1 | use std::cmp; |
2 | use std::fmt; |
3 | use std::mem; |
4 | |
5 | use crate::errors::InvalidThreadAccess; |
6 | use crate::fragile::Fragile; |
7 | use crate::sticky::Sticky; |
8 | use crate::StackToken; |
9 | |
10 | enum SemiStickyImpl<T: 'static> { |
11 | Fragile(Box<Fragile<T>>), |
12 | Sticky(Sticky<T>), |
13 | } |
14 | |
15 | /// A [`SemiSticky<T>`] keeps a value T stored in a thread if it has a drop. |
16 | /// |
17 | /// This is a combined version of [`Fragile`] and [`Sticky`]. If the type |
18 | /// does not have a drop it will effectively be a [`Fragile`], otherwise it |
19 | /// will be internally behave like a [`Sticky`]. |
20 | /// |
21 | /// This type requires `T: 'static` for the same reasons as [`Sticky`] and |
22 | /// also uses [`StackToken`]s. |
23 | pub struct SemiSticky<T: 'static> { |
24 | inner: SemiStickyImpl<T>, |
25 | } |
26 | |
27 | impl<T> SemiSticky<T> { |
28 | /// Creates a new [`SemiSticky`] wrapping a `value`. |
29 | /// |
30 | /// The value that is moved into the `SemiSticky` can be non `Send` and |
31 | /// will be anchored to the thread that created the object. If the |
32 | /// sticky wrapper type ends up being send from thread to thread |
33 | /// only the original thread can interact with the value. In case the |
34 | /// value does not have `Drop` it will be stored in the [`SemiSticky`] |
35 | /// instead. |
36 | pub fn new(value: T) -> Self { |
37 | SemiSticky { |
38 | inner: if mem::needs_drop::<T>() { |
39 | SemiStickyImpl::Sticky(Sticky::new(value)) |
40 | } else { |
41 | SemiStickyImpl::Fragile(Box::new(Fragile::new(value))) |
42 | }, |
43 | } |
44 | } |
45 | |
46 | /// Returns `true` if the access is valid. |
47 | /// |
48 | /// This will be `false` if the value was sent to another thread. |
49 | pub fn is_valid(&self) -> bool { |
50 | match self.inner { |
51 | SemiStickyImpl::Fragile(ref inner) => inner.is_valid(), |
52 | SemiStickyImpl::Sticky(ref inner) => inner.is_valid(), |
53 | } |
54 | } |
55 | |
56 | /// Consumes the [`SemiSticky`], returning the wrapped value. |
57 | /// |
58 | /// # Panics |
59 | /// |
60 | /// Panics if called from a different thread than the one where the |
61 | /// original value was created. |
62 | pub fn into_inner(self) -> T { |
63 | match self.inner { |
64 | SemiStickyImpl::Fragile(inner) => inner.into_inner(), |
65 | SemiStickyImpl::Sticky(inner) => inner.into_inner(), |
66 | } |
67 | } |
68 | |
69 | /// Consumes the [`SemiSticky`], returning the wrapped value if successful. |
70 | /// |
71 | /// The wrapped value is returned if this is called from the same thread |
72 | /// as the one where the original value was created, otherwise the |
73 | /// [`SemiSticky`] is returned as `Err(self)`. |
74 | pub fn try_into_inner(self) -> Result<T, Self> { |
75 | match self.inner { |
76 | SemiStickyImpl::Fragile(inner) => inner.try_into_inner().map_err(|inner| SemiSticky { |
77 | inner: SemiStickyImpl::Fragile(Box::new(inner)), |
78 | }), |
79 | SemiStickyImpl::Sticky(inner) => inner.try_into_inner().map_err(|inner| SemiSticky { |
80 | inner: SemiStickyImpl::Sticky(inner), |
81 | }), |
82 | } |
83 | } |
84 | |
85 | /// Immutably borrows the wrapped value. |
86 | /// |
87 | /// # Panics |
88 | /// |
89 | /// Panics if the calling thread is not the one that wrapped the value. |
90 | /// For a non-panicking variant, use [`try_get`](Self::try_get). |
91 | pub fn get<'stack>(&'stack self, _proof: &'stack StackToken) -> &'stack T { |
92 | match self.inner { |
93 | SemiStickyImpl::Fragile(ref inner) => inner.get(), |
94 | SemiStickyImpl::Sticky(ref inner) => inner.get(_proof), |
95 | } |
