Bug: 153120147

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  1. 3ccc6c3 Update Android.bp by running cargo_embargo am: ca35b243c5 by James Farrell · 8 weeks ago main master
  2. ca35b24 Update Android.bp by running cargo_embargo by James Farrell · 8 weeks ago
  3. 6b1ebd5 Migrate to cargo_embargo. am: becc9dc0d0 am: 44612c5b78 am: 76bcd4057b by Andrew Walbran · 8 months ago android14-qpr3-release android14-qpr3-s2-release emu-34-2-dev main-16k android-14.0.0_r50 android-14.0.0_r51 android-14.0.0_r52 android-14.0.0_r53 android-14.0.0_r54
  4. ec812f2 Migrate to cargo_embargo. am: becc9dc0d0 am: 8293b5ba65 am: 15859b17aa by Andrew Walbran · 8 months ago
  5. 76bcd40 Migrate to cargo_embargo. am: becc9dc0d0 am: 44612c5b78 by Andrew Walbran · 8 months ago

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.