fix(driver/kmod): count the right number of events and drops

[Andreagit97]

What type of PR is this?

/kind bug

Any specific area of the project related to this PR?

/area driver-kmod

Does this PR require a change in the driver versions?

No

What this PR does / why we need it:

This PR provides 2 fixes:

• The preemptions are now taken into consideration and we don't increment the n_evts since the event is always dropped.
• In case of some unknown error we had just an ASSERT(false) but not a n_drops_buffer increment. This means that in production we were not able to detect if we fell into the wrong branch or not. Now we increment the n_drops_buffer metric.

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[github-actions]

Perf diff from master - unit tests

     1.68%     +1.84%  [.] libsinsp::sinsp_suppress::process_event
     6.66%     -0.93%  [.] sinsp_evt::get_type
     0.34%     +0.58%  [.] sinsp_evt::get_param
     0.67%     -0.56%  [.] libsinsp::state::value_table_entry_adapter<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::dynamic_fields_t::dynamic_fields_t
     5.66%     -0.56%  [.] sinsp_parser::process_event
     4.65%     -0.48%  [.] gzfile_read
     0.89%     +0.47%  [.] libsinsp::events::is_unknown_event
     1.63%     -0.47%  [.] std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char const*>
     0.88%     -0.37%  [.] sinsp_split[abi:cxx11]
     4.81%     +0.37%  [.] next

Perf diff from master - scap file

    20.67%     -2.19%  [.] sinsp_evt_formatter::tostring_withformat
     8.26%     -2.00%  [.] sinsp_filter_check_container::extract_single
     4.14%     +1.95%  [.] sinsp_utils::ts_to_string
     8.28%     +1.81%  [.] sinsp_filter_check::extract_nocache
     5.36%     -0.64%  [.] sinsp_filter_check_thread::extract_single
    11.79%     +0.22%  [.] 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
     4.55%     -0.20%  [.] sinsp_threadinfo::~sinsp_threadinfo
     8.25%     -0.09%  [.] sinsp::next
     4.14%     -0.07%  [.] sinsp_filter_check::apply_transformers
     4.13%     -0.05%  [.] sinsp_parser::reset

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

All modified and coverable lines are covered by tests ✅

Project coverage is 74.08%. Comparing base (a118b0f) to head (b64057c).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2000      +/-   ##
==========================================
- Coverage   74.08%   74.08%   -0.01%     
==========================================
  Files         253      253              
  Lines       30766    30766              
  Branches     5399     5417      +18     
==========================================
- Hits        22794    22792       -2     
- Misses       7946     7970      +24     
+ Partials       26        4      -22     

Flag	Coverage Δ
libsinsp	74.08% <ø> (-0.01%)	⬇️

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[poiana]

LGTM label has been added.

Git tree hash: 074d6896e3619b806bab345fb12befa56ca0cd9d

[incertum]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• driver/OWNERS [Andreagit97,incertum]

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