mirror of https://github.com/xacrimon/dashmap
279 lines
7.6 KiB
Rust
279 lines
7.6 KiB
Rust
use super::one::RefMut;
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use crate::lock::RwLockWriteGuard;
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use crate::util;
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use crate::util::SharedValue;
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use crate::HashMap;
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use core::hash::{BuildHasher, Hash};
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use core::mem;
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use core::ptr;
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use std::collections::hash_map::RandomState;
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pub enum Entry<'a, K, V, S = RandomState> {
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Occupied(OccupiedEntry<'a, K, V, S>),
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Vacant(VacantEntry<'a, K, V, S>),
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}
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impl<'a, K: Eq + Hash, V, S: BuildHasher> Entry<'a, K, V, S> {
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/// Apply a function to the stored value if it exists.
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pub fn and_modify(self, f: impl FnOnce(&mut V)) -> Self {
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match self {
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Entry::Occupied(mut entry) => {
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f(entry.get_mut());
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Entry::Occupied(entry)
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}
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Entry::Vacant(entry) => Entry::Vacant(entry),
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}
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}
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/// Get the key of the entry.
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pub fn key(&self) -> &K {
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match *self {
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Entry::Occupied(ref entry) => entry.key(),
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Entry::Vacant(ref entry) => entry.key(),
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}
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}
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/// Into the key of the entry.
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pub fn into_key(self) -> K {
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match self {
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Entry::Occupied(entry) => entry.into_key(),
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Entry::Vacant(entry) => entry.into_key(),
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}
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}
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/// Return a mutable reference to the element if it exists,
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/// otherwise insert the default and return a mutable reference to that.
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pub fn or_default(self) -> RefMut<'a, K, V, S>
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where
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V: Default,
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{
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match self {
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Entry::Occupied(entry) => entry.into_ref(),
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Entry::Vacant(entry) => entry.insert(V::default()),
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}
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}
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/// Return a mutable reference to the element if it exists,
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/// otherwise a provided value and return a mutable reference to that.
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pub fn or_insert(self, value: V) -> RefMut<'a, K, V, S> {
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match self {
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Entry::Occupied(entry) => entry.into_ref(),
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Entry::Vacant(entry) => entry.insert(value),
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}
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}
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/// Return a mutable reference to the element if it exists,
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/// otherwise insert the result of a provided function and return a mutable reference to that.
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pub fn or_insert_with(self, value: impl FnOnce() -> V) -> RefMut<'a, K, V, S> {
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match self {
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Entry::Occupied(entry) => entry.into_ref(),
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Entry::Vacant(entry) => entry.insert(value()),
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}
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}
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pub fn or_try_insert_with<E>(
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self,
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value: impl FnOnce() -> Result<V, E>,
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) -> Result<RefMut<'a, K, V, S>, E> {
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match self {
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Entry::Occupied(entry) => Ok(entry.into_ref()),
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Entry::Vacant(entry) => Ok(entry.insert(value()?)),
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}
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}
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/// Sets the value of the entry, and returns a reference to the inserted value.
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pub fn insert(self, value: V) -> RefMut<'a, K, V, S> {
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match self {
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Entry::Occupied(mut entry) => {
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entry.insert(value);
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entry.into_ref()
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}
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Entry::Vacant(entry) => entry.insert(value),
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}
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}
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/// Sets the value of the entry, and returns an OccupiedEntry.
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///
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/// If you are not interested in the occupied entry,
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/// consider [`insert`] as it doesn't need to clone the key.
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///
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/// [`insert`]: Entry::insert
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pub fn insert_entry(self, value: V) -> OccupiedEntry<'a, K, V, S>
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where
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K: Clone,
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{
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match self {
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Entry::Occupied(mut entry) => {
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entry.insert(value);
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entry
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}
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Entry::Vacant(entry) => entry.insert_entry(value),
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}
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}
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}
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pub struct VacantEntry<'a, K, V, S = RandomState> {
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shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
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key: K,
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}
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unsafe impl<'a, K: Eq + Hash + Sync, V: Sync, S: BuildHasher> Send for VacantEntry<'a, K, V, S> {}
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unsafe impl<'a, K: Eq + Hash + Sync, V: Sync, S: BuildHasher> Sync for VacantEntry<'a, K, V, S> {}
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impl<'a, K: Eq + Hash, V, S: BuildHasher> VacantEntry<'a, K, V, S> {
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pub(crate) unsafe fn new(shard: RwLockWriteGuard<'a, HashMap<K, V, S>>, key: K) -> Self {
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Self { shard, key }
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}
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pub fn insert(mut self, value: V) -> RefMut<'a, K, V, S> {
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unsafe {
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let c: K = ptr::read(&self.key);
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self.shard.insert(self.key, SharedValue::new(value));
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let (k, v) = self.shard.get_key_value(&c).unwrap();
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let k = util::change_lifetime_const(k);
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let v = &mut *v.as_ptr();
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let r = RefMut::new(self.shard, k, v);
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mem::forget(c);
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r
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}
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}
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/// Sets the value of the entry with the VacantEntry’s key, and returns an OccupiedEntry.
