Add benchmarks to otelslog

[MrAlias]

Part of #5195

Benchmarks

goos: linux
goarch: amd64
pkg: go.opentelemetry.io/contrib/bridges/otelslog
cpu: Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz
                                          │   out.txt   │
                                          │   sec/op    │
Handler/Handle-8                            67.78n ± 5%
Handler/WithAttrs/5-8                       331.8n ± 2%
Handler/WithAttrs/10-8                      570.6n ± 3%
Handler/WithGroup-8                         108.8n ± 6%
Handler/WithGroup.WithAttrs/5-8             443.3n ± 1%
Handler/WithGroup.WithAttrs/10-8            677.4n ± 2%
Handler/(WithGroup.WithAttrs).Handle/5-8    119.2n ± 8%
Handler/(WithGroup.WithAttrs).Handle/10-8   127.1n ± 4%
geomean                                     224.1n

                                          │   out.txt    │
                                          │     B/op     │
Handler/Handle-8                            0.000 ± 0%
Handler/WithAttrs/5-8                       264.0 ± 0%
Handler/WithAttrs/10-8                      472.0 ± 0%
Handler/WithGroup-8                         64.00 ± 0%
Handler/WithGroup.WithAttrs/5-8             328.0 ± 0%
Handler/WithGroup.WithAttrs/10-8            536.0 ± 0%
Handler/(WithGroup.WithAttrs).Handle/5-8    0.000 ± 0%
Handler/(WithGroup.WithAttrs).Handle/10-8   0.000 ± 0%
geomean                                                ¹
¹ summaries must be >0 to compute geomean

                                          │   out.txt    │
                                          │  allocs/op   │
Handler/Handle-8                            0.000 ± 0%
Handler/WithAttrs/5-8                       3.000 ± 0%
Handler/WithAttrs/10-8                      3.000 ± 0%
Handler/WithGroup-8                         2.000 ± 0%
Handler/WithGroup.WithAttrs/5-8             5.000 ± 0%
Handler/WithGroup.WithAttrs/10-8            5.000 ± 0%
Handler/(WithGroup.WithAttrs).Handle/5-8    0.000 ± 0%
Handler/(WithGroup.WithAttrs).Handle/10-8   0.000 ± 0%
geomean                                                ¹
¹ summaries must be >0 to compute geomean

JSONHandler Benchmarks

For a rough "ballpark" reference, here are the same tests against the slog.JSONHandler:

goos: linux
goarch: amd64
pkg: go.opentelemetry.io/contrib/bridges/otelslog
cpu: Intel(R) Core(TM) i7-8550U CPU @ 1.80GHz
                                              │   json.txt   │
                                              │    sec/op    │
JSONHandler/Handle-8                            359.2n ± 23%
JSONHandler/WithAttrs/5-8                       1.044µ ± 16%
JSONHandler/WithAttrs/10-8                      1.837µ ±  3%
JSONHandler/WithGroup-8                         252.7n ± 10%
JSONHandler/WithGroup.WithAttrs/5-8             1.355µ ±  1%
JSONHandler/WithGroup.WithAttrs/10-8            2.074µ ±  3%
JSONHandler/(WithGroup.WithAttrs).Handle/5-8    402.2n ±  6%
JSONHandler/(WithGroup.WithAttrs).Handle/10-8   379.6n ± 10%
geomean                                         722.9n

                                              │   json.txt   │
                                              │     B/op     │
JSONHandler/Handle-8                            0.000 ± 0%
JSONHandler/WithAttrs/5-8                       328.0 ± 0%
JSONHandler/WithAttrs/10-8                      520.0 ± 0%
JSONHandler/WithGroup-8                         168.0 ± 0%
JSONHandler/WithGroup.WithAttrs/5-8             552.0 ± 0%
JSONHandler/WithGroup.WithAttrs/10-8            680.0 ± 0%
JSONHandler/(WithGroup.WithAttrs).Handle/5-8    0.000 ± 0%
JSONHandler/(WithGroup.WithAttrs).Handle/10-8   0.000 ± 0%
geomean                                                    ¹
¹ summaries must be >0 to compute geomean

                                              │   json.txt   │
                                              │  allocs/op   │
JSONHandler/Handle-8                            0.000 ± 0%
JSONHandler/WithAttrs/5-8                       8.000 ± 0%
JSONHandler/WithAttrs/10-8                      10.00 ± 0%
JSONHandler/WithGroup-8                         3.000 ± 0%
JSONHandler/WithGroup.WithAttrs/5-8             11.00 ± 0%
JSONHandler/WithGroup.WithAttrs/10-8            12.00 ± 0%
JSONHandler/(WithGroup.WithAttrs).Handle/5-8    0.000 ± 0%
JSONHandler/(WithGroup.WithAttrs).Handle/10-8   0.000 ± 0%
geomean                                                    ¹
¹ summaries must be >0 to compute geomean

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.9%. Comparing base (59ebbee) to head (2ba8d28).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5330   +/-   ##
=====================================
  Coverage   61.8%   61.9%           
=====================================
  Files        186     186           
  Lines      11388   11388           
=====================================
+ Hits        7049    7051    +2     
+ Misses      4137    4136    -1     
+ Partials     202     201    -1     

see 1 file with indirect coverage changes