Optimize RichTextCodec

[kyri-petrou]

/claim #2573

I know the issue was only for fixing the encoding performance, but as a welcoming side-effect these changes also improve the overall performance of the RichTextCodec. Also, the rendering of the content-type header is now cached (in a lazy val), so users that reuse the same instance of a ContentType will not incur any runtime overhead for encoding it on repeated requests.

Breaking(?) changes:

• RichTextCodec is now a sealed abstract class instead of a sealed trait. This improved performance marginally although I'm happy to revert it if you prefer to have it as a sealed trait instead.
• The description of repeated codecs was changed (see changed unit test). The main reasoning for this is that it was very hard to replicate the same error message now that the implementation of repeated codecs is different. I saw that in the unit test there was a recommendation for changing the description (which personally I think is clearer) and since that was easy to do with the new Repeated implementation I went with that

Benchmark results

Summary

Parsing:

• ~5x increased throughput
• ~10x reduced memory allocations

Encoding:

• ~15x increased throughput
• ~20x reduced memory allocations

JMH results (click to expand)

main branch:

[info] Benchmark                                                                 Mode  Cnt       Score      Error   Units
[info] ProbeContentTypeBenchmark.benchmarkParseContentType                      thrpt    5  110070.585 ±  371.643   ops/s
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.alloc.rate        thrpt    5    3551.249 ±   12.025  MB/sec
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.alloc.rate.norm   thrpt    5   33832.021 ±    0.001    B/op
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.count             thrpt    5     168.000             counts
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.time              thrpt    5      81.000                 ms
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType                     thrpt    5  294430.289 ± 1231.373   ops/s
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.alloc.rate       thrpt    5    3272.757 ±   13.771  MB/sec
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.alloc.rate.norm  thrpt    5   11656.008 ±    0.001    B/op
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.count            thrpt    5     198.000             counts
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.time             thrpt    5      91.000                 ms

PR:

[info] ProbeContentTypeBenchmark.benchmarkParseContentType                      thrpt    5   567862.566 ± 45382.116   ops/s
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.alloc.rate        thrpt    5     1732.915 ±   138.500  MB/sec
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.alloc.rate.norm   thrpt    5     3200.004 ±     0.001    B/op
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.count             thrpt    5      155.000              counts
[info] ProbeContentTypeBenchmark.benchmarkParseContentType:gc.time              thrpt    5       59.000                  ms
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType                     thrpt    5  4756430.171 ± 53198.579   ops/s
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.alloc.rate       thrpt    5     2104.663 ±    23.531  MB/sec
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.alloc.rate.norm  thrpt    5      464.000 ±     0.001    B/op
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.count            thrpt    5      193.000              counts
[info] ProbeContentTypeBenchmark.benchmarkRenderContentType:gc.time             thrpt    5       71.000                  ms

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[codecov-commenter]

Codecov Report

Attention: 5 lines in your changes are missing coverage. Please review.

Comparison is base (f4b2b3f) 64.23% compared to head (d0e61af) 64.39%.

Files	Patch %	Lines
.../src/main/scala/zio/http/codec/RichTextCodec.scala	94.25%	5 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2597      +/-   ##
==========================================
+ Coverage   64.23%   64.39%   +0.16%     
==========================================
  Files         140      140              
  Lines        8358     8407      +49     
  Branches     1604     1608       +4     
==========================================
+ Hits         5369     5414      +45     
- Misses       2989     2993       +4     

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