Function parallel_invoke_impl

benchmarks/tbb/parallel_invoke.h:212–222

    // task_group_context is known to be at the back of the parameter pack
    template<typename F0, typename F1, typename... F>
    void parallel_invoke_impl(true_type, F0&& f0, F1&& f1, F&&... f) {
        __TBB_STATIC_ASSERT(sizeof...(F)>0, "Variadic parallel_invoke implementation broken?");
        // # of child tasks: f0, f1, and a task for each two elements of the pack except the last
        const size_t number_of_children = 2 + sizeof...(F)/2;
        parallel_invoke_cleaner cleaner(number_of_children, get_context(std::forward<F>(f)...));
        parallel_invoke_helper& root = cleaner.root;

        root.add_children(std::forward<F>(f)...);
        root.add_children(std::forward<F1>(f1));
        root.run_and_finish(std::forward<F0>(f0));
    }

    // task_group_context is not in the pack, needs to be added
    template<typename F0, typename F1, typename... F>