fix(libsinsp/tests): assorted fixes (memory layout, synchronization)

[LucaGuerra]

What type of PR is this?

Uncomment one (or more) /kind <> lines:

/kind bug

Any specific area of the project related to this PR?

Uncomment one (or more) /area <> lines:

/area libsinsp

/area tests

Does this PR require a change in the driver versions?

No

What this PR does / why we need it:

I noticed a couple inconsistencies in libsinsp tests:

1. in a spot we had auto for a string literal which may be interpreted as char [N] and trip asan. Use a const char* instead.
2. In an attempt to reduce flakiness in our async key value tests, I introduced a bit more thread safety in some of our tests, especially when there were no synchronization primitives and the use of two threads.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[github-actions]

Perf diff from master - unit tests

     4.17%     +1.16%  [.] sinsp_parser::process_event
    10.29%     -0.81%  [.] sinsp_parser::reset
     3.28%     -0.81%  [.] scap_event_decode_params
     1.17%     -0.63%  [.] thread_group_info::get_first_thread
     0.89%     +0.60%  [.] sinsp_parser::parse_context_switch
     0.67%     -0.57%  [.] std::_Hashtable<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, libsinsp::state::dynamic_struct::field_info>, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, libsinsp::state::dynamic_struct::field_info> >, std::__detail::_Select1st, std::equal_to<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::hash<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, false, true> >::_M_emplace<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, libsinsp::state::dynamic_struct::field_info> >
     4.01%     +0.55%  [.] sinsp_evt::load_params
     0.78%     +0.49%  [.] sinsp_evt::get_direction
     1.19%     -0.45%  [.] sinsp_filter_check::parse_field_name
     0.45%     +0.44%  [.] sinsp_split[abi:cxx11]

Perf diff from master - scap file

    28.22%     -7.11%  [.] sinsp_filter_check::tostring
     4.08%     +4.09%  [.] sinsp_filter_check::get_field_info
     4.08%     +3.66%  [.] std::_Hashtable<long, std::pair<long const, std::shared_ptr<sinsp_threadinfo> >, std::allocator<std::pair<long const, std::shared_ptr<sinsp_threadinfo> > >, std::__detail::_Select1st, std::equal_to<long>, std::hash<long>, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<false, false, true> >::_M_find_before_node
    12.22%     +2.26%  [.] sinsp_evt_formatter::tostring_withformat
     7.84%     +2.09%  [.] sinsp_thread_manager::get_thread_ref
    20.21%     +0.49%  [.] sinsp_filter_check::extract_nocache
     3.52%     +0.36%  [.] libsinsp::runc::match_container_id
     3.61%     +0.33%  [.] std::vector<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::allocator<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >::emplace_back<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >
     3.98%     +0.15%  [.] sinsp_parser::event_cleanup
     4.08%     +0.12%  [.] 0x00000000000a77d4

Heap diff from master - unit tests

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Heap diff from master - scap file

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

[codecov]

Codecov Report

Attention: Patch coverage is 96.77419% with 1 line in your changes missing coverage. Please review.

Project coverage is 74.13%. Comparing base (df21b63) to head (da4dfbe).
Report is 9 commits behind head on master.

Files	Patch %	Lines
...rspace/libsinsp/test/async_key_value_source.ut.cpp	96.42%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2013      +/-   ##
==========================================
+ Coverage   74.12%   74.13%   +0.01%     
==========================================
  Files         253      253              
  Lines       30805    30814       +9     
  Branches     5415     5415              
==========================================
+ Hits        22834    22844      +10     
- Misses       7967     7968       +1     
+ Partials        4        2       -2     

Flag	Coverage Δ
libsinsp	74.13% <96.77%> (+0.01%)	⬆️

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[LucaGuerra]

/milestone 0.18.0

[incertum]

Nice!

/approve

[poiana]

LGTM label has been added.

Git tree hash: 2fcbd72cc487207834ff07e1521c94be3b008ee1

[FedeDP]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FedeDP, incertum, LucaGuerra

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