diff options
Diffstat (limited to 'library/std')
| -rw-r--r-- | library/std/src/sys/sync/condvar/mod.rs | 8 | ||||
| -rw-r--r-- | library/std/src/sys/sync/condvar/pthread.rs | 38 | ||||
| -rw-r--r-- | library/std/src/sys/sync/condvar/sgx.rs | 29 | ||||
| -rw-r--r-- | library/std/src/sys/sync/condvar/teeos.rs | 101 | ||||
| -rw-r--r-- | library/std/src/sys/sync/mod.rs | 3 | ||||
| -rw-r--r-- | library/std/src/sys/sync/mutex/mod.rs | 2 | ||||
| -rw-r--r-- | library/std/src/sys/sync/mutex/pthread.rs | 81 | ||||
| -rw-r--r-- | library/std/src/sys/sync/mutex/sgx.rs | 28 | ||||
| -rw-r--r-- | library/std/src/sys/sync/once_box.rs | 82 | ||||
| -rw-r--r-- | library/std/src/sys/sync/rwlock/teeos.rs | 8 | ||||
| -rw-r--r-- | library/std/src/sys_common/lazy_box.rs | 88 | ||||
| -rw-r--r-- | library/std/src/sys_common/mod.rs | 1 |
12 files changed, 185 insertions, 284 deletions
diff --git a/library/std/src/sys/sync/condvar/mod.rs b/library/std/src/sys/sync/condvar/mod.rs index 6849cacf88e..d0c998a5597 100644 --- a/library/std/src/sys/sync/condvar/mod.rs +++ b/library/std/src/sys/sync/condvar/mod.rs @@ -12,7 +12,10 @@ cfg_if::cfg_if! { ))] { mod futex; pub use futex::Condvar; - } else if #[cfg(target_family = "unix")] { + } else if #[cfg(any( + target_family = "unix", + target_os = "teeos", + ))] { mod pthread; pub use pthread::Condvar; } else if #[cfg(all(target_os = "windows", target_vendor = "win7"))] { @@ -24,9 +27,6 @@ cfg_if::cfg_if! { } else if #[cfg(target_os = "solid_asp3")] { mod itron; pub use itron::Condvar; - } else if #[cfg(target_os = "teeos")] { - mod teeos; - pub use teeos::Condvar; } else if #[cfg(target_os = "xous")] { mod xous; pub use xous::Condvar; diff --git a/library/std/src/sys/sync/condvar/pthread.rs b/library/std/src/sys/sync/condvar/pthread.rs index 5b5e7770b06..986cd0cb7d1 100644 --- a/library/std/src/sys/sync/condvar/pthread.rs +++ b/library/std/src/sys/sync/condvar/pthread.rs @@ -2,31 +2,25 @@ use crate::cell::UnsafeCell; use crate::ptr; use crate::sync::atomic::AtomicPtr; use crate::sync::atomic::Ordering::Relaxed; -use crate::sys::sync::{Mutex, mutex}; +use crate::sys::sync::{Mutex, OnceBox}; #[cfg(not(target_os = "nto"))] use crate::sys::time::TIMESPEC_MAX; #[cfg(target_os = "nto")] use crate::sys::time::TIMESPEC_MAX_CAPPED; -use crate::sys_common::lazy_box::{LazyBox, LazyInit}; use crate::time::Duration; struct AllocatedCondvar(UnsafeCell<libc::pthread_cond_t>); pub struct Condvar { - inner: LazyBox<AllocatedCondvar>, + inner: OnceBox<AllocatedCondvar>, mutex: AtomicPtr<libc::pthread_mutex_t>, } -#[inline] -fn raw(c: &Condvar) -> *mut libc::pthread_cond_t { - c.inner.0.get() -} - unsafe impl Send for AllocatedCondvar {} unsafe impl Sync for AllocatedCondvar {} -impl LazyInit for AllocatedCondvar { - fn init() -> Box<Self> { +impl AllocatedCondvar { + fn new() -> Box<Self> { let condvar = Box::new(AllocatedCondvar(UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER))); cfg_if::cfg_if! { @@ -37,7 +31,7 @@ impl LazyInit for AllocatedCondvar { target_vendor = "apple", ))] { // `pthread_condattr_setclock` is unfortunately not supported on these platforms. - } else if #[cfg(any(target_os = "espidf", target_os = "horizon"))] { + } else if #[cfg(any(target_os = "espidf", target_os = "horizon", target_os = "teeos"))] { // NOTE: ESP-IDF's PTHREAD_COND_INITIALIZER support is not released