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dashmap
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chore: get rid of num_cpus and hardcode a sensible shard number

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Acrimon 2020-07-31 23:15:29 +02:00
parent 7abb7a4699
commit df4b09ba01
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2 changed files with 6 additions and 14 deletions
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1
Cargo.toml
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@ -18,7 +18,6 @@ raw-api = []
no_std = ["hashbrown"]
[dependencies]
num_cpus = "1.13.0"
ahash = "0.3.8"
serde = { version = "1.0.114", optional = true, features = ["derive"] }
cfg-if = "0.1.10"

19
src/lib.rs
View File

@ -49,13 +49,8 @@ cfg_if! {
}
}
fn shard_amount() -> usize {
(num_cpus::get() * 4).next_power_of_two()
}
fn ncb(shard_amount: usize) -> usize {
shard_amount.trailing_zeros() as usize
}
const SHARD_AMOUNT: usize = 8;
const NCB: usize = SHARD_AMOUNT.trailing_zeros() as usize;
/// DashMap is an implementation of a concurrent associative array/hashmap in Rust.
///
@ -172,17 +167,15 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> DashMap<K, V, S> {
/// ```
pub fn with_capacity_and_hasher(mut capacity: usize, hasher: S) -> Self {
let shard_amount = shard_amount();
let shift = util::ptr_size_bits() - ncb(shard_amount);
let shift = util::ptr_size_bits() - NCB;
if capacity != 0 {
capacity = (capacity + (shard_amount - 1)) & !(shard_amount - 1);
capacity = (capacity + (SHARD_AMOUNT - 1)) & !(SHARD_AMOUNT - 1);
}
let cps = capacity / shard_amount;
let cps = capacity / SHARD_AMOUNT;
let shards = (0..shard_amount)
let shards = (0..SHARD_AMOUNT)
.map(|_| RwLock::new(HashMap::with_capacity_and_hasher(cps, hasher.clone())))
.collect();