Fix active? and trace_context to properly handle inactive traces

- Fix Traces.active? to return false when there is no active trace
  (previously always returned true even for INVALID spans)
- Fix Traces.trace_context to return nil when there is no active trace
  (previously returned invalid Context objects with zero trace_ids)
- Both methods now use OpenTelemetry::Trace::Span::INVALID for proper
  detection of inactive traces instead of manual trace_id checking
- Add test case to ensure trace_context returns nil in clean Fiber context
- Resolves issues with Async incorrectly detecting active traces

Author: samuel-williams-shopify

lib/traces/backend/open_telemetry/interface.rb

@@ -36,7 +36,15 @@ def trace_context=(context)
 					end
 				end
 
+				def active?
+					# Check if there's a real active trace using OpenTelemetry's INVALID span:
+					::OpenTelemetry::Trace.current_span != ::OpenTelemetry::Trace::Span::INVALID
+				end
+				
 				def trace_context(span = ::OpenTelemetry::Trace.current_span)
+					# Return nil if no active trace (using INVALID span check):
+					return nil if span == ::OpenTelemetry::Trace::Span::INVALID
+					
 					if span_context = span.context
 						flags = 0
 
@@ -87,6 +95,24 @@ def inject(headers = nil, context = nil)
 				def extract(headers)
 					::OpenTelemetry.propagation.extract(headers)
 				end
+				
+				def active?
+					# Check if there's a real active trace by examining the current span
+					span = ::OpenTelemetry::Trace.current_span
+					return false unless span
+					
+					span_context = span.context
+					return false unless span_context
+					
+					# A trace is only "active" if it has a non-zero trace_id
+					# An all-zero trace_id indicates no real trace is active
+					trace_id = span_context.trace_id
+					return false if trace_id.nil?
+					
+					# Check if trace_id is all zeros (16 bytes of zeros)
+					null_trace_id = "\x00" * 16
+					return trace_id != null_trace_id
+				end
 			end
 		end
 

releases.md

@@ -1,5 +1,13 @@
 # Releases
 
+## Unreleased
+
+### Bug Fixes
+
+  - Fixed `Traces.active?` to correctly return `false` when there is no active trace, instead of always returning `true`.
+  - Fixed `Traces.trace_context` to return `nil` when there is no active trace, instead of returning invalid Context objects.
+  - Both methods now use OpenTelemetry's `INVALID` span for proper detection of inactive traces. 
+
 ## v0.3.0
 
 ### New Context Propagation Interface

test/traces/backend/open_telemetry.rb

@@ -117,6 +117,21 @@ def my_span_and_context
 				)
 			end
 		end
+		
+		with "#trace_context when no active trace" do
+			it "returns nil when there is no active trace" do
+				# Use a new Fiber to create a clean context without any active traces
+				result = Fiber.new do
+					# Verify there's no active trace
+					expect(Traces.active?).to be == false
+					
+					# trace_context should return nil when there's no active trace
+					Traces.trace_context
+				end.resume
+				
+				expect(result).to be_nil
+			end
+		end
 	end
 
 	describe "Context Propagation Methods" do