change Sampler description from string to string_view (open-telemetry…

…#193)

sdk/include/opentelemetry/sdk/trace/sampler.h

@@ -77,7 +77,7 @@ class Sampler
    *
    * @return the description of this Sampler.
    */
-  virtual std::string GetDescription() const noexcept = 0;
+  virtual nostd::string_view GetDescription() const noexcept = 0;
 };
 }  // namespace trace
 }  // namespace sdk

sdk/include/opentelemetry/sdk/trace/samplers/always_off.h

@@ -19,23 +19,19 @@ class AlwaysOffSampler : public Sampler
   /**
    * @return Returns NOT_RECORD always
    */
-  SamplingResult ShouldSample(
-    const trace_api::SpanContext * /*parent_context*/,
-    trace_api::TraceId /*trace_id*/,
-    nostd::string_view /*name*/,
-    trace_api::SpanKind /*span_kind*/,
-    const trace_api::KeyValueIterable & /*attributes*/) noexcept override
+  SamplingResult ShouldSample(const trace_api::SpanContext * /*parent_context*/,
+                              trace_api::TraceId /*trace_id*/,
+                              nostd::string_view /*name*/,
+                              trace_api::SpanKind /*span_kind*/,
+                              const trace_api::KeyValueIterable & /*attributes*/) noexcept override
   {
-    return { Decision::NOT_RECORD, nullptr };
+    return {Decision::NOT_RECORD, nullptr};
   }
-  
+
   /**
    * @return Description MUST be AlwaysOffSampler
    */
-  std::string GetDescription() const noexcept override
-  {
-    return "AlwaysOffSampler";
-  }
+  nostd::string_view GetDescription() const noexcept override { return "AlwaysOffSampler"; }
 };
 }  // namespace trace
 }  // namespace sdk

sdk/include/opentelemetry/sdk/trace/samplers/always_on.h

@@ -30,7 +30,7 @@ class AlwaysOnSampler : public Sampler
   /**
    * @return Description MUST be AlwaysOnSampler
    */
-  inline std::string GetDescription() const noexcept override { return "AlwaysOnSampler"; }
+  inline nostd::string_view GetDescription() const noexcept override { return "AlwaysOnSampler"; }
 };
 }  // namespace trace
 }  // namespace sdk

sdk/include/opentelemetry/sdk/trace/samplers/parent_or_else.h

@@ -31,7 +31,7 @@ class ParentOrElseSampler : public Sampler
   /**
    * @return Description MUST be ParentOrElse{delegate_sampler_.getDescription()}
    */
-  std::string GetDescription() const noexcept override;
+  nostd::string_view GetDescription() const noexcept override;
 
 private:
   const std::shared_ptr<Sampler> delegate_sampler_;

sdk/include/opentelemetry/sdk/trace/samplers/probability.h

@@ -39,10 +39,10 @@ class ProbabilitySampler : public Sampler
   /**
    * @return Description MUST be ProbabilitySampler{0.000100}
    */
-  std::string GetDescription() const noexcept override;
+  nostd::string_view GetDescription() const noexcept override;
 
 private:
-  std::string sampler_description_;
+  std::string description_;
   const uint64_t threshold_;
 };
 }  // namespace trace

sdk/src/trace/samplers/parent_or_else.cc

@@ -7,7 +7,7 @@ namespace trace
 {
 ParentOrElseSampler::ParentOrElseSampler(std::shared_ptr<Sampler> delegate_sampler) noexcept
     : delegate_sampler_(delegate_sampler),
-      description_("ParentOrElse{" + delegate_sampler->GetDescription() + "}")
+      description_("ParentOrElse{" + std::string{delegate_sampler->GetDescription()} + "}")
 {}
 
 SamplingResult ParentOrElseSampler::ShouldSample(
@@ -32,7 +32,7 @@ SamplingResult ParentOrElseSampler::ShouldSample(
   return {Decision::NOT_RECORD, nullptr};
 }
 
-std::string ParentOrElseSampler::GetDescription() const noexcept
+nostd::string_view ParentOrElseSampler::GetDescription() const noexcept
 {
   return description_;
 }

sdk/src/trace/samplers/probability.cc

@@ -77,7 +77,7 @@ ProbabilitySampler::ProbabilitySampler(double probability)
 {
     if (probability > 1.0) probability = 1.0;
     if (probability < 0.0) probability = 0.0;
-    sampler_description_ = "ProbabilitySampler{" + std::to_string(probability) + "}";
+    description_ = "ProbabilitySampler{" + std::to_string(probability) + "}";
   }
 
 SamplingResult ProbabilitySampler::ShouldSample(
@@ -105,9 +105,9 @@ SamplingResult ProbabilitySampler::ShouldSample(
   return { Decision::NOT_RECORD, nullptr };
 }
 
-std::string ProbabilitySampler::GetDescription() const noexcept
+nostd::string_view ProbabilitySampler::GetDescription() const noexcept
 {
-  return sampler_description_;
+  return description_;
 }
 }  // namespace trace
 }  // namespace sdk

sdk/test/trace/tracer_test.cc

@@ -33,7 +33,7 @@ class MockSampler final : public Sampler
                     {{"sampling_attr1", 123}, {"sampling_attr2", "string"}}))};
   }
 
-  std::string GetDescription() const noexcept override { return "MockSampler"; }
+  nostd::string_view GetDescription() const noexcept override { return "MockSampler"; }
 };
 
 /**