96 | } |
97 | |
98 | /// Mutably borrows the wrapped value. |
99 | /// |
100 | /// # Panics |
101 | /// |
102 | /// Panics if the calling thread is not the one that wrapped the value. |
103 | /// For a non-panicking variant, use [`try_get_mut`](Self::try_get_mut). |
104 | pub fn get_mut<'stack>(&'stack mut self, _proof: &'stack StackToken) -> &'stack mut T { |
105 | match self.inner { |
106 | SemiStickyImpl::Fragile(ref mut inner) => inner.get_mut(), |
107 | SemiStickyImpl::Sticky(ref mut inner) => inner.get_mut(_proof), |
108 | } |
109 | } |
110 | |
111 | /// Tries to immutably borrow the wrapped value. |
112 | /// |
113 | /// Returns `None` if the calling thread is not the one that wrapped the value. |
114 | pub fn try_get<'stack>( |
115 | &'stack self, |
116 | _proof: &'stack StackToken, |
117 | ) -> Result<&'stack T, InvalidThreadAccess> { |
118 | match self.inner { |
119 | SemiStickyImpl::Fragile(ref inner) => inner.try_get(), |
120 | SemiStickyImpl::Sticky(ref inner) => inner.try_get(_proof), |
121 | } |
122 | } |
123 | |
124 | /// Tries to mutably borrow the wrapped value. |
125 | /// |
126 | /// Returns `None` if the calling thread is not the one that wrapped the value. |
127 | pub fn try_get_mut<'stack>( |
128 | &'stack mut self, |
129 | _proof: &'stack StackToken, |
130 | ) -> Result<&'stack mut T, InvalidThreadAccess> { |
131 | match self.inner { |
132 | SemiStickyImpl::Fragile(ref mut inner) => inner.try_get_mut(), |
133 | SemiStickyImpl::Sticky(ref mut inner) => inner.try_get_mut(_proof), |
134 | } |
135 | } |
136 | } |
137 | |
138 | impl<T> From<T> for SemiSticky<T> { |
139 | #[inline ] |
140 | fn from(t: T) -> SemiSticky<T> { |
141 | SemiSticky::new(t) |
142 | } |
143 | } |
144 | |
145 | impl<T: Clone> Clone for SemiSticky<T> { |
146 | #[inline ] |
147 | fn clone(&self) -> SemiSticky<T> { |
148 | crate::stack_token!(tok); |
149 | SemiSticky::new(self.get(tok).clone()) |
150 | } |
151 | } |
152 | |
153 | impl<T: Default> Default for SemiSticky<T> { |
154 | #[inline ] |
155 | fn default() -> SemiSticky<T> { |
156 | SemiSticky::new(T::default()) |
157 | } |
158 | } |
159 | |
160 | impl<T: PartialEq> PartialEq for SemiSticky<T> { |
161 | #[inline ] |
162 | fn eq(&self, other: &SemiSticky<T>) -> bool { |
163 | crate::stack_token!(tok); |
164 | *self.get(tok) == *other.get(tok) |
165 | } |
166 | } |
167 | |
168 | impl<T: Eq> Eq for SemiSticky<T> {} |
169 | |
170 | impl<T: PartialOrd> PartialOrd for SemiSticky<T> { |
171 | #[inline ] |
172 | fn partial_cmp(&self, other: &SemiSticky<T>) -> Option<cmp::Ordering> { |
173 | crate::stack_token!(tok); |
174 | self.get(tok).partial_cmp(other.get(tok)) |
175 | } |
176 | |
177 | #[inline ] |
178 | fn lt(&self, other: &SemiSticky<T>) -> bool { |
179 | crate::stack_token!(tok); |
180 | *self.get(tok) < *other.get(tok) |
181 | } |
182 | |
183 | #[inline ] |
184 | fn le(&self, other: &SemiSticky<T>) -> bool { |
185 | crate::stack_token!(tok); |
186 | *self.get(tok) <= *other.get(tok) |
187 | } |
188 | |
189 | #[inline ] |
190 | fn gt(&self, other: &SemiSticky<T>) -> bool { |
191 | crate::stack_token!(tok); |
192 | *self.get(tok) > *other.get(tok) |
193 | } |
194 | |
195 | #[inline ] |
196 | fn ge(&self, other: &SemiSticky<T>) -> bool { |
197 | crate::stack_token!(tok); |
198 | *self.get(tok) >= *other.get(tok) |
199 | } |
200 | } |
201 | |
202 | impl<T: Ord> Ord for SemiSticky<T> { |
203 | #[inline ] |
204 | fn cmp(&self, other: &SemiSticky<T>) -> cmp::Ordering { |
205 | crate::stack_token!(tok); |
206 | self.get(tok).cmp(other.get(tok)) |
207 | } |
208 | } |
209 | |
210 | impl<T: fmt::Display> fmt::Display for SemiSticky<T> { |
