Struct sharded_slab::pool::OwnedRef

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pub struct OwnedRef<T, C = DefaultConfig>
where T: Clear + Default, C: Config,
{ /* private fields */ }
Expand description

An owned guard that allows shared immutable 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 the guard exists, the removal will be deferred until all guards are dropped.

Unlike Ref, which borrows the pool, an OwnedRef clones the Arc around the pool. Therefore, it keeps the pool from being dropped until all such guards have been dropped. This means that an OwnedRef may be held for an arbitrary lifetime.

Examples

use std::sync::Arc;

let pool: Arc<Pool<String>> = Arc::new(Pool::new());
let key = pool.create_with(|item| item.push_str("hello world")).unwrap();

// Look up the created `Key`, returning an `OwnedRef`.
let value = pool.clone().get_owned(key).unwrap();

// Now, the original `Arc` clone of the pool may be dropped, but the
// returned `OwnedRef` can still access the value.
assert_eq!(value, String::from("hello world"));

Unlike Ref, an OwnedRef may be stored in a struct which must live for the 'static lifetime:

use sharded_slab::pool::OwnedRef;
use std::sync::Arc;

pub struct MyStruct {
    pool_ref: OwnedRef<String>,
    // ... other fields ...
}

// Suppose this is some arbitrary function which requires a value that
// lives for the 'static lifetime...
fn function_requiring_static<T: 'static>(t: &T) {
    // ... do something extremely important and interesting ...
}

let pool: Arc<Pool<String>> = Arc::new(Pool::new());
let key = pool.create_with(|item| item.push_str("hello world")).unwrap();

// Look up the created `Key`, returning an `OwnedRef`.
let pool_ref = pool.clone().get_owned(key).unwrap();
let my_struct = MyStruct {
    pool_ref,
    // ...
};

// We can use `my_struct` anywhere where it is required to have the
// `'static` lifetime:
function_requiring_static(&my_struct);

OwnedRefs may be sent between threads:

use std::{thread, sync::Arc};

let pool: Arc<Pool<String>> = Arc::new(Pool::new());
let key = pool.create_with(|item| item.push_str("hello world")).unwrap();

// Look up the created `Key`, returning an `OwnedRef`.
let value = pool.clone().get_owned(key).unwrap();

thread::spawn(move || {
    assert_eq!(value, String::from("hello world"));
    // ...
}).join().unwrap();

Implementations§

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impl<T, C> OwnedRef<T, C>
where T: Clear + Default, C: Config,

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pub fn key(&self) -> usize

Returns the key used to access this guard

Trait Implementations§

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impl<T, C> Debug for OwnedRef<T, C>
where T: Debug + Clear + Default, C: Config,

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

Formats the value using the given formatter. Read more
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impl<T, C> Drop for OwnedRef<T, C>
where T: Clear + Default, C: Config,

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fn drop(&mut self)

Executes the destructor for this type. Read more
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impl<T, C> PartialEq<T> for OwnedRef<T, C>
where T: PartialEq<T> + Clear + Default, C: Config,

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

This method tests for self and other values to be equal, and is used by ==.
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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.
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impl<T, C> Deref for OwnedRef<T, C>
where T: Clear + Default, C: Config,

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &Self::Target

Dereferences the value.
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impl<T, C> Send for OwnedRef<T, C>
where T: Sync + Clear + Default, C: Config,

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impl<T, C> Sync for OwnedRef<T, C>
where T: Sync + Clear + Default, C: Config,

Auto Trait Implementations§

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impl<T, C = DefaultConfig> !RefUnwindSafe for OwnedRef<T, C>

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impl<T, C> Unpin for OwnedRef<T, C>

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impl<T, C = DefaultConfig> !UnwindSafe for OwnedRef<T, C>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.