如何实现TBB input_node？

如何解决如何实现TBB input_node？

显然，在tbb :: flow中，不推荐使用source_node，从2021.1版本开始，我们仅应使用input_node。但是，仅替换类似乎无效。我在2020.3版中使用source_node有一个工作代码。如果我尝试使用input_node，则会收到一条隐秘消息。

似乎input_node希望Body实现一个采用flow_control对象的函数。是这样吗否则这里出什么问题了？

我似乎无法使用input_body运行任何示例代码。

====================[ Build | capybara | Debug-System ]==========================
/home/nicolau/bin/clion-2020.1.1/bin/cmake/linux/bin/cmake --build /home/nicolau/src/capybara/cmake-build-debug-system --target capybara -- -j 9
Scanning dependencies of target capybara
[ 50%] Building CXX object CMakeFiles/capybara.dir/main.cpp.o
In file included from /home/nicolau/src/oneapi-tbb-2021.1-beta08/include/tbb/flow_graph.h:345:0,from /home/nicolau/src/capybara/main.cpp:9:
/home/nicolau/src/oneapi-tbb-2021.1-beta08/include/tbb/detail/_flow_graph_body_impl.h: In instantiation of ‘Output tbb::detail::d1::input_body_leaf<Output,Body>::operator()(tbb::detail::d1::flow_control&) [with Output = std::tuple<cv::Mat,std::chrono::time_point<std::chrono::_V2::system_clock,std::chrono::duration<long int,std::ratio<1,1000000000> > > >; Body = main(int,char**)::<lambda(imgtv&)>]’:
/home/nicolau/src/capybara/main.cpp:424:1:   required from here
/home/nicolau/src/oneapi-tbb-2021.1-beta08/include/tbb/detail/_flow_graph_body_impl.h:88:66: error: no match for call to ‘(main(int,char**)::<lambda(imgtv&)>) (tbb::detail::d1::flow_control&)’
     Output operator()(flow_control& fc) override { return body(fc); }
                                                                  ^
/home/nicolau/src/capybara/main.cpp:350:58: note: candidate: main(int,char**)::<lambda(imgtv&)>
     tbb::flow::input_node<imgtv> src(g,[&](imgtv &v) -> bool {
                                                          ^~~~
/home/nicolau/src/capybara/main.cpp:350:58: note:   no kNown conversion for argument 1 from ‘tbb::detail::d1::flow_control’ to ‘imgtv& {aka std::tuple<cv::Mat,1000000000> > > >&}’
CMakeFiles/capybara.dir/build.make:82: recipe for target 'CMakeFiles/capybara.dir/main.cpp.o' Failed
make[3]: *** [CMakeFiles/capybara.dir/main.cpp.o] Error 1
CMakeFiles/Makefile2:95: recipe for target 'CMakeFiles/capybara.dir/all' Failed
make[2]: *** [CMakeFiles/capybara.dir/all] Error 2
CMakeFiles/Makefile2:102: recipe for target 'CMakeFiles/capybara.dir/rule' Failed
make[1]: *** [CMakeFiles/capybara.dir/rule] Error 2
Makefile:138: recipe for target 'capybara' Failed
make: *** [capybara] Error 2

解决方法

显然，与source_node相比，该接口已更改，并且该函数现在应该采用flow_control引用并返回新的输入对象作为输出。

https://github.com/oneapi-src/oneTBB/issues/270#issuecomment-683645172