docs(bpf_engine): add some docs and rename some variables

[Andreagit97]

What type of PR is this?

/kind cleanup

/kind documentation

Any specific area of the project related to this PR?

/area libscap-engine-bpf

Does this PR require a change in the driver versions?

No

What this PR does / why we need it:

This PR adds some docs and renames some variables in the bpf engine

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[github-actions]

Please double check driver/API_VERSION file. See versioning.

/hold

[github-actions]

Perf diff from master - unit tests

     8.09%     -1.36%  [.] sinsp::next
     0.89%     +0.92%  [.] scap_event_encode_params_v
     0.72%     +0.83%  [.] std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>
     9.16%     +0.77%  [.] sinsp_parser::reset
     4.68%     +0.71%  [.] next
     1.62%     +0.65%  [.] scap_event_decode_params
     1.02%     +0.63%  [.] sinsp_parser::event_cleanup
     4.31%     -0.56%  [.] sinsp_evt::load_params
     1.68%     +0.54%  [.] 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
     0.59%     +0.45%  [.] sinsp_evt::get_param

Perf diff from master - scap file

    14.88%     +6.13%  [.] sinsp_filter_check::extract_nocache
     9.53%     -3.63%  [.] sinsp_filter_check::rawval_to_string
    13.63%     -2.57%  [.] next
    13.96%     -2.29%  [.] sinsp_evt_formatter::tostring_withformat
     6.60%     -1.94%  [.] scap_event_decode_params
     6.24%     -1.76%  [.] sinsp_filter_check::get_transformed_field_info
     3.40%     +1.75%  [.] 0x00000000000a70e0
     6.27%     -1.75%  [.] sinsp_filter_check::tostring
     3.62%     -0.21%  [.] main
     6.13%     +0.20%  [.] sinsp_filter_check_event::extract_single

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 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 50.99%. Comparing base (3ce0a2d) to head (ab24259).
Report is 5 commits behind head on master.

Files	Patch %	Lines
userspace/libscap/engine/bpf/scap_bpf.h	0.00%	6 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1984   +/-   ##
=======================================
  Coverage   50.98%   50.99%           
=======================================
  Files         310      310           
  Lines       39612    39609    -3     
  Branches    17793    17868   +75     
=======================================
  Hits        20197    20197           
- Misses      14350    14356    +6     
+ Partials     5065     5056    -9     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[FedeDP]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Andreagit97, FedeDP

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• OWNERS [Andreagit97,FedeDP]

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[poiana]

LGTM label has been added.

Git tree hash: 7fb01af9eb0d34d072524f649092bd6df3dfab14