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[ETW Exporter] - Add Trace flags in SpanContext (#1618)
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@lalitb
lalitb authored Sep 19, 2022
1 parent ed9f583 commit 2142d00
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Showing 2 changed files with 113 additions and 40 deletions.
83 changes: 44 additions & 39 deletions exporters/etw/include/opentelemetry/exporters/etw/etw_tracer.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,9 +64,10 @@ class Span;
template <class SpanType, class TracerType>
SpanType *new_span(TracerType *objPtr,
nostd::string_view name,
const opentelemetry::trace::StartSpanOptions &options)
const opentelemetry::trace::StartSpanOptions &options,
std::unique_ptr<opentelemetry::trace::SpanContext> spanContext)
{
return new (std::nothrow) SpanType{*objPtr, name, options};
return new (std::nothrow) SpanType{*objPtr, name, options, std::move(spanContext)};
}

/**
Expand Down Expand Up @@ -374,30 +375,6 @@ class Tracer : public opentelemetry::trace::Tracer,
const opentelemetry::trace::SpanContextKeyValueIterable &links,
const opentelemetry::trace::StartSpanOptions &options = {}) noexcept override
{
const auto &cfg = GetConfiguration(tracerProvider_);

// Parent Context:
// - either use current span
// - or attach to parent SpanContext specified in options
opentelemetry::trace::SpanContext parentContext = GetCurrentSpan()->GetContext();
if (nostd::holds_alternative<opentelemetry::trace::SpanContext>(options.parent))
{
auto span_context = nostd::get<opentelemetry::trace::SpanContext>(options.parent);
if (span_context.IsValid())
{
parentContext = span_context;
}
}
auto sampling_result =
GetSampler(tracerProvider_)
.ShouldSample(parentContext, traceId_, name, options.kind, attributes, links);
if (sampling_result.decision == sdk::trace::Decision::DROP)
{
static nostd::shared_ptr<trace::Span> noop_span(
new trace::NoopSpan{this->shared_from_this()});
return noop_span;
}

#ifdef OPENTELEMETRY_RTTI_ENABLED
common::KeyValueIterable &attribs = const_cast<common::KeyValueIterable &>(attributes);
Properties *evt = dynamic_cast<Properties *>(&attribs);
Expand Down Expand Up @@ -433,12 +410,42 @@ class Tracer : public opentelemetry::trace::Tracer,
opentelemetry::trace::SpanContext parentContext = GetCurrentSpan()->GetContext();
if (nostd::holds_alternative<opentelemetry::trace::SpanContext>(options.parent))
{
auto span_context = nostd::get<opentelemetry::trace::SpanContext>(options.parent);
if (span_context.IsValid())
auto spanContext = nostd::get<opentelemetry::trace::SpanContext>(options.parent);
if (spanContext.IsValid())
{
parentContext = span_context;
parentContext = spanContext;
}
}
auto traceId = parentContext.IsValid() ? parentContext.trace_id() : traceId_;

// Sampling based on attributes is not supported for now, so passing empty below.
std::map<std::string, int> emptyAttributes = {{}};
opentelemetry::sdk::trace::SamplingResult sampling_result =
GetSampler(tracerProvider_)
.ShouldSample(parentContext, traceId, name, options.kind,
opentelemetry::common::KeyValueIterableView<std::map<std::string, int>>(
emptyAttributes),
links);

opentelemetry::trace::TraceFlags traceFlags =
sampling_result.decision == opentelemetry::sdk::trace::Decision::DROP
? opentelemetry::trace::TraceFlags{}
: opentelemetry::trace::TraceFlags{opentelemetry::trace::TraceFlags::kIsSampled};

auto spanContext =
std::unique_ptr<opentelemetry::trace::SpanContext>(new opentelemetry::trace::SpanContext(
traceId, GetIdGenerator(tracerProvider_).GenerateSpanId(), traceFlags, false,
sampling_result.trace_state
? sampling_result.trace_state
: parentContext.IsValid() ? parentContext.trace_state()
: opentelemetry::trace::TraceState::GetDefault()));

if (sampling_result.decision == sdk::trace::Decision::DROP)
{
auto noopSpan = nostd::shared_ptr<trace::Span>{
new (std::nothrow) trace::NoopSpan(this->shared_from_this(), std::move(spanContext))};
return noopSpan;
}

// Populate Etw.RelatedActivityId at envelope level if enabled
GUID RelatedActivityId;
Expand All @@ -456,11 +463,9 @@ class Tracer : public opentelemetry::trace::Tracer,

// This template pattern allows us to forward-declare the etw::Span,
// create an instance of it, then assign it to tracer::Span result.
auto currentSpan = new_span<Span, Tracer>(this, name, options);
auto currentSpan = new_span<Span, Tracer>(this, name, options, std::move(spanContext));
nostd::shared_ptr<opentelemetry::trace::Span> result = to_span_ptr<Span>(currentSpan);

auto spanContext = result->GetContext();

// Decorate with additional standard fields
std::string eventName = name.data();

Expand All @@ -475,13 +480,13 @@ class Tracer : public opentelemetry::trace::Tracer,
{
evt[ETW_FIELD_SPAN_PARENTID] = ToLowerBase16(parentContext.span_id());
}
evt[ETW_FIELD_SPAN_ID] = ToLowerBase16(spanContext.span_id());
evt[ETW_FIELD_SPAN_ID] = ToLowerBase16(result.get()->GetContext().span_id());
}

// Populate Etw.Payload["TraceId"] attribute
if (cfg.enableTraceId)
{
evt[ETW_FIELD_TRACE_ID] = ToLowerBase16(spanContext.trace_id());
evt[ETW_FIELD_TRACE_ID] = ToLowerBase16(result.get()->GetContext().trace_id());
}

