Add support for loading System plugin from static plugin registry

src/SystemLoader.cc

@@ -18,6 +18,7 @@
 #include <optional>
 #include <sstream>
 #include <string>
+#include <string_view>
 #include <unordered_set>
 
 #include <gz/sim/SystemLoader.hh>
@@ -39,6 +40,10 @@ using namespace gz::sim;
 
 class gz::sim::SystemLoaderPrivate
 {
+  //////////////////////////////////////////////////
+  public: static constexpr std::string_view kStaticPluginFilenamePrefix =
+              "static://";
+
   //////////////////////////////////////////////////
   public: explicit SystemLoaderPrivate() = default;
 
@@ -60,6 +65,62 @@ class gz::sim::SystemLoaderPrivate
     return systemPaths.PluginPaths();
   }
 
+  //////////////////////////////////////////////////
+  public: std::string FixDeprecatedPluginName(const std::string &_pluginName)
+  {
+    std::string newPluginName = _pluginName;
+    constexpr std::string_view deprecatedPluginNamePrefix{"ignition::gazebo"};
+    if (auto pos = _pluginName.find(deprecatedPluginNamePrefix);
+        pos != std::string::npos)
+    {
+      newPluginName.replace(pos, deprecatedPluginNamePrefix.size(), "gz::sim");
+      gzwarn << "Trying to load deprecated plugin name [" << _pluginName
+             << "]. Using [" << newPluginName << "] instead."
+             << std::endl;
+    }
+    return newPluginName;
+  }
+
+  //////////////////////////////////////////////////
+  public: bool InstantiateStaticSystemPlugin(const sdf::Plugin &_sdfPlugin,
+              gz::plugin::PluginPtr &_gzPlugin)
+  {
+    const size_t prefixLen = kStaticPluginFilenamePrefix.size();
+    const std::string filenameWoPrefix =
+        _sdfPlugin.Filename().substr(prefixLen);
+    std::string pluginToInstantiate =
+        this->FixDeprecatedPluginName(filenameWoPrefix);
+
+    _gzPlugin = this->loader.Instantiate(pluginToInstantiate);
+
+    if (!_gzPlugin)
+    {
+      gzerr << "Failed to load system plugin: "
+            << "(Reason: static plugin registry does not contain the requested "
+               "plugin)\n"
+            << "- Requested plugin name: [" << _sdfPlugin.Name() << "]\n"
+            << "- Requested library name: [" << _sdfPlugin.Filename() << "]\n";
+      return false;
+    }
+
+    if (!_gzPlugin->HasInterface<System>())
+    {
+      std::stringstream ss;
+      ss << "Failed to load system plugin: "
+         << "(Reason: plugin does not implement System interface)\n"
+         << "- Requested plugin name: [" << _sdfPlugin.Name() << "]\n"
+         << "- Requested library name: [" << _sdfPlugin.Filename() << "]\n"
+         << "- Plugin Interfaces Implemented:\n";
+      for (const auto &interfaceIt : this->loader.InterfacesImplemented())
+      {
+        ss << "  - " << interfaceIt << "\n";
+      }
+      return false;
+    }
+
+    return true;
+  }
+
   //////////////////////////////////////////////////
   public: bool InstantiateSystemPlugin(const sdf::Plugin &_sdfPlugin,
               gz::plugin::PluginPtr &_gzPlugin)
@@ -75,6 +136,12 @@ class gz::sim::SystemLoaderPrivate
              << "]. Using [" << filename << "] instead." << std::endl;
     }
 
+    if (filename.substr(0, kStaticPluginFilenamePrefix.size()) ==
+          kStaticPluginFilenamePrefix)
+    {
+      return this->InstantiateStaticSystemPlugin(_sdfPlugin, _gzPlugin);
+    }
+
     const std::list<std::string> paths = this->PluginPaths();
     common::SystemPaths systemPaths;
     for (const auto &p : paths)
@@ -125,17 +192,8 @@ class gz::sim::SystemLoaderPrivate
         pluginName : _sdfPlugin.Name();
 
