fix(libpman): try to get a new event on the same CPU after increasing the producer

[Andreagit97]

What type of PR is this?

/kind bug

/kind cleanup

Any specific area of the project related to this PR?

/area libpman

Does this PR require a change in the driver versions?

No

What this PR does / why we need it:

This PR reduces the possibility of facing out-of-order events with the modern ebpf probe. When we reach the producer the right thing to do is to insist on the same CPU to check if the producer has pushed some new events instead of skipping the current buffer returning a NULL event. Otherwise, there is the risk that we skip some events with a lower timestamp with respect to the others in the other buffers.

Added also some handy debug print. Example

-----------------------------
Iterate over all the buffers
[NULL Event] buf: 0
[NULL Event] buf: 1
[NULL Event] buf: 2
[NULL Event] buf: 3
[NULL Event] buf: 4
[NULL Event] buf: 5
[Event] ts: 1724060673955668930, buf: 6
Found new min with ts '1724060673955668930'  on buffer 6
[NULL Event] buf: 7
Send event -> [Event] ts: 1724060673955668930, buf: 6

-----------------------------
Iterate over all the buffers
[NULL Event] buf: 0
[NULL Event] buf: 1
[NULL Event] buf: 2
[NULL Event] buf: 3
[NULL Event] buf: 4
[NULL Event] buf: 5
[Event] ts: 1724060673955681382, buf: 6
Found new min with ts '1724060673955681382'  on buffer 6
[NULL Event] buf: 7
Send event -> [Event] ts: 1724060673955681382, buf: 6

Which issue(s) this PR fixes:

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

fix(libpman): try to get a new event on the same CPU after increasing the producer

[github-actions]

Perf diff from master - unit tests

    12.04%     -1.34%  [.] sinsp_parser::reset
     4.98%     +1.22%  [.] sinsp_evt::get_type
     8.17%     -1.09%  [.] sinsp::next
     3.45%     +0.72%  [.] gzfile_read
     5.14%     -0.58%  [.] next
     1.37%     -0.48%  [.] std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char*>
     2.22%     -0.47%  [.] scap_event_decode_params
     0.95%     -0.42%  [.] std::_Hashtable<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, 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> > >, std::__detail::_Identity, 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, true, true> >::find
     1.17%     +0.41%  [.] sinsp_evt::get_ts
     0.58%     -0.39%  [.] thread_group_info::get_first_thread

Heap diff from master - unit tests

peak heap memory consumption: 0B
peak RSS (including heaptrack overhead): 0B
total memory leaked: -765.17K

Heap diff from master - scap file

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

[FedeDP]

This needs to be rebased on latest master to fix CI, right?

[Andreagit97]

This needs to be rebased on latest master to fix CI, right?

done :)

[FedeDP]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

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

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• OWNERS [Andreagit97,FedeDP]

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[poiana]

LGTM label has been added.

Git tree hash: 53a37e06692505a971307bfc53f2cfcbdf253f9b

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.14%. Comparing base (839efec) to head (a384441).
Report is 4 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2009   +/-   ##
=======================================
  Coverage   74.14%   74.14%           
=======================================
  Files         253      253           
  Lines       30834    30834           
  Branches     5404     5410    +6     
=======================================
  Hits        22863    22863           
- Misses       7946     7970   +24     
+ Partials       25        1   -24     

Flag	Coverage Δ
libsinsp	74.14% <ø> (ø)

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