dashmap/mapref/
entry.rs

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1use super::one::RefMut;
2use crate::util;
3use crate::util::SharedValue;
4use crate::HashMap;
5use core::hash::{BuildHasher, Hash};
6use core::mem;
7use core::ptr;
8use parking_lot::RwLockWriteGuard;
9use std::collections::hash_map::RandomState;
10
11pub enum Entry<'a, K, V, S = RandomState> {
12    Occupied(OccupiedEntry<'a, K, V, S>),
13    Vacant(VacantEntry<'a, K, V, S>),
14}
15
16impl<'a, K: Eq + Hash, V, S: BuildHasher> Entry<'a, K, V, S> {
17    /// Apply a function to the stored value if it exists.
18    pub fn and_modify(self, f: impl FnOnce(&mut V)) -> Self {
19        match self {
20            Entry::Occupied(mut entry) => {
21                f(entry.get_mut());
22
23                Entry::Occupied(entry)
24            }
25
26            Entry::Vacant(entry) => Entry::Vacant(entry),
27        }
28    }
29
30    /// Get the key of the entry.
31    pub fn key(&self) -> &K {
32        match *self {
33            Entry::Occupied(ref entry) => entry.key(),
34            Entry::Vacant(ref entry) => entry.key(),
35        }
36    }
37
38    /// Into the key of the entry.
39    pub fn into_key(self) -> K {
40        match self {
41            Entry::Occupied(entry) => entry.into_key(),
42            Entry::Vacant(entry) => entry.into_key(),
43        }
44    }
45
46    /// Return a mutable reference to the element if it exists,
47    /// otherwise insert the default and return a mutable reference to that.
48    pub fn or_default(self) -> RefMut<'a, K, V, S>
49    where
50        V: Default,
51    {
52        match self {
53            Entry::Occupied(entry) => entry.into_ref(),
54            Entry::Vacant(entry) => entry.insert(V::default()),
55        }
56    }
57
58    /// Return a mutable reference to the element if it exists,
59    /// otherwise a provided value and return a mutable reference to that.
60    pub fn or_insert(self, value: V) -> RefMut<'a, K, V, S> {
61        match self {
62            Entry::Occupied(entry) => entry.into_ref(),
63            Entry::Vacant(entry) => entry.insert(value),
64        }
65    }
66
67    /// Return a mutable reference to the element if it exists,
68    /// otherwise insert the result of a provided function and return a mutable reference to that.
69    pub fn or_insert_with(self, value: impl FnOnce() -> V) -> RefMut<'a, K, V, S> {
70        match self {
71            Entry::Occupied(entry) => entry.into_ref(),
72            Entry::Vacant(entry) => entry.insert(value()),
73        }
74    }
75
76    pub fn or_try_insert_with<E>(
77        self,
78        value: impl FnOnce() -> Result<V, E>,
79    ) -> Result<RefMut<'a, K, V, S>, E> {
80        match self {
81            Entry::Occupied(entry) => Ok(entry.into_ref()),
82            Entry::Vacant(entry) => Ok(entry.insert(value()?)),
83        }
84    }
85}
86
87pub struct VacantEntry<'a, K, V, S> {
88    shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
89    key: K,
90}
91
92unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for VacantEntry<'a, K, V, S> {}
93
94unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
95    for VacantEntry<'a, K, V, S>
96{
97}
98
99impl<'a, K: Eq + Hash, V, S: BuildHasher> VacantEntry<'a, K, V, S> {
100    pub(crate) unsafe fn new(shard: RwLockWriteGuard<'a, HashMap<K, V, S>>, key: K) -> Self {
101        Self { shard, key }
102    }
103
104    pub fn insert(mut self, value: V) -> RefMut<'a, K, V, S> {
105        unsafe {
106            let c: K = ptr::read(&self.key);
107
108            self.shard.insert(self.key, SharedValue::new(value));
109
110            let (k, v) = self.shard.get_key_value(&c).unwrap();
111
112            let k = util::change_lifetime_const(k);
113
114            let v = &mut *v.as_ptr();
115
116            let r = RefMut::new(self.shard, k, v);
117
118            mem::forget(c);
119
120            r
121        }
122    }
123
124    pub fn into_key(self) -> K {
125        self.key
126    }
127
128    pub fn key(&self) -> &K {
129        &self.key
130    }
131}
132
133pub struct OccupiedEntry<'a, K, V, S> {
134    shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
135    elem: (*const K, *mut V),
136    key: K,
137}
138
139unsafe impl<'a, K: Eq + Hash + Send, V: Send, S: BuildHasher> Send for OccupiedEntry<'a, K, V, S> {}
140
141unsafe impl<'a, K: Eq + Hash + Send + Sync, V: Send + Sync, S: BuildHasher> Sync
142    for OccupiedEntry<'a, K, V, S>
143{
144}
145
146impl<'a, K: Eq + Hash, V, S: BuildHasher> OccupiedEntry<'a, K, V, S> {
147    pub(crate) unsafe fn new(
148        shard: RwLockWriteGuard<'a, HashMap<K, V, S>>,
149        key: K,
150        elem: (*const K, *mut V),
151    ) -> Self {
152        Self { shard, elem, key }
153    }
154
155    pub fn get(&self) -> &V {
156        unsafe { &*self.elem.1 }
157    }
158
159    pub fn get_mut(&mut self) -> &mut V {
160        unsafe { &mut *self.elem.1 }
161    }
162
163    pub fn insert(&mut self, value: V) -> V {
164        mem::replace(self.get_mut(), value)
165    }
166
167    pub fn into_ref(self) -> RefMut<'a, K, V, S> {
168        unsafe { RefMut::new(self.shard, self.elem.0, self.elem.1) }
169    }
170
171    pub fn into_key(self) -> K {
172        self.key
173    }
174
175    pub fn key(&self) -> &K {
176        unsafe { &*self.elem.0 }
177    }
178
179    pub fn remove(mut self) -> V {
180        let key = unsafe { &*self.elem.0 };
181        self.shard.remove(key).unwrap().into_inner()
182    }
183
184    pub fn remove_entry(mut self) -> (K, V) {
185        let key = unsafe { &*self.elem.0 };
186        let (k, v) = self.shard.remove_entry(key).unwrap();
187        (k, v.into_inner())
188    }
189
190    pub fn replace_entry(mut self, value: V) -> (K, V) {
191        let nk = self.key;
192        let key = unsafe { &*self.elem.0 };
193        let (k, v) = self.shard.remove_entry(key).unwrap();
194        self.shard.insert(nk, SharedValue::new(value));
195        (k, v.into_inner())
196    }
197}
dashmap/mapref/entry.rs

dashmap/mapref/
entry.rs
