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use crate::sys::locks as imp;
/// An OS-based mutual exclusion lock, meant for use in static variables.
///
/// This mutex has a const constructor ([`StaticMutex::new`]), does not
/// implement `Drop` to cleanup resources, and causes UB when used reentrantly.
///
/// This mutex does not implement poisoning.
///
/// This is a wrapper around `imp::Mutex` that does *not* call `init()` and
/// `destroy()`.
pub struct StaticMutex(imp::Mutex);
unsafe impl Sync for StaticMutex {}
impl StaticMutex {
/// Creates a new mutex for use.
#[inline]
pub const fn new() -> Self {
Self(imp::Mutex::new())
}
/// Calls raw_lock() and then returns an RAII guard to guarantee the mutex
/// will be unlocked.
///
/// It is undefined behaviour to call this function while locked by the
/// same thread.
#[inline]
pub unsafe fn lock(&'static self) -> StaticMutexGuard {
self.0.lock();
StaticMutexGuard(&self.0)
}
}
#[must_use]
pub struct StaticMutexGuard(&'static imp::Mutex);
impl Drop for StaticMutexGuard {
#[inline]
fn drop(&mut self) {
unsafe {
self.0.unlock();
}
}
}
/// An OS-based mutual exclusion lock.
///
/// This mutex cleans up its resources in its `Drop` implementation, may safely
/// be moved (when not borrowed), and does not cause UB when used reentrantly.
///
/// This mutex does not implement poisoning.
///
/// This is either a wrapper around `LazyBox<imp::Mutex>` or `imp::Mutex`,
/// depending on the platform. It is boxed on platforms where `imp::Mutex` may
/// not be moved.
pub struct MovableMutex(imp::MovableMutex);
unsafe impl Sync for MovableMutex {}
impl MovableMutex {
/// Creates a new mutex.
#[inline]
pub const fn new() -> Self {
Self(imp::MovableMutex::new())
}
pub(super) fn raw(&self) -> &imp::Mutex {
&self.0
}
/// Locks the mutex blocking the current thread until it is available.
#[inline]
pub fn raw_lock(&self) {
unsafe { self.0.lock() }
}
/// Attempts to lock the mutex without blocking, returning whether it was
/// successfully acquired or not.
#[inline]
pub fn try_lock(&self) -> bool {
unsafe { self.0.try_lock() }
}
/// Unlocks the mutex.
///
/// Behavior is undefined if the current thread does not actually hold the
/// mutex.
#[inline]
pub unsafe fn raw_unlock(&self) {
self.0.unlock()
}
}
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