Rust String Benchmarks

This repo tries to assess Rust string types.

We currently compare:

Name	Size	Heap	Inline	`&'static str`	Mutable	Unsafe	Notes
`String`	24 bytes	Y	-	N	Y	-	Universal
`Cow<'static, str>`	24 bytes	Y	-	Y	N	-
`arcstr`	8 bytes	?	?	?	?	?	?
`compact_str`	24 bytes	Y	24 bytes	Y	Y	Y (miri, proptest, fuzz)	Space optimized for `Option<_>`
`ecow`	16 bytes	Y	15 bytes	N	Y	Y (miri)	O(1) clone unless mutated, Space optimized for `Option<_>`
`flexstr`	24 bytes	Y	22 bytes	Y	N	Y (miri)	O(1) clone
`hipstr`	24 bytes	Y	23 bytes	Y	Y	Y (miri)	O(1) clone, O(1) substring
`imstr`	24 bytes	?	?	?	?	?	?
`kstring`	24 bytes	Y	15 bytes	Y	N	Optional (miri, proptest)	Optional O(1) clone, optional 22 byte small string, Ref/Cow API for preserving `&'static str`
`smartstring`	24 bytes	Y	23 bytes	N	Y	Y (miri, proptest, fuzz)

Suggestions:

Generally, String
If you deal mostly with string literals but want some flexibility (like clap), generally you'll want Cow<'static, str>
If a profiler says your strings are a problem:
- Try different crates and settings for that crate out with a profiler
- O(1) clones are important when doing a lot of clones. For one-off allocations, they are slower.
- For short-lived programs, look into string interning

Note: smol_str was removed in favor of ecow

Terms:

Results

new summary:

clone summary:

access summary:

(smartstring is skipped due to how slow it is)

self_eq summary: