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fix for sampling root span #784

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merged 4 commits into from
May 24, 2021
Merged

fix for sampling root span #784

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de5295d
fix passing correct trace_id to sampler
lalitb May 21, 2021
9493845
add test
lalitb May 21, 2021
f1a4ed5
assert
lalitb May 21, 2021
515be01
Merge branch 'main' into root-span-sample
lalitb May 23, 2021
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33 changes: 5 additions & 28 deletions sdk/src/trace/span.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -47,11 +47,11 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
const trace_api::SpanContextKeyValueIterable &links,
const trace_api::StartSpanOptions &options,
const trace_api::SpanContext &parent_span_context,
const nostd::shared_ptr<opentelemetry::trace::TraceState> trace_state,
const bool sampled) noexcept
std::unique_ptr<trace_api::SpanContext> span_context) noexcept
: tracer_{std::move(tracer)},
recordable_{tracer_->GetProcessor().MakeRecordable()},
start_steady_time{options.start_steady_time},
span_context_(std::move(span_context)),
has_ended_{false}
{
if (recordable_ == nullptr)
Expand All @@ -60,32 +60,9 @@ Span::Span(std::shared_ptr<Tracer> &&tracer,
}
recordable_->SetName(name);
recordable_->SetInstrumentationLibrary(tracer_->GetInstrumentationLibrary());

trace_api::TraceId trace_id;
trace_api::SpanId span_id = tracer_->GetIdGenerator().GenerateSpanId();
trace_api::SpanId parent_span_id;
bool is_parent_span_valid = false;

if (parent_span_context.IsValid())
{
trace_id = parent_span_context.trace_id();
parent_span_id = parent_span_context.span_id();
is_parent_span_valid = true;
}
else
{
trace_id = tracer_->GetIdGenerator().GenerateTraceId();
}

span_context_ = std::unique_ptr<trace_api::SpanContext>(new trace_api::SpanContext(
trace_id, span_id,
sampled ? trace_api::TraceFlags{trace_api::TraceFlags::kIsSampled} : trace_api::TraceFlags{},
false,
trace_state ? trace_state
: is_parent_span_valid ? parent_span_context.trace_state()
: trace_api::TraceState::GetDefault()));

recordable_->SetIdentity(*span_context_, parent_span_id);
recordable_->SetIdentity(*span_context_, parent_span_context.IsValid()
? parent_span_context.span_id()
: trace_api::SpanId());

attributes.ForEachKeyValue(
[&](nostd::string_view key, opentelemetry::common::AttributeValue value) noexcept {
Expand Down
4 changes: 1 addition & 3 deletions sdk/src/trace/span.h
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Expand Up @@ -21,9 +21,7 @@ class Span final : public trace_api::Span
const trace_api::SpanContextKeyValueIterable &links,
const trace_api::StartSpanOptions &options,
const trace_api::SpanContext &parent_span_context,
const nostd::shared_ptr<opentelemetry::trace::TraceState> trace_state =
trace_api::TraceState::GetDefault(),
const bool sampled = false) noexcept;
std::unique_ptr<trace_api::SpanContext> span_context) noexcept;

~Span() override;

Expand Down
32 changes: 28 additions & 4 deletions sdk/src/trace/tracer.cc
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Expand Up @@ -5,6 +5,8 @@
#include "opentelemetry/version.h"
#include "src/trace/span.h"

#include <memory>

OPENTELEMETRY_BEGIN_NAMESPACE
namespace sdk
{
Expand All @@ -22,11 +24,26 @@ nostd::shared_ptr<trace_api::Span> Tracer::StartSpan(
const trace_api::SpanContextKeyValueIterable &links,
const trace_api::StartSpanOptions &options) noexcept
{
trace_api::SpanContext parent =
trace_api::SpanContext parent_context =
options.parent.IsValid() ? options.parent : GetCurrentSpan()->GetContext();

auto sampling_result = context_->GetSampler().ShouldSample(parent, parent.trace_id(), name,
trace_api::TraceId trace_id;
trace_api::SpanId span_id = GetIdGenerator().GenerateSpanId();
bool is_parent_span_valid = false;

if (parent_context.IsValid())
{
trace_id = parent_context.trace_id();
is_parent_span_valid = true;
}
else
{
trace_id = GetIdGenerator().GenerateTraceId();
}

