Import 'rustc-hash' package version 1.1.0 am: adb9edf32a

Change-Id: I7c8ab53be8b79aafaf58dcfbbbc8b1cd05940cbe
tree: 24bb0c51836106463c55353f9a0626efd8e88aa4
  1. .cargo_vcs_info.json
  2. .gitignore
  3. Android.bp
  4. CODE_OF_CONDUCT.md
  5. Cargo.toml
  6. Cargo.toml.orig
  7. LICENSE-APACHE
  8. LICENSE-MIT
  9. METADATA
  10. MODULE_LICENSE_APACHE2
  11. OWNERS
  12. README.md
  13. src/
README.md

rustc-hash

crates.io Documentation

A speedy hash algorithm used within rustc. The hashmap in liballoc by default uses SipHash which isn‘t quite as speedy as we want. In the compiler we’re not really worried about DOS attempts, so we use a fast non-cryptographic hash.

This is the same as the algorithm used by Firefox -- which is a homespun one not based on any widely-known algorithm -- though modified to produce 64-bit hash values instead of 32-bit hash values. It consistently out-performs an FNV-based hash within rustc itself -- the collision rate is similar or slightly worse than FNV, but the speed of the hash function itself is much higher because it works on up to 8 bytes at a time.

Usage

use rustc_hash::FxHashMap;

let mut map: FxHashMap<u32, u32> = FxHashMap::default();
map.insert(22, 44);

no_std

This crate can be used as a no_std crate by disabling the std feature, which is on by default, as follows:

rustc-hash = { version = "1.0", default-features = false }

In this configuration, FxHasher is the only export, and the FxHashMap/FxHashSet type aliases are omitted.