ETW Exporter - Add support for Sampler and ID Generator (#1547)

exporters/etw/include/opentelemetry/exporters/etw/etw_config.h

@@ -10,7 +10,9 @@
 #include "opentelemetry/nostd/variant.h"
 #include "opentelemetry/trace/span_id.h"
 
+#include "opentelemetry//sdk/trace/sampler.h"
 #include "opentelemetry/exporters/etw/etw_provider.h"
+#include "opentelemetry/sdk/trace/id_generator.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace exporter
@@ -146,6 +148,24 @@ TelemetryProviderConfiguration &GetConfiguration(T &t)
   return t.config_;
 }
 
+/**
+ * @brief Utility function to obtain etw::TracerProvider.id_generator_
+ */
+template <class T>
+sdk::trace::IdGenerator &GetIdGenerator(T &t)
+{
+  return *t.id_generator_;
+}
+
+/**
+ * @brief Utility function to obtain etw::TracerProvider.sampler_
+ */
+template <class T>
+sdk::trace::Sampler &GetSampler(T &t)
+{
+  return *t.sampler_;
+}
+
 /**
  * @brief Utility template to convert SpanId or TraceId to hex.
  * @param id - value of SpanId or TraceId

exporters/etw/include/opentelemetry/exporters/etw/etw_random_id_generator.h

@@ -0,0 +1,47 @@
+// Copyright The OpenTelemetry Authors
+// SPDX-License-Identifier: Apache-2.0
+
+#pragma once
+#include "opentelemetry/sdk/trace/id_generator.h"
+#include "opentelemetry/version.h"
+
+#ifdef _WIN32
+#  include "Windows.h"
+#endif
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace sdk
+{
+namespace trace
+{
+
+class ETWRandomIdGenerator : public IdGenerator
+{
+
+  opentelemetry::trace::SpanId GenerateSpanId() noexcept override
+  {
+    GUID span_id;
+    // Generate random GUID
+    CoCreateGuid(&span_id);
+    const auto *spanIdPtr = reinterpret_cast<const uint8_t *>(std::addressof(span_id));
+
+    // Populate SpanId with that GUID
+    nostd::span<const uint8_t, opentelemetry::trace::SpanId::kSize> spanIdBytes(
+        spanIdPtr, spanIdPtr + opentelemetry::trace::SpanId::kSize);
+    return opentelemetry::trace::SpanId(spanIdBytes);
+  }
+
+  opentelemetry::trace::TraceId GenerateTraceId() noexcept override
+  {
+    GUID trace_id;
+    CoCreateGuid(&trace_id);
+    // Populate TraceId of the Tracer with the above GUID
+    const auto *traceIdPtr = reinterpret_cast<const uint8_t *>(std::addressof(trace_id));
+    nostd::span<const uint8_t, opentelemetry::trace::TraceId::kSize> traceIdBytes(
+        traceIdPtr, traceIdPtr + opentelemetry::trace::TraceId::kSize);
+    return opentelemetry::trace::TraceId(traceIdBytes);
+  }
+};
+}  // namespace trace
+}  // namespace sdk
+OPENTELEMETRY_END_NAMESPACE

exporters/etw/include/opentelemetry/exporters/etw/etw_tracer.h

@@ -26,18 +26,20 @@
 
 #include "opentelemetry/common/key_value_iterable_view.h"
 
-#include "opentelemetry/trace/span.h"
+#include "opentelemetry/trace/noop.h"
 #include "opentelemetry/trace/span_context_kv_iterable_view.h"
 #include "opentelemetry/trace/span_id.h"
 #include "opentelemetry/trace/trace_id.h"
 #include "opentelemetry/trace/tracer_provider.h"
 
 #include "opentelemetry/sdk/trace/exporter.h"
+#include "opentelemetry/sdk/trace/samplers/always_on.h"
 
 #include "opentelemetry/exporters/etw/etw_config.h"
 #include "opentelemetry/exporters/etw/etw_fields.h"
 #include "opentelemetry/exporters/etw/etw_properties.h"
 #include "opentelemetry/exporters/etw/etw_provider.h"
+#include "opentelemetry/exporters/etw/etw_random_id_generator.h"
 #include "opentelemetry/exporters/etw/utils.h"
 
