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dashmap
mirror of https://github.com/xacrimon/dashmap
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Only hash keys once, taking advantage of hashbrown raw entry api (#259)

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Arthur Silva 2023-08-22 01:57:35 +02:00 committed by GitHub
parent ea4ea24a63
commit 3448b6f070
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2 changed files with 62 additions and 67 deletions
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104
src/lib.rs
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@ -34,6 +34,7 @@ use core::fmt;
use core::hash::{BuildHasher, Hash, Hasher};
use core::iter::FromIterator;
use core::ops::{BitAnd, BitOr, Shl, Shr, Sub};
use hashbrown::hash_map::RawEntryMut;
use iter::{Iter, IterMut, OwningIter};
use mapref::entry::{Entry, OccupiedEntry, VacantEntry};
use mapref::multiple::RefMulti;
@ -295,11 +296,15 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> DashMap<K, V, S> {
/// Hash a given item to produce a usize.
/// Uses the provided or default HashBuilder.
pub fn hash_usize<T: Hash>(&self, item: &T) -> usize {
self.hash_u64(item) as usize
}
fn hash_u64<T: Hash>(&self, item: &T) -> u64 {
let mut hasher = self.hasher.build_hasher();
item.hash(&mut hasher);
hasher.finish() as usize
hasher.finish()
}
cfg_if! {
@ -916,9 +921,9 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
}
fn _insert(&self, key: K, value: V) -> Option<V> {
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let mut shard = unsafe { self._yield_write_shard(idx) };
@ -932,9 +937,9 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let mut shard = unsafe { self._yield_write_shard(idx) };
@ -946,22 +951,20 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let mut shard = unsafe { self._yield_write_shard(idx) };
if let Some((kptr, vptr)) = shard.get_key_value(key) {
unsafe {
let kptr: *const K = kptr;
let vptr: *mut V = vptr.as_ptr();
if f(&*kptr, &mut *vptr) {
shard.remove_entry(key).map(|(k, v)| (k, v.into_inner()))
} else {
None
}
if let RawEntryMut::Occupied(entry) =
shard.raw_entry_mut().from_key_hashed_nocheck(hash, key)
{
if f(&entry.key(), &entry.get().get()) {
let (k, v) = entry.remove_entry();
Some((k, v.into_inner()))
} else {
None
}
} else {
None
@ -973,22 +976,21 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let mut shard = unsafe { self._yield_write_shard(idx) };
if let Some((kptr, vptr)) = shard.get_key_value(key) {
unsafe {
let kptr: *const K = kptr;
let vptr: *mut V = vptr.as_ptr();
if f(&*kptr, &mut *vptr) {
shard.remove_entry(key).map(|(k, v)| (k, v.into_inner()))
} else {
None
}
if let RawEntryMut::Occupied(mut entry) =
shard.raw_entry_mut().from_key_hashed_nocheck(hash, key)
{
let (k, v) = entry.get_key_value_mut();
if f(k, v.get_mut()) {
let (k, v) = entry.remove_entry();
Some((k, v.into_inner()))
} else {
None
}
} else {
None
@ -1008,13 +1010,13 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let shard = unsafe { self._yield_read_shard(idx) };
if let Some((kptr, vptr)) = shard.get_key_value(key) {
if let Some((kptr, vptr)) = shard.raw_entry().from_key_hashed_nocheck(hash, key) {
unsafe {
let kptr: *const K = kptr;
let vptr: *const V = vptr.get();
@ -1030,16 +1032,18 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let shard = unsafe { self._yield_write_shard(idx) };
let mut shard = unsafe { self._yield_write_shard(idx) };
if let Some((kptr, vptr)) = shard.get_key_value(key) {
if let RawEntryMut::Occupied(mut entry) =
shard.raw_entry_mut().from_key_hashed_nocheck(hash, key)
{
unsafe {
let kptr: *const K = kptr;
let vptr: *mut V = vptr.as_ptr();
let kptr: *const K = entry.key();
let vptr: *mut V = entry.get_mut().as_ptr();
Some(RefMut::new(shard, kptr, vptr))
}
} else {
@ -1052,16 +1056,16 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let shard = match unsafe { self._try_yield_read_shard(idx) } {
Some(shard) => shard,
None => return TryResult::Locked,
};
if let Some((kptr, vptr)) = shard.get_key_value(key) {
if let Some((kptr, vptr)) = shard.raw_entry().from_key_hashed_nocheck(hash, key) {
unsafe {
let kptr: *const K = kptr;
let vptr: *const V = vptr.get();
@ -1077,16 +1081,16 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let shard = match unsafe { self._try_yield_write_shard(idx) } {
Some(shard) => shard,
None => return TryResult::Locked,
};
if let Some((kptr, vptr)) = shard.get_key_value(key) {
if let Some((kptr, vptr)) = shard.raw_entry().from_key_hashed_nocheck(hash, key) {
unsafe {
let kptr: *const K = kptr;
let vptr: *mut V = vptr.as_ptr();
@ -1145,13 +1149,13 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
}
fn _entry(&'a self, key: K) -> Entry<'a, K, V, S> {
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let shard = unsafe { self._yield_write_shard(idx) };
if let Some((kptr, vptr)) = shard.get_key_value(&key) {
if let Some((kptr, vptr)) = shard.raw_entry().from_key_hashed_nocheck(hash, &key) {
unsafe {
let kptr: *const K = kptr;
let vptr: *mut V = vptr.as_ptr();
@ -1163,16 +1167,16 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: 'a + BuildHasher + Clone> Map<'a, K, V, S>
}
fn _try_entry(&'a self, key: K) -> Option<Entry<'a, K, V, S>> {
let hash = self.hash_usize(&key);
let hash = self.hash_u64(&key);
let idx = self.determine_shard(hash);
let idx = self.determine_shard(hash as usize);
let shard = match unsafe { self._try_yield_write_shard(idx) } {
Some(shard) => shard,
None => return None,
};
if let Some((kptr, vptr)) = shard.get_key_value(&key) {
if let Some((kptr, vptr)) = shard.raw_entry().from_key_hashed_nocheck(hash, &key) {
unsafe {
let kptr: *const K = kptr;
let vptr: *mut V = vptr.as_ptr();

