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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604
#![doc(html_root_url = "https://docs.rs/high_mem_utils/0.2.3/")] #![feature(vec_leak, untagged_unions, const_fn, manually_drop_take)] #![allow(unused_unsafe)] /*! This crate provides high-level memory abstractions used for ensure memory and exception safety in some patterns. High-level signifies that it only brings safe abstractions for some cases of transmute and others unsafe functions in the mem or ptr module,does not provide a custom allocator or garbage collector neither depends on the [core::alloc] unstable lib. At the moment this crate is nightly only,this will change if the features [`vec_leak`], [`const_fn`], [`untagged_unions`] and [`manually_drop_take`] get stabilished. # Examples ``` use high_mem_utils::{CatchStr, DontDrop, DropBy}; let mut string = String::from("Hello world!"); let catch = CatchStr::new(string.clone()); assert_eq!(catch.leaked().to_string(), string); // leaked returns &&mut str,not use to_string // it's a bit difficult cast rigth now assert_eq!(catch.seal(), string); // catch consumed let mut a = [1, 2, 3]; { let elem = DropBy::new([2, 3, 4], |e: [u32; 3]| { a = e.clone(); }); assert_eq!(*elem, Some([2, 3, 4])); } assert_eq!(a, [2, 3, 4]); unsafe { let b = DontDrop([1, 2, 3]); // we're not dropping here because we will have two variables // pointing to the same memory and "b" lives for shorter a = [0; 3]; b.as_ptr().copy_to(a.as_mut_ptr(), 3); } assert_eq!(a, [1, 2, 3]); ``` [`vec_leak`]: https://github.com/rust-lang/rust/issues/62195 [`untagged_unions`]: https://github.com/rust-lang/rust/issues/32836 [`manually_drop_take`]: https://github.com/rust-lang/rust/issues/55422 [`const_fn`]: https://github.com/rust-lang/rust/issues/57563 [core::alloc]: https://doc.rust-lang.org/core/alloc/index.html */ use std::mem::{take, ManuallyDrop, MaybeUninit, forget}; use std::ops::{Deref, DerefMut}; use std::collections::BTreeMap; use std::hint::unreachable_unchecked; /// This macro panics with the given message with debug_assertions on and call /// [unreachable_unchecked](https://doc.rust-lang.org/std/hint/fn.unreachable_unchecked.html) when off. /// /// # Safety /// /// You should use this macro for code that must not reach.But all the cases where can are not handled and /// will be handled on release or otherwise the responsability of do it passed to another caller,via unsafe /// interfaces. #[macro_export] macro_rules! unreachable_debug { () => { unreachable!("entered unreachable code") }; ($e:expr) => { if cfg!(not(debug_assertions)) { unsafe { std::hint::unreachable_unchecked() }; } else { panic!($e); } } } /// An union type that can be leaked or sealed(owned),useful when you want to give temporal global access to a particular value. pub union Catch<'a, T> { leaked: &'a mut T, sealed: ManuallyDrop<Box<T>>, } impl<'a, T> Catch<'a, T> { /// Creates a new Catch with a leak, you can lately get the underlying value and consume the Catch /// with the [`seal`](#method.seal) method. pub fn new(a: Box<T>) -> Self { Catch { leaked: Box::leak(a), } } /// Returns a a reference to the leaked field,'cause the only ways for construct this union returns /// a leaked one,for warranty never transmute stack to heap data,this method does not use transmute /// implicitly. pub fn leaked(&self) -> &&'a mut T { unsafe { &self.leaked } } /// Consumes the Catch and gets the inner Box\<T\>,preventing the memory leak. /// /// This does a call to transmute but,as the only ways to construct this union gives you a leaked one /// this never trigger undefined behavior by itself. pub fn seal(self) -> Box<T> { unsafe { ManuallyDrop::into_inner(self.sealed) } } /// Consumes the Catch and returns a mutable reference pointing to leaked data. pub fn leak(self) -> &'a mut T { unsafe { self.leaked } } /// Creates a new Catch from a mutable reference to T,without checking if T is in the heap. /// /// # Safety /// /// This function should only be used with data returned by the [`leak`](#method.leak) method from a safely constructed /// Catch or with data returned by `Box::leak(t)` otherwise this will trigger undefined behavior if the [`seal`](#method.seal) /// method is called. pub unsafe fn from_leaked(leaked: &'a mut T) -> Self { Catch { leaked } } } impl<'a, T: Default> Catch<'a, T> { /// Takes the sealed data and leaves T::default in their place,useful when you want to use the sealed /// value but you don't have ownership of the Catch. pub fn take(&mut self) -> Box<T> { let tmp = unsafe { ManuallyDrop::take(&mut self.sealed) }; let ptr = self as *mut Self; unsafe { ptr.write( Self::new(Box::new(T::default())) ); } tmp } } // /// I have my doubts if implement this `Drop` which drop the sealed data but,as temporal global access does not mean neccesarily a // /// memory leak and,many of the methods that this type implement returns or consumes the `Catch`.If you do know that your catch may // /// be dropped,use the (leak)[#method.leak] or (seal)[#method.seal] method,depending at the need of static or owned access. // impl<'a, T> Drop for Catch<'a, T> { // fn drop(&mut self) { // unsafe { ManuallyDrop::drop(&mut self.sealed) }; // } // } /// An union slice that can be leaked or sealed(owned),useful when you want to give temporal global access /// to a particular sequence. pub union CatchSeq<'a, T> { leaked: &'a mut [T], sealed: ManuallyDrop<Box<[T]>>, } impl<'a, T> CatchSeq<'a, T> { /// Creates a new CatchSeq with a leak, you can lately get the underlying sequence and consume the CatchSeq /// with the [`seal`](#method.seal) method. pub fn new(a: Vec<T>) -> Self { CatchSeq { leaked: Vec::leak(a), } } /// Returns a a reference to the leaked field,as the only safe ways for construct this union returns a leaked /// one,for warranty never transmute stack to heap data,this method does not use transmute implicitly. pub fn leaked(&self) -> &&'a mut [T] { unsafe { &self.leaked } } /// Consumes the Catch and gets the inner Vec<T>, preventing the memory leak. /// /// This does a call to transmute but,as the only safe ways for construct this union returns a leaked /// one,this never trigger undefined behavior by itself. pub fn seal(self) -> Vec<T> { unsafe { ManuallyDrop::into_inner(self.sealed).into_vec() } } /// Consumes the CatchSeq and returns a mutable reference pointing to leaked data. pub fn leak(self) -> &'a mut [T] { unsafe { self.leaked } } /// Creates a new CatchSeq from a `&mut [T]`,without checking if the referent is in the heap. /// /// # Safety /// /// This function should only be used with data returned by the [`leak`](#method.leak) method from a safely constructed /// CatchSeq or with data returned by `Vec::leak` otherwise this will trigger undefined behavior /// if the [`seal`](#method.seal) method is called. pub unsafe fn from_leaked(leaked: &'a mut [T]) -> Self { CatchSeq { leaked } } } // /// I have my doubts if implement this `Drop` which drop the sealed data but,as temporal global access does not mean neccesarily a // /// memory leak and,many of the methods that this type implement returns or consumes the `CatchSeq`.If you do know that your catch // /// may be dropped,use the (leak)[#method.leak] or (seal)[#method.seal] method,depending at the need of static or owned access. // impl<'a, T> Drop for CatchSeq<'a, T> { // fn drop(&mut self) { // unsafe { ManuallyDrop::drop(&mut self.sealed) }; // } // } /// An union string that can be leaked or sealed(owned),useful when you want to give temporal global access /// to a particular string. pub union CatchStr<'a> { leaked: &'a mut str, sealed: ManuallyDrop<Box<str>>, } impl<'a> CatchStr<'a> { /// Creates a new CatchStr with a leak, you can