rack.rb in opentelemetry-instrumentation-rack-0.9.0

- old
+ new

@@ -8,9 +8,43 @@
 
 module OpenTelemetry
   module Instrumentation
     # Contains the OpenTelemetry instrumentation for the Rack gem
     module Rack
+      extend self
+
+      CURRENT_SPAN_KEY = Context.create_key('current-span')
+
+      private_constant :CURRENT_SPAN_KEY
+
+      # Returns the current span from the current or provided context
+      #
+      # @param [optional Context] context The context to lookup the current
+      #   {Span} from. Defaults to Context.current
+      def current_span(context = nil)
+        context ||= Context.current
+        context.value(CURRENT_SPAN_KEY) || Span::INVALID
+      end
+
+      # Returns a context containing the span, derived from the optional parent
+      # context, or the current context if one was not provided.
+      #
+      # @param [optional Context] context The context to use as the parent for
+      #   the returned context
+      def context_with_span(span, parent_context: Context.current)
+        parent_context.set_value(CURRENT_SPAN_KEY, span)
+      end
+
+      # Activates/deactivates the Span within the current Context, which makes the "current span"
+      # available implicitly.
+      #
+      # On exit, the Span that was active before calling this method will be reactivated.
+      #
+      # @param [Span] span the span to activate
+      # @yield [span, context] yields span and a context containing the span to the block.
+      def with_span(span)
+        Context.with_value(CURRENT_SPAN_KEY, span) { |c, s| yield s, c }
+      end
     end
   end
 end
 
 require_relative './rack/instrumentation'