Struct MappedRwLockReadGuard 

pub struct MappedRwLockReadGuard<'rwlock, T: ?Sized + 'rwlock> {
    data: NonNull<T>,
    inner_lock: &'rwlock RwLock,
}

🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

RAII structure used to release the shared read access of a lock when dropped, which can point to a subfield of the protected data.

This structure is created by the map and filter_map methods on RwLockReadGuard.

Fields

data: NonNull<T>

🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

A pointer to the data protected by the RwLock. Note that we use a pointer here instead of &'rwlock T to avoid noalias violations, because a MappedRwLockReadGuard instance only holds immutability until it drops, not for its whole scope. NonNull is preferable over *const T to allow for niche optimizations. NonNull is also covariant over T, just like we would have with &T.

inner_lock: &'rwlock RwLock

🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

A reference to the internal sys::RwLock that we have read-locked.

Implementations

impl<'rwlock, T: ?Sized> MappedRwLockReadGuard<'rwlock, T>

pub fn map<U, F>(orig: Self, f: F) -> MappedRwLockReadGuard<'rwlock, U>

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

🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

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

The RwLock is already locked for reading, so this cannot fail.

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

Panics

If the closure panics, the guard will be dropped (unlocked) and the RwLock will not be poisoned.

pub fn filter_map<U, F>( orig: Self, f: F, ) -> Result<MappedRwLockReadGuard<'rwlock, U>, Self>

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

🔬This is a nightly-only experimental API. (mapped_lock_guards #117108)

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

The RwLock is already locked for reading, so this cannot fail.

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

Panics

If the closure panics, the guard will be dropped (unlocked) and the RwLock will not be poisoned.

Trait Implementations

impl<T: ?Sized + Debug> Debug for MappedRwLockReadGuard<'_, T>

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

Formats the value using the given formatter.

impl<T: ?Sized> Deref for MappedRwLockReadGuard<'_, T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T: ?Sized + Display> Display for MappedRwLockReadGuard<'_, T>

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

Formats the value using the given formatter.

impl<T: ?Sized> Drop for MappedRwLockReadGuard<'_, T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: ?Sized> !Send for MappedRwLockReadGuard<'_, T>

impl<T: ?Sized + Sync> Sync for MappedRwLockReadGuard<'_, T>