zone-alloc

This crate provides data types for zone-based (also known as region-based or arena-based) data allocation. Zone-based allocation is a type of memory management in which allocated objects are assigned to a specific zone. Data in the zone remain valid and usable for the lifetime of the zone, and all data in the zone are deallocated together after use.

[dependencies]
zone-alloc = "0.1"

Usage

This crate defines three containers:

Arena<T> - A container that can be used for arena allocation of values of a given type.
Registry<T> - An extension of Arena<T> that provides integer handles for allocated data.
StrongRegistry<H, T> - An extension of Registry<T> that provides strongly-typed handles for allocated data.
KeyedArena<K, T> - An extension of Arena<T> that maintains a mapping of keys to values.

Additional Crates

zone-alloc-strong-handle-derive - Procedural macro for deriving the StrongHandle interface on simple wrappers around the Handle type when working with StrongRegistry.

Features

While the crate is by default built with the Rust standard library, this feature can be removed for no-std environments.

default - std, ahash
std - Depend on the Rust standard library.
ahash - Use the ahash library for hash maps.

Examples

Linked List Nodes with `Arena<T>`

use zone_alloc::Arena;

#[derive(Debug, PartialEq, Eq)]
struct Node<'a, T> {
    parent: Option<&'a Node<'a, T>>,
    value: T,
}

impl<'a, T> Node<'a, T> {
    pub fn new(parent: Option<&'a Node<'a, T>>, value: T) -> Self {
        Self { parent, value }
    }
}

fn main() {
    let arena = Arena::new();
    let node = arena.alloc(Node::new(None, 1));
    let node = arena.alloc(Node::new(Some(node), 2));
    let node = arena.alloc(Node::new(Some(node), 3));

    assert_eq!(node.value, 3);
    assert_eq!(node.parent.unwrap().value, 2);
    assert_eq!(node.parent.unwrap().parent.unwrap().value, 1);
    assert_eq!(node.parent.unwrap().parent.unwrap().parent, None);
}

Circular References with `Registry<T>`

use zone_alloc::{
    Handle,
    Registry,
};

#[derive(Debug, PartialEq, Eq)]
struct Node<T> {
    parent: Option<Handle>,
    value: T,
}

impl<T> Node<T> {
    pub fn new(parent: Option<Handle>, value: T) -> Self {
        Self { parent, value }
    }
}

fn main() {
    let registry = Registry::new();
    let root_handle = registry.register(Node::new(None, "first"));
    let handle = registry.register(Node::new(Some(root_handle), "second"));
    let handle = registry.register(Node::new(Some(handle), "third"));
    registry.get_mut(root_handle).unwrap().parent = Some(handle);

    let node = registry.get(handle).unwrap();
    assert_eq!(node.value, "third");
    let node = registry.get(node.parent.unwrap()).unwrap();
    assert_eq!(node.value, "second");
    let node = registry.get(node.parent.unwrap()).unwrap();
    assert_eq!(node.value, "first");
    let node = registry.get(node.parent.unwrap()).unwrap();
    assert_eq!(node.value, "third");
}

zone-alloc 0.2.0