Struct sharded_slab::pool::OwnedRef

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

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

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

pub fn key(&self) -> usize

Returns the key used to access this guard

Trait Implementations

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

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

Formats the value using the given formatter.

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

type Target = T

The resulting type after dereferencing.

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

Dereferences the value.

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

fn drop(&mut self)

Executes the destructor for this type.

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

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