Support non-deterministic resource configuration

lib/semian/adapter.rb

@@ -9,19 +9,25 @@ def semian_identifier
     end
 
     def semian_resource
-      @semian_resource ||= case semian_options
+      return @semian_resource if @semian_resource
+
+      case semian_options
       when false
-        UnprotectedResource.new(semian_identifier)
+        @semian_resource = UnprotectedResource.new(semian_identifier)
       when nil
         Semian.logger.info("Semian is not configured for #{self.class.name}: #{semian_identifier}")
-        UnprotectedResource.new(semian_identifier)
+        @semian_resource = UnprotectedResource.new(semian_identifier)
       else
         options = semian_options.dup
         options.delete(:name)
         options[:consumer] = self
         options[:exceptions] ||= []
         options[:exceptions] += resource_exceptions
-        ::Semian.retrieve_or_register(semian_identifier, **options)
+        resource = ::Semian.retrieve_or_register(semian_identifier, **options)
+
+        @semian_resource = resource unless options.fetch(:dynamic, false)
+
+        resource
       end
     end
 
@@ -53,7 +59,11 @@ def semian_options
       return @semian_options if defined? @semian_options
 
       options = raw_semian_options
-      @semian_options = options && options.map { |k, v| [k.to_sym, v] }.to_h
+
+      symbolized_options = options && options.transform_keys(&:to_sym) # rubocop:disable Style/SafeNavigation
+      symbolized_options.tap do
+        @semian_options = symbolized_options if !symbolized_options || !symbolized_options.fetch(:dynamic, false)
+      end
     end
 
     def raw_semian_options

lib/semian/net_http.rb

@@ -91,16 +91,20 @@ def disabled?
     end
 
     def connect
-      return super if disabled?
+      with_cleared_dynamic_options do
+        return super if disabled?
 
-      acquire_semian_resource(adapter: :http, scope: :connection) { super }
+        acquire_semian_resource(adapter: :http, scope: :connection) { super }
+      end
     end
 
     def transport_request(*)
-      return super if disabled?
+      with_cleared_dynamic_options do
+        return super if disabled?
 
-      acquire_semian_resource(adapter: :http, scope: :query) do
-        handle_error_responses(super)
+        acquire_semian_resource(adapter: :http, scope: :query) do
+          handle_error_responses(super)
+        end
       end
     end
 
@@ -125,6 +129,24 @@ def handle_error_responses(result)
       end
       result
     end
+
+    def with_cleared_dynamic_options
+      unless @resource_acquisition_in_progress
+        @resource_acquisition_in_progress = true
+        resource_acquisition_started = true
+      end
+
+      yield
+    ensure
+      if resource_acquisition_started
+        if @raw_semian_options&.fetch(:dynamic, false)
+          # Clear @raw_semian_options if the resource was flagged as dynamic.
+          @raw_semian_options = nil
+        end
+
+        @resource_acquisition_in_progress = false
+      end
+    end
   end
 end
 

test/adapter_test.rb

@@ -91,6 +91,15 @@ def test_consumer_registration_does_not_prevent_gc
     end
   end
 
+  def test_does_not_memoize_dynamic_options
+    dynamic_client = Semian::DynamicAdapterTestClient.new(quota: 0.5)
+
+    refute_nil(dynamic_client.semian_resource)
+    assert_equal(4, dynamic_client.raw_semian_options[:success_threshold])
+    assert_equal(5, dynamic_client.raw_semian_options[:success_threshold])
+    assert_nil(dynamic_client.instance_variable_get("@semian_options"))
+  end
+
   class MyAdapterError < StandardError
     include Semian::AdapterError
   end

test/adapters/net_http_test.rb

@@ -23,6 +23,10 @@ def setup
     destroy_all_semian_resources
   end
 
+  def teardown
+    Thread.current[:sub_resource_name] = nil
+  end
+
   def test_semian_identifier
     with_server do
       with_semian_configuration do
@@ -484,6 +488,31 @@ def test_semian_disabled_env
     ENV.delete("SEMIAN_DISABLED")
   end
 
+  def test_dynamic_config
+    options = proc do |host, port|
+      DEFAULT_SEMIAN_OPTIONS.merge(
+        dynamic: true,
+        name: "#{host}_#{port}_#{Thread.current[:sub_resource_name]}",
+      )
+    end
+    host = SemianConfig["toxiproxy_upstream_host"]
+    port = SemianConfig["http_toxiproxy_port"]
+    http = Net::HTTP.new(host, port)
+    Thread.current[:sub_resource_name] = "service_a"
+
+    with_semian_configuration(options) do
+      with_server do
+        http.get("/200")
+
+        Thread.current[:sub_resource_name] = "service_b"
+        http.get("/200")
+
+        assert_includes(Semian.resources.keys, "nethttp_#{host}_#{port}_service_a")
+        assert_includes(Semian.resources.keys, "nethttp_#{host}_#{port}_service_b")
+      end
+    end
+  end
+
   private
 
   def half_open_cicuit!(backwards_time_travel = 10)

test/helpers/adapter_helper.rb

@@ -19,6 +19,28 @@ def resource_exceptions
     end
   end
 
+  module DynamicAdapterTest
+    include Semian::Adapter
+
+    def semian_identifier
+      :dynamic_semian_adapter_test
+    end
+
+    def raw_semian_options
+      {
+        bulkhead: false,
+        error_threshold: 1,
+        error_timeout: 1,
+        dynamic: true,
+        success_threshold: @current_success_threshold += 1,
+      }
+    end
+
+    def resource_exceptions
+      []
+    end
+  end
+
   class AdapterTestClient
     include AdapterTest
 
@@ -34,4 +56,16 @@ def ==(other)
       inspect == other.inspect
     end
   end
+
+  class DynamicAdapterTestClient
+    include DynamicAdapterTest
+
+    def initialize(**args)
+      @current_success_threshold = 1
+    end
+
+    def ==(other)
+      inspect == other.inspect
+    end
+  end
 end