Type Alias parking_lot::MappedMutexGuard
source · pub type MappedMutexGuard<'a, T> = MappedMutexGuard<'a, RawMutex, T>;
Expand description
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.
Aliased Type§
struct MappedMutexGuard<'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.