lately get the underlying string and consume the CatchStr /// with the [`seal`](#method.seal) method. pub fn new(a: String) -> Self { CatchStr { leaked: Box::leak(a.into_boxed_str()), } } /// Returns a a reference to the leaked field,as the only safe ways for construct this union returns a leaked /// one,for warranty never transmute stack to heap data,this method does not use transmute implicitly. pub fn leaked(&self) -> &&'a mut str { unsafe { &self.leaked } } /// Consumes the Catch and gets the inner String, preventing the memory leak. /// /// This does a call to transmute but,as the only safe ways for construct this union return a leaked /// one,this never trigger undefined behavior by itself. pub fn seal(self) -> String { unsafe { ManuallyDrop::into_inner(self.sealed).into_string() } } /// Consumes the CatchStr and returns a mutable reference pointing to leaked data. pub fn leak(self) -> &'a mut str { unsafe { self.leaked } } /// Creates a new CatchStr from a `&mut str`,without checking if the referent is in the heap. /// /// # Safety /// /// This function should only be used with data returned by the [`leak`](#method.leak) method from a safely constructed /// CatchStr or with data returned by `Box::leak(string.into_boxed_str())` otherwise this will trigger undefined behavior /// if the [`seal`](#method.seal) method is called. pub unsafe fn from_leaked(leaked: &'a mut str) -> Self { CatchStr { leaked } } } // /// I have my doubts if implement this `Drop` which drop the sealed data but,as temporal global access does not mean neccesarily a // /// memory leak and,many of the methods that this type implement returns or consumes the `CatchStr`.If you do know that your catch // /// may be dropped,use the [leak](#method.leak) or [seal](#method.seal) method,depending at the need of static or owned access. // impl<'a> Drop for CatchStr<'a> { // fn drop(&mut self) { // unsafe { ManuallyDrop::drop(&mut self.sealed) }; // } // } /// A wrapper for an implementation of drop that [`mem::take`] the value and [`mem::forget`]s it. /// /// This might be useful if you want assuring that a particular destructor not run if it can lead to /// a double-free or another memory issue. /// /// This type is particularly not recomended for reference types because as such they can never be null /// and the value is still dropped. Neither on types with a costly initialization because it replaces the /// forgotten value with the `Default` one,these values should not implement it anyways. /// /// This type has the same implications that forget except for the fact that this ensures that the value /// is never dropped even on panic,unless you abort.In general [`DontDropOpt`](./struct.DontDropOpt.html) is preferred. /// /// It derefs to T. /// /// [`mem::take`]: https://doc.rust-lang.org/core/mem/fn.take.html /// [`mem::forget`]: https://doc.rust-lang.org/core/mem/fn.forget.html #[repr(transparent)] pub struct DontDrop<T: Default>(pub T); impl<T: Default> DontDrop<T> { /// Returns the field,allowing it to be dropped again. pub fn into_inner(&mut self) -> T { take(&mut self.0) } } impl<T: Default> Deref for DontDrop<T> { type Target = T; fn deref(&self) -> &Self::Target { &self.0 } } impl<T: Default> DerefMut for DontDrop<T> { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } impl<T: Default> Drop for DontDrop<T> { fn drop(&mut self) { forget(take(&mut self.0)); } } /// A wrapper for an implementation of drop that [`mem::forget`] the previous value and replace it with None. /// /// This might be useful if you want assuring that a particular destructor not run if it can lead to /// a double-free or another memory issue. /// /// This type is particularly not recomended for reference types because as such they can never be null /// and the value is still dropped. /// /// This type has the same implications that [`mem::forget`] except