instrumentation config: use :unsatisfied

lib/new_relic/agent/configuration/manager.rb

@@ -15,7 +15,7 @@ module NewRelic
   module Agent
     module Configuration
       class Manager
-        DEPENDENCY_DETECTION_VALUES = %i[prepend chain].freeze
+        DEPENDENCY_DETECTION_VALUES = %i[prepend chain unsatisfied].freeze
 
         # Defining these explicitly saves object allocations that we incur
         # if we use Forwardable and def_delegators.
@@ -366,7 +366,8 @@ def reset_cache
 
           preserved = @cache.select { |_k, v| DEPENDENCY_DETECTION_VALUES.include?(v) }
           new_cache
-          preserved.each { |k, v| @cache[k] = v unless @cache[k] && @cache[k] != 'auto' }
+          preserved.each { |k, v| @cache[k] = v }
+
           @cache
         end
 

lib/new_relic/dependency_detection.rb

@@ -27,6 +27,8 @@ def detect!
     @items.each do |item|
       if item.dependencies_satisfied?
         item.execute
+      else
+        item.configure_as_unsatisfied unless item.disabled_configured?
       end
     end
   end
@@ -62,6 +64,10 @@ def dependencies_satisfied?
       !executed and check_dependencies
     end
 
+    def configure_as_unsatisfied
+      NewRelic::Agent.config.instance_variable_get(:@cache)[config_key] = :unsatisfied
+    end
+
     def source_location_for(klass, method_name)
       Object.instance_method(:method).bind(klass.allocate).call(method_name).source_location.to_s
     end

test/new_relic/agent/configuration/manager_test.rb

@@ -509,6 +509,27 @@ def test_auto_determined_values_stay_cached
       end
     end
 
+    def test_unsatisfied_values_stay_cached
+      name = :tears_of_the_kingdom
+
+      dd = DependencyDetection.defer do
+        named(name)
+
+        # guarantee the instrumentation's dependencies are unsatisfied
+        depends_on { return false }
+        executes { use_prepend? }
+      end
+
+      key = :"instrumentation.#{name}"
+      with_config(key => 'prepend') do
+        DependencyDetection.detect!
+
+        @manager.replace_or_add_config(ServerSource.new({}))
+
+        assert_equal :unsatisfied, @manager.instance_variable_get(:@cache)[key]
+      end
+    end
+
     private
 
     def assert_parsed_labels(expected)

test/new_relic/agent/local_log_decorator_test.rb

@@ -20,6 +20,7 @@ def setup
           :'instrumentation.logger' => 'auto'
         }
         NewRelic::Agent.config.add_config_for_testing(@enabled_config)
+        NewRelic::Agent.config.send(:new_cache)
       end
 
       def teardown

test/new_relic/dependency_detection_test.rb

@@ -8,6 +8,7 @@ class DependencyDetectionTest < Minitest::Test
   def setup
     @original_items = DependencyDetection.instance_variable_get(:@items)
     DependencyDetection.instance_variable_set(:@items, [])
+    NewRelic::Agent.config.send(:new_cache)
   end
 
   def teardown
@@ -132,7 +133,7 @@ def test_config_defaults_to_auto
     assert_equal :auto, setting
   end
 
-  def test_config_disabling
+  def test_config_disabling_with_disabled
     executed = false
 
     dd = DependencyDetection.defer do
@@ -149,6 +150,15 @@ def test_config_disabling
       refute dd.allowed_by_config?
       refute executed
     end
+  end
+
+  def test_config_disabling_with_enabled
+    executed = false
+
+    dd = DependencyDetection.defer do
+      named(:testing)
+      executes { executed = true }
+    end
 
     with_config(:'instrumentation.testing' => 'enabled') do
       executed = false
@@ -159,8 +169,17 @@ def test_config_disabling
       assert_predicate dd, :allowed_by_config?
       assert executed
     end
+  end
+
+  # TODO: MAJOR VERSION - Deprecated!
+  def test_config_disabling_with_disable_testing
+    executed = false
+
+    dd = DependencyDetection.defer do
+      named(:testing)
+      executes { executed = true }
+    end
 
-    # TODO: MAJOR VERSION - Deprecated!
     with_config(:disable_testing => true) do
       executed = false
       DependencyDetection.detect!
@@ -172,7 +191,7 @@ def test_config_disabling
     end
   end
 
-  def test_config_enabling
+  def test_config_enabling_with_enabled
     executed = false
 
     dd = DependencyDetection.defer do
@@ -189,6 +208,15 @@ def test_config_enabling
       assert executed
       assert_predicate dd, :use_prepend?
     end
+  end
+
+  def test_config_enabling_with_auto
+    executed = false
+
+    dd = DependencyDetection.defer do
+      named(:testing)
+      executes { executed = true }
+    end
 
     with_config(:'instrumentation.testing' => 'auto') do
       DependencyDetection.detect!
@@ -197,6 +225,15 @@ def test_config_enabling
       refute dd.deprecated_disabled_configured?
       assert_predicate dd, :use_prepend?
     end
+  end
+
+  def test_config_enabling_with_prepend
+    executed = false
+
+    dd = DependencyDetection.defer do
+      named(:testing)
+      executes { executed = true }
+    end
 
     with_config(:'instrumentation.testing' => 'prepend') do
       DependencyDetection.detect!
@@ -205,6 +242,15 @@ def test_config_enabling
       refute dd.deprecated_disabled_configured?
       assert_predicate dd, :use_prepend?
     end
+  end
+
+  def test_config_enabling_with_chain
+    executed = false
+
+    dd = DependencyDetection.defer do
+      named(:testing)
+      executes { executed = true }
+    end
 
     with_config(:'instrumentation.testing' => 'chain') do
       DependencyDetection.detect!
@@ -215,7 +261,7 @@ def test_config_enabling
     end
   end
 
-  def test_config_prepend
+  def test_config_prepend_with_default_config
     dd = DependencyDetection.defer do
       named(:testing)
       executes { true }
@@ -227,13 +273,27 @@ def test_config_prepend
       assert_equal :auto, dd.config_value
       assert_predicate dd, :use_prepend?
     end
+  end
+
+  def test_config_prepend_with_prepend
+    dd = DependencyDetection.defer do
+      named(:testing)
+      executes { true }
+    end
 
     with_config(:'instrumentation.testing' => 'prepend') do
       DependencyDetection.detect!
 
       assert_equal :prepend, dd.config_value
       assert_predicate dd, :use_prepend?
     end
+  end
+
+  def test_config_prepend_with_disabled
+    dd = DependencyDetection.defer do
+      named(:testing)
+      executes { true }
+    end
 
     with_config(:'instrumentation.testing' => 'disabled') do
       DependencyDetection.detect!
@@ -416,4 +476,22 @@ def test_auto_is_replaced_by_chain_when_chain_is_used
       assert_equal :chain, dd.config_value
     end
   end
+
+  # confirm that :auto/:chain/:prepend becomes :unsatisfied when the detection
+  # logic finds that the library is either missing or known to not be supported
+  def test_prepend_is_replaced_by_unsatisfied_when_appropriate
+    name = :calm_calm_belong
+
+    dd = DependencyDetection.defer do
+      named(name)
+      depends_on { return false } # unsatisfied
+      executes { use_prepend? }
+    end
+
+    with_config(:"instrumentation.#{name}" => 'prepend') do
+      DependencyDetection.detect!
+
+      assert_equal :unsatisfied, dd.config_value
+    end
+  end
 end