54 lines
1.4 KiB
Rust
54 lines
1.4 KiB
Rust
//! System Mutexes
|
|
//!
|
|
//! The Windows implementation of mutexes is a little odd and it might not be
|
|
//! immediately obvious what's going on. The primary oddness is that SRWLock is
|
|
//! used instead of CriticalSection, and this is done because:
|
|
//!
|
|
//! 1. SRWLock is several times faster than CriticalSection according to
|
|
//! benchmarks performed on both Windows 8 and Windows 7.
|
|
//!
|
|
//! 2. CriticalSection allows recursive locking while SRWLock deadlocks. The
|
|
//! Unix implementation deadlocks so consistency is preferred. See #19962 for
|
|
//! more details.
|
|
//!
|
|
//! 3. While CriticalSection is fair and SRWLock is not, the current Rust policy
|
|
//! is that there are no guarantees of fairness.
|
|
|
|
use crate::cell::UnsafeCell;
|
|
use crate::sys::c;
|
|
|
|
pub struct Mutex {
|
|
srwlock: UnsafeCell<c::SRWLOCK>,
|
|
}
|
|
|
|
unsafe impl Send for Mutex {}
|
|
unsafe impl Sync for Mutex {}
|
|
|
|
#[inline]
|
|
pub unsafe fn raw(m: &Mutex) -> c::PSRWLOCK {
|
|
m.srwlock.get()
|
|
}
|
|
|
|
impl Mutex {
|
|
#[inline]
|
|
pub const fn new() -> Mutex {
|
|
Mutex { srwlock: UnsafeCell::new(c::SRWLOCK_INIT) }
|
|
}
|
|
|
|
#[inline]
|
|
pub fn lock(&self) {
|
|
unsafe {
|
|
c::AcquireSRWLockExclusive(raw(self));
|
|
}
|
|
}
|
|
|
|
#[inline]
|
|
pub fn try_lock(&self) -> bool {
|
|
unsafe { c::TryAcquireSRWLockExclusive(raw(self)) != 0 }
|
|
}
|
|
|
|
#[inline]
|
|
pub unsafe fn unlock(&self) {
|
|
c::ReleaseSRWLockExclusive(raw(self));
|
|
}
|
|
}
|