Struct sharded_slab::OwnedEntry
source · [−]pub struct OwnedEntry<T, C = DefaultConfig> where
C: Config, { /* private fields */ }Expand description
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();