Implement shutdown functionality for API layer with complete state reset

.gitignore

@@ -9,3 +9,4 @@
 
 # rspec failure tracking
 .rspec_status
+vendor/bundle

README.md

@@ -105,7 +105,7 @@ object = client.fetch_object_value(flag_key: 'object_value', default_value: JSON
 | ❌      | [Logging](#logging)                                                 | Integrate with popular logging packages.                                                                                                                     |
 | ✅      | [Domains](#domains)                                                 | Logically bind clients with providers.                                                                                                                       |
 | ❌      | [Eventing](#eventing)                                               | React to state changes in the provider or flag management system.                                                                                            |
-| ⚠️      | [Shutdown](#shutdown)                                               | Gracefully clean up a provider during application shutdown.                                                                                                  |
+| ✅      | [Shutdown](#shutdown)                                               | Gracefully clean up a provider during application shutdown.                                                                                                  |
 | ❌      | [Transaction Context Propagation](#transaction-context-propagation) | Set a specific [evaluation context](https://openfeature.dev/docs/reference/concepts/evaluation-context) for a transaction (e.g. an HTTP request or a thread) |
 | ⚠️      | [Extending](#extending)                                             | Extend OpenFeature with custom providers and hooks.                                                                                                          |
 
@@ -206,19 +206,41 @@ Please refer to the documentation of the provider you're using to see what event
 
 ### Shutdown
 
-Coming Soon! [Issue available](https://github.com/open-feature/ruby-sdk/issues/149) to be worked on.
-
-<!-- TODO The OpenFeature API provides a close function to perform a cleanup of all registered providers.
+The OpenFeature API provides a shutdown function to perform a cleanup of all registered providers.
 This should only be called when your application is in the process of shutting down.
 
+```ruby
+# Configure providers
+OpenFeature::SDK.configure do |config|
+  config.set_provider(OpenFeature::SDK::Provider::InMemoryProvider.new(
+    {
+      "v2_enabled" => true,
+    }
+  ))
+end
+
+# During application shutdown
+OpenFeature::SDK.shutdown
+```
+
+When you call `OpenFeature::SDK.shutdown`, it will:
+
+1. Call the `shutdown` method on all registered providers that support it
+2. Clear all registered providers from the configuration 
+3. Reset the SDK to its initial state
+
+After shutdown, no providers will be available and the SDK will need to be reconfigured if you want to continue using it.
+
+To implement shutdown in your custom provider:
+
 ```ruby
 class MyProvider
   def shutdown
     # Perform any shutdown/reclamation steps with flag management system here
     # Return value is ignored
   end
 end
-``` -->
+```
 
 ### Transaction Context Propagation
 

lib/open_feature/sdk/api.rb

@@ -32,7 +32,7 @@ class API
       include Singleton # Satisfies Flag Evaluation API Requirement 1.1.1
       extend Forwardable
 
-      def_delegators :configuration, :provider, :set_provider, :hooks, :evaluation_context
+      def_delegators :configuration, :provider, :set_provider, :hooks, :evaluation_context, :shutdown
 
       def configuration
         @configuration ||= Configuration.new

lib/open_feature/sdk/configuration.rb

@@ -36,6 +36,16 @@ def set_provider(provider, domain: nil)
           @providers = new_providers
         end
       end
+
+      # Shutdown all registered providers and clear the configuration
+      def shutdown
+        @provider_mutex.synchronize do
+          @providers.each_value do |provider|
+            provider.shutdown if provider.respond_to?(:shutdown)
+          end
+          @providers.clear
+        end
+      end
     end
   end
 end

spec/open_feature/sdk/configuration_spec.rb

@@ -55,4 +55,43 @@
       end
     end
   end
+
+  describe "#shutdown" do
+    context "when providers have shutdown methods" do
+      let(:provider1) { OpenFeature::SDK::Provider::InMemoryProvider.new }
+      let(:provider2) { OpenFeature::SDK::Provider::InMemoryProvider.new }
+
+      it "calls shutdown on all providers and clears them" do
+        configuration.set_provider(provider1)
+        configuration.set_provider(provider2, domain: "testing")
+
+        expect(provider1).to receive(:shutdown)
+        expect(provider2).to receive(:shutdown)
+
+        configuration.shutdown
+
+        # Verify providers are cleared
+        expect(configuration.provider).to be_nil
+        expect(configuration.provider(domain: "testing")).to be_nil
+      end
+    end
+
+    context "when providers do not have shutdown methods" do
+      it "does not raise errors for providers without shutdown and clears them" do
+        provider_without_shutdown = OpenFeature::SDK::Provider::NoOpProvider.new
+        configuration.set_provider(provider_without_shutdown)
+
+        expect { configuration.shutdown }.not_to raise_error
+
+        # Verify providers are cleared
+        expect(configuration.provider).to be_nil
+      end
+    end
+
+    context "when no providers are set" do
+      it "does not raise errors" do
+        expect { configuration.shutdown }.not_to raise_error
+      end
+    end
+  end
 end

spec/specification/flag_evaluation_api_spec.rb

@@ -127,6 +127,35 @@
         end.not_to raise_error
       end
     end
+
+    context "Shutdown functionality" do
+      specify "The API must provide a shutdown function to gracefully clean up all providers" do
+        provider1 = OpenFeature::SDK::Provider::InMemoryProvider.new
+        provider2 = OpenFeature::SDK::Provider::InMemoryProvider.new
+
+        OpenFeature::SDK.set_provider(provider1)
+        OpenFeature::SDK.set_provider(provider2, domain: "testing")
+
+        expect(provider1).to receive(:shutdown)
+        expect(provider2).to receive(:shutdown)
+
+        expect { OpenFeature::SDK.shutdown }.not_to raise_error
+
+        # Verify providers are cleared after shutdown
+        expect(OpenFeature::SDK.provider).to be_nil
+        expect(OpenFeature::SDK.provider(domain: "testing")).to be_nil
+      end
+
+      specify "Shutdown does not raise errors when providers don't have shutdown methods" do
+        provider_without_shutdown = OpenFeature::SDK::Provider::NoOpProvider.new
+        OpenFeature::SDK.set_provider(provider_without_shutdown)
+
+        expect { OpenFeature::SDK.shutdown }.not_to raise_error
+
+        # Verify providers are cleared after shutdown
+        expect(OpenFeature::SDK.provider).to be_nil
+      end
+    end
   end
 
   context "1.2 - Client Usage" do