Log-Trace Correlation

The trace scope: whatever logs inside it is correlated for free -- and the OTel triad completes

Every code block below is real, and every output block is its actual output (the run lives in base/test/perf/_logtrace_narration_demo.ring; the guard suite is base/test/perf/log_trace_narrated.ring, 24 assertions; stzLog's own suite re-runs green). Performance system P9 -- doc/design/SOFTANZA_PERF_SYSTEM.md.

The last unlinked telemetry

The trace scope

StzOpenTraceScope() puts a W3C traceparent in an engine-global slot; every stzLog record written while it is open -- any log, in any object, on any Haro face -- stamps the active trace id as an ordinary queryable field. Close the scope and logging is anonymous again:

StzOpenTraceScope("")
$oLog.Info("charging the card")
$oLog.Record(:warn, "gateway slow, retrying", [ [ :gateway, "stripe" ] ])
StzCloseTraceScope()
$oLog.Info("nightly cleanup")
see $oLog.AsText()

1785482186005 INFO restolean: charging the card  {traceId=6e262c37f3c493b30f6a4297aad02273}
1785482186005 WARN restolean: gateway slow, retrying  {gateway=stripe, traceId=6e262c37f3c493b30f6a4297aad02273}
1785482186005 INFO restolean: nightly cleanup

The engine slot is the point (a Haro-side "current trace" would be per-face state, and a handler's log would never see the server's scope). Inside a scope, StzCurrentTraceParent() is what a downstream call sends onward, and a stopwatch JoinTrace()s it -- spans and log lines, one trace.

The server does it for you

An observed, tracing server opens the scope around every request -- after the trace identity is settled, before dispatch -- and closes it with the bracket. A handler that just logs is correlated with no plumbing at all:

oSrv.Get_("/order", func oReq, oResp {
	$oLog.Info("taking the order")     # no trace code anywhere
	$oLog.Info("order placed")
	oResp.Text("placed")
})
# ... two real requests ...
aL = $oLog.OfTrace(aT[2][:traceId])

request 1 trace: 688c026d3fdcce0a58d0e0ad9d629e20
request 2 trace: 5a980994ab7e582b3f76e50517bbc7d9
lines of request 2 alone:
  taking the order
  order placed

Two requests through the same handler, two distinct traces, and OfTrace() separates their interleaved lines exactly.

The 3 a.m. circle, complete

P7 taught the black box to name the requests nearest a breach. Those ids were addresses into someone else's systems (Jaeger, Tempo). Now they are also addresses into your own logs:

cTrip = oSent.LastBlackBox()[:traces][1][:traceId]
aL = $oLog.OfTrace(cTrip)

breach trip 688c026d3fdcce0a58d0e0ad9d629e20 -> its log lines:
  taking the order
  order placed

Alert -> the requests that tripped it -> the handler's own words while serving them. The investigation that used to start with grep and a timestamp guess starts with evidence, all of it recorded before anyone was awake.

The triad closes

stzLog.OtelJson() renders the OTLP logs envelope -- what a collector ingests at /v1/logs -- with severity text and standard numbers, fields as attributes, and the trace id promoted to the logRecord's first-class traceId field, where tracing backends expect it (an unscoped record simply has none):

{"resourceLogs":[{"resource":{"attributes":[{"key":"service.name","value":{"stringValue":"restolean"}}]},"scopeLogs":[{"scope":{"name":"softanza.log"},"logRecords":[{"timeUnixNano":"1785482186005000000","severityText":"INFO","seve...

Spans (P0/P7), metrics (P2), logs (P9): the three OpenTelemetry signals, all exported natively, all sharing W3C trace identity. A Softanza app now speaks the industry's full telemetry language -- in and out, no agent, no sidecar.

Honest limits

The scope is one slot, which matches the runtime: one request in flight per serve loop. Concurrent in-process request handling (if the reactor ever dispatches handlers in parallel) would need per-task scopes -- noted for that day. And correlation reaches logs written THROUGH stzLog; a bare ? print stays a bare print.

Prouvé par

L'article nomme ces gardes de scénario de la bibliothèque :

• log_trace_narrated.ring(s'ouvre dans un nouvel onglet)

Citer

Mansour Ayouni. « Log-Trace Correlation ». Softanza narrations, 2026. https://mayouni.github.io/stzsite/fr/narrations/stz-perf-log-trace-narration.html

Exécuté au nom de Haro le 2026-10-08 20:42 dans la bibliothèque au commit 4a184e6f0, bloc après bloc dans un seul processus : 0 bloc(s) sur 3 ont tenu leur promesse ; les autres sont des illustrations. Le code des articles est du code Haro. Là où un article a été écrit avant que la langue prenne son nom actuel, le nom a été changé et rien d'autre. Genre, domaine et série lus dans le nom du fichier, année tirée du premier commit : dérivés, jusqu'à ce que l'article porte son propre en-tête. Le fichier sur GitHub(s'ouvre dans un nouvel onglet)