     // Deprecated: accept ignition plugins.
-    std::string deprecatedPluginNamePrefix{"ignition::gazebo"};
-    pos = pluginToInstantiate.find(deprecatedPluginNamePrefix);
-    if (pos != std::string::npos)
-    {
-      auto origPluginName = pluginToInstantiate;
-      pluginToInstantiate.replace(pos, deprecatedPluginNamePrefix.size(),
-          "gz::sim");
-      gzwarn << "Trying to load deprecated plugin name [" << origPluginName
-             << "]. Using [" << pluginToInstantiate << "] instead."
-             << std::endl;
-    }
+    pluginToInstantiate =
+        this->FixDeprecatedPluginName(pluginToInstantiate);
 
     _gzPlugin = this->loader.Instantiate(pluginToInstantiate);
     if (!_gzPlugin)

test/BUILD.bazel

@@ -53,6 +53,36 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "TestStaticModelSystem",
+    testonly = 1,
+    srcs = [
+        "plugins/TestModelSystem.hh",
+        "plugins/TestStaticModelSystem.cc",
+    ],
+    deps = [
+        "//:gz-sim",
+        "@gz-msgs//:gzmsgs_cc_proto",
+        "@gz-plugin//:register",
+        "@gz-transport",
+    ],
+    alwayslink = 1,
+)
+
+cc_test(
+    name = "INTEGRATION_load_system_static_registry",
+    srcs = ["integration/load_system_static_registry.cc"],
+    deps = [
+        ":Helpers",
+        ":MockSystem",
+        ":TestStaticModelSystem",
+        "//:gz-sim",
+        "@googletest//:gtest",
+        "@googletest//:gtest_main",
+        "@gz-common",
+    ],
+)
+
 filegroup(
     name = "worlds",
     srcs = glob(["worlds/**"]),

test/integration/CMakeLists.txt

@@ -47,6 +47,7 @@ set(tests
   light.cc
   lighter_than_air_dynamics.cc
   link.cc
+  load_system_static_registry.cc
   logical_camera_system.cc
   logical_audio_sensor_plugin.cc
   magnetometer_system.cc
@@ -249,3 +250,26 @@ if (TARGET INTEGRATION_python_system_loader)
   set_tests_properties(INTEGRATION_python_system_loader PROPERTIES
     ENVIRONMENT "PYTHONPATH=${CMAKE_INSTALL_PREFIX}/${CMAKE_INSTALL_LIBDIR}/python/:$ENV{PYTHONPATH}")
 endif()
+
+if (TARGET INTEGRATION_load_system_static_registry)
+  # The linker option -force_load (for Clang) or --whole-archive (for GNU)
+  # or /WHOLEARCHIVE: (for MSVC) needs to be specified to ensure that the
+  # global structs specified in the static plugin module get loaded even
+  # without any explicit reference to the loaded symbols
+  # (only the interfaces are referenced).
+  if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    target_link_libraries(INTEGRATION_load_system_static_registry
+      -WHOLEARCHIVE:$<TARGET_FILE:TestStaticModelSystem>)
+
+    # The whole-archive invocation doesn't correctly compute dependencies,
+    # so explicitly require the plugin before the test can build.
+    add_dependencies(INTEGRATION_load_system_static_registry
+      TestStaticModelSystem)
+  else()
+    target_link_libraries(INTEGRATION_load_system_static_registry
+      $<$<CXX_COMPILER_ID:GNU>:-Wl,--whole-archive>
+      $<$<CXX_COMPILER_ID:Clang>:-force_load>
+      $<$<CXX_COMPILER_ID:AppleClang>:-force_load> TestStaticModelSystem
+      $<$<CXX_COMPILER_ID:GNU>:-Wl,--no-whole-archive>)
+  endif()
+endif()