for the fact that this ensures that the /// value is never dropped even on panic,unless you abort. /// /// It derefs to Option<T>. /// /// [`mem::forget`]: https://doc.rust-lang.org/core/mem/fn.forget.html #[repr(transparent)] pub struct DontDropOpt<T>(Option<T>); impl<T> DontDropOpt<T> { /// Construct a new `DontDropOpt` from a value,this has no effect if the value is a reference. pub fn new(a: T) -> Self { DontDropOpt(Some(a)) } /// Returns the value,allowing it to be dropped again. pub fn into_inner(&mut self) -> Option<T> { self.0.take() } /// Unwraps the Option<T>,allowing it to be dropped again. /// /// # Safety /// /// This will panic if the type contained is None with debug_assertions enabled,otherwise triggers UB. pub unsafe fn into_inner_unchecked(&mut self) -> T { self.0.take().unwrap_or_else(|| unreachable_debug!("Called into_inner_unchecked with None value on DontDropOpt in debug.")) } } impl<T> Drop for DontDropOpt<T> { fn drop(&mut self) { forget((&mut self.0).take()); } } impl<T> Deref for DontDropOpt<T> { type Target = Option<T>; fn deref(&self) -> &Self::Target { &self.0 } } impl<T> DerefMut for DontDropOpt<T> { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.0 } } /// A wrapper that calls the given closure at Drop. Useful when you have a conditional assign of one /// that,once assigned,you want to warranty a call to it with the given T,and then drop it. /// /// Currently this type has a value field of an `Option<T>`,because the closure needs to take ownership /// doing use of the [take](https://doc.rust-lang.org/std/option/enum.Option.html#method.take) method on /// `Option`.In case of `None` because there's no meaningful value for the closure,drop returns at that point. /// /// It derefs to Option<T>. pub struct DropBy<T, F: FnMut(T)> { pub value: Option<T>, pub clos: F } impl<T, F: FnMut(T)> DropBy<T, F> { /// Creates a new `DropBy` with the value and the closure that takes the value at their `Drop` impl. pub const fn new(value: T, clos: F) -> Self { let value = Some(value); DropBy { value, clos } } /// Takes the value,disabling any code in the closure. pub fn into_inner(&mut self) -> Option<T> { self.value.take() } /// Takes and unwraps the value,disabling any code in the closure. /// /// # Safety /// /// This will panic if the type contained is `None` with debug_assertions enabled,otherwise triggers UB. pub unsafe fn into_inner_unchecked(&mut self) -> T { self.value.take().unwrap_or_else(|| unreachable_debug!("Called into_inner_unchecked with None value on DropBy in debug.")) } } impl<T, F: FnMut(T)> Deref for DropBy<T, F> { type Target = Option<T>; fn deref(&self) -> &Self::Target { &self.value } } impl<T, F: FnMut(T)> DerefMut for DropBy<T, F> { fn deref_mut(&mut self) -> &mut Self::Target { &mut self.value } } impl<T, F: FnMut(T)> Drop for DropBy<T, F> { fn drop(&mut self) { let value = match self.value.take() { Some(a) => a, _ => return, }; (self.clos)(value); } } /// An enum that can be all sorts of Catch's over T,useful when you do not known if you gonna have a Box,Vec or String and you want to /// grant static temporal access to any of them safely. pub enum CatchT<'a, T> { Catch(Catch<'a, T>), CatchSeq(CatchSeq<'a, T>), CatchStr(CatchStr<'a>), } /// A lazy-iniatialiazed cache for a Fn closure with a constant constructor. pub struct LazyCache<P: Ord, V: Clone, C: Fn(P) -> V> { cache: MaybeUninit<BTreeMap<P, V>>, pub closure: C, init: bool } impl<P: Ord + Clone, V: Clone, C: Fn(P) -> V> LazyCache<P, V, C> { /// Construct a cache for a closure that is initialized in the first call to [call_cache](#method.call_cache). /// /// This is particularly useful for fn pointers of recurrently used functions because it can be used /// on statics,althought you need make them mutable for actually call [call_cache](#method.call_cache). pub const fn new(closure: