Allow profiler to run without "no signals" workaround on passenger 6.0.19+

lib/datadog/profiling/component.rb

@@ -171,12 +171,11 @@ def self.build_profiler_component(settings:, agent_settings:, optional_tracer:)
           return true
         end
 
-        if defined?(::PhusionPassenger)
+        if (defined?(::PhusionPassenger) || Gem.loaded_specs['passenger']) && incompatible_passenger_version?
           Datadog.logger.warn(
-            'Enabling the profiling "no signals" workaround because the passenger web server is in use. ' \
-            'This is needed because passenger is currently incompatible with the normal working mode ' \
-            'of the profiler, as detailed in <https://github.com/DataDog/dd-trace-rb/issues/2976>. ' \
-            'Profiling data will have lower quality.'
+            'Enabling the profiling "no signals" workaround because an incompatible version of the passenger gem is ' \
+            'installed. Profiling data will have lower quality.' \
+            'To fix this, upgrade the passenger gem to version 6.0.19 or above.'
           )
           return true
         end
@@ -237,6 +236,15 @@ def self.build_profiler_component(settings:, agent_settings:, optional_tracer:)
           true
         end
       end
+
+      # See https://github.com/datadog/dd-trace-rb/issues/2976 for details.
+      private_class_method def self.incompatible_passenger_version?
+        if Gem.loaded_specs['passenger']
+          Gem.loaded_specs['passenger'].version < Gem::Version.new('6.0.19')
+        else
+          true
+        end
+      end
     end
   end
 end

sig/datadog/profiling/component.rbs

@@ -23,6 +23,7 @@ module Datadog
       def self.no_signals_workaround_enabled?: (untyped settings) -> bool
 
       def self.incompatible_libmysqlclient_version?: (untyped settings) -> bool
+      def self.incompatible_passenger_version?: () -> bool
     end
   end
 end

spec/datadog/profiling/component_spec.rb

@@ -480,7 +480,9 @@
           end
         end
 
-        context 'when running inside the passenger web server' do
+        context 'when running inside the passenger web server, even when gem is not available' do
+          include_context('loaded gems', passenger: nil, rugged: nil, mysql2: nil)
+
           before do
             stub_const('::PhusionPassenger', Module.new)
             allow(Datadog.logger).to receive(:warn)
@@ -495,8 +497,30 @@
           end
         end
 
+        context 'when passenger gem is available' do
+          context 'on passenger >= 6.0.19' do
+            include_context('loaded gems', passenger: Gem::Version.new('6.0.19'), rugged: nil, mysql2: nil)
+
+            it { is_expected.to be false }
+          end
+
+          context 'on passenger < 6.0.19' do
+            include_context('loaded gems', passenger: Gem::Version.new('6.0.18'), rugged: nil, mysql2: nil)
+
+            before { allow(Datadog.logger).to receive(:warn) }
+
+            it { is_expected.to be true }
+
+            it 'logs a warning message mentioning that the no signals workaround is going to be used' do
+              expect(Datadog.logger).to receive(:warn).with(/Enabling the profiling "no signals" workaround/)
+
+              no_signals_workaround_enabled?
+            end
+          end
+        end
+
         context 'when mysql2 / rugged gems + passenger are not available' do
-          include_context('loaded gems', mysql2: nil, rugged: nil)
+          include_context('loaded gems', passenger: nil, mysql2: nil, rugged: nil)
 
           it { is_expected.to be false }
         end