File size: 1,320 Bytes
1e92f2d | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 | use std::hash::{BuildHasher, BuildHasherDefault, Hash};
use parking_lot::{Mutex, MutexGuard};
use rustc_hash::FxHasher;
pub struct Sharded<T, H = BuildHasherDefault<FxHasher>> {
data: Box<[Mutex<T>]>,
hasher: H,
bitmask: u16,
}
impl<T, H> Sharded<T, H> {
pub fn new(mut shard_amount: usize) -> Self
where
T: Default,
H: Default,
{
assert!(shard_amount.is_power_of_two());
shard_amount = shard_amount.min(u16::MAX as usize + 1);
let data = (0..shard_amount)
.map(|_| Mutex::new(T::default()))
.collect::<Vec<_>>()
.into_boxed_slice();
Self {
data,
hasher: H::default(),
bitmask: (shard_amount - 1) as u16,
}
}
pub fn lock<K>(&self, key: K) -> MutexGuard<'_, T>
where
K: Hash,
H: BuildHasher,
{
let hash = self.hasher.hash_one(key);
let shard = hash as u16 & self.bitmask;
self.data[shard as usize].lock()
}
pub fn take<R>(&self, map: impl Fn(T) -> R) -> Vec<R>
where
T: Default,
{
let locked = self.data.iter().map(|m| m.lock()).collect::<Vec<_>>();
locked
.into_iter()
.map(|mut m| map(std::mem::take(&mut *m)))
.collect()
}
}
|