// Populate Etw.ActivityId at envelope level if enabled
Expand Down Expand Up @@ -705,7 +710,7 @@ class Span : public opentelemetry::trace::Span
*/
Span *GetParent() const { return parent_; }

opentelemetry::trace::SpanContext context_;
std::unique_ptr<opentelemetry::trace::SpanContext> context_;

public:
/**
Expand Down Expand Up @@ -759,13 +764,13 @@ class Span : public opentelemetry::trace::Span
Span(Tracer &owner,
nostd::string_view name,
const opentelemetry::trace::StartSpanOptions &options,
std::unique_ptr<opentelemetry::trace::SpanContext> spanContext,
Span *parent = nullptr) noexcept
: opentelemetry::trace::Span(),
start_time_(std::chrono::system_clock::now()),
owner_(owner),
parent_(parent),
context_{owner.traceId_, GetIdGenerator(owner.tracerProvider_).GenerateSpanId(),
opentelemetry::trace::TraceFlags{0}, false}
context_(std::move(spanContext)),
parent_(parent)
{
name_ = name;
UNREFERENCED_PARAMETER(options);
Expand Down Expand Up @@ -883,7 +888,7 @@ class Span : public opentelemetry::trace::Span
* @brief Obtain SpanContext
* @return
*/
opentelemetry::trace::SpanContext GetContext() const noexcept override { return context_; }
opentelemetry::trace::SpanContext GetContext() const noexcept override { return *context_.get(); }

/**
* @brief Check if Span is recording data.
Expand Down
70 changes: 69 additions & 1 deletion exporters/etw/test/etw_tracer_test.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -7,13 +7,15 @@
# include <map>
# include <string>

# include "opentelemetry//sdk/trace/sampler.h"
# include "opentelemetry/exporters/etw/etw_tracer_exporter.h"
# include "opentelemetry/sdk/trace/samplers/always_off.h"
# include "opentelemetry/sdk/trace/simple_processor.h"

using namespace OPENTELEMETRY_NAMESPACE;

using namespace opentelemetry::exporter::etw;
using namespace opentelemetry::sdk::trace;

const char *kGlobalProviderName = "OpenTelemetry-ETW-TLD";

Expand All @@ -40,6 +42,42 @@ class MockIdGenerator : public sdk::trace::IdGenerator
uint8_t buf_trace[16] = {1, 2, 3, 4, 5, 6, 7, 8, 8, 7, 6, 5, 4, 3, 2, 1};
};

/* A Custom Sampler, implementing parent based sampler*/
class MockSampler : public sdk::trace::Sampler
{
public:
MockSampler(std::shared_ptr<Sampler> delegate_sampler) noexcept
: delegate_sampler_(delegate_sampler)
{}
sdk::trace::SamplingResult ShouldSample(
const trace_api::SpanContext &parent_context,
trace_api::TraceId trace_id,
nostd::string_view name,
trace_api::SpanKind span_kind,
const opentelemetry::common::KeyValueIterable &attributes,
const trace_api::SpanContextKeyValueIterable &links) noexcept
{
if (!parent_context.IsValid())
{
// If no parent (root span) exists returns the result of the delegateSampler
return delegate_sampler_->ShouldSample(parent_context, trace_id, name, span_kind, attributes,
links);
}

// If parent exists:
if (parent_context.IsSampled())
{
return {Decision::RECORD_AND_SAMPLE, nullptr, parent_context.trace_state()};
}
return {Decision::DROP, nullptr, parent_context.trace_state()};
}

nostd::string_view GetDescription() const noexcept { return "Custom Sampler"; }

private:
std::shared_ptr<Sampler> delegate_sampler_;
};

/* clang-format off */
TEST(ETWTracer, TracerCheck)
{
Expand Down Expand Up @@ -417,7 +455,8 @@ TEST(ETWTracer, AlwayOffSampler)
std::move(always_off));
auto tracer = tp.GetTracer(providerName);
auto span = tracer->StartSpan("span_off");
EXPECT_EQ(span->GetContext().IsValid(), false);
EXPECT_EQ(span->GetContext().IsValid(), true);
EXPECT_EQ(span->GetContext().IsSampled(), false);
}

TEST(ETWTracer, CustomIdGenerator)
Expand All @@ -440,6 +479,35 @@ TEST(ETWTracer, CustomIdGenerator)
EXPECT_EQ(span->GetContext().trace_id(), id_generator->GenerateTraceId());
}

TEST(ETWTracer, CustomSampler)
{
std::string providerName = kGlobalProviderName; // supply unique instrumentation name here
auto parent_off = std::unique_ptr<Sampler>(new MockSampler(std::make_shared<AlwaysOnSampler>()));
exporter::etw::TracerProvider tp
({
{"enableTraceId", true},
{"enableSpanId", true},
{"enableActivityId", true},
{"enableRelatedActivityId", true},
{"enableAutoParent", true}
},
std::move(parent_off));
auto tracer = tp.GetTracer(providerName);
{
auto span = tracer->StartSpan("span_off");
EXPECT_EQ(span->GetContext().IsValid(), true);
EXPECT_EQ(span->GetContext().IsSampled(), true);
auto scope = tracer->WithActiveSpan(span);
auto trace_id = span->GetContext().trace_id();
{
auto child_span = tracer->StartSpan("span on");
EXPECT_EQ(child_span->GetContext().IsValid(), true);
EXPECT_EQ(child_span->GetContext().IsSampled(), true);
EXPECT_EQ(child_span->GetContext().trace_id(), trace_id);
}
}
}

/* clang-format on */

#endif

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