102 lines
3.0 KiB
Rust
102 lines
3.0 KiB
Rust
use crate::sys::mutex as imp;
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/// An OS-based mutual exclusion lock.
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///
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/// This is the thinnest cross-platform wrapper around OS mutexes. All usage of
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/// this mutex is unsafe and it is recommended to instead use the safe wrapper
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/// at the top level of the crate instead of this type.
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pub struct Mutex(imp::Mutex);
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unsafe impl Sync for Mutex {}
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impl Mutex {
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/// Creates a new mutex for use.
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///
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/// Behavior is undefined if the mutex is moved after it is
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/// first used with any of the functions below.
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/// Also, until `init` is called, behavior is undefined if this
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/// mutex is ever used reentrantly, i.e., `raw_lock` or `try_lock`
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/// are called by the thread currently holding the lock.
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#[rustc_const_stable(feature = "const_sys_mutex_new", since = "1.0.0")]
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pub const fn new() -> Mutex {
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Mutex(imp::Mutex::new())
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}
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/// Prepare the mutex for use.
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///
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/// This should be called once the mutex is at a stable memory address.
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/// If called, this must be the very first thing that happens to the mutex.
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/// Calling it in parallel with or after any operation (including another
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/// `init()`) is undefined behavior.
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#[inline]
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pub unsafe fn init(&mut self) {
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self.0.init()
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}
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/// Locks the mutex blocking the current thread until it is available.
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///
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/// Behavior is undefined if the mutex has been moved between this and any
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/// previous function call.
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#[inline]
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pub unsafe fn raw_lock(&self) {
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self.0.lock()
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}
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/// Calls raw_lock() and then returns an RAII guard to guarantee the mutex
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/// will be unlocked.
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#[inline]
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pub unsafe fn lock(&self) -> MutexGuard<'_> {
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self.raw_lock();
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MutexGuard(&self.0)
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}
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/// Attempts to lock the mutex without blocking, returning whether it was
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/// successfully acquired or not.
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///
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/// Behavior is undefined if the mutex has been moved between this and any
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/// previous function call.
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#[inline]
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pub unsafe fn try_lock(&self) -> bool {
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self.0.try_lock()
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}
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/// Unlocks the mutex.
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///
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/// Behavior is undefined if the current thread does not actually hold the
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/// mutex.
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///
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/// Consider switching from the pair of raw_lock() and raw_unlock() to
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/// lock() whenever possible.
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#[inline]
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pub unsafe fn raw_unlock(&self) {
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self.0.unlock()
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}
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/// Deallocates all resources associated with this mutex.
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///
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/// Behavior is undefined if there are current or will be future users of
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/// this mutex.
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#[inline]
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pub unsafe fn destroy(&self) {
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self.0.destroy()
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}
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}
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// not meant to be exported to the outside world, just the containing module
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pub fn raw(mutex: &Mutex) -> &imp::Mutex {
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&mutex.0
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}
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#[must_use]
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/// A simple RAII utility for the above Mutex without the poisoning semantics.
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pub struct MutexGuard<'a>(&'a imp::Mutex);
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impl Drop for MutexGuard<'_> {
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#[inline]
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fn drop(&mut self) {
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unsafe {
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self.0.unlock();
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}
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}
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}
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