Use pthread_setaffinity_np for setting affinity rather than sched_setaffinity

[saikishor]

This PR aims to change the earlier approach with pthread_setaffinity_np as it is more generic and it can be scalable to all other controllers.

The good thing is it doesn't affect the recently merged changes : https://github.com/ros-controls/ros2_control/pull/1852

I've also added corresponding tests in different places

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 90.90909% with 1 line in your changes missing coverage. Please review.

Project coverage is 72.97%. Comparing base (45e93d7) to head (593dc27).

Files with missing lines	Patch %	Lines
src/realtime_helpers.cpp	90.90%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #190 +/- ## ========================================== + Coverage 72.13% 72.97% +0.84% ========================================== Files 8 8 Lines 384 396 +12 Branches 64 65 +1 ========================================== + Hits 277 289 +12 + Misses 69 68 -1 - Partials 38 39 +1 ``` | [Flag](https://app.codecov.io/gh/ros-controls/realtime_tools/pull/190/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-controls) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/ros-controls/realtime_tools/pull/190/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-controls) | `72.97% <90.90%> (+0.84%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-controls#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files with missing lines](https://app.codecov.io/gh/ros-controls/realtime_tools/pull/190?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-controls) | Coverage Δ | | |---|---|---| | [include/realtime\_tools/async\_function\_handler.hpp](https://app.codecov.io/gh/ros-controls/realtime_tools/pull/190?src=pr&el=tree&filepath=include%2Frealtime_tools%2Fasync_function_handler.hpp&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-controls#diff-aW5jbHVkZS9yZWFsdGltZV90b29scy9hc3luY19mdW5jdGlvbl9oYW5kbGVyLmhwcA==) | `91.25% <ø> (ø)` | | | [src/realtime\_helpers.cpp](https://app.codecov.io/gh/ros-controls/realtime_tools/pull/190?src=pr&el=tree&filepath=src%2Frealtime_helpers.cpp&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=ros-controls#diff-c3JjL3JlYWx0aW1lX2hlbHBlcnMuY3Bw) | `37.34% <90.90%> (+10.58%)` | :arrow_up: |

[saikishor]

@firesurfer can you check this once?

[saikishor]

In general this looks good to me with a minor notes: https://en.cppreference.com/w/cpp/thread/thread/native_handle native_handle is only available for systems with a posix threading model. I am not sure if there might be some weird combination of systems (apart from windows) where it is not available and might lead to compilation errors

Most of the systems now supports. The following information, I got it using Copilot

Systems that support a POSIX threading model (also known as POSIX threads or Pthreads) include most Unix-like operating systems. POSIX threads are a standard for thread creation and synchronization, defined by the POSIX.1c standard (IEEE Std 1003.1c-1995). Here are some systems that support POSIX threads:

Unix-like Operating Systems

• Linux: Most Linux distributions support POSIX threads natively. The GNU C Library (glibc) provides the implementation of POSIX threads on Linux.
• macOS: macOS (formerly OS X) supports POSIX threads. The implementation is provided by the system's libc.
• FreeBSD: FreeBSD supports POSIX threads through its native threading library.
• NetBSD: NetBSD also supports POSIX threads.
• OpenBSD: OpenBSD includes support for POSIX threads.
• Solaris: Solaris (and its derivatives like OpenSolaris and illumos) supports POSIX threads.

Other Operating Systems

• AIX: IBM's AIX operating system supports POSIX threads.
• HP-UX: Hewlett-Packard's HP-UX supports POSIX threads.
• QNX: QNX, a real-time operating system, supports POSIX threads.
• VxWorks: VxWorks, another real-time operating system, supports POSIX threads.
• Windows: While Windows does not natively support POSIX threads, there are libraries like Pthreads-w32 that provide a POSIX threads API on top of the native Windows threading model.

As this is the case, I think this should be good to go