pub type MappedBackoffSpinlockGuard<'a, T> = MappedMutexGuard<'a, RawSpinlock<Backoff>, T>;
Expand description
A RAII guard returned by BackoffSpinlockGuard::map
.
§Example
use spinning_top::{
guard::{BackoffSpinlockGuard, MappedBackoffSpinlockGuard},
BackoffSpinlock,
};
let spinlock = BackoffSpinlock::new(Some(3));
// Begin a new scope.
{
// Lock the spinlock to create a `BackoffSpinlockGuard`.
let mut guard: BackoffSpinlockGuard<_> = spinlock.lock();
// Map the internal value of `guard`. `guard` is moved.
let mut mapped: MappedBackoffSpinlockGuard<'_, _> =
BackoffSpinlockGuard::map(guard, |g| g.as_mut().unwrap());
assert_eq!(*mapped, 3);
*mapped = 5;
assert_eq!(*mapped, 5);
} // `mapped` is dropped -> frees the spinlock again.
// The operation is reflected to the original lock.
assert_eq!(*spinlock.lock(), Some(5));
Aliased Type§
struct MappedBackoffSpinlockGuard<'a, T> { /* private fields */ }
Implementations
Source§impl<'a, R, T> MappedMutexGuard<'a, R, T>
impl<'a, R, T> MappedMutexGuard<'a, R, T>
Sourcepub fn map<U, F>(
s: MappedMutexGuard<'a, R, T>,
f: F,
) -> MappedMutexGuard<'a, R, U>
pub fn map<U, F>( s: MappedMutexGuard<'a, R, T>, f: F, ) -> MappedMutexGuard<'a, R, U>
Makes a new MappedMutexGuard
for a component of the locked data.
This operation cannot fail as the MappedMutexGuard
passed
in already locked the mutex.
This is an associated function that needs to be
used as MappedMutexGuard::map(...)
. A method would interfere with methods of
the same name on the contents of the locked data.
Sourcepub fn try_map<U, F>(
s: MappedMutexGuard<'a, R, T>,
f: F,
) -> Result<MappedMutexGuard<'a, R, U>, MappedMutexGuard<'a, R, T>>
pub fn try_map<U, F>( s: MappedMutexGuard<'a, R, T>, f: F, ) -> Result<MappedMutexGuard<'a, R, U>, MappedMutexGuard<'a, R, T>>
Attempts to make a new MappedMutexGuard
for a component of the
locked data. The original guard is returned if the closure returns None
.
This operation cannot fail as the MappedMutexGuard
passed
in already locked the mutex.
This is an associated function that needs to be
used as MappedMutexGuard::try_map(...)
. A method would interfere with methods of
the same name on the contents of the locked data.
Source§impl<'a, R, T> MappedMutexGuard<'a, R, T>where
R: RawMutexFair + 'a,
T: 'a + ?Sized,
impl<'a, R, T> MappedMutexGuard<'a, R, T>where
R: RawMutexFair + 'a,
T: 'a + ?Sized,
Sourcepub fn unlock_fair(s: MappedMutexGuard<'a, R, T>)
pub fn unlock_fair(s: MappedMutexGuard<'a, R, T>)
Unlocks the mutex using a fair unlock protocol.
By default, mutexes are unfair and allow the current thread to re-lock the mutex before another has the chance to acquire the lock, even if that thread has been blocked on the mutex for a long time. This is the default because it allows much higher throughput as it avoids forcing a context switch on every mutex unlock. This can result in one thread acquiring a mutex many more times than other threads.
However in some cases it can be beneficial to ensure fairness by forcing
the lock to pass on to a waiting thread if there is one. This is done by
using this method instead of dropping the MutexGuard
normally.