yet // So on that platform, init() should always be called // Moreover, that platform does not have pthread_condattr_setclock support, @@ -82,7 +76,11 @@ impl Drop for AllocatedCondvar { impl Condvar { pub const fn new() -> Condvar { - Condvar { inner: LazyBox::new(), mutex: AtomicPtr::new(ptr::null_mut()) } + Condvar { inner: OnceBox::new(), mutex: AtomicPtr::new(ptr::null_mut()) } + } + + fn get(&self) -> *mut libc::pthread_cond_t { + self.inner.get_or_init(AllocatedCondvar::new).0.get() } #[inline] @@ -98,21 +96,21 @@ impl Condvar { #[inline] pub fn notify_one(&self) { - let r = unsafe { libc::pthread_cond_signal(raw(self)) }; + let r = unsafe { libc::pthread_cond_signal(self.get()) }; debug_assert_eq!(r, 0); } #[inline] pub fn notify_all(&self) { - let r = unsafe { libc::pthread_cond_broadcast(raw(self)) }; + let r = unsafe { libc::pthread_cond_broadcast(self.get()) }; debug_assert_eq!(r, 0); } #[inline] pub unsafe fn wait(&self, mutex: &Mutex) { - let mutex = mutex::raw(mutex); + let mutex = mutex.get_assert_locked(); self.verify(mutex); - let r = libc::pthread_cond_wait(raw(self), mutex); + let r = libc::pthread_cond_wait(self.get(), mutex); debug_assert_eq!(r, 0); } @@ -129,7 +127,7 @@ impl Condvar { pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { use crate::sys::time::Timespec; - let mutex = mutex::raw(mutex); + let mutex = mutex.get_assert_locked(); self.verify(mutex); #[cfg(not(target_os = "nto"))] @@ -144,7 +142,7 @@ impl Condvar { .and_then(|t| t.to_timespec_capped()) .unwrap_or(TIMESPEC_MAX_CAPPED); - let r = libc::pthread_cond_timedwait(raw(self), mutex, &timeout); + let r = libc::pthread_cond_timedwait(self.get(), mutex, &timeout); assert!(r == libc::ETIMEDOUT || r == 0); r == 0 } @@ -162,7 +160,7 @@ impl Condvar { use crate::sys::time::SystemTime; use crate::time::Instant; - let mutex = mutex::raw(mutex); + let mutex = mutex.get_assert_locked(); self.verify(mutex); // OSX implementation of `pthread_cond_timedwait` is buggy @@ -188,7 +186,7 @@ impl Condvar { .and_then(|t| t.to_timespec()) .unwrap_or(TIMESPEC_MAX); - let r = libc::pthread_cond_timedwait(raw(self), mutex, &timeout); + let r = libc::pthread_cond_timedwait(self.get(), mutex, &timeout); debug_assert!(r == libc::ETIMEDOUT || r == 0); // ETIMEDOUT is not a totally reliable method of determining timeout due diff --git a/library/std/src/sys/sync/condvar/sgx.rs b/library/std/src/sys/sync/condvar/sgx.rs index ecb5872f60d..e60715e4b59 100644 --- a/library/std/src/sys/sync/condvar/sgx.rs +++ b/library/std/src/sys/sync/condvar/sgx.rs @@ -1,44 +1,39 @@ use crate::sys::pal::waitqueue::{SpinMutex, WaitQueue, WaitVariable}; -use crate::sys::sync::Mutex; -use crate::sys_common::lazy_box::{LazyBox, LazyInit}; +use crate::sys::sync::{Mutex, OnceBox}; use crate::time::Duration; -/// FIXME: `UnsafeList` is not movable. -struct AllocatedCondvar(SpinMutex<WaitVariable<()>>); - pub struct Condvar { - inner: LazyBox<AllocatedCondvar>, -} - -impl LazyInit for AllocatedCondvar { - fn init() -> Box<Self> { - Box::new(AllocatedCondvar(SpinMutex::new(WaitVariable::new(())))) - } + // FIXME: `UnsafeList` is not movable. + inner: OnceBox<SpinMutex<WaitVariable<()>>>, } impl Condvar { pub const fn new() -> Condvar { - Condvar { inner: LazyBox::new() } + Condvar { inner: OnceBox::new() } + } + + fn