refactor(libsinp): refactor filter transformers to use interfaces

[therealbobo]

What type of PR is this?

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

/kind bug

/kind cleanup

/kind design

/kind documentation

/kind failing-test

/kind feature

Any specific area of the project related to this PR?

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

/area API-version

/area build

/area CI

/area driver-kmod

/area driver-bpf

/area driver-modern-bpf

/area libscap-engine-bpf

/area libscap-engine-gvisor

/area libscap-engine-kmod

/area libscap-engine-modern-bpf

/area libscap-engine-nodriver

/area libscap-engine-noop

/area libscap-engine-source-plugin

/area libscap-engine-savefile

/area libscap

/area libpman

/area libsinsp

/area tests

/area proposals

Does this PR require a change in the driver versions?

/version driver-API-version-major

/version driver-API-version-minor

/version driver-API-version-patch

/version driver-SCHEMA-version-major

/version driver-SCHEMA-version-minor

/version driver-SCHEMA-version-patch

What this PR does / why we need it:

Just a cleanup to enhance the maintainability of the transfomers.

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

    11.81%     -1.62%  [.] sinsp::next
     7.73%     +1.01%  [.] sinsp_evt::get_type
     4.97%     +0.90%  [.] next_event_from_file
    11.05%     -0.86%  [.] sinsp_parser::reset
     3.23%     +0.77%  [.] gzfile_read
     2.01%     -0.36%  [.] scap_event_decode_params
     1.15%     -0.35%  [.] sinsp_parser::event_cleanup
     1.51%     +0.34%  [.] sinsp_evt_filter::sinsp_evt_filter
     2.91%     -0.33%  [.] sinsp_parser::process_event
     1.78%     +0.30%  [.] 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

Heap diff from master - unit tests

peak heap memory consumption: -1.22K
peak RSS (including heaptrack overhead): 0B
total memory leaked: 0B

Heap diff from master - scap file

peak heap memory consumption: -1.22K
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                                            +0.0017         +0.0017           147           147           147           147
BM_sinsp_split_median                                          +0.0054         +0.0053           147           147           146           147
BM_sinsp_split_stddev                                          +1.5466         +1.5487             1             2             1             2
BM_sinsp_split_cv                                              +1.5423         +1.5444             0             0             0             0
BM_sinsp_concatenate_paths_relative_path_mean                  -0.0153         -0.0153            58            57            58            57
BM_sinsp_concatenate_paths_relative_path_median                -0.0152         -0.0152            58            57            58            57
BM_sinsp_concatenate_paths_relative_path_stddev                -0.1682         -0.1700             0             0             0             0
BM_sinsp_concatenate_paths_relative_path_cv                    -0.1553         -0.1571             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_mean                     +0.0283         +0.0282            24            24            24            24
BM_sinsp_concatenate_paths_empty_path_median                   +0.0286         +0.0286            24            24            24            24
BM_sinsp_concatenate_paths_empty_path_stddev                   +0.3224         +0.3253             0             0             0             0
BM_sinsp_concatenate_paths_empty_path_cv                       +0.2861         +0.2889             0             0             0             0
BM_sinsp_concatenate_paths_absolute_path_mean                  -0.0001         -0.0001            56            56            56            56
BM_sinsp_concatenate_paths_absolute_path_median                -0.0035         -0.0035            56            56            56            56
BM_sinsp_concatenate_paths_absolute_path_stddev                +1.8443         +1.8508             0             1             0             1
BM_sinsp_concatenate_paths_absolute_path_cv                    +1.8446         +1.8511             0             0             0             0
BM_sinsp_split_container_image_mean                            +0.0079         +0.0079           389           392           389           392
BM_sinsp_split_container_image_median                          +0.0053         +0.0053           390           392           390           392
BM_sinsp_split_container_image_stddev                          -0.0950         -0.0952             3             3             3             3
BM_sinsp_split_container_image_cv                              -0.1021         -0.1023             0             0             0             0

[codecov]

Codecov Report

Attention: Patch coverage is 93.65079% with 12 lines in your changes missing coverage. Please review.

Project coverage is 75.10%. Comparing base (f535e22) to head (4f86dba).
Report is 6 commits behind head on master.

Files with missing lines	Patch %	Lines
...lter_transformers/sinsp_filter_transformer_len.cpp	82.97%	8 Missing ⚠️
userspace/libsinsp/sinsp_filter_transformers.h	87.50%	2 Missing ⚠️
...p_filter_transformers/sinsp_filter_transformer.cpp	94.11%	1 Missing ⚠️
..._transformers/sinsp_filter_transformer_storage.cpp	94.11%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2224      +/-   ##
==========================================
+ Coverage   75.06%   75.10%   +0.04%     
==========================================
  Files         267      274       +7     
  Lines       34259    34302      +43     
  Branches     5930     5934       +4     
==========================================
+ Hits        25715    25762      +47     
+ Misses       8544     8540       -4     

Flag	Coverage Δ
libsinsp	75.10% <93.65%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

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[FedeDP]

I really like the design; what about splitting the new sinsp_filter_FOO_transformer classes in new files?
It would lead to much better readability.

Also RE naming: i suggest
sinsp_filter_transformer_toupper instead of sinsp_filter_toupper_transformer; it is easier to lookup.

[FedeDP]

/milestone 0.20.0

[FedeDP]

/approve

[poiana]

LGTM label has been added.

Git tree hash: 93f9c93317c891c21789435ed9f9e42e6744159d

[FedeDP]

/cc @jasondellaluce @LucaGuerra

[FedeDP]

/approve

[poiana]

LGTM label has been added.

Git tree hash: 291034fad4f680d7ffc44427c26a47d18cf2635d

[poiana]

[APPROVALNOTIFIER] This PR is APPROVED

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

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