Support FT Python (#436)

Author: mthrok

packaging/spdl_io/setup.py

@@ -42,6 +42,13 @@ def _env(var, default=False):
 _SPDL_BUILD_STUB = _env("SPDL_BUILD_STUB")
 
 
+def _is_gil_enabled():
+    try:
+        return sys._is_gil_enabled()
+    except AttributeError:
+        return True
+
+
 def _get_ext_modules():
     ext_modules = []
     for v in ["4", "5", "6", "7"]:
@@ -101,6 +108,7 @@ def _b(var):
             f"-DPython_EXECUTABLE={sys.executable}",
             "-DSPDL_BUILD_PYTHON_BINDING=ON",
             f"-DSPDL_PYTHON_BINDING_INSTALL_PREFIX={install_dir}",
+            f"-DSPDL_IS_GIL_ENABLED={_b(_is_gil_enabled())}",
             ###################################################################
             # Options based on env vars
             ###################################################################

src/CMakeLists.txt

@@ -9,6 +9,7 @@ option(SPDL_USE_NPPI "Enable NVIDIA 2D Image And Signal Performance Primitives s
 option(SPDL_LINK_STATIC_NVJPEG "Link nvJPEG and NPPI statically." OFF)
 
 option(SPDL_DEBUG_REFCOUNT "Enable debug print for reference counting of AVFrame objects." OFF)
+option(SPDL_IS_GIL_ENABLED "Whether the target Python has the GIL enabled" ON)
 option(SPDL_HOLD_GIL "Hold GIL in IO functions." OFF)
 option(SPDL_BUILD_STUB "Build Python binding stub file" OFF)
 option(SPDL_BUILD_PYTHON_BINDING "Build Python binding" ON)
@@ -64,6 +65,7 @@ endif ()
 add_subdirectory(libspdl)
 
 if (SPDL_BUILD_PYTHON_BINDING)
+  find_package(Python COMPONENTS Interpreter Development.Module REQUIRED)
   add_subdirectory(third_party/nanobind)
   add_subdirectory(spdl/io/lib)
 endif()

src/spdl/io/lib/CMakeLists.txt

@@ -31,6 +31,10 @@ set(src
   io/encoding.cpp
 )
 
+if (NOT SPDL_IS_GIL_ENABLED)
+  set(ft FREE_THREADED)
+endif()
+
 function(add_spdl_extension ffmpeg_version)
   set(name "_spdl_ffmpeg${ffmpeg_version}")
   message(STATUS "Building ${name}")
@@ -46,11 +50,10 @@ function(add_spdl_extension ffmpeg_version)
     list(APPEND defs SPDL_HOLD_GIL)
   endif ()
 
-  nanobind_add_module(${name} ${src})
+  nanobind_add_module(${name} ${ft} ${src})
   target_compile_definitions(${name} PRIVATE "${defs}")
   target_link_libraries(${name} PRIVATE "spdl_ffmpeg${ffmpeg_version}")
   target_include_directories(${name} PRIVATE "${Python_INCLUDE_DIR}")
-  target_include_directories(nanobind-static PRIVATE "${Python_INCLUDE_DIR}")
 
   install(
     TARGETS ${name}