Struct sharded_slab::OwnedEntry

pub struct OwnedEntry<T, C = DefaultConfig>
where
    C: Config,
{ /* private fields */ }

An owned reference to an occupied entry in a Slab.

While the guard exists, it indicates to the slab that the item the guard references is currently being accessed. If the item is removed from the slab while the guard exists, the removal will be deferred until all guards are dropped.

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

Examples

use std::sync::Arc;

let slab: Arc<Slab<&'static str>> = Arc::new(Slab::new());
let key = slab.insert("hello world").unwrap();

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

// Now, the original `Arc` clone of the slab may be dropped, but the
// returned `OwnedEntry` can still access the value.
assert_eq!(value, "hello world");

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

use sharded_slab::OwnedEntry;
use std::sync::Arc;

pub struct MyStruct {
    entry: OwnedEntry<&'static str>,
    // ... 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 slab: Arc<Slab<&'static str>> = Arc::new(Slab::new());
let key = slab.insert("hello world").unwrap();

// Look up the created key, returning an `OwnedEntry`.
let entry = slab.clone().get_owned(key).unwrap();
let my_struct = MyStruct {
    entry,
    // ...
};

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

OwnedEntrys may be sent between threads:

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

let slab: Arc<Slab<&'static str>> = Arc::new(Slab::new());
let key = slab.insert("hello world").unwrap();

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

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

Implementations

impl<T, C> OwnedEntry<T, C>

where C: Config,

pub fn key(&self) -> usize

Returns the key used to access this guard

Trait Implementations

impl<T, C> Debug for OwnedEntry<T, C>

where T: Debug, C: Config,

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

Formats the value using the given formatter.

impl<T, C> Drop for OwnedEntry<T, C>

where C: Config,

fn drop(&mut self)

Executes the destructor for this type.

impl<T, C> PartialEq<T> for OwnedEntry<T, C>

where T: PartialEq<T>, 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> Deref for OwnedEntry<T, C>

where C: Config,

type Target = T

The resulting type after dereferencing.

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

Dereferences the value.

impl<T, C> Send for OwnedEntry<T, C>

where T: Sync, C: Config,

impl<T, C> Sync for OwnedEntry<T, C>

where T: Sync, C: Config,