Hot reloading

[lilleyse]

Omniverse Code will automatically hot-reload extensions when files that match the fswatcher pattern are changed. This works pretty well for Python code. Hot reloading C++ code is more complicated for several reasons:

• We may need to clear the USD stage after each hot-reload, or some other "reset" behavior
• The C++ code is built as a Python Dynamic Module (.pyd) — essentially a DLL — and the Python interpreter within Omniverse Code will hold onto this until program exit. Therefore trying to replace the file at runtime with a new version is not permitted by Windows.

One possibility is to handle the hot-reloading completely within the DLL's. On every update CesiumOmniversePythonBindings.cp37-win_amd64.pyd could check if a new variant of CesiumOmniverse[N].dll has been created and dynamically load it.

Also see:

• https://discuss.python.org/t/how-to-unload-native-extensions-pyd-on-windows/3749/2
• https://stackoverflow.com/questions/59906132/reloading-cython-modules-on-the-fly

[lilleyse]

Since we don't have hot reloading yet, here are the commands I run whenever I makes C++ changes on Windows:

taskkill //f //im kit.exe
cmake -B build && cmake --build build --config Release
cmake --install build --config Release --component kit
../cesium-kit-exts/app/omni.code.bat --ext-folder exts --enable cesium.omniverse

Or as a one liner in git bash:

taskkill //f //im kit.exe ; cmake -B build && cmake --build build --config Release && cmake --install build --config Release --component kit && ../cesium-kit-exts/app/omni.code.bat --ext-folder exts --enable cesium.omniverse

[lilleyse]

Carbonite plugins might be hot reloadable

const struct carb::PluginImplDesc pluginImplDesc = { "omni.example.cpp.hello_world.plugin",
                                                     "An example C++ extension.", "NVIDIA",
                                                     carb::PluginHotReload::eEnabled, "dev" };

From https://github.com/NVIDIA-Omniverse/kit-extension-template-cpp/blob/main/source/extensions/omni.example.cpp.hello_world/plugins/omni.example.cpp.hello_world/HelloWorldExtension.cpp#L17-L19

[lilleyse]

Unlikely to tackle this any time soon