get(&self) -> &SpinMutex<WaitVariable<()>> { + self.inner.get_or_init(|| Box::new(SpinMutex::new(WaitVariable::new(())))) } #[inline] pub fn notify_one(&self) { - let _ = WaitQueue::notify_one(self.inner.0.lock()); + let _ = WaitQueue::notify_one(self.get().lock()); } #[inline] pub fn notify_all(&self) { - let _ = WaitQueue::notify_all(self.inner.0.lock()); + let _ = WaitQueue::notify_all(self.get().lock()); } pub unsafe fn wait(&self, mutex: &Mutex) { - let guard = self.inner.0.lock(); + let guard = self.get().lock(); WaitQueue::wait(guard, || unsafe { mutex.unlock() }); mutex.lock() } pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { - let success = WaitQueue::wait_timeout(&self.inner.0, dur, || unsafe { mutex.unlock() }); + let success = WaitQueue::wait_timeout(self.get(), dur, || unsafe { mutex.unlock() }); mutex.lock(); success } diff --git a/library/std/src/sys/sync/condvar/teeos.rs b/library/std/src/sys/sync/condvar/teeos.rs deleted file mode 100644 index 943867cd761..00000000000 --- a/library/std/src/sys/sync/condvar/teeos.rs +++ /dev/null @@ -1,101 +0,0 @@ -use crate::cell::UnsafeCell; -use crate::ptr; -use crate::sync::atomic::AtomicPtr; -use crate::sync::atomic::Ordering::Relaxed; -use crate::sys::sync::mutex::{self, Mutex}; -use crate::sys::time::TIMESPEC_MAX; -use crate::sys_common::lazy_box::{LazyBox, LazyInit}; -use crate::time::Duration; - -extern "C" { - pub fn pthread_cond_timedwait( - cond: *mut libc::pthread_cond_t, - lock: *mut libc::pthread_mutex_t, - adstime: *const libc::timespec, - ) -> libc::c_int; -} - -struct AllocatedCondvar(UnsafeCell<libc::pthread_cond_t>); - -pub struct Condvar { - inner: LazyBox<AllocatedCondvar>, - mutex: AtomicPtr<libc::pthread_mutex_t>, -} - -#[inline] -fn raw(c: &Condvar) -> *mut libc::pthread_cond_t { - c.inner.0.get() -} - -unsafe impl Send for AllocatedCondvar {} -unsafe impl Sync for AllocatedCondvar {} - -impl LazyInit for AllocatedCondvar { - fn init() -> Box<Self> { - let condvar = Box::new(AllocatedCondvar(UnsafeCell::new(libc::PTHREAD_COND_INITIALIZER))); - - let r = unsafe { libc::pthread_cond_init(condvar.0.get(), crate::ptr::null()) }; - assert_eq!(r, 0); - - condvar - } -} - -impl Drop for AllocatedCondvar { - #[inline] - fn drop(&mut self) { - let r = unsafe { libc::pthread_cond_destroy(self.0.get()) }; - debug_assert_eq!(r, 0); - } -} - -impl Condvar { - pub const fn new() -> Condvar { - Condvar { inner: LazyBox::new(), mutex: AtomicPtr::new(ptr::null_mut()) } - } - - #[inline] - fn verify(&self, mutex: *mut libc::pthread_mutex_t) { - match self.mutex.compare_exchange(ptr::null_mut(), mutex, Relaxed, Relaxed) { - Ok(_) => {} // Stored the address - Err(n) if n == mutex => {} // Lost a race to store the same address - _ => panic!("attempted to use a condition variable with two mutexes"), - } - } - - #[inline] - pub fn notify_one(&self) { - let r = unsafe { libc::pthread_cond_signal(raw(self)) }; - debug_assert_eq!(r, 0); - } - - #[inline] - pub fn notify_all(&self) { - let r = unsafe { libc::pthread_cond_broadcast(raw(self)) }; - debug_assert_eq!(r, 0); - } - - #[inline] - pub unsafe fn wait(&self, mutex: &Mutex) { - let mutex = unsafe { mutex::raw(mutex) }; - self.verify(mutex); - let r = unsafe { libc::pthread_cond_wait(raw(self), mutex) }; - debug_assert_eq!