orx_concurrent_vec/unsafe_api.rs
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425
use crate::{ConcurrentElement, ConcurrentVec};
use core::sync::atomic::Ordering;
use orx_pinned_vec::IntoConcurrentPinnedVec;
impl<T, P> ConcurrentVec<T, P>
where
P: IntoConcurrentPinnedVec<ConcurrentElement<T>>,
{
/// Returns:
/// * a raw `*const T` pointer to the underlying data if element at the `i`-th position is pushed,
/// * `None` otherwise.
///
/// # Safety
///
/// Please see below the safety guarantees and potential safety risks using the pointer obtained by this method.
///
/// ## Safety Guarantees
///
/// Pointer obtained by this method will be valid:
///
/// * `ConcurrentVec` prevents access to elements which are not added yet.
/// * `ConcurrentOption` wrapper prevents access during initialization, and hence, prevents data race during initialization.
/// * `PinnedVec` storage makes sure that memory location of the elements never change.
///
/// Therefore, the caller can hold on the obtained pointer throughout the lifetime of the vec.
/// It is guaranteed that it will be valid pointing to the correct position with initialized data.
///
/// ## Unsafe Bits
///
/// However, this method still leaks out a pointer, using which can cause data races as follows:
/// * The value of the position can be `replace`d or `set` or `update`d concurrently by another thread.
/// * If at the same instant, we attempt to read using this pointer, we would end up with a data-race.
///
/// ## Safe Usage
///
/// This method can be safely used as long as the caller is able to guarantee that the position will not be being mutated
/// while using the pointer to directly access the data.
///
/// A common use case to this is the grow-only scenarios where added elements are not mutated:
/// * elements can be added to the vector by multiple threads,
/// * while already pushed elements can safely be accessed by other threads using `get_raw`.
pub fn get_raw(&self, i: usize) -> Option<*const T> {
match i < self.reserved_len() {
true => {
let maybe = unsafe { self.core.get(i) };
maybe.and_then(|x| x.0.get_raw_with_order(Ordering::SeqCst))
}
false => None,
}
}
/// Returns a reference to the element at the `i`-th position of the vec.
/// It returns `None` if index is out of bounds.
///
/// See also [`get`] and [`get_cloned`] for thread-safe alternatives of concurrent access to data.
///
/// [`get`]: crate::ConcurrentVec::get
/// [`get_cloned`]: crate::ConcurrentVec::get_cloned
///
/// # Safety
///
/// All methods that leak out `&T` or `&mut T` references are marked as unsafe.
/// Please see the reason and possible scenarios to use it safely below.
///
/// ## Safety Guarantees
///
/// Reference obtained by this method will be valid:
///
/// * `ConcurrentVec` prevents access to elements which are not added yet.
/// * `ConcurrentOption` wrapper prevents access during initialization, and hence, prevents data race during initialization.
/// * `PinnedVec` storage makes sure that memory location of the elements never change.
///
/// Therefore, the caller can hold on the obtained reference throughout the lifetime of the vec.
/// It is guaranteed that the reference will be valid pointing to the correct position.
///
/// ## Unsafe Bits
///
/// However, this method still leaks out a reference, which can cause data races as follows:
/// * The value of the position can be `replace`d or `set` or `update`d concurrently by another thread.
/// * If at the same instant, we attempt to read using this reference, we would end up with a data-race.
///
/// ## Safe Usage
///
/// This method can be safely used as long as the caller is able to guarantee that the position will not be being mutated
/// while using the reference to directly access the data.
///
/// A common use case to this is the grow-only scenarios where added elements are not mutated:
/// * elements can be added to the vector by multiple threads,
/// * while already pushed elements can safely be accessed by other threads using `get`.
///
/// # Examples
///
/// As explained above, the following constructs a safe usage example of the unsafe get method.
///
/// ```rust
/// use orx_concurrent_vec::*;
/// use std::time::Duration;
///
/// #[derive(Debug, Default)]
/// struct Metric {
/// sum: i32,
/// count: i32,
/// }
///
/// impl Metric {
/// fn aggregate(self, value: &i32) -> Self {
/// Self {
/// sum: self.sum + value,
/// count: self.count + 1,
/// }
/// }
/// }
///
/// // record measurements in random intervals, roughly every 2ms
/// let measurements = ConcurrentVec::new();
///
/// // collect metrics every 100 milliseconds
/// let metrics = ConcurrentVec::new();
///
/// std::thread::scope(|s| {
/// // thread to store measurements as they arrive
/// s.spawn(|| {
/// for i in 0..100 {
/// std::thread::sleep(Duration::from_millis(i % 5));
///
/// // collect measurements and push to measurements vec
/// measurements.push(i as i32);
/// }
/// });
///
/// // thread to collect metrics every 100 milliseconds
/// s.spawn(|| {
/// for _ in 0..10 {
/// // safely read from measurements vec to compute the metric
/// // since pushed elements are not being mutated
/// let len = measurements.len();
/// let mut metric = Metric::default();
/// for i in 0..len {
/// if let Some(value) = unsafe { measurements.get_ref(i) } {
/// metric = metric.aggregate(value);
/// }
/// }
///
/// // push result to metrics
/// metrics.push(metric);
///
/// std::thread::sleep(Duration::from_millis(100));
/// }
/// });
/// });
///
/// let measurements: Vec<_> = measurements.to_vec();
/// let averages: Vec<_> = metrics.to_vec();
///
/// assert_eq!(measurements.len(), 100);
/// assert_eq!(averages.len(), 10);
/// ```
pub unsafe fn get_ref(&self, i: usize) -> Option<&T> {
match i < self.reserved_len() {
true => {
let maybe = self.core.get(i);
maybe.and_then(|x| x.0.as_ref_with_order(Ordering::SeqCst))
}
false => None,
}
}
/// Returns an iterator to references of elements of the vec.
