runtime: Move block_gateway from gnuradio-runtime into gr_python

This eliminates the need to link gnuradio-runtime with Python and fixes
segfaults on conda+macOS when trying to use any Python block. Those
segfaults would happen because the Python library was loaded twice: once
dynamically from linking with gnuradio-runtime, and once from the
running Python interpreter which conda-forge links statically with
libpython. The block_gateway was only used from its Python binding, so
the implementation now just lives there.

This is an API change!

Signed-off-by: Ryan Volz <[email protected]>

Author: ryanvolz

cmake/Modules/GrPybind.cmake

@@ -181,7 +181,6 @@ macro(GR_PYBIND_MAKE_CHECK_HASH name updir filter files)
             ${name}_python
             PRIVATE
             ${pybind11_INCLUDE_DIR}/pybind11/pybind11.h
-            ${pybind11_INCLUDE_DIR}/pybind11/embed.h
             ${pybind11_INCLUDE_DIR}/pybind11/complex.h
             ${pybind11_INCLUDE_DIR}/pybind11/operators.h
             ${pybind11_INCLUDE_DIR}/pybind11/stl.h)

gnuradio-runtime/CMakeLists.txt

@@ -28,26 +28,14 @@ find_package(spdlog CONFIG)
 # Register component
 ########################################################################
 include(GrComponent)
-if(ENABLE_PYTHON)
-    gr_register_component(
-        "gnuradio-runtime"
-        ENABLE_GNURADIO_RUNTIME
-        Boost_FOUND
-        PYTHONINTERP_FOUND
-        MPLIB_FOUND
-        spdlog_FOUND
-        pybind11_FOUND
-        Volk_FOUND)
-else()
-    gr_register_component(
-        "gnuradio-runtime"
-        ENABLE_GNURADIO_RUNTIME
-        Boost_FOUND
-        PYTHONINTERP_FOUND
-        MPLIB_FOUND
-        spdlog_FOUND
-        Volk_FOUND)
-endif()
+gr_register_component(
+    "gnuradio-runtime"
+    ENABLE_GNURADIO_RUNTIME
+    Boost_FOUND
+    PYTHONINTERP_FOUND
+    MPLIB_FOUND
+    spdlog_FOUND
+    Volk_FOUND)
 
 get_filename_component(GNURADIO_RUNTIME_PYTHONPATH ${PROJECT_SOURCE_DIR}/python ABSOLUTE)
 ########################################################################

gnuradio-runtime/include/gnuradio/CMakeLists.txt

@@ -17,7 +17,6 @@ install(
           basic_block.h
           block.h
           block_detail.h
-          block_gateway.h
           block_registry.h
           buffer.h
           buffer_double_mapped.h

gnuradio-runtime/include/gnuradio/block_gateway.h

@@ -94,10 +94,6 @@ add_library(
     vmcircbuf_prefs.cc
     vmcircbuf_sysv_shm.cc)
 
-if(ENABLE_PYTHON)
-    target_sources(gnuradio-runtime PRIVATE block_gateway_impl.cc)
-endif()
-
 # Messages
 target_sources(
     gnuradio-runtime
@@ -130,18 +126,8 @@ target_link_libraries(
         Boost::thread
         spdlog::spdlog
         MPLib::mplib
-        # INTERFACE/PRIVATE split so users of the library can choose how to link to Python
-        # (importantly, extension modules can avoid linking against Python and resolve
-        #  their own Python symbols at runtime through the Python interpreter's linking)
     PRIVATE libunwind::libunwind)
 
-if(ENABLE_PYTHON)
-    target_link_libraries(
-        gnuradio-runtime
-        INTERFACE Python::Module
-        PRIVATE Python::Python pybind11::pybind11)
-endif()
-
 # Address linker issues with std::filesystem on Centos 8 and Debian
 target_link_libraries(
     gnuradio-runtime