(r, 0); - } - - pub unsafe fn wait_timeout(&self, mutex: &Mutex, dur: Duration) -> bool { - use crate::sys::time::Timespec; - - let mutex = unsafe { mutex::raw(mutex) }; - self.verify(mutex); - - let timeout = Timespec::now(libc::CLOCK_MONOTONIC) - .checked_add_duration(&dur) - .and_then(|t| t.to_timespec()) - .unwrap_or(TIMESPEC_MAX); - - let r = unsafe { pthread_cond_timedwait(raw(self), mutex, &timeout) }; - assert!(r == libc::ETIMEDOUT || r == 0); - r == 0 - } -} diff --git a/library/std/src/sys/sync/mod.rs b/library/std/src/sys/sync/mod.rs index 52fac5902a2..0691e967851 100644 --- a/library/std/src/sys/sync/mod.rs +++ b/library/std/src/sys/sync/mod.rs @@ -1,11 +1,14 @@ mod condvar; mod mutex; mod once; +mod once_box; mod rwlock; mod thread_parking; pub use condvar::Condvar; pub use mutex::Mutex; pub use once::{Once, OnceState}; +#[allow(unused)] // Only used on some platforms. +use once_box::OnceBox; pub use rwlock::RwLock; pub use thread_parking::Parker; diff --git a/library/std/src/sys/sync/mutex/mod.rs b/library/std/src/sys/sync/mutex/mod.rs index 73d9bd273de..360df3fc4b5 100644 --- a/library/std/src/sys/sync/mutex/mod.rs +++ b/library/std/src/sys/sync/mutex/mod.rs @@ -19,7 +19,7 @@ cfg_if::cfg_if! { target_os = "teeos", ))] { mod pthread; - pub use pthread::{Mutex, raw}; + pub use pthread::Mutex; } else if #[cfg(all(target_os = "windows", target_vendor = "win7"))] { mod windows7; pub use windows7::{Mutex, raw}; diff --git a/library/std/src/sys/sync/mutex/pthread.rs b/library/std/src/sys/sync/mutex/pthread.rs index 1c407bc2537..87c95f45f96 100644 --- a/library/std/src/sys/sync/mutex/pthread.rs +++ b/library/std/src/sys/sync/mutex/pthread.rs @@ -2,24 +2,19 @@ use crate::cell::UnsafeCell; use crate::io::Error; use crate::mem::{MaybeUninit, forget}; use crate::sys::cvt_nz; -use crate::sys_common::lazy_box::{LazyBox, LazyInit}; +use crate::sys::sync::OnceBox; struct AllocatedMutex(UnsafeCell<libc::pthread_mutex_t>); pub struct Mutex { - inner: LazyBox<AllocatedMutex>, -} - -#[inline] -pub unsafe fn raw(m: &Mutex) -> *mut libc::pthread_mutex_t { - m.inner.0.get() + inner: OnceBox<AllocatedMutex>, } unsafe impl Send for AllocatedMutex {} unsafe impl Sync for AllocatedMutex {} -impl LazyInit for AllocatedMutex { - fn init() -> Box<Self> { +impl AllocatedMutex { + fn new() -> Box<Self> { let mutex = Box::new(AllocatedMutex(UnsafeCell::new(libc::PTHREAD_MUTEX_INITIALIZER))); // Issue #33770 @@ -60,24 +55,6 @@ impl LazyInit for AllocatedMutex { mutex } - - fn destroy(mutex: Box<Self>) { - // We're not allowed to pthread_mutex_destroy a locked mutex, - // so check first if it's unlocked. - if unsafe { libc::pthread_mutex_trylock(mutex.0.get()) == 0 } { - unsafe { libc::pthread_mutex_unlock(mutex.0.get()) }; - drop(mutex); - } else { - // The mutex is locked. This happens if a MutexGuard is leaked. - // In this case, we just leak the Mutex too. - forget(mutex); - } - } - - fn cancel_init(_: Box<Self>) { - // In this case, we can just drop it without any checks, - // since it cannot have been locked yet. - } } impl Drop for AllocatedMutex { @@ -99,11 +76,33 @@ impl Drop for AllocatedMutex { impl Mutex { #[inline] pub const fn new() -> Mutex { - Mutex { inner: LazyBox::new() } + Mutex { inner: OnceBox::new() } + } + + /// Gets access to the pthread mutex under the assumption that the mutex is + /// locked. + /// + /// This allows skipping the initialization check, as the mutex can only be + /// locked if it is already