PuduLangHttpClient.Handlers.Metrics

type: module path: "@root/src/PuduLangHttpClient/Handlers/Metrics.pudu" fidelity: Active grammar: "[[grammar/pudu]]" depth_score: 0.4 depth_status: SHALLOW tags: [module, leaf] aliases: [PuduLangHttpClient.Handlers.Metrics]

Purpose

Counts and durations of the requests through a pipeline, kept in a shared snapshot.

Interface

Signatures

export type Snapshot = {
  requests: Int,
  active: Int,
  informational: Int,
  successful: Int,
  redirected: Int,
  clientErrors: Int,
  serverErrors: Int,
  failed: Int,
  totalMillis: Int,
  longestMillis: Int
} derives Json.Encode

export type Meter = { held: Shared.Shared[Snapshot] }

export fn meter() -> Meter

export fn handler(target: &Meter) -> Handler.Handler

export fn snapshot(source: &Meter) -> Snapshot

Linkage

• Requires: [[src/PuduLangHttpClient]], [[src/PuduLangHttpClient/Handler]], [[src/PuduLangHttpClient/Request]], [[src/PuduLangHttpClient/Response]], [[src/PuduLangHttpClient/Utils/Shared]], the standard library.
• Consumed by: the program.

Algorithm

1. Each request counts as started and in flight, then by status class or as failed, with its duration added and the longest kept.

Negative Logic (Prohibited Paths)

• Measuring never changes an outcome.

Edge Cases

• The snapshot derives Json.Encode so it can be exported as it is.

Depth

DEPTH 0.4 (SHALLOW). Tested by the suite mirroring this module under test/.

Grill Log

• Q: Why a snapshot rather than a metrics library? A: The counts a dashboard needs fit in one record; exporting it is the program's choice. _Rejected:_ a dependency on a metrics package.

Referenced by

[[src/PuduLangHttpClient]] · [[src/PuduLangHttpClient/Handler]] · [[src/PuduLangHttpClient/Handlers/_MOC]] · [[src/PuduLangHttpClient/Request]] · [[src/PuduLangHttpClient/Response]] · [[src/PuduLangHttpClient/Utils/Shared]] · [[subsystems/Handlers]]