 OPENTELEMETRY_BEGIN_NAMESPACE
@@ -154,7 +156,9 @@ void UpdateStatus(T &t, Properties &props)
 /**
  * @brief Tracer class that allows to send spans to ETW Provider.
  */
-class Tracer : public opentelemetry::trace::Tracer
+
+class Tracer : public opentelemetry::trace::Tracer,
+               public std::enable_shared_from_this<trace::Tracer>
 {
 
   /**
@@ -353,14 +357,7 @@ class Tracer : public opentelemetry::trace::Tracer
         encoding(encoding),
         provHandle(initProvHandle())
   {
-    // Generate random GUID
-    GUID trace_id;
-    CoCreateGuid(&trace_id);
-    // Populate TraceId of the Tracer with the above GUID
-    const auto *traceIdPtr = reinterpret_cast<const uint8_t *>(std::addressof(trace_id));
-    nostd::span<const uint8_t, opentelemetry::trace::TraceId::kSize> traceIdBytes(
-        traceIdPtr, traceIdPtr + opentelemetry::trace::TraceId::kSize);
-    traceId_ = opentelemetry::trace::TraceId(traceIdBytes);
+    traceId_ = GetIdGenerator(tracerProvider_).GenerateTraceId();
   }
 
   /**
@@ -377,6 +374,30 @@ 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);
@@ -686,27 +707,6 @@ class Span : public opentelemetry::trace::Span
 
   opentelemetry::trace::SpanContext context_;
 
-  const opentelemetry::trace::SpanContext CreateContext()
-  {
-    GUID activity_id;
-    // Generate random GUID
-    CoCreateGuid(&activity_id);
-    const auto *activityIdPtr = reinterpret_cast<const uint8_t *>(std::addressof(activity_id));
-
-    // Populate SpanId with that GUID
-    nostd::span<const uint8_t, opentelemetry::trace::SpanId::kSize> spanIdBytes(
-        activityIdPtr, activityIdPtr + opentelemetry::trace::SpanId::kSize);
-    const opentelemetry::trace::SpanId spanId(spanIdBytes);
-
-    // Inherit trace_id from Tracer
-    const opentelemetry::trace::TraceId traceId{owner_.trace_id()};
-    // TODO: TraceFlags are not supported by ETW exporter.
-    const opentelemetry::trace::TraceFlags flags{0};
-    // TODO: Remote parent is not supported by ETW exporter.
-    const bool hasRemoteParent = false;
-    return opentelemetry::trace::SpanContext{traceId, spanId, flags, hasRemoteParent};
-  }
-
 public:
   /**
    * @brief Update Properties object with current Span status
@@ -764,7 +764,8 @@ class Span : public opentelemetry::trace::Span
         start_time_(std::chrono::system_clock::now()),
         owner_(owner),
         parent_(parent),
-        context_(CreateContext())
+        context_{owner.traceId_, GetIdGenerator(owner.tracerProvider_).GenerateSpanId(),
+                 opentelemetry::trace::TraceFlags{0}, false}
   {
     name_ = name;
     UNREFERENCED_PARAMETER(options);
@@ -920,11 +921,31 @@ class TracerProvider : public opentelemetry::trace::TracerProvider
    */
   TelemetryProviderConfiguration config_;
 
+  /**
+   * @brief Sampler configured
+   *
+   */
+  std::unique_ptr<sdk::trace::Sampler> sampler_;
+
+  /**
+   * @brief IdGenerator for trace_id and span_id
+   *
+   */
+  std::unique_ptr<sdk::trace::IdGenerator> id_generator_;
+
   /**
    * @brief Construct instance of TracerProvider with given options
    * @param options Configuration options
    */
-  TracerProvider(TelemetryProviderOptions options) : opentelemetry::trace::TracerProvider()
+  TracerProvider(TelemetryProviderOptions options,
+                 std::unique_ptr<sdk::trace::Sampler> sampler =
+                     std::unique_ptr<sdk::trace::AlwaysOnSampler>(new sdk::trace::AlwaysOnSampler),
+                 std::unique_ptr<sdk::trace::IdGenerator> id_generator =
+                     std::unique_ptr<opentelemetry::sdk::trace::IdGenerator>(
+                         new sdk::trace::ETWRandomIdGenerator()))
+      : opentelemetry::trace::TracerProvider(),
+        sampler_{std::move(sampler)},
+        id_generator_{std::move(id_generator)}
   {
     // By default we ensure that all events carry their with TraceId and SpanId
     GetOption(options, "enableTraceId", config_.enableTraceId, true);
@@ -955,7 +976,11 @@ class TracerProvider : public opentelemetry::trace::TracerProvider
     config_.encoding = GetEncoding(options);
   }
 
