[−][src]Struct lock_api::MappedMutexGuard
An RAII mutex guard returned by MutexGuard::map
, which can point to a
subfield of the protected data.
The main difference between MappedMutexGuard
and MutexGuard
is that the
former doesn't support temporarily unlocking and re-locking, since that
could introduce soundness issues if the locked object is modified by another
thread.
Implementations
impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> MappedMutexGuard<'a, R, T>
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pub fn map<U: ?Sized, F>(s: Self, f: F) -> MappedMutexGuard<'a, R, U> where
F: FnOnce(&mut T) -> &mut U,
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F: FnOnce(&mut T) -> &mut 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.
pub fn try_map<U: ?Sized, F>(
s: Self,
f: F
) -> Result<MappedMutexGuard<'a, R, U>, Self> where
F: FnOnce(&mut T) -> Option<&mut U>,
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s: Self,
f: F
) -> Result<MappedMutexGuard<'a, R, U>, Self> where
F: FnOnce(&mut T) -> Option<&mut U>,
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.
impl<'a, R: RawMutexFair + 'a, T: ?Sized + 'a> MappedMutexGuard<'a, R, T>
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pub fn unlock_fair(s: Self)
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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.
Trait Implementations
impl<'a, R: RawMutex + 'a, T: Debug + ?Sized + 'a> Debug for MappedMutexGuard<'a, R, T>
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impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> Deref for MappedMutexGuard<'a, R, T>
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impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> DerefMut for MappedMutexGuard<'a, R, T>
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impl<'a, R: RawMutex + 'a, T: Display + ?Sized + 'a> Display for MappedMutexGuard<'a, R, T>
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impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> Drop for MappedMutexGuard<'a, R, T>
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impl<'a, R: RawMutex + 'a, T: ?Sized + 'a> Send for MappedMutexGuard<'a, R, T> where
R::GuardMarker: Send,
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R::GuardMarker: Send,
impl<'a, R: RawMutex + Sync + 'a, T: ?Sized + Sync + 'a> Sync for MappedMutexGuard<'a, R, T>
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Auto Trait Implementations
impl<'a, R, T: ?Sized> Unpin for MappedMutexGuard<'a, R, T>
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,