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
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
use std::collections::HashSet;
use std::sync::RwLock;
use std::ops::Deref;
use std::marker::PhantomData;
pub struct ExternalSet<T> {
items: RwLock<HashSet<*mut T>>
}
impl<T> ExternalSet<T> {
pub fn new() -> ExternalSet<T> {
ExternalSet { items: RwLock::new(HashSet::new()) }
}
pub fn insert<'s>(&'s self, item: T) -> ItemOwner<'s, T> {
let ptr = Box::into_raw(Box::new(item));
self.items.write().unwrap().insert(ptr);
ItemOwner { collection: self, ptr: ptr, _marker: PhantomData }
}
pub fn lock(&self) -> ExternalSetReadGuard<T> {
ExternalSetReadGuard(self.items.read().unwrap())
}
}
unsafe impl<T: Sync> Sync for ExternalSet<T> {}
unsafe impl<T: Send + Sync> Send for ExternalSet<T> {}
pub struct ExternalSetReadGuard<'c, T: 'c>(::std::sync::RwLockReadGuard<'c, HashSet<*mut T>>);
impl<'c, T> ExternalSetReadGuard<'c, T> {
pub fn iter<'g: 'c>(&'g self) -> ExternalSetIter<'g, T> {
ExternalSetIter { iter: self.0.iter(), except: None, }
}
pub fn others<'g: 'c>(&'g self, except: &ItemOwner<T>) -> ExternalSetIter<'g, T> {
ExternalSetIter { iter: self.0.iter(), except: Some(except.ptr) }
}
}
pub struct ExternalSetIter<'g, T: 'g> {
iter: ::std::collections::hash_set::Iter<'g, *mut T>,
except: Option<*mut T>
}
impl<'g, T> Iterator for ExternalSetIter<'g, T> {
type Item = &'g T;
fn next(&mut self) -> Option<&'g T> {
if let Some(&i) = self.iter.next() {
if Some(i) == self.except { return self.next(); }
Some(unsafe { &*i })
} else {
None
}
}
}
pub struct ItemOwner<'s, T: 's> {
collection: &'s ExternalSet<T>,
ptr: *mut T,
_marker: PhantomData<T>,
}
impl<'s, T> ItemOwner<'s, T> {
pub fn take(self) -> T {
unsafe {
self.collection.items.write().unwrap().remove(&self.ptr);
let ret = *Box::from_raw(self.ptr);
::std::mem::forget(self);
ret
}
}
}
unsafe impl<'s, T: Send + Sync> Send for ItemOwner<'s, T> {}
unsafe impl<'s, T: Sync> Sync for ItemOwner<'s, T> {}
impl<'s, T> Drop for ItemOwner<'s, T> {
fn drop(&mut self) {
self.collection.items.write().unwrap().remove(&self.ptr);
drop(unsafe { *Box::from_raw(self.ptr) });
}
}
impl <'s, T> Deref for ItemOwner<'s, T> {
type Target = T;
fn deref(&self) -> &T {
unsafe { &*self.ptr }
}
}
#[test]
fn test1() {
let c = ExternalSet::<u32>::new();
let i1 = c.insert(1);
let i2 = c.insert(2);
let i3 = c.insert(3);
let mut items = c.lock().iter().map(|&i| i).collect::<Vec<_>>();
items.sort();
assert_eq!(items, vec![1, 2, 3]);
let mut items = c.lock().others(&i1).map(|&i| i).collect::<Vec<_>>();
items.sort();
assert_eq!(items, vec![2, 3]);
assert_eq!(i2.take(), 2);
let mut items = c.lock().iter().map(|&i| i).collect::<Vec<_>>();
items.sort();
assert_eq!(items, vec![1, 3]);
assert_eq!(*i1, 1);
drop(i1);
drop(i3);
assert_eq!(c.lock().iter().count(), 0);
}