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tracing: use span id for correlation #2216

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Merged
e-eygin merged 1 commit into from
Sep 8, 2026
Merged

tracing: use span id for correlation #2216

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8 changes: 6 additions & 2 deletions src/core/tracing/trace_context.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -84,9 +84,13 @@ nixl::trace::TraceContext::sampled() const noexcept {

std::uint64_t
nixl::trace::TraceContext::correlationId64() const noexcept {
if (!valid()) {
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return 0;
}

std::uint64_t result = 0;
for (std::size_t index = 0; index < sizeof(result); ++index) {
result = (result << 8) | traceId[index];
for (const auto byte : spanId) {
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result = (result << 8) | byte;
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}
return result;
}
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39 changes: 37 additions & 2 deletions test/gtest/unit/tracing/trace_context_test.cpp
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Expand Up @@ -148,11 +148,46 @@ TEST(TraceContext, InvalidContextHasNoTextRepresentation) {
EXPECT_TRUE(nixl::trace::formatTraceparent({}).empty());
}

TEST(TraceContext, ProjectsTraceIdBigEndian) {
TEST(TraceContext, ProjectsSpanIdBigEndian) {
const auto context = nixl::trace::parseTraceparent(kCanonicalTraceparent);

ASSERT_TRUE(context.has_value());
EXPECT_EQ(context->correlationId64(), 0x4bf92f3577b34da6ULL);
EXPECT_EQ(context->correlationId64(), 0x00f067aa0ba902b7ULL);
}

TEST(TraceContext, InvalidContextsProjectZero) {
EXPECT_EQ(nixl::trace::TraceContext{}.correlationId64(), 0ULL);

nixl::trace::TraceContext no_span;
no_span.traceId = {0x4b, 0xf9, 0x2f, 0x35, 0x77, 0xb3, 0x4d, 0xa6};
ASSERT_FALSE(no_span.valid());
EXPECT_EQ(no_span.correlationId64(), 0ULL);
}

TEST(TraceContext, ValidSpanIdProjectsNonzero) {
nixl::trace::TraceContext context;
context.traceId[15] = 0x01;
context.spanId[7] = 0x01;

ASSERT_TRUE(context.valid());
EXPECT_EQ(context.correlationId64(), 0x01ULL);
}

TEST(TraceContext, ProjectionFollowsSpanIdAndIsStable) {
auto context = nixl::trace::parseTraceparent(kCanonicalTraceparent);
ASSERT_TRUE(context.has_value());
const auto baseline = context->correlationId64();

EXPECT_EQ(context->correlationId64(), baseline);

auto trace_changed = *context;
trace_changed.traceId[0] ^= 0xFF;
trace_changed.traceId[15] ^= 0xFF;
EXPECT_EQ(trace_changed.correlationId64(), baseline);

auto span_changed = *context;
span_changed.spanId[7] ^= 0xFF;
EXPECT_NE(span_changed.correlationId64(), baseline);
}

TEST(TraceContext, GeneratesDistinctValidContexts) {
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