auto sampling_result = context_->GetSampler().ShouldSample(parent_context, trace_id, name,
options.kind, attributes, links);

if (sampling_result.decision == Decision::DROP)
{
// Don't allocate a no-op span for every DROP decision, but use a static
Expand All @@ -38,9 +55,16 @@ nostd::shared_ptr<trace_api::Span> Tracer::StartSpan(
}
else
{

auto span_context = std::unique_ptr<trace_api::SpanContext>(new trace_api::SpanContext(
trace_id, span_id, trace_api::TraceFlags{trace_api::TraceFlags::kIsSampled}, false,
sampling_result.trace_state ? sampling_result.trace_state
: is_parent_span_valid ? parent_context.trace_state()
: trace_api::TraceState::GetDefault()));

auto span = nostd::shared_ptr<trace_api::Span>{
new (std::nothrow) Span{this->shared_from_this(), name, attributes, links, options, parent,
sampling_result.trace_state, true}};
new (std::nothrow) Span{this->shared_from_this(), name, attributes, links, options,
parent_context, std::move(span_context)}};

// if the attributes is not nullptr, add attributes to the span.
if (sampling_result.attributes)
Expand Down
38 changes: 30 additions & 8 deletions sdk/test/trace/tracer_test.cc
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Expand Up @@ -21,25 +21,35 @@ using opentelemetry::exporter::memory::InMemorySpanExporter;
using opentelemetry::trace::SpanContext;

/**
* A mock sampler that returns non-empty sampling results attributes.
* A mock sampler with ShouldSample returning:
* Decision::RECORD_AND_SAMPLE if trace_id is valid
* Decision::DROP otherwise.
*/
class MockSampler final : public Sampler
{
public:
SamplingResult ShouldSample(
const SpanContext & /*parent_context*/,
trace_api::TraceId /*trace_id*/,
trace_api::TraceId trace_id,
nostd::string_view /*name*/,
trace_api::SpanKind /*span_kind*/,
const opentelemetry::common::KeyValueIterable & /*attributes*/,
const opentelemetry::trace::SpanContextKeyValueIterable & /*links*/) noexcept override
{
// Return two pairs of attributes. These attributes should be added to the
// span attributes
return {Decision::RECORD_AND_SAMPLE,
nostd::unique_ptr<const std::map<std::string, opentelemetry::common::AttributeValue>>(
new const std::map<std::string, opentelemetry::common::AttributeValue>(
{{"sampling_attr1", 123}, {"sampling_attr2", "string"}}))};
// Sample only if valid trace_id ( This is to test Sampler get's valid trace id)
if (trace_id.IsValid())
{
// Return two pairs of attributes. These attributes should be added to the
// span attributes
return {Decision::RECORD_AND_SAMPLE,
nostd::unique_ptr<const std::map<std::string, opentelemetry::common::AttributeValue>>(
new const std::map<std::string, opentelemetry::common::AttributeValue>(
{{"sampling_attr1", 123}, {"sampling_attr2", "string"}}))};
}
else
{
return {Decision::DROP};
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Should we assert(false) here? Seems invalid trace Id should not be passed to sampler.

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Instead of asserting in unit-test, better would be to fail the particular unit-test and let other tests run? Like in this case, ValidTraceIdToSampler test will fail.

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Yes, fail this particular unit-test works too.

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ok got it. Have changed it.

}
}

nostd::string_view GetDescription() const noexcept override { return "MockSampler"; }
Expand Down Expand Up @@ -599,3 +609,15 @@ TEST(Tracer, ExpectParent)
EXPECT_EQ(spandata_first->GetSpanId(), spandata_second->GetParentSpanId());
EXPECT_EQ(spandata_second->GetSpanId(), spandata_third->GetParentSpanId());
}

TEST(Tracer, ValidTraceIdToSampler)
{
std::unique_ptr<InMemorySpanExporter> exporter(new InMemorySpanExporter());
std::shared_ptr<InMemorySpanData> span_data = exporter->GetData();
auto tracer = initTracer(std::move(exporter), new MockSampler());

auto span = tracer->StartSpan("span 1");
// sampler was fed with valid trace_id, so span shouldn't be NoOp Span.
EXPECT_TRUE(span->IsRecording());
EXPECT_TRUE(span->GetContext().IsValid());
}