Span kind was derived from TraceCategory alone, so every Rpc-category span was
kServer. A category cannot tell an inbound handler from the internal work under
it, and trace backends pair kServer with kClient, so internal spans left as
kServer become unpaired edges in a service graph and read as extra inbound
requests.
SpanRole is a new xrpl-owned enum, orthogonal to TraceCategory: the category
names the subsystem and gates the span on config, the role says whether the span
handles a remote call. It is a defaulted fourth parameter on span(), freshRoot()
and the ScopedSpanGuard equivalents, defaulting to SpanRole::FromCategory, so no
existing call site changes. resolveSpanKind() applies an explicit role and falls
back to the category map, which keeps its single responsibility. The
telemetry-disabled stubs mirror all four signatures.
No call site passes a role yet. The two that need it are on a later branch.
Also fixes a ScopedSpanGuard example that passed a bare op:: suffix to
childSpan(), which takes the name verbatim. Naming the child rpc.command made it
a child of rpc.command.<cmd>, inverting the hierarchy, so the example's parent is
now rpc.process and the command attribute moved onto the command span.
Two review findings on the telemetry library.
SpanContext::isValid() returned impl_ != nullptr, so it answered true for a
context holding no span. threadLocalContext() wraps whatever GetCurrent()
returns, and that is an empty Context on a thread with no active span, which
contradicted the documented "invalid context if none is active". It now asks the
Context for its span. childSpan(name, ctx) is the one caller whose behaviour
changes: a context with no span used to produce a new root span, and now returns
a null guard as its @return already promised.
The three batch settings went to the OTel BatchSpanProcessor unchecked. Three
ways that failed: zero was accepted for all of them; batch_size could exceed
max_queue_size, which the SDK documents as a precondition and does not enforce;
and a mistyped value let boost::bad_lexical_cast escape, which derives from
std::bad_cast rather than std::runtime_error, so the operator saw a bare "bad
cast" naming no key. Reading unsigned also turned "-1" into 4294967295 instead
of failing, so the value is parsed signed and negatives are rejected.
xrpld-example.cfg now states the ranges.
[telemetry] endpoint carried one OTLP signal while its name implied it
covered every signal. That asymmetry is what let the metrics URL be
guessed later by rewriting this one's path suffix, so anything not
ending /v1/traces silently posted metrics to the traces path.
Renames the key to traces_endpoint and Setup::exporterEndpoint to
tracesEndpoint. The default value is unchanged and the URL is still used
verbatim, with no path derived from it. The startup log line and the
compose-file example name the new key, the latter being where an
operator copies it from.
No metrics_endpoint is added here: this branch has no metrics pipeline,
so the key would parse into a member nothing reads.
getInstance(), getTracer(), both startSpan() overloads and networkTypeFromId()
return values that a caller must use. A discarded startSpan() result destroys
the returned span immediately, so the span opens and closes with no content.
Six methods in Telemetry.h already carried the attribute, on the base and on
every override. The new attributes follow that: the overrides in Telemetry.cpp
and NullTelemetry.cpp get it too, because [[nodiscard]] is not inherited and a
call bound to the derived type would otherwise be unchecked.
No caller anywhere in the chain discards any of these results.
With telemetry compiled out, <string_view> in Telemetry.h and <memory> in
SpanGuard.h are named only by declarations that are themselves guarded, so
clang-tidy's include-cleaner reports them unused and warnings-as-errors fails
the build. NullTelemetry.cpp has the mirror problem: it names beast::Journal
only in the compiled-out makeTelemetry(), reaching the type transitively.
Guard each include to match the configuration that uses it, and correct three
comments that overstated what the empty destructors cost.
