make instance more of a black box

Author: lia-viam

src/viam/examples/modules/complex/main.cpp

@@ -32,8 +32,8 @@ int main(int argc, char** argv) {
     Model mybase_model("viam", "base", "mybase");
 
     // Make sure to explicity register resources with custom APIs.
-    inst.registry()->register_resource_server<GizmoServer>();
-    inst.registry()->register_resource_server<SummationServer>();
+    Registry::get().register_resource_server<GizmoServer>();
+    Registry::get().register_resource_server<SummationServer>();
 
     std::shared_ptr<ModelRegistration> mybase_mr = std::make_shared<ModelRegistration>(
         API::get<Base>(),

src/viam/examples/modules/complex/test_complex_module.cpp

@@ -24,9 +24,9 @@ using namespace viam::sdktests;
 
 struct RegisterGizmoAndSummationFixture {
     RegisterGizmoAndSummationFixture() {
-        auto* registry = Instance::current().registry();
-        registry->register_resource<GizmoClient, GizmoServer>();
-        registry->register_resource<SummationClient, SummationServer>();
+        auto& registry = Registry::get();
+        registry.register_resource<GizmoClient, GizmoServer>();
+        registry.register_resource<SummationClient, SummationServer>();
     }
 
     // Test teardown is a noop;

src/viam/examples/modules/tflite/main.cpp

@@ -742,7 +742,7 @@ int serve(const std::string& socket_path) try {
         });
 
     // Register the newly created registration with the Registry.
-    inst.registry()->register_model(module_registration);
+    Registry::get().register_model(module_registration);
 
     // Construct the module service and tell it where to place the socket path.
     auto module_service = std::make_shared<vsdk::ModuleService>(socket_path, inst.registry());

src/viam/sdk/common/instance.cpp

@@ -1,6 +1,7 @@
 #include <viam/sdk/common/instance.hpp>
 
 #include <viam/sdk/common/exception.hpp>
+#include <viam/sdk/common/private/instance.hpp>
 #include <viam/sdk/registry/registry.hpp>
 
 #include <atomic>
@@ -17,10 +18,6 @@ std::atomic<Instance*> current_instance{nullptr};
 
 }  // namespace
 
-struct Instance::Impl {
-    Registry registry;
-};
-
 Instance::Instance() {
     Instance* expected = nullptr;
 
@@ -52,9 +49,5 @@ Instance& Instance::current() {
     return *current;
 }
 
-Registry* Instance::registry() {
-    return &(impl_->registry);
-}
-
 }  // namespace sdk
 }  // namespace viam

src/viam/sdk/common/instance.hpp

@@ -5,8 +5,6 @@
 namespace viam {
 namespace sdk {
 
-class Registry;
-
 /// @brief Instance management for Viam C++ SDK applications.
 /// This is a single instance class which is responsible for global setup and teardown related to
 /// the SDK. An Instance must be constructed before doing anything else in a program, and it must
@@ -19,9 +17,9 @@ class Instance {
 
     static Instance& current();
 
-    Registry* registry();
-
    private:
+    friend class Registry;
+
     struct Impl;
     std::unique_ptr<Impl> impl_;
 };

src/viam/sdk/registry/registry.cpp

@@ -12,7 +12,7 @@
 #include <grpcpp/ext/proto_server_reflection_plugin.h>
 
 #include <viam/sdk/common/exception.hpp>
-#include <viam/sdk/common/instance.hpp>
+#include <viam/sdk/common/private/instance.hpp>
 #include <viam/sdk/components/private/arm_client.hpp>
 #include <viam/sdk/components/private/arm_server.hpp>
 #include <viam/sdk/components/private/base_client.hpp>
@@ -92,7 +92,7 @@ const Model& ModelRegistration::model() const {
 };
 
 Registry& Registry::get() {
-    return *Instance::current().registry();
+    return Instance::current().impl_->registry;
 }
 
 void Registry::register_model(std::shared_ptr<const ModelRegistration> resource) {

src/viam/sdk/tests/mocks/mock_robot.cpp

@@ -26,7 +26,7 @@ std::vector<Name> registered_models_for_resource(const std::shared_ptr<Resource>
     std::string resource_type;
     std::string resource_subtype;
     std::vector<Name> resource_names;
-    for (const auto& kv : Instance::current().registry()->registered_models()) {
+    for (const auto& kv : Registry::get().registered_models()) {
         const std::shared_ptr<const ModelRegistration> reg = kv.second;
         if (reg->api() == resource->api()) {
             resource_type = reg->api().resource_type();