Struct sharded_slab::pool::RefMut

pub struct RefMut<'a, T, C = DefaultConfig>
where
    T: Clear + Default,
    C: Config,
{ /* private fields */ }

A guard that allows exclusive mutable access to an object in a pool.

While the guard exists, it indicates to the pool that the item the guard references is currently being accessed. If the item is removed from the pool while a guard exists, the removal will be deferred until the guard is dropped. The slot cannot be accessed by other threads while it is accessed mutably.

Implementations

impl<'a, T, C> RefMut<'a, T, C>

where T: Clear + Default, C: Config,

pub fn key(&self) -> usize

Returns the key used to access the guard.

pub fn downgrade(self) -> Ref<'a, T, C>

Downgrades the mutable guard to an immutable guard, allowing access to the pooled value from other threads.

Examples

let pool = Arc::new(Pool::<String>::new());

let mut guard_mut = pool.clone().create_owned().unwrap();
let key = guard_mut.key();
guard_mut.push_str("Hello");

// The pooled string is currently borrowed mutably, so other threads
// may not access it.
let pool2 = pool.clone();
thread::spawn(move || {
    assert!(pool2.get(key).is_none())
}).join().unwrap();

// Downgrade the guard to an immutable reference.
let guard = guard_mut.downgrade();

// Now, other threads may also access the pooled value.
let pool2 = pool.clone();
thread::spawn(move || {
    let guard = pool2.get(key)
        .expect("the item may now be referenced by other threads");
    assert_eq!(guard, String::from("Hello"));
}).join().unwrap();

// We can still access the value immutably through the downgraded guard.
assert_eq!(guard, String::from("Hello"));

Trait Implementations

impl<'a, T, C> Debug for RefMut<'a, T, C>

where T: Debug + Clear + Default, C: Config,

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

Formats the value using the given formatter.

impl<'a, T, C> DerefMut for RefMut<'a, T, C>

where T: Clear + Default, C: Config,

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<'a, T, C> Drop for RefMut<'a, T, C>

where T: Clear + Default, C: Config,

fn drop(&mut self)

Executes the destructor for this type.

impl<'a, T, C> PartialEq<T> for RefMut<'a, T, C>

where T: PartialEq<T> + Clear + Default, C: Config,

fn eq(&self, other: &T) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a, T, C> Deref for RefMut<'a, T, C>

where T: Clear + Default, C: Config,

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.