KString

Key String: Optimized for map keys.

Background

Considerations: - Large maps - Most keys live and drop without being used in any other way - Most keys are relatively small (single to double digit bytes) - Keys are immutable - Allow zero-cost abstractions between structs and maps (e.g. no allocating when dealing with struct field names)

Ramifications: - Inline small strings rather than going to the heap. - Preserve &'static str across strings (KString), references (KStringRef), and lifetime abstractions (KStringCow) to avoid allocating for struct field names. - Use Box<str> rather than String to use less memory.

Features - max_inline: Instead of aligning the inline-string for performance (15 bytes + length on 64-bit), use the full width (22 bytes on 64-bit) - arc: Instead of using Box<str>, use Arc<str>. Note: allocations are fast enough that this can actually slow things down for small enough strings.

Alternatives - smol_str - Size of String - Always uses Arc instead of Box - Always inlines 22 bytes - Whitespace-only optimizations - smartstring - Size of String - Allows mutability at the cost of relying on implementation details of String - Always inlines 23 bytes - compact_str - Size of String - Always uses Arc instead of Box - Inlines 22-23 bytes, depending on implementation

License

Licensed under either of

• Apache License, Version 2.0, (http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.