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pub fn insert_entry(mut self, value: V) -> OccupiedEntry<'a, K, V, S>
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where
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K: Clone,
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{
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unsafe {
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self.shard.insert(self.key.clone(), SharedValue::new(value));
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let (k, v) = self.shard.get_key_value(&self.key).unwrap();
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let kptr: *const K = k;
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let vptr: *mut V = v.as_ptr();
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OccupiedEntry::new(self.shard, self.key, (kptr, vptr))
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}
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}
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pub fn into_key(self) -> K {
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self.key
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}
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pub fn key(&self) -> &K {
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&self.key
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}
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}
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pub struct OccupiedEntry<'a, K, V, S = RandomState> {
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shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
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elem: (*const K, *mut V),
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key: K,
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}
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unsafe impl<'a, K: Eq + Hash + Sync, V: Sync, S: BuildHasher> Send for OccupiedEntry<'a, K, V, S> {}
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unsafe impl<'a, K: Eq + Hash + Sync, V: Sync, S: BuildHasher> Sync for OccupiedEntry<'a, K, V, S> {}
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impl<'a, K: Eq + Hash, V, S: BuildHasher> OccupiedEntry<'a, K, V, S> {
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pub(crate) unsafe fn new(
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shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
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key: K,
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elem: (*const K, *mut V),
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) -> Self {
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Self { shard, elem, key }
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}
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pub fn get(&self) -> &V {
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unsafe { &*self.elem.1 }
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}
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pub fn get_mut(&mut self) -> &mut V {
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unsafe { &mut *self.elem.1 }
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}
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pub fn insert(&mut self, value: V) -> V {
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mem::replace(self.get_mut(), value)
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}
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pub fn into_ref(self) -> RefMut<'a, K, V, S> {
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unsafe { RefMut::new(self.shard, self.elem.0, self.elem.1) }
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}
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pub fn into_key(self) -> K {
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self.key
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}
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pub fn key(&self) -> &K {
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unsafe { &*self.elem.0 }
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}
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pub fn remove(mut self) -> V {
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let key = unsafe { &*self.elem.0 };
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self.shard.remove(key).unwrap().into_inner()
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}
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pub fn remove_entry(mut self) -> (K, V) {
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let key = unsafe { &*self.elem.0 };
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let (k, v) = self.shard.remove_entry(key).unwrap();
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(k, v.into_inner())
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}
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pub fn replace_entry(mut self, value: V) -> (K, V) {
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let nk = self.key;
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let key = unsafe { &*self.elem.0 };
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let (k, v) = self.shard.remove_entry(key).unwrap();
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self.shard.insert(nk, SharedValue::new(value));
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(k, v.into_inner())
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::DashMap;
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use super::*;
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#[test]
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fn test_insert_entry_into_vacant() {
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let map: DashMap<u32, u32> = DashMap::new();
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let entry = map.entry(1);
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assert!(matches!(entry, Entry::Vacant(_)));
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let entry = entry.insert_entry(2);
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assert_eq!(*entry.get(), 2);
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drop(entry);
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assert_eq!(*map.get(&1).unwrap(), 2);
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}
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#[test]
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fn test_insert_entry_into_occupied() {
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let map: DashMap<u32, u32> = DashMap::new();
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map.insert(1, 1000);
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let entry = map.entry(1);
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assert!(matches!(&entry, Entry::Occupied(entry) if *entry.get() == 1000));
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let entry = entry.insert_entry(2);
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assert_eq!(*entry.get(), 2);
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drop(entry);
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assert_eq!(*map.get(&1).unwrap(), 2);
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}
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}
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