feat: add default handler

instrumentation/active_job/lib/opentelemetry/instrumentation/active_job/subscriber.rb

@@ -50,7 +50,20 @@ module OpenTelemetry
   module Instrumentation
     module ActiveJob
 
-      class EnqueueSubscriber
+      class DefaultHandler
+        def initialize(tracer)
+          @tracer = tracer
+        end
+
+        def on_start(name, _id, payload, subscriber)
+          span = @tracer.start_span(name, attributes: subscriber.as_otel_semconv_attrs(payload.fetch(:job)))
+          tokens = [OpenTelemetry::Context.attach(OpenTelemetry::Trace.context_with_span(span))]
+          OpenTelemetry.propagation.inject(payload.fetch(:job).__otel_headers) # This must be transmitted over the wire
+          { span: span, ctx_tokens: tokens }
+        end
+      end
+
+      class EnqueueHandler
         def initialize(tracer)
           @tracer = tracer
         end
@@ -65,7 +78,7 @@ def on_start(name, _id, payload, subscriber)
         end
       end
 
-      class PerformSubscriber
+      class PerformHandler
         def initialize(tracer)
           @tracer = tracer
         end
@@ -101,19 +114,22 @@ class Subscriber < ::ActiveSupport::Subscriber
         def initialize(...)
           super
           @tracer = OpenTelemetry.tracer_provider.tracer('otel-active_job', '0.0.1')
+          default_handler = DefaultHandler.new(@tracer)
           @handlers_by_pattern = {
-            'enqueue.active_job' => EnqueueSubscriber.new(@tracer),
-            'perform.active_job' => PerformSubscriber.new(@tracer),
+            'enqueue.active_job' => EnqueueHandler.new(@tracer),
+            'perform.active_job' => PerformHandler.new(@tracer),
           }
+          @handlers_by_pattern.default = default_handler
         end
 
         # The methods below are the events the Subscriber is interested in.
         def enqueue(...); end
+        def perform_start(...); end
         def perform(...);end
 
         def start(name, id, payload)
           begin
-            payload.merge!(__otel: @handlers_by_pattern.fetch(name).on_start(name, id, payload, self)) # The payload is _not_ transmitted over the wire
+            payload.merge!(__otel: @handlers_by_pattern[name].on_start(name, id, payload, self)) # The payload is _not_ transmitted over the wire
           rescue StandardError => error
             OpenTelemetry.handle_error(exception: error)
           end
@@ -147,12 +163,6 @@ def finish(_name, _id, payload)
           end
         end
 
-        def on_start(name, _id, payload)
-          span = tracer.start_span(name, attributes: as_otel_semconv_attrs(payload.fetch(:job)))
-          tokens = [OpenTelemetry::Context.attach(OpenTelemetry::Trace.context_with_span(span))]
-          OpenTelemetry.propagation.inject(payload.fetch(:job).__otel_headers) # This must be transmitted over the wire
-          { span: span, ctx_tokens: tokens }
-        end
 
         def as_otel_semconv_attrs(job)
           test_adapters = %w[async inline]