C) -> Self { Self {cache: MaybeUninit::uninit(), closure, init: false} } /// Construct a cache for a closure providing an iniatialized cache. pub const fn with_cache(cache: BTreeMap<P, V>, closure: C) -> Self { Self {cache: MaybeUninit::new(cache), closure, init: true } } /// Cosntruct a cache for a closure providing a maybe unininitialized one along with the init state. /// /// If you do know that `init` is true the [`with_cache`](#method.with_cache) is preferred. /// /// # Safety /// /// This function is unsafe due to being unable to prove that the init value is correct and `true` /// only for initialiazed caches. /// /// Considering that a bad use can lead to try to read or destruct uninitializated memory the /// use of this function is discouraged and it only exist to give flexibility while maintaining the /// fields private. pub const unsafe fn with_cache_unchecked(cache: MaybeUninit<BTreeMap<P, V>>, closure: C, init: bool) -> Self { Self {cache, closure, init} } fn init(&mut self) { unsafe { self.cache.as_mut_ptr().write(BTreeMap::new()); self.init = true; } } /// calls the inner closure with the given arg after init the cache if it did not before. /// /// # Panics /// /// If the given closure panic the variable reading the cache from the MaybeUninit is guaranteed to not /// drop and the [Drop](#impl-Drop) impl will do the job. /// /// # Examples /// /// ``` /// use high_mem_utils::LazyCache; /// /// fn foo(num: u32) -> u32 { /// num /// } /// /// let mut cache = LazyCache::new(foo); /// /// assert_eq!(cache.call_cache(2), 2); /// assert_eq!(cache.call_cache(2), 2); /// assert_eq!(cache.call_cache(4), 4); /// ``` pub fn call_cache(&mut self, arg: P) -> V { if !self.init { self.init(); } let mut_ref = unsafe { (&mut *self.cache.as_mut_ptr()) }; let value = if mut_ref.contains_key(&arg) { (mut_ref.get(&arg).unwrap()).clone() } else { let temp = (self.closure)(arg.clone()); mut_ref.insert(arg, temp.clone()); temp }; value } /// This method removes an argument from the cache and returns the value or None if there's no one /// or the cache is uninitialized. /// /// # Examples /// /// ``` /// use high_mem_utils::LazyCache; /// /// fn foo(num: u32) -> u32 { /// num /// } /// /// let mut cache = LazyCache::new(foo); /// /// assert_eq!(cache.call_cache(2), 2); /// assert_eq!(cache.pop(&2), Some(2)); /// assert_eq!(cache.pop(&2), None); /// ``` pub fn pop(&mut self, arg: &P) -> Option<V> { if !self.init { return None; } let rem = (unsafe { &mut *self.cache.as_mut_ptr() }).remove(arg); rem } /// Clears the cache,removing all their values.This is no-op if the cache is not initialized. pub fn clear(&mut self) { if !self.init { return; } (unsafe { &mut *self.cache.as_mut_ptr() }).clear(); } /// Returns true if the cache is initialized,not neccesarily filled with an argument. Use \![is_empty](#method.is_empty) /// for that purpose. pub fn is_init(&self) -> bool { self.init } /// Returns true if the cache has no arguments or if it's not initialized. pub fn is_empty(&self) -> bool { if self.init { (unsafe { &*self.cache.as_ptr() }).is_empty() } else { true } } /// This method takes a closure that receives a mutable reference to the cache. /// /// # Examples /// /// ``` /// use high_mem_utils::LazyCache; /// /// let mut cache = LazyCache::new(|x| x); /// /// cache.cache(|c| {c.insert(2, 2);}); /// assert_eq!(cache.pop(&2), Some(2)); /// assert_eq!(cache.call_cache(2), 2); /// assert_eq!(cache.pop(&2), Some(2)); /// assert_eq!(cache.pop(&2), None); /// ``` pub fn cache<F: Fn(&mut BTreeMap<P, V>)>(&mut self, f: F) { if !self.init { self.init(); } unsafe { f(&mut *self.cache.as_mut_ptr()); } } } /// This impl drops the cache only if it's initialiazed. impl<P: Ord, V: Clone, C: Fn(P) -> V> Drop for LazyCache<P, V, C> { fn drop(&mut self) { if self.init { unsafe { self.cache.as_mut_ptr().drop_in_place() } } } }