initialized, and allows relaxing the ordering + /// on the pointer load, since the allocation cannot have been modified + /// since the `lock` and the lock must have occurred on the current thread. + /// + /// # Safety + /// Causes undefined behaviour if the mutex is not locked. + #[inline] + pub(crate) unsafe fn get_assert_locked(&self) -> *mut libc::pthread_mutex_t { + unsafe { self.inner.get_unchecked().0.get() } } #[inline] - pub unsafe fn lock(&self) { + fn get(&self) -> *mut libc::pthread_mutex_t { + // If initialization fails, the mutex is destroyed. This is always sound, + // however, as the mutex cannot have been locked yet. + self.inner.get_or_init(AllocatedMutex::new).0.get() + } + + #[inline] + pub fn lock(&self) { #[cold] #[inline(never)] fn fail(r: i32) -> ! { @@ -111,7 +110,7 @@ impl Mutex { panic!("failed to lock mutex: {error}"); } - let r = libc::pthread_mutex_lock(raw(self)); + let r = unsafe { libc::pthread_mutex_lock(self.get()) }; // As we set the mutex type to `PTHREAD_MUTEX_NORMAL` above, we expect // the lock call to never fail. Unfortunately however, some platforms // (Solaris) do not conform to the standard, and instead always provide @@ -126,13 +125,29 @@ impl Mutex { #[inline] pub unsafe fn unlock(&self) { - let r = libc::pthread_mutex_unlock(raw(self)); + let r = libc::pthread_mutex_unlock(self.get_assert_locked()); debug_assert_eq!(r, 0); } #[inline] - pub unsafe fn try_lock(&self) -> bool { - libc::pthread_mutex_trylock(raw(self)) == 0 + pub fn try_lock(&self) -> bool { + unsafe { libc::pthread_mutex_trylock(self.get()) == 0 } + } +} + +impl Drop for Mutex { + fn drop(&mut self) { + let Some(mutex) = self.inner.take() else { return }; + // We're not allowed to pthread_mutex_destroy a locked mutex, + // so check first if it's unlocked. + if unsafe { libc::pthread_mutex_trylock(mutex.0.get()) == 0 } { + unsafe { libc::pthread_mutex_unlock(mutex.0.get()) }; + drop(mutex); + } else { + // The mutex is locked. This happens if a MutexGuard is leaked. + // In this case, we just leak the Mutex too. + forget(mutex); + } } } diff --git a/library/std/src/sys/sync/mutex/sgx.rs b/library/std/src/sys/sync/mutex/sgx.rs index 65d1e880f7b..8529e857970 100644 --- a/library/std/src/sys/sync/mutex/sgx.rs +++ b/library/std/src/sys/sync/mutex/sgx.rs @@ -1,28 +1,24 @@ use crate::sys::pal::waitqueue::{SpinMutex, WaitQueue, WaitVariable, try_lock_or_false}; -use crate::sys_common::lazy_box::{LazyBox, LazyInit}; - -/// FIXME: `UnsafeList` is not movable. -struct AllocatedMutex(SpinMutex<WaitVariable<bool>>); +use crate::sys::sync::OnceBox; pub struct Mutex { - inner: LazyBox<AllocatedMutex>, -} - -impl LazyInit for AllocatedMutex { - fn init() -> Box<Self> { - Box::new(AllocatedMutex(SpinMutex::new(WaitVariable::new(false)))) - } + // FIXME: `UnsafeList` is not movable. + inner: OnceBox<SpinMutex<WaitVariable<bool>>>, } // Implementation according to “Operating Systems: Three Easy Pieces”, chapter 28 impl Mutex { pub const fn new() -> Mutex { - Mutex { inner: LazyBox::new() } + Mutex { inner: OnceBox::new() } + } + + fn get(&self) -> &SpinMutex<WaitVariable<bool>> { + self.inner.get_or_init(|| Box::new(SpinMutex::new(WaitVariable::new(false)))) } #[inline] pub fn lock(&self) { - let mut guard = self.inner.0.lock(); + let mut guard = self.get().lock(); if *guard.lock_var() { // Another thread has