An attempt to collect several proposals of rust-lang/wg-allocators into an MVP.
Alloc traitThe first thing to notice is, that [Alloc] was renamed to [AllocRef] in order to show that they are typically
implemented for a reference or smart pointer or ZST, not directly for the type that actually holds the allocator’s
state.
Issue on WG repository: rust-lang/wg-allocators#8
[AllocRef] was split up into [AllocRef], [DeallocRef], and [ReallocRef] to make more flexible allocators
possible.
Issue on WG repository: rust-lang/wg-allocators#9
All three traits were associated with a Builder: [BuildAlloc], [BuildDealloc], and [BuildRealloc] such those
traits are related to their association similar how BuildHasher is related to Hasher. Although the signatures are
different, it makes an even more flexible allocator design possible.
Issue on WG repository: rust-lang/wg-allocators#12
Add an associative error type to [AllocRef]. Besides adding the possibility of returning additional information on
allocation failure, it's also possible to split the usage of the AllocRef into a fallible and an infallible case.
Personally I think this is a pretty big deal, as kernel programmer can rely on allocation, which will never fail. If
an allocation can fail, only a try_*_in method may be available. To maintain backwards compatibility, [AbortAlloc]
was introduced. [AbortAlloc] wraps another allocator, but aborts on OOM thus AbortAlloc<Global> may be used as
default allocator for Box or Vec. To realize this, [AbortAlloc] implements AllocRef<Error=!>.
Issue on WG repository: rust-lang/wg-allocators#23
The new layout type [NonZeroLayout] was introduced. Currently, implementors of [Alloc] can chose to allow
zero-sized allocation so in a generic context it's impossible to rely on this, so banning zero-sized allocation is a
possible step to prevent this. This also removes unsafe from [AllocRef::alloc] and [AllocRef::alloc_zeroed], and
unlocks the possibility to move the extension API like alloc_array into a separate trait.
Issue on WG repository: rust-lang/wg-allocators#16
Box<T, B: BuildDealloc>. So far I'm basically done with this, but things has
to be cleaned up a bit before.Alloc-WG is distributed under the terms of both the MIT license and the Apache License (Version 2.0).
See LICENSE-APACHE and LICENSE-MIT for details.