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[EXPORTER ETW] Generate a fresh trace id for every root span #4101

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[EXPORTER ETW] Generate a fresh trace id for every root span #4101

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11 changes: 10 additions & 1 deletion exporters/etw/include/opentelemetry/exporters/etw/etw_tracer.h
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Original file line number Diff line number Diff line change
Expand Up @@ -483,7 +483,16 @@ class Tracer : public opentelemetry::trace::Tracer,
parentContext = spanContext;
}
}
auto traceId = parentContext.IsValid() ? parentContext.trace_id() : traceId_;
// Generate a brand-new trace id from the IdGenerator on every root
// span. Do NOT fall back to the Tracer-scoped cached traceId_,
// because that collapses every root span produced by this Tracer
// into a single logical trace -- breaking per-request correlation
// in Geneva/Jarvis and disagreeing with the OTel spec and the
// sdk::trace::Tracer reference implementation, where each root
// span gets a fresh trace id.
// See https://github.com/open-telemetry/opentelemetry-cpp/issues/3846
auto traceId = parentContext.IsValid() ? parentContext.trace_id()
: GetIdGenerator(tracerProvider_).GenerateTraceId();

// Sampling based on attributes is not supported for now, so passing empty below.
std::map<std::string, int> emptyAttributes = {{}};
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25 changes: 20 additions & 5 deletions exporters/etw/test/etw_tracer_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -392,7 +392,9 @@ TEST(ETWTracer, GlobalSingletonTracer)
}
*/

// Obtain a different tracer withs its own trace-id.
// Each root span minted by the ETW Tracer now gets a fresh trace id from
// the IdGenerator (see issue #3846). That holds whether you call StartSpan
// on the global Tracer or on another Tracer obtained from the provider.
auto localTracer = GetGlobalTracerProvider().GetTracer(kGlobalProviderName);
auto s2 = localTracer->StartSpan("Span2");
auto traceId2 = s2->GetContext().trace_id();
Expand Down Expand Up @@ -424,12 +426,16 @@ TEST(ETWTracer, GlobalSingletonTracer)
}
*/

// Obtain the same global tracer with the same trace-id as before.
// Re-obtain the global tracer via the C++11 magic static -- this returns
// the same Tracer reference as `globalTracer` above. Starting a new root
// span on it still produces a brand-new trace id; there is no tracer-level
// cache.
auto& globalTracer2 = GetGlobalTracer();
auto s3 = globalTracer2.StartSpan("Span3");
auto traceId3 = s3->GetContext().trace_id();
s3->End();
/* === Span 3 - "TraceId": "182a64258fb1864ca4e1a542eecbd9bf"
/* === Span 3 - sample event payload (TraceId differs from Span 1 -- each
root span gets a fresh trace id)
{
"Timestamp": "2021-05-10T11:45:27.0290936-07:00",
"ProviderName": "OpenTelemetry-ETW-TLD",
Expand All @@ -450,13 +456,22 @@ TEST(ETWTracer, GlobalSingletonTracer)
"StatusCode": 0,
"StatusMessage": "",
"Success": "True",
"TraceId": "182a64258fb1864ca4e1a542eecbd9bf",
"TraceId": "9fbb18d2c9874340b6e4581a8b21c5a7",
"_name": "Span"
}
}
*/
// GetGlobalTracer() is backed by a C++11 magic static, so both invocations
// return the same Tracer reference.
EXPECT_EQ(&globalTracer, &globalTracer2);
// Every root span gets its own freshly-generated trace id -- there is no
// tracer-scoped caching. See issue #3846.
EXPECT_TRUE(traceId1.IsValid());
EXPECT_TRUE(traceId2.IsValid());
EXPECT_TRUE(traceId3.IsValid());
EXPECT_NE(traceId1, traceId2);
EXPECT_EQ(traceId1, traceId3);
EXPECT_NE(traceId1, traceId3);
EXPECT_NE(traceId2, traceId3);

# if OPENTELEMETRY_ABI_VERSION_NO == 1
localTracer->CloseWithMicroseconds(0);
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