test/integration/load_system_static_registry.cc

@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2025 Open Source Robotics Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+#include <gtest/gtest.h>
+
+#include <gz/common/Util.hh>
+
+#include "../helpers/EnvTestFixture.hh"
+#include "gz/sim/Server.hh"
+#include "plugins/MockSystem.hh"
+
+using namespace gz;
+using namespace sim;
+
+/// \brief Test loading system from static plugin registry
+class LoadSystemStaticRegistryTest : public InternalFixture<::testing::Test> {};
+
+TEST_F(LoadSystemStaticRegistryTest, LoadWorks)
+{
+  // Start server
+  ServerConfig serverConfig;
+  serverConfig.SetSdfString(R"(
+    <?xml version="1.0"?>
+    <sdf version="1.12">
+      <world name="default">
+        <model name="test_model1">
+          <static>true</static>
+          <link name="link_1" />
+          <plugin filename="static://gz::sim::TestModelSystem"
+                  name="gz::sim::TestModelSystem">
+            <model_key>98765</model_key>
+          </plugin>
+        </model>
+        <model name="test_model2">
+          <static>true</static>
+          <link name="link_1" />
+          <!-- Plugin filename with registered alias -->
+          <plugin filename="static://StaticTestModelSystem"
+                  name="gz::sim::TestModelSystem">
+            <model_key>54321</model_key>
+          </plugin>
+        </model>
+      </world>
+    </sdf>)");
+
+  Server server(serverConfig);
+
+  // Verify that server was initialized correctly
+  auto iterationCount = server.IterationCount();
+  ASSERT_NE(iterationCount, std::nullopt);
+  ASSERT_EQ(*iterationCount, 0);
+
+  std::optional<Entity> model1Id = server.EntityByName("test_model1");
+  ASSERT_NE(model1Id, std::nullopt);
+  std::optional<Entity> model2Id = server.EntityByName("test_model2");
+  ASSERT_NE(model2Id, std::nullopt);
+
+  // Verify that the System was instantiated for both models by checking the ECM
+  // for the configured `ModelPluginComponent`.
+  auto mockSystem = std::make_shared<MockSystem>();
+  mockSystem->postUpdateCallback =
+      [model1Id, model2Id](const sim::UpdateInfo &,
+                           const sim::EntityComponentManager &_ecm)
+      {
+        const std::string modelComponentName{"ModelPluginComponent"};
+        auto modelComponentId = common::hash64(modelComponentName);
+        EXPECT_TRUE(_ecm.HasComponentType(modelComponentId));
+        EXPECT_TRUE(_ecm.EntityHasComponentType(*model1Id, modelComponentId));
+        EXPECT_TRUE(_ecm.EntityHasComponentType(*model2Id, modelComponentId));
+      };
+  ASSERT_TRUE(server.AddSystem(mockSystem));
+  server.RunOnce();
+  EXPECT_EQ(1, mockSystem->postUpdateCallCount);
+}

test/plugins/CMakeLists.txt

@@ -49,3 +49,10 @@ if(BUILD_TESTING)
     endif()
   endforeach (src)
 endif()
+
+# Statically linked test plugin
+add_library(TestStaticModelSystem STATIC TestStaticModelSystem.cc)
+target_link_libraries(TestStaticModelSystem PRIVATE
+    gz-plugin${GZ_PLUGIN_VER}::register
+    gz-transport${GZ_TRANSPORT_VER}::gz-transport${GZ_TRANSPORT_VER}
+    gz-sim${PROJECT_VERSION_MAJOR})

test/plugins/TestStaticModelSystem.cc

@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2025 Open Source Robotics Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+*/
+#include <gz/plugin/RegisterStatic.hh>
+
+#include "TestModelSystem.hh"
+
+GZ_ADD_STATIC_PLUGIN(gz::sim::TestModelSystem,
+    gz::sim::System,
+    gz::sim::TestModelSystem::ISystemConfigure)
+
+GZ_ADD_STATIC_PLUGIN_ALIAS(gz::sim::TestModelSystem, "StaticTestModelSystem")