PuduLangLog.SelfLog

type: module path: "@root/src/PuduLangLog/SelfLog.pudu" fidelity: Active grammar: "[[grammar/pudu]]" depth_score: 0.4 depth_status: SHALLOW tags: [module] aliases: [PuduLangLog.SelfLog]

Purpose

Reports problems inside the pipeline — a failing sink, a template bound to the wrong number of arguments, an invalid property name — without ever failing the program's own log call.

Interface

Signatures

export type SelfLog = { writer: Sync.Cell[Option[fn(Str) -> ()]] }

export fn create() -> SelfLog

export fn toErrorStream() -> SelfLog

export fn enable(log: &SelfLog, writer: fn(Str) -> ()) -> ()

export fn disable(log: &SelfLog) -> ()

export fn isEnabled(log: &SelfLog) -> Bool

export fn write(log: &SelfLog, message: Str) -> ()

Linkage

• Requires: [[src/PuduLangLog]], [[src/PuduLangLog/Domain/Dates]], Std.Io, Std.Sync, Std.Time.
• Consumed by: [[src/PuduLangLog/Configuration]], [[src/PuduLangLog/Pipeline]], [[src/PuduLangLog/Logger]], [[src/PuduLangLog/Sink]], and every sink that can fail.

Algorithm

1. A self-log holds an optional writer in a shared cell; it starts disabled.
2. write prefixes the message with the UTC time in round-trip form and calls the writer, if any.

Negative Logic (Prohibited Paths)

• The self-log never writes to a configured sink, so a failing sink cannot loop.

Edge Cases

• Enabling after a logger was built takes effect at once, since the writer is shared.

Depth

DEPTH 0.4 (SHALLOW). Tested by test/PuduLangLog/LoggerTest.

Grill Log

• Q: Why is the self-log part of the configuration instead of global? A: Pudu has no mutable module state; each pipeline names where its problems go. _Rejected:_ a process-wide switch.

Referenced by

[[decisions/ADR-0001-logging-never-fails-the-caller]] · [[src/PuduLangLog/_MOC]] · [[src/PuduLangLog/Configuration]] · [[src/PuduLangLog/Logger]] · [[src/PuduLangLog/Pipeline]] · [[src/PuduLangLog/Sink]] · [[src/PuduLangLog/Sinks/Async]] · [[src/PuduLangLog/Sinks/Batching]]