-  TracerProvider() : opentelemetry::trace::TracerProvider()
+  TracerProvider()
+      : opentelemetry::trace::TracerProvider(),
+        sampler_{std::unique_ptr<sdk::trace::AlwaysOnSampler>(new sdk::trace::AlwaysOnSampler)},
+        id_generator_{std::unique_ptr<opentelemetry::sdk::trace::IdGenerator>(
+            new sdk::trace::ETWRandomIdGenerator())}
   {
     config_.enableTraceId           = true;
     config_.enableSpanId            = true;
@@ -985,8 +1010,9 @@ class TracerProvider : public opentelemetry::trace::TracerProvider
     UNREFERENCED_PARAMETER(args);
     UNREFERENCED_PARAMETER(schema_url);
     ETWProvider::EventFormat evtFmt = config_.encoding;
-    return nostd::shared_ptr<opentelemetry::trace::Tracer>{new (std::nothrow)
-                                                               Tracer(*this, name, evtFmt)};
+    std::shared_ptr<opentelemetry::trace::Tracer> tracer{new (std::nothrow)
+                                                             Tracer(*this, name, evtFmt)};
+    return nostd::shared_ptr<opentelemetry::trace::Tracer>{tracer};
   }
 };
 

exporters/etw/test/etw_tracer_test.cc

@@ -8,6 +8,7 @@
 #  include <string>
 
 #  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;
@@ -21,6 +22,24 @@ std::string getTemporaryValue()
   return std::string("Value from Temporary std::string");
 }
 
+/**
+ * A Mock Custom Id Generator
+ */
+class MockIdGenerator : public sdk::trace::IdGenerator
+{
+  opentelemetry::trace::SpanId GenerateSpanId() noexcept override
+  {
+    return opentelemetry::trace::SpanId(buf_span);
+  }
+
+  opentelemetry::trace::TraceId GenerateTraceId() noexcept override
+  {
+    return opentelemetry::trace::TraceId(buf_trace);
+  }
+  uint8_t buf_span[8]   = {1, 2, 3, 4, 5, 6, 7, 8};
+  uint8_t buf_trace[16] = {1, 2, 3, 4, 5, 6, 7, 8, 8, 7, 6, 5, 4, 3, 2, 1};
+};
+
 /* clang-format off */
 TEST(ETWTracer, TracerCheck)
 {
@@ -383,6 +402,44 @@ TEST(ETWTracer, GlobalSingletonTracer)
   globalTracer.CloseWithMicroseconds(0);
 }
 
+TEST(ETWTracer, AlwayOffSampler)
+{
+  std::string providerName = kGlobalProviderName; // supply unique instrumentation name here
+  std::unique_ptr<sdk::trace::Sampler> always_off{new sdk::trace::AlwaysOffSampler()};
+  exporter::etw::TracerProvider tp
+    ({
+      {"enableTraceId", true},
+      {"enableSpanId", true},
+      {"enableActivityId", true},
+      {"enableRelatedActivityId", true},
+      {"enableAutoParent", true}
+     },
+     std::move(always_off));
+  auto tracer = tp.GetTracer(providerName);
+  auto span = tracer->StartSpan("span_off");
+  EXPECT_EQ(span->GetContext().IsValid(), false);
+}
+
+TEST(ETWTracer, CustomIdGenerator)
+{
+  std::string providerName = kGlobalProviderName; // supply unique instrumentation name here
+  sdk::trace::IdGenerator *id_generator = new MockIdGenerator();
+  std::unique_ptr<sdk::trace::Sampler> always_on{new sdk::trace::AlwaysOnSampler()};
+  exporter::etw::TracerProvider tp
+    ({
+      {"enableTraceId", true},
+      {"enableSpanId", true},
+      {"enableActivityId", true},
+      {"enableRelatedActivityId", true},
+      {"enableAutoParent", true}
+     },
+     std::move(always_on),
+     std::unique_ptr<sdk::trace::IdGenerator>(id_generator));
+  auto tracer = tp.GetTracer(providerName);
+  auto span = tracer->StartSpan("span_on");
+  EXPECT_EQ(span->GetContext().trace_id(), id_generator->GenerateTraceId());
+}
+
 /* clang-format on */
 
 #endif