &Q, info: &Message.Info, context: Context.Context, next: Request.Next[R, E]) -> Messaging.Outcome[R, E] {39    started(self, info)40    let began = Time.elapsed()41    let outcome = next(context)42    let took = Time.elapsed() - began43    match outcome {44      case Ok(_) => self.logger.information(SUCCEEDED, [Value.text(info.name), Value.int(took)])45      case Err(failure) => failed(self, info, took, &failure)46    }47    outcome48  }49}5051impl Open.StreamBehavior for Recorder {52  /// Writes a debug event before the stream and, after it, the items it emitted or its failure.53  fn handleStream[Q, T, E](self: &Self, request: &Q, info: &Message.Info, context: Context.Context, sink: Stream.Sink[T], next: Stream.Next[T, E]) -> Messaging.Outcome[(), E] {54    started(self, info)55    let began = Time.elapsed()56    let emitted = Shared.shared(0)57    let outcome = next(context, fn(item: T) -> Bool {58        Shared.update(&emitted, |count: Int| count + 1)59        sink(item)60      })61    let took = Time.elapsed() - began62    match outcome {63      case Ok(_) => self.logger.information(STREAMED, [Value.text(info.name), Value.int(Shared.current(&emitted)), Value.int(took)])64      case Err(failure) => failed(self, info, took, &failure)65    }66    outcome67  }68}6970impl Open.NotificationHandler for Recorder {71  /// Writes an information event for every notification published.72  fn handleNotification[N, E](self: &Self, notification: &N, info: &Message.Info, context: Context.Context) -> Messaging.Outcome[(), E] {73    self.logger.information(HEARD, [Value.text(info.name)])74    Ok(())75  }76}7778/// Writes the debug event of a message starting.79fn started(recorder: &Recorder, info: &Message.Info) -> () {80  recorder.logger.debug(STARTED, [Value.text(info.name), Value.text(Message.shapeName(&info.shape))])81}8283/// Writes the warning event of a message failing.84fn failed[E](recorder: &Recorder, info: &Message.Info, took: Int, failure: &Messaging.Failure[E]) -> () {85  recorder.logger.warning(FAILED, [Value.text(info.name), Value.int(took), Value.text(Messaging.describe(failure))])86}87