reusable-id-pool

A pool for RAII IDs.

This crate provides two structs, ReusableIdPool and ReusableIdPoolManual.

Example

use reusable_id_pool::ReusableIdPool;

let reusable_id_pool = ReusableIdPool::new();
let id = reusable_id_pool.allocate();

// Do something with the `id`, like move it into a struct. It will be returned
// to the pool when it is dropped.

ReusableIdPool

A std-only struct that hands out ArcIds, which are opaque to the user.

To assign an ID to multiple things, use ArcId::clone(&id) (uses Arc::clone under the hood) to get further instances of the ID. They compare (PartialEq) as equal.

An ID is released by dropping — when all its ArcIds are dropped. ArcId drop is constant time (decrementing a reference count, or appending to a free list for the final one).

ReusableIdPoolManual

A struct that hands out u64 IDs. This should be used instead of ReusableIdPool when the ID needs to be serialised, for example over a binary ABI, as nushift-core needs to do. The IDs must be manually returned to the pool.

#![no_std] is supported for ReusableIdPoolManual (set default-features = false if this is required), but alloc is required.

Time complexity

ReusableIdPool (std-only):

Allocate: O(1)
Release: O(1)

ReusableIdPoolManual (std):

Allocate: O(1)
Release: O(1)

ReusableIdPoolManual (#![no_std]):

Allocate: O(log n)
Release: O(log n)

The id-pool crate has more functionality than ReusableIdPoolManual, is always #![no_std], and has O(1) allocate and O(log n) release, so it probably should be used instead of ReusableIdPoolManual for this case.