Optimized the exact filter performance

[Cali0707]

Fixes #7307

Currently, we use the attributes filter internally when running the exact filter. However, the attributes filter supports cases which the exact filter does not allow. Specifically, the current implementation of the exact filter requires that all filters have a non-empty string value for both the attribute and the desired value, while the attributes filter checks if the desired value is "", and treats that as a special "allow anything" case. By rewriting the exact filter with these more strict requirements, we see a speed up in terms of performance.

To see the current creation-time validation logic, look here:

eventing/pkg/eventfilter/subscriptionsapi/exact_filter.go

Lines 39 to 44 in 44aa15e

	func NewExactFilter(filters map[string]string) (eventfilter.Filter, error) {
	for attribute, value := range filters {
	if attribute == "" || value == "" {
	return nil, fmt.Errorf("invalid arguments, attribute and value can't be empty")
	}
	}

Proposed Changes

• Instead of using the attributes filter internally, just handle the filtering logic directly

With these changes, the performance difference is:

benchmark                                                                                          old ns/op     new ns/op     delta
BenchmarkExactFilter/Creation:_Pass_with_exact_match_of_id-8                                       81.4          53.4          -34.38%
BenchmarkExactFilter/Run:_Pass_with_exact_match_of_id-8                                            502           425           -15.31%
BenchmarkExactFilter/Creation:_Pass_with_exact_match_of_all_context_attributes_(except_time)-8     109           89.1          -18.44%
BenchmarkExactFilter/Run:_Pass_with_exact_match_of_all_context_attributes_(except_time)-8          1441          1326          -7.98%
BenchmarkExactFilter/Creation:_No_pass_with_exact_match_of_id_and_source-8                         84.7          61.8          -27.04%
BenchmarkExactFilter/Run:_No_pass_with_exact_match_of_id_and_source-8                              762           727           -4.50%

benchmark                                                                                          old allocs     new allocs     delta
BenchmarkExactFilter/Creation:_Pass_with_exact_match_of_id-8                                       1              1              +0.00%
BenchmarkExactFilter/Run:_Pass_with_exact_match_of_id-8                                            4              4              +0.00%
BenchmarkExactFilter/Creation:_Pass_with_exact_match_of_all_context_attributes_(except_time)-8     1              1              +0.00%
BenchmarkExactFilter/Run:_Pass_with_exact_match_of_all_context_attributes_(except_time)-8          15             15             +0.00%
BenchmarkExactFilter/Creation:_No_pass_with_exact_match_of_id_and_source-8                         1              1              +0.00%
BenchmarkExactFilter/Run:_No_pass_with_exact_match_of_id_and_source-8                              7              7              +0.00%

benchmark                                                                                          old bytes     new bytes     delta
BenchmarkExactFilter/Creation:_Pass_with_exact_match_of_id-8                                       24            8             -66.67%
BenchmarkExactFilter/Run:_Pass_with_exact_match_of_id-8                                            208           208           +0.00%
BenchmarkExactFilter/Creation:_Pass_with_exact_match_of_all_context_attributes_(except_time)-8     24            8             -66.67%
BenchmarkExactFilter/Run:_Pass_with_exact_match_of_all_context_attributes_(except_time)-8          448           448           +0.00%
BenchmarkExactFilter/Creation:_No_pass_with_exact_match_of_id_and_source-8                         24            8             -66.67%
BenchmarkExactFilter/Run:_No_pass_with_exact_match_of_id_and_source-8                              410           410           +0.00%

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior
• Docs PR for any user-facing impact
• Spec PR for any new API feature
• Conformance test for any change to the spec

Release Note

The exact filter now uses less memory and is faster!

Docs

[Cali0707]

/cc @Leo6Leo @creydr @pierDipi

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (ff9444d) 77.66% compared to head (42d850a) 77.63%.
Report is 16 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7311      +/-   ##
==========================================
- Coverage   77.66%   77.63%   -0.04%     
==========================================
  Files         250      250              
  Lines       13436    13444       +8     
==========================================
+ Hits        10435    10437       +2     
- Misses       2478     2482       +4     
- Partials      523      525       +2     

Files	Coverage Δ
pkg/apis/duck/v1/subscribable_types.go	100.00% <ø> (ø)
pkg/apis/eventing/v1/trigger_types.go	100.00% <ø> (ø)
pkg/apis/flows/v1/parallel_types.go	100.00% <ø> (ø)
pkg/apis/flows/v1/sequence_types.go	100.00% <ø> (ø)
pkg/apis/messaging/v1/subscription_types.go	66.66% <ø> (ø)
pkg/eventfilter/subscriptionsapi/exact_filter.go	66.66% <80.00%> (+12.12%)	⬆️

... and 2 files with indirect coverage changes

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[Leo6Leo]

/lgtm

[Cali0707]

/cc @matzew

[pierDipi]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

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