///
/// See also [`iter`] and [`iter_cloned`] for thread-safe alternatives of concurrent access to elements.
///
/// [`iter`]: crate::ConcurrentVec::iter
/// [`iter_cloned`]: crate::ConcurrentVec::iter_cloned
///
/// # Safety
///
/// All methods that leak out `&T` or `&mut T` references are marked as unsafe.
/// Please see the reason and possible scenarios to use it safely below.
///
/// ## Safety Guarantees
///
/// References obtained by this method will be valid:
///
/// * `ConcurrentVec` prevents access to elements which are not added yet.
/// * `ConcurrentOption` wrapper prevents access during initialization, and hence, prevents data race during initialization.
/// * `PinnedVec` storage makes sure that memory location of the elements never change.
///
/// Therefore, the caller can hold on the obtained references throughout the lifetime of the vec.
/// It is guaranteed that the references will be valid pointing to the correct positions.
///
/// ## Unsafe Bits
///
/// However, this method still leaks out references that can cause data races as follows:
/// * Values of elements in the vector can be concurrently mutated by methods such as `replace` or `update` by other threads.
/// * If at the same instant, we attempt to read using these references, we would end up with a data-race.
///
/// ## Safe Usage
///
/// This method can be safely used as long as the caller is able to guarantee that the position will not be being mutated
/// while using these references to directly access the data.
///
/// A common use case to this is the grow-only scenarios where added elements are not mutated:
/// * elements can be added to the vector by multiple threads,
/// * while already pushed elements can safely be accessed by other threads using `iter`.
///
/// # Examples
///
/// As explained above, the following constructs a safe usage example of the unsafe iter method.
///
/// ```rust
/// use orx_concurrent_vec::*;
/// use std::time::Duration;
///
/// #[derive(Debug, Default)]
/// struct Metric {
/// sum: i32,
/// count: i32,
/// }
///
/// impl Metric {
/// fn aggregate(self, value: &i32) -> Self {
/// Self {
/// sum: self.sum + value,
/// count: self.count + 1,
/// }
/// }
/// }
///
/// // record measurements in random intervals, roughly every 2ms
/// let measurements = ConcurrentVec::new();
///
/// // collect metrics every 100 milliseconds
/// let metrics = ConcurrentVec::new();
///
/// std::thread::scope(|s| {
/// // thread to store measurements as they arrive
/// s.spawn(|| {
/// for i in 0..100 {
/// std::thread::sleep(Duration::from_millis(i % 5));
///
/// // collect measurements and push to measurements vec
/// measurements.push(i as i32);
/// }
/// });
///
/// // thread to collect metrics every 100 milliseconds
/// s.spawn(|| {
/// for _ in 0..10 {
/// // safely read from measurements vec to compute the metric
/// // since pushed elements are never mutated
/// let metric = unsafe {
/// measurements
/// .iter_ref()
/// .fold(Metric::default(), |x, value| x.aggregate(value))
/// };
///
/// // push result to metrics
/// metrics.push(metric);
///
/// std::thread::sleep(Duration::from_millis(100));
/// }
/// });
/// });
///
/// let measurements: Vec<_> = measurements.to_vec();
/// let averages: Vec<_> = metrics.to_vec();
///
/// assert_eq!(measurements.len(), 100);
/// assert_eq!(averages.len(), 10);
/// ```
pub unsafe fn iter_ref(&self) -> impl Iterator<Item = &T> {
let x = self.core.iter(self.reserved_len());
x.flat_map(|x| unsafe { x.0.as_ref_with_order(Ordering::SeqCst) })
}
// mut
/// Returns:
/// * a raw `*mut T` pointer to the underlying data if element at the `i`-th position is pushed,
/// * `None` otherwise.
///
/// # Safety
///
/// Please see below the safety guarantees and potential safety risks using the pointer obtained by this method.
///
/// ## Safety Guarantees
///
/// Pointer obtained by this method will be valid:
///
/// * `ConcurrentVec` prevents access to elements which are not added yet.
/// * `ConcurrentOption` wrapper prevents access during initialization, and hence, prevents data race during initialization.