25
src/read_only.rs
View File

@ -61,13 +61,7 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> ReadOnlyView<K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.map.hash_usize(&key);
let idx = self.map.determine_shard(hash);
let shard = unsafe { self.map._get_read_shard(idx) };
shard.contains_key(key)
self.get(key).is_some()
}
/// Returns a reference to the value corresponding to the key.
@ -76,13 +70,7 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> ReadOnlyView<K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.map.hash_usize(&key);
let idx = self.map.determine_shard(hash);
let shard = unsafe { self.map._get_read_shard(idx) };
shard.get(key).map(|v| v.get())
self.get_key_value(key).map(|(_k, v)| v)
}
/// Returns the key-value pair corresponding to the supplied key.
@ -91,13 +79,16 @@ impl<'a, K: 'a + Eq + Hash, V: 'a, S: BuildHasher + Clone> ReadOnlyView<K, V, S>
K: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
let hash = self.map.hash_usize(&key);
let hash = self.map.hash_u64(&key);
let idx = self.map.determine_shard(hash);
let idx = self.map.determine_shard(hash as usize);
let shard = unsafe { self.map._get_read_shard(idx) };
shard.get_key_value(key).map(|(k, v)| (k, v.get()))
shard
.raw_entry()
.from_key_hashed_nocheck(hash, key)
.map(|(k, v)| (k, v.get()))
}
fn shard_read_iter(&'a self) -> impl Iterator<Item = &'a HashMap<K, V, S>> + 'a {