Struct futures_util::lock::MappedMutexGuard

pub struct MappedMutexGuard<'a, T: ?Sized, U: ?Sized> {
    mutex: &'a Mutex<T>,
    value: *mut U,
    _marker: PhantomData<&'a mut U>,
}

An RAII guard returned by the MutexGuard::map and MappedMutexGuard::map methods. When this structure is dropped (falls out of scope), the lock will be unlocked.

Fields

mutex: &'a Mutex<T>

value: *mut U

_marker: PhantomData<&'a mut U>

Implementations

impl<'a, T: ?Sized, U: ?Sized> MappedMutexGuard<'a, T, U>

pub fn map<V: ?Sized, F>(this: Self, f: F) -> MappedMutexGuard<'a, T, V>

where F: FnOnce(&mut U) -> &mut V,

Returns a locked view over a portion of the locked data.

Example

use futures::lock::{MappedMutexGuard, Mutex, MutexGuard};

let data = Mutex::new(Some("value".to_string()));
{
    let locked_str = MutexGuard::map(data.lock().await, |opt| opt.as_mut().unwrap());
    let locked_char = MappedMutexGuard::map(locked_str, |s| s.get_mut(0..1).unwrap());
    assert_eq!(&*locked_char, "v");
}

Trait Implementations

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

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

Formats the value using the given formatter.

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

type Target = U

The resulting type after dereferencing.

fn deref(&self) -> &U

Dereferences the value.

impl<T: ?Sized, U: ?Sized> DerefMut for MappedMutexGuard<'_, T, U>

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

Mutably dereferences the value.

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

fn drop(&mut self)

Executes the destructor for this type.

impl<T: ?Sized + Send, U: ?Sized + Send> Send for MappedMutexGuard<'_, T, U>

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