85 lines
2.8 KiB
Rust
85 lines
2.8 KiB
Rust
use crate::sys::mutex as imp;
|
|
|
|
/// An OS-based mutual exclusion lock.
|
|
///
|
|
/// This is the thinnest cross-platform wrapper around OS mutexes. All usage of
|
|
/// this mutex is unsafe and it is recommended to instead use the safe wrapper
|
|
/// at the top level of the crate instead of this type.
|
|
pub struct Mutex(imp::Mutex);
|
|
|
|
unsafe impl Sync for Mutex {}
|
|
|
|
impl Mutex {
|
|
/// Creates a new mutex for use.
|
|
///
|
|
/// Behavior is undefined if the mutex is moved after it is
|
|
/// first used with any of the functions below.
|
|
/// Also, until `init` is called, behavior is undefined if this
|
|
/// mutex is ever used reentrantly, i.e., `raw_lock` or `try_lock`
|
|
/// are called by the thread currently holding the lock.
|
|
pub const fn new() -> Mutex { Mutex(imp::Mutex::new()) }
|
|
|
|
/// Prepare the mutex for use.
|
|
///
|
|
/// This should be called once the mutex is at a stable memory address.
|
|
/// If called, this must be the very first thing that happens to the mutex.
|
|
/// Calling it in parallel with or after any operation (including another
|
|
/// `init()`) is undefined behavior.
|
|
#[inline]
|
|
pub unsafe fn init(&mut self) { self.0.init() }
|
|
|
|
/// Locks the mutex blocking the current thread until it is available.
|
|
///
|
|
/// Behavior is undefined if the mutex has been moved between this and any
|
|
/// previous function call.
|
|
#[inline]
|
|
pub unsafe fn raw_lock(&self) { self.0.lock() }
|
|
|
|
/// Calls raw_lock() and then returns an RAII guard to guarantee the mutex
|
|
/// will be unlocked.
|
|
#[inline]
|
|
pub unsafe fn lock(&self) -> MutexGuard<'_> {
|
|
self.raw_lock();
|
|
MutexGuard(&self.0)
|
|
}
|
|
|
|
/// Attempts to lock the mutex without blocking, returning whether it was
|
|
/// successfully acquired or not.
|
|
///
|
|
/// Behavior is undefined if the mutex has been moved between this and any
|
|
/// previous function call.
|
|
#[inline]
|
|
pub unsafe fn try_lock(&self) -> bool { self.0.try_lock() }
|
|
|
|
/// Unlocks the mutex.
|
|
///
|
|
/// Behavior is undefined if the current thread does not actually hold the
|
|
/// mutex.
|
|
///
|
|
/// Consider switching from the pair of raw_lock() and raw_unlock() to
|
|
/// lock() whenever possible.
|
|
#[inline]
|
|
pub unsafe fn raw_unlock(&self) { self.0.unlock() }
|
|
|
|
/// Deallocates all resources associated with this mutex.
|
|
///
|
|
/// Behavior is undefined if there are current or will be future users of
|
|
/// this mutex.
|
|
#[inline]
|
|
pub unsafe fn destroy(&self) { self.0.destroy() }
|
|
}
|
|
|
|
// not meant to be exported to the outside world, just the containing module
|
|
pub fn raw(mutex: &Mutex) -> &imp::Mutex { &mutex.0 }
|
|
|
|
#[must_use]
|
|
/// A simple RAII utility for the above Mutex without the poisoning semantics.
|
|
pub struct MutexGuard<'a>(&'a imp::Mutex);
|
|
|
|
impl Drop for MutexGuard<'_> {
|
|
#[inline]
|
|
fn drop(&mut self) {
|
|
unsafe { self.0.unlock(); }
|
|
}
|
|
}
|