Improve performance of eventfilter lookups

[benmoss]

Only do event field lookups as needed, don't pre-emptively cache them into a map

Fixes #5277

Previous:

$ go test -benchtime 10s -bench=. ./pkg/eventfilter/benchmarks/
goos: linux
goarch: amd64
pkg: knative.dev/eventing/pkg/eventfilter/benchmarks
cpu: Intel(R) Core(TM) i7-9850H CPU @ 2.60GHz
BenchmarkAttributesFilter/Creation:_Pass_with_exact_match_of_id-12              1000000000               2.699 ns/op
BenchmarkAttributesFilter/Run:_Pass_with_exact_match_of_id-12                    1675917              7419 ns/op
BenchmarkAttributesFilter/Creation:_Pass_with_exact_match_of_all_context_attributes_(except_time)-12            1000000000               2.697 ns/op
BenchmarkAttributesFilter/Run:_Pass_with_exact_match_of_all_context_attributes_(except_time)-12                  1697353              7299 ns/op
BenchmarkAttributesFilter/Creation:_No_pass_with_exact_match_of_id_and_source-12                                1000000000               2.683 ns/op
BenchmarkAttributesFilter/Run:_No_pass_with_exact_match_of_id_and_source-12                                      1570285              6987 ns/op

Now:

$ go test -benchtime 10s -bench=. ./pkg/eventfilter/benchmarks/
goos: linux
goarch: amd64
pkg: knative.dev/eventing/pkg/eventfilter/benchmarks
cpu: Intel(R) Core(TM) i7-9850H CPU @ 2.60GHz
BenchmarkAttributesFilter/Creation:_Pass_with_exact_match_of_id-12              1000000000               2.686 ns/op
BenchmarkAttributesFilter/Run:_Pass_with_exact_match_of_id-12                   143855318               82.71 ns/op
BenchmarkAttributesFilter/Creation:_Pass_with_exact_match_of_all_context_attributes_(except_time)-12            1000000000               2.689 ns/op
BenchmarkAttributesFilter/Run:_Pass_with_exact_match_of_all_context_attributes_(except_time)-12                 14394333               999.9 ns/op
BenchmarkAttributesFilter/Creation:_No_pass_with_exact_match_of_id_and_source-12                                1000000000               2.733 ns/op
BenchmarkAttributesFilter/Run:_No_pass_with_exact_match_of_id_and_source-12                                     39759967               563.0 ns/op

Release Note

:page_facing_up: MTChannelBasedBrokers will see improved filter performance for triggers with few or no trigger filters

[n3wscott]

Am I reading those numbers right? this is a 10x improvement?

[knative-metrics-robot]

The following is the coverage report on the affected files.
Say /test pull-knative-eventing-go-coverage to re-run this coverage report

File	Old Coverage	New Coverage	Delta
pkg/eventfilter/attributes/filter.go	100.0%	66.7%	-33.3

[codecov]

Codecov Report

Merging #5288 (bcdec63) into main (60bc1cf) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #5288      +/-   ##
==========================================
+ Coverage   83.63%   83.65%   +0.02%     
==========================================
  Files         243      243              
  Lines        6879     6891      +12     
==========================================
+ Hits         5753     5765      +12     
  Misses        783      783              
  Partials      343      343              

Impacted Files	Coverage Δ
pkg/eventfilter/attributes/filter.go	100.00% <100.00%> (ø)

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[benmoss]

Am I reading those numbers right? this is a 10x improvement?

Avoiding unnecessary function calls and using a switch instead of a map, who knew!

[benmoss]

/test pull-knative-eventing-go-coverage

[antoineco]

/LGTM
Amazing finding!

[n3wscott]

Thanks for taking care of that so fast!!

[knative-prow-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: antoineco, n3wscott

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