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.
The emitted key is close_time_ripple_epoch_s, which names its unit and
epoch. Update the ledger attribute table to match.
ledger_index and ledger_tx_count in the same table belong to a separate
rename and are left as they are.
The commented [telemetry] block in cfg/xrpld-example.cfg documented 8 of the 14
keys the parser accepts. Add the six that were missing - service_instance_id,
use_tls, tls_ca_cert, batch_size, batch_delay_ms and max_queue_size - each with
the unit and default read from the parser, and rename the documented endpoint
key to traces_endpoint so it matches what makeTelemetrySetup reads.
use_tls is documented for what it does rather than what its name suggests: it
gates whether tls_ca_cert reaches the exporter as a CA bundle, while the scheme
of traces_endpoint is what selects TLS. The path is not opened during parsing,
so an unreadable file surfaces as an export failure at runtime.
05-configuration-reference.md named three symbols that do not exist:
setup_Telemetry, make_Telemetry and Section::value_or. Correct them to
makeTelemetrySetup, makeTelemetry and Section::valueOr.
The [telemetry] option table documents the config key operators copy.
The key is now traces_endpoint, named for the one OTLP signal it
carries, so the old row pointed at a key the parser no longer reads.
Two prose mentions of "endpoint" further down describe the concept
rather than naming the key, and are left alone.
[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.
The default setServiceInstanceId() body ignores its argument. Use the
attribute rather than a (void) cast: the codebase already uses it 104 times
and the build is C++23.
The conditional-compilation section promised zero overhead when telemetry is
not wanted. The span disappears, but the arguments passed to it do not: the
compiled-out guards are ordinary inline functions, so a to_string() or a hash
in an argument list still runs and its result is then discarded.
State that, show the guard that does remove the work, and name the opposite
case -- the metric macros, which discard their arguments and need no guard.
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.
The compiled-out ScopedActivation, SpanGuard and ScopedSpanGuard each used a
defaulted destructor. A defaulted destructor on an empty class is trivial, so
compilers report any guard held only for its scope as an unused variable. With
telemetry compiled out that produced seven -Wunused-variable errors under
-Werror, across the ledger acquire, consensus, ledger master and overlay paths.
Write the three destructors by hand so destruction is not trivial, matching the
telemetry-enabled types, and assert that property so it cannot quietly regress
to `= default`. The bodies are empty, so no code is generated either way.
Also move <memory> inside the telemetry guard: only the telemetry-enabled types
hold a unique_ptr, so the include is unused when telemetry is compiled out.
