strings: smarter growth of temporal buffer and avoid copying on return
The implementation for single strings had two optimization opportunities:
1. Grow the temporary buffer by known size before appending.
2. Avoid a full copy of the result since the underlying buffer won't be mutated afterward.
Both things were leveraged by using a Builder instead of a byte slice.
Relevant benchmark results:
name old time/op new time/op delta
SingleMatch-8 32.0µs ± 3% 26.1µs ± 3% -18.41% (p=0.000 n=9+10)
name old speed new speed delta
SingleMatch-8 469MB/s ± 3% 574MB/s ± 3% +22.56% (p=0.000 n=9+10)
name old alloc/op new alloc/op delta
SingleMatch-8 81.3kB ± 0% 49.0kB ± 0% -39.67% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
SingleMatch-8 19.0 ± 0% 11.0 ± 0% -42.11% (p=0.000 n=10+10)
Change-Id: I23af56a15875206c0ff4ce29a51bec95fd48bb11
GitHub-Last-Rev:
403cfc3c2794b5da27792c51999417a2a052b365
GitHub-Pull-Request: golang/go#47766
Reviewed-on: https://go-review.googlesource.com/c/go/+/343089
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Trust: Robert Griesemer <gri@golang.org>