211 | fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { |
212 | crate::stack_token!(tok); |
213 | fmt::Display::fmt(self.get(tok), f) |
214 | } |
215 | } |
216 | |
217 | impl<T: fmt::Debug> fmt::Debug for SemiSticky<T> { |
218 | fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> { |
219 | crate::stack_token!(tok); |
220 | match self.try_get(tok) { |
221 | Ok(value) => f.debug_struct("SemiSticky" ).field("value" , value).finish(), |
222 | Err(..) => { |
223 | struct InvalidPlaceholder; |
224 | impl fmt::Debug for InvalidPlaceholder { |
225 | fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
226 | f.write_str("<invalid thread>" ) |
227 | } |
228 | } |
229 | |
230 | f.debug_struct("SemiSticky" ) |
231 | .field("value" , &InvalidPlaceholder) |
232 | .finish() |
233 | } |
234 | } |
235 | } |
236 | } |
237 | |
238 | #[test] |
239 | fn test_basic() { |
240 | use std::thread; |
241 | let val = SemiSticky::new(true); |
242 | crate::stack_token!(tok); |
243 | assert_eq!(val.to_string(), "true" ); |
244 | assert_eq!(val.get(tok), &true); |
245 | assert!(val.try_get(tok).is_ok()); |
246 | thread::spawn(move || { |
247 | crate::stack_token!(tok); |
248 | assert!(val.try_get(tok).is_err()); |
249 | }) |
250 | .join() |
251 | .unwrap(); |
252 | } |
253 | |
254 | #[test] |
255 | fn test_mut() { |
256 | let mut val = SemiSticky::new(true); |
257 | crate::stack_token!(tok); |
258 | *val.get_mut(tok) = false; |
259 | assert_eq!(val.to_string(), "false" ); |
260 | assert_eq!(val.get(tok), &false); |
261 | } |
262 | |
263 | #[test] |
264 | #[should_panic ] |
265 | fn test_access_other_thread() { |
266 | use std::thread; |
267 | let val = SemiSticky::new(true); |
268 | thread::spawn(move || { |
269 | crate::stack_token!(tok); |
270 | val.get(tok); |
271 | }) |
272 | .join() |
273 | .unwrap(); |
274 | } |
275 | |
276 | #[test] |
277 | fn test_drop_same_thread() { |
278 | use std::sync::atomic::{AtomicBool, Ordering}; |
279 | use std::sync::Arc; |
280 | let was_called = Arc::new(AtomicBool::new(false)); |
281 | struct X(Arc<AtomicBool>); |
282 | impl Drop for X { |
283 | fn drop(&mut self) { |
284 | self.0.store(true, Ordering::SeqCst); |
285 | } |
286 | } |
287 | let val = SemiSticky::new(X(was_called.clone())); |
288 | mem::drop(val); |
289 | assert!(was_called.load(Ordering::SeqCst)); |
290 | } |
291 | |
292 | #[test] |
293 | fn test_noop_drop_elsewhere() { |
294 | use std::sync::atomic::{AtomicBool, Ordering}; |
295 | use std::sync::Arc; |
296 | use std::thread; |
297 | |
298 | let was_called = Arc::new(AtomicBool::new(false)); |
299 | |
300 | { |
301 | let was_called = was_called.clone(); |
302 | thread::spawn(move || { |
303 | struct X(Arc<AtomicBool>); |
304 | impl Drop for X { |
305 | fn drop(&mut self) { |
306 | self.0.store(true, Ordering::SeqCst); |
307 | } |
308 | } |
309 | |
310 | let val = SemiSticky::new(X(was_called.clone())); |
311 | assert!(thread::spawn(move || { |
312 | // moves it here but do not deallocate |
313 | crate::stack_token!(tok); |
314 | val.try_get(tok).ok(); |
315 | }) |
316 | .join() |
317 | .is_ok()); |
318 | |
319 | assert!(!was_called.load(Ordering::SeqCst)); |
320 | }) |
321 | .join() |
322 | .unwrap(); |
323 | } |
324 | |
325 | assert!(was_called.load(Ordering::SeqCst)); |
326 | } |
327 | |
328 | #[test] |
329 | fn test_rc_sending() { |
330 | use std::rc::Rc; |
331 | use std::thread; |
332 | let val = SemiSticky::new(Rc::new(true)); |
333 | thread::spawn(move || { |
334 | crate::stack_token!(tok); |
335 | assert!(val.try_get(tok).is_err()); |
336 | }) |
337 | .join() |
338 | .unwrap(); |
339 | } |
340 | |