Struct MutexGuard

pub(in journal) struct MutexGuard<'a, T>
where
    T: 'a + ?Sized,
{
    lock: &'a Mutex<T>,
    poison: Guard,
}

An RAII implementation of a “scoped lock” of a mutex. When this structure is dropped (falls out of scope), the lock will be unlocked.

The data protected by the mutex can be accessed through this guard via its Deref and DerefMut implementations.

This structure is created by the lock and try_lock methods on Mutex.

Fields

lock: &'a Mutex<T>

poison: Guard

Implementations

impl<'a, T> MutexGuard<'a, T>

where T: ?Sized,

pub fn map<U, F>(orig: MutexGuard<'a, T>, f: F) -> MappedMutexGuard<'a, U>

where F: FnOnce(&mut T) -> &mut U, U: ?Sized,

🔬This is a nightly-only experimental API. (mapped_lock_guards)

Makes a MappedMutexGuard for a component of the borrowed data, e.g. an enum variant.

The Mutex is already locked, so this cannot fail.

This is an associated function that needs to be used as MutexGuard::map(...). A method would interfere with methods of the same name on the contents of the MutexGuard used through Deref.

pub fn try_map<U, F>( orig: MutexGuard<'a, T>, f: F, ) -> Result<MappedMutexGuard<'a, U>, MutexGuard<'a, T>>

where F: FnOnce(&mut T) -> Option<&mut U>, U: ?Sized,

🔬This is a nightly-only experimental API. (mapped_lock_guards)

Makes a MappedMutexGuard for a component of the borrowed data. The original guard is returned as an Err(...) if the closure returns None.

The Mutex is already locked, so this cannot fail.

This is an associated function that needs to be used as MutexGuard::try_map(...). A method would interfere with methods of the same name on the contents of the MutexGuard used through Deref.

Trait Implementations

impl<T> Debug for MutexGuard<'_, T>

where T: Debug + ?Sized,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> Deref for MutexGuard<'_, T>

where T: ?Sized,

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T> DerefMut for MutexGuard<'_, T>

where T: ?Sized,

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<T> Display for MutexGuard<'_, T>

where T: Display + ?Sized,

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> Drop for MutexGuard<'_, T>

where T: ?Sized,

fn drop(&mut self)

Executes the destructor for this type.

impl<T> !Send for MutexGuard<'_, T>

where T: ?Sized,

A MutexGuard is not Send to maximize platform portablity.

On platforms that use POSIX threads (commonly referred to as pthreads) there is a requirement to release mutex locks on the same thread they were acquired. For this reason, MutexGuard must not implement Send to prevent it being dropped from another thread.

impl<'a, T> StableDeref for MutexGuard<'a, T>

where T: ?Sized,

impl<T> Sync for MutexGuard<'_, T>

where T: Sync + ?Sized,

T must be Sync for a MutexGuard<T> to be Sync because it is possible to get a &T from &MutexGuard (via Deref).