/// * `PinnedVec` storage makes sure that memory location of the elements never change.
///
/// Therefore, the caller can hold on the obtained pointer throughout the lifetime of the vec.
/// It is guaranteed that it will be valid pointing to the correct position with initialized data.
///
/// ## Unsafe Bits
///
/// However, this method still leaks out a pointer, using which can cause data races as follows:
/// * The value of the position can be `replace`d or `set` or `update`d concurrently by another thread.
/// * If at the same instant, we attempt to read using this pointer, we would end up with a data-race.
///
/// ## Safe Usage
///
/// This method can be safely used as long as the caller is able to guarantee that the position will not be being
/// read or written by another thread while using the pointer to directly access the data.
pub fn get_raw_mut(&self, i: usize) -> Option<*mut T> {
match i < self.reserved_len() {
true => {
let maybe = unsafe { self.core.get(i) };
maybe.and_then(|x| x.0.get_raw_mut_with_order(Ordering::SeqCst))
}
false => None,
}
}
/// Returns a mutable reference to the element at the `i`-th position of the vec.
/// It returns `None` if index is out of bounds.
///
/// # Safety
///
/// All methods that return `&T` or `&mut T` references are marked as unsafe.
/// Please see the reason and possible scenarios to use it safely below.
///
/// ## Safety Guarantees
///
/// Reference obtained by this method will be valid:
///
/// * `ConcurrentVec` prevents access to elements which are not added yet.
/// * `ConcurrentOption` wrapper prevents access during initialization, and hence, prevents data race during initialization.
/// * `PinnedVec` storage makes sure that memory location of the elements never change.
///
/// Therefore, the caller can hold on the obtained reference throughout the lifetime of the vec.
/// It is guaranteed that the reference will be valid pointing to the correct position.
///
/// ## Unsafe Bits
///
/// However, this method still leaks out a reference, which can cause data races as follows:
/// * The value of the position can be `replace`d or `set` or `update`d concurrently by another thread.
/// * And it maybe read by safe access methods such as `map` or `cloned`.
/// * If at the same instant, we attempt to read or write using this reference, we would end up with a data-race.
///
/// ## Safe Usage
///
/// This method can be safely used as long as the caller is able to guarantee that the position will not be being
/// read or written by another thread while using the reference to directly access the data.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_vec::*;
///
/// let vec = ConcurrentVec::new();
/// vec.extend(['a', 'b', 'c', 'd']);
///
/// assert_eq!(unsafe { vec.get_mut(4) }, None);
///
/// *unsafe { vec.get_mut(1).unwrap() } = 'x';
/// assert_eq!(unsafe { vec.get_ref(1) }, Some(&'x'));
///
/// assert_eq!(&vec, &['a', 'x', 'c', 'd']);
/// ```
pub unsafe fn get_mut(&self, i: usize) -> Option<&mut T> {
match i < self.reserved_len() {
true => {
let elem = self.core.get(i);
elem.and_then(|option| option.0.get_raw_mut().map(|p| &mut *p))
}
false => None,
}
}
/// Returns an iterator to mutable references of elements of the vec.
///
/// See also [`iter`] for thread-safe alternative of concurrent mutation of elements.
///
/// [`iter`]: crate::ConcurrentVec::iter
///
/// # Safety
///
/// All methods that leak out `&T` or `&mut T` references are marked as unsafe.
/// Please see the reason and possible scenarios to use it safely below.
///
/// ## Safety Guarantees
///
/// References obtained by this method will be valid:
///
/// * `ConcurrentVec` prevents access to elements which are not added yet.
/// * `ConcurrentOption` wrapper prevents access during initialization, and hence, prevents data race during initialization.
/// * `PinnedVec` storage makes sure that memory location of the elements never change.
///
/// Therefore, the caller can hold on the obtained references throughout the lifetime of the vec.
/// It is guaranteed that the references will be valid pointing to the correct position.
///
/// ## Unsafe Bits
///
/// However, this method still leaks out references, which can cause data races as follows:
/// * Values of elements can be concurrently read by other threads.
/// * Likewise, they can be concurrently mutated by thread-safe mutation methods.
/// * If at the same instant, we attempt to read or write using these references, we would end up with a data-race.
///
/// ## Safe Usage
///
/// This method can be safely used as long as the caller is able to guarantee that the elements will not be being
/// read or written by another thread while using the reference to directly access the data.
///
/// # Examples
///
/// ```rust
/// use orx_concurrent_vec::*;
///
/// let vec = ConcurrentVec::from_iter([0, 1, 2, 3]);
///
/// let iter = unsafe { vec.iter_mut() };
/// for x in iter {
/// *x *= 2;
/// }
///
/// assert_eq!(&vec, &[0, 2, 4, 6]);
/// ```
pub unsafe fn iter_mut(&self) -> impl Iterator<Item = &mut T> {
let x = self.core.iter(self.reserved_len());
x.flat_map(|x| x.0.get_raw_mut().map(|p| &mut *p))
}
}