the lock, wait WaitQueue::wait(guard, || {}) @@ -35,7 +31,9 @@ impl Mutex { #[inline] pub unsafe fn unlock(&self) { - let guard = self.inner.0.lock(); + // SAFETY: the mutex was locked by the current thread, so it has been + // initialized already. + let guard = unsafe { self.inner.get_unchecked().lock() }; if let Err(mut guard) = WaitQueue::notify_one(guard) { // No other waiters, unlock *guard.lock_var_mut() = false; @@ -46,7 +44,7 @@ impl Mutex { #[inline] pub fn try_lock(&self) -> bool { - let mut guard = try_lock_or_false!(self.inner.0); + let mut guard = try_lock_or_false!(self.get()); if *guard.lock_var() { // Another thread has the lock false diff --git a/library/std/src/sys/sync/once_box.rs b/library/std/src/sys/sync/once_box.rs new file mode 100644 index 00000000000..1422b5a1721 --- /dev/null +++ b/library/std/src/sys/sync/once_box.rs @@ -0,0 +1,82 @@ +//! A racily-initialized alternative to `OnceLock<Box<T>>`. +//! +//! This is used to implement synchronization primitives that need allocation, +//! like the pthread versions. + +#![allow(dead_code)] // Only used on some platforms. + +use crate::mem::replace; +use crate::ptr::null_mut; +use crate::sync::atomic::AtomicPtr; +use crate::sync::atomic::Ordering::{AcqRel, Acquire, Relaxed}; + +pub(crate) struct OnceBox<T> { + ptr: AtomicPtr<T>, +} + +impl<T> OnceBox<T> { + #[inline] + pub const fn new() -> Self { + Self { ptr: AtomicPtr::new(null_mut()) } + } + + /// Gets access to the value, assuming it is already initialized and this + /// initialization has been observed by the current thread. + /// + /// Since all modifications to the pointer have already been observed, the + /// pointer load in this function can be performed with relaxed ordering, + /// potentially allowing the optimizer to turn code like this: + /// ```rust, ignore + /// once_box.get_or_init(|| Box::new(42)); + /// unsafe { once_box.get_unchecked() } + /// ``` + /// into + /// ```rust, ignore + /// once_box.get_or_init(|| Box::new(42)) + /// ``` + /// + /// # Safety + /// This causes undefined behaviour if the assumption above is violated. + #[inline] + pub unsafe fn get_unchecked(&self) -> &T { + unsafe { &*self.ptr.load(Relaxed) } + } + + #[inline] + pub fn get_or_init(&self, f: impl FnOnce() -> Box<T>) -> &T { + let ptr = self.ptr.load(Acquire); + match unsafe { ptr.as_ref() } { + Some(val) => val, + None => self.initialize(f), + } + } + + #[inline] + pub fn take(&mut self) -> Option<Box<T>> { + let ptr = replace(self.ptr.get_mut(), null_mut()); + if !ptr.is_null() { Some(unsafe { Box::from_raw(ptr) }) } else { None } + } + + #[cold] + fn initialize(&self, f: impl FnOnce() -> Box<T>) -> &T { + let new_ptr = Box::into_raw(f()); + match self.ptr.compare_exchange(null_mut(), new_ptr, AcqRel, Acquire) { + Ok(_) => unsafe { &*new_ptr }, + Err(ptr) => { + // Lost the race to another thread. + // Drop the value we created, and use the one from the other thread instead. + drop(unsafe { Box::from_raw(new_ptr) }); + unsafe { &*ptr } + } + } + } +} + +unsafe impl<T: Send> Send for OnceBox<T> {} +unsafe impl<T: Send + Sync> Sync for OnceBox<T> {} + +impl<T> Drop for OnceBox<T> { + fn drop(&mut self) { + self.take(); + } +} diff --git a/library/std/src/sys/sync/rwlock/teeos.rs b/library/std/src/sys/sync/rwlock/teeos.rs index ef9b1ab5154..76343022383 100644 --- a/library/std/src/sys/sync/rwlock/teeos.rs +++ b/library/std/src/sys/sync/rwlock/teeos.rs @@ -14,22 +14,22 @@ impl RwLock { #[inline] pub fn read(&self) { - unsafe { self.inner.lock() }; + self.inner.lock() } #[inline] pub fn try_read(&self) -> bool { - unsafe { self.inner.try_lock() } + self.inner.try_lock() } #[inline] pub fn write(&self) { - unsafe { self.inner.lock() }; + self.inner.lock() } #[inline] pub unsafe fn try_write(&self) -> bool { - unsafe { self.inner.try_lock() } + self.inner.try_lock() } #[inline] diff --git a/library/std/src/sys_common/lazy_box.rs b/library/std/src/sys_common/lazy_box.rs deleted file mode 100644 index b45b05f63ba..00000000000 --- a/library/std/src/sys_common/lazy_box.rs +++ /dev/null @@ -1,88 +0,0 @@ -#![allow(dead_code)] // Only used on some platforms. - -// This is used to wrap pthread {Mutex, Condvar, RwLock} in. - -use crate::marker::PhantomData; -use crate::ops::{Deref, DerefMut}; -use crate::ptr::null_mut; -use crate::sync::atomic::AtomicPtr; -use crate::sync::atomic::Ordering::{AcqRel, Acquire}; - -pub(crate) struct LazyBox<T: LazyInit> { - ptr: AtomicPtr<T>, - _phantom: PhantomData<T>, -} - -pub(crate) trait LazyInit { - /// This is called before the box is allocated, to provide the value to - /// move into the new box. - /// - /// It might be called more than once per LazyBox, as multiple threads - /// might race to initialize it concurrently, each constructing and initializing - /// their own box. All but one of them will be passed to `cancel_init` right after. - fn init() -> Box<Self>; - - /// Any surplus boxes from `init()` that lost the initialization race - /// are passed to this function for disposal. - /// - /// The default implementation calls destroy(). - fn cancel_init(x: Box<Self>) { - Self::destroy(x); - } - - /// This is called to destroy a used box. - /// - /// The default implementation just drops it. - fn destroy(_: Box<Self>) {} -} - -impl<T: LazyInit> LazyBox<T> { - #[inline] - pub const fn new() -> Self { - Self { ptr: AtomicPtr::new(null_mut()), _phantom: PhantomData } - } - - #[inline] - fn get_pointer(&self) -> *mut T { - let ptr = self.ptr.load(Acquire); - if ptr.is_null() { self.initialize() } else { ptr } - } - - #[cold] - fn initialize(&self) -> *mut T { - let new_ptr = Box::into_raw(T::init()); - match self.ptr.compare_exchange(null_mut(), new_ptr, AcqRel, Acquire) { - Ok(_) => new_ptr, - Err(ptr) => { - // Lost the race to another thread. - // Drop the box we created, and use the one from the other thread instead. - T::cancel_init(unsafe { Box::from_raw(new_ptr) }); - ptr - } - } - } -} - -impl<T: LazyInit> Deref for LazyBox<T> { - type Target = T; - #[inline] - fn deref(&self) -> &T { - unsafe { &*self.get_pointer() } - } -} - -impl<T: LazyInit> DerefMut for LazyBox<T> { - #[inline] - fn deref_mut(&mut self) -> &mut T { - unsafe { &mut *self.get_pointer() } - } -} - -impl<T: LazyInit> Drop for LazyBox<T> { - fn drop(&mut self) { - let ptr = *self.ptr.get_mut(); - if !ptr.is_null() { - T::destroy(unsafe { Box::from_raw(ptr) }); - } - } -} diff --git a/library/std/src/sys_common/mod.rs b/library/std/src/sys_common/mod.rs index aa27886ff6f..4f7a131f6bb 100644 --- a/library/std/src/sys_common/mod.rs +++ b/library/std/src/sys_common/mod.rs @@ -22,7 +22,6 @@ mod tests; pub mod fs; pub mod io; -pub mod lazy_box; pub mod process; pub mod wstr; pub mod wtf8; |