Improve performance of SearchSource.findMatchingTests by 15%

[scotthovestadt]

Summary

This PR is a 15% performance improvement for SearchSource.findMatchingTests. I benchmarked a test data set of 300k files at 975ms~ with the current code. The same search pattern now executes in 830ms~.

At Facebook, this means that for the common use case of triggering jest MyFileName, Jest will launch >100ms faster. Sometimes you have to take the small wins. :)

I optimized this by looking for inefficiencies in code that is called for every file. In this case:

• One of the inner functions triggered for each file called Object.keys for the stats object every time. Not efficient.
• Dummy functions were being created that always returned true. It still costs CPU time to call a function, even an extremely fast one. Better to never call it.

I refactored away the issues by adapting the data structures to better fit the way they are being used. Since our stat filters are optional and we want to iterate them, they make more sense as an array. I maintained full type safety.

Test plan

• All existing tests path, which already cover this functionality.
• Careful benchmarking of the performance.

[codecov-io]

Codecov Report

Merging #8184 into master will decrease coverage by <.01%.
The diff coverage is 76.66%.

@@            Coverage Diff             @@
##           master    #8184      +/-   ##
==========================================
- Coverage   62.32%   62.32%   -0.01%     
==========================================
  Files         265      265              
  Lines       10469    10465       -4     
  Branches     2545     2541       -4     
==========================================
- Hits         6525     6522       -3     
  Misses       3361     3361              
+ Partials      583      582       -1

Impacted Files	Coverage Δ
packages/jest-core/src/getNoTestFoundVerbose.ts	0% <0%> (ø)	⬆️
packages/jest-core/src/SearchSource.ts	58.42% <85.18%> (-0.72%)	⬇️

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[SimenB]

nice! I thought the code looked weird when I migrated this to TS, makes sense to use an array instead here

(changelog)

[thymikee]

Sweet! Left some minor comments. Missing changelog

[cpojer]

Nice!

[thymikee]

Thanks!

[github-actions]

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