Thread safety warnings in rmw_node_info_and_types.cpp

[emersonknapp]

Bug report

The nightly thread safety build is marked unstable because some potentially thread-unsafe code was introduced -

reading variable 'discovered_namespaces' requires holding mutex 'impl->listener->names_mutex_' [-Wthread-safety-analysis]

see the CI job for warning details https://ci.ros2.org/view/nightly/job/nightly_linux_clang_libcxx/67/warnings23Result/

Required Info:

• Operating System:
  • Linux x86_64
• Installation type:
  • CI Build
• Version or commit hash:
  • Last 36 builds
• DDS implementation:
  • rmw_fastrtps_shared_cpp
• Client library (if applicable):
  • N/A

[ivanpauno]

I guess the warning was introduced in #283.

[MiguelCompany]

I guess the warning was introduced in #283.

Good guess. That PR introduced a RCPPUTILS_TSA_GUARDED_BY annotation for the two maps the warnings are complaining about. The change was necessary because tsan was complaining on concurrent access to both of them.