fix(userspace/libsinsp): do not immediately process async events whose timestamp is in the future in case a SCAP_TIMEOUT is received

[FedeDP]

What type of PR is this?

/kind bug

Any specific area of the project related to this PR?

/area libsinsp

Does this PR require a change in the driver versions?

What this PR does / why we need it:

Right now, when a SCAP_TIMEOUT is received from the scap_engine, if the async queue contains any event, it gets popped and processed without further investigation about the event's timestamp.
With the proposed patch, the async queue gets scanned considering now as timestamp; this way, we honor the requested timestamp by the async event generator: if it is in the future, we hold the event until that time in the future has arrived.

This PR was originally made as part of the work for #2207, but since it could be extracted, here i am :)

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

fix(userspace/libsinsp): do not immediately process async events whose timestamp is in the future in case a SCAP_TIMEOUT is received

[FedeDP]

/milestone 0.21.0

[github-actions]

Perf diff from master - unit tests

     5.30%     +0.89%  [.] next_event_from_file
     1.14%     +0.75%  [.] libsinsp::sinsp_suppress::process_event
    10.59%     +0.66%  [.] sinsp::next
     8.16%     -0.61%  [.] sinsp_evt::get_type
     3.80%     -0.60%  [.] sinsp_evt::load_params
    10.75%     -0.47%  [.] sinsp_parser::reset
     3.04%     -0.44%  [.] sinsp_thread_manager::find_thread
     3.16%     -0.43%  [.] sinsp_thread_manager::get_thread_ref
     1.78%     +0.34%  [.] std::_Hashtable<unsigned long, std::pair<unsigned long const, std::shared_ptr<ppm_evt_hdr> >, std::allocator<std::pair<unsigned long const, std::shared_ptr<ppm_evt_hdr> > >, std::__detail::_Select1st, std::equal_to<unsigned long>, std::hash<unsigned 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
     0.88%     +0.33%  [.] sinsp_evt::get_syscall_return_value

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

Benchmarks diff from master

Comparing gbench_data.json to /root/actions-runner/_work/libs/libs/build/gbench_data.json
Benchmark                                                         Time             CPU      Time Old      Time New       CPU Old       CPU New
----------------------------------------------------------------------------------------------------------------------------------------------
BM_sinsp_split_mean                                            +0.0590         +0.0590           144           153           144           153
BM_sinsp_split_median                                          +0.0643         +0.0643           144           153           144           153
BM_sinsp_split_stddev                                          +1.1572         +1.1566             1             2             1             2
BM_sinsp_split_cv                                              +1.0370         +1.0365             0             0             0             0
BM_sinsp_concatenate_paths_relative_path_mean                  +0.0553         +0.0553            57            60            57            60
BM_sinsp_concatenate_paths_relative_path_median                +0.0557         +0.0557            57            60            57            60
BM_sinsp_concatenate_paths_relative_path_stddev                +8.9541         +8.9572             0             2             0             2
BM_sinsp_concatenate_paths_relative_path_cv                    +8.4323         +8.4353             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_mean                     +0.0148         +0.0148            25            25            25            25
BM_sinsp_concatenate_paths_empty_path_median                   +0.0119         +0.0119            25            25            25            25
BM_sinsp_concatenate_paths_empty_path_stddev                   +0.3239         +0.3238             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_cv                       +0.3045         +0.3044             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_mean                  +0.0457         +0.0457            56            59            56            59
BM_sinsp_concatenate_paths_absolute_path_median                -0.0003         -0.0003            56            56            56            56
BM_sinsp_concatenate_paths_absolute_path_stddev                +8.7887         +8.7887             0             4             0             4
BM_sinsp_concatenate_paths_absolute_path_cv                    +8.3607         +8.3608             0             0             0             0
BM_sinsp_split_container_image_mean                            +0.0015         +0.0015           389           389           389           389
BM_sinsp_split_container_image_median                          +0.0004         +0.0004           389           389           389           389
BM_sinsp_split_container_image_stddev                          +0.1865         +0.1859             3             4             3             4
BM_sinsp_split_container_image_cv                              +0.1847         +0.1841             0             0             0             0

[FedeDP]

/cc @jasondellaluce

[codecov]

Codecov Report

Attention: Patch coverage is 14.28571% with 6 lines in your changes missing coverage. Please review.

Project coverage is 75.16%. Comparing base (6c46ed3) to head (efc25f0).

Files with missing lines	Patch %	Lines
userspace/libsinsp/sinsp.cpp	14.28%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2250      +/-   ##
==========================================
- Coverage   75.16%   75.16%   -0.01%     
==========================================
  Files         278      278              
  Lines       34478    34479       +1     
  Branches     5922     5924       +2     
==========================================
  Hits        25916    25916              
- Misses       8562     8563       +1     

Flag	Coverage Δ
libsinsp	75.16% <14.28%> (-0.01%)	⬇️

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[Andreagit97]

/approve

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[FedeDP]

/hold for a review by Jason

[FedeDP]

/unhold