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## Unreleased
Released YYYY-MM-DD.
### Added
* TODO (or remove section if none)
### Changed
* TODO (or remove section if none)
### Deprecated
* TODO (or remove section if none)
### Removed
* TODO (or remove section if none)
### Fixed
* TODO (or remove section if none)
### Security
* TODO (or remove section if none)
--------------------------------------------------------------------------------
## 3.15.4
Released 2024-03-07.
### Added
* Added the `bumpalo::collections::Vec::extend_from_slices_copy` method, which
is a faster way to extend a vec from multiple slices when the element is
`Copy` than calling `extend_from_slice_copy` N times.
--------------------------------------------------------------------------------
## 3.15.3
Released 2024-02-22.
### Added
* Added additional performance improvements to `bumpalo::collections::Vec`
related to reserving capacity.
--------------------------------------------------------------------------------
## 3.15.2
Released 2024-02-21.
### Added
* Add a `bumpalo::collections::Vec::extend_from_slice_copy` method. This doesn't
exist on the standard library's `Vec` but they have access to specialization,
so their regular `extend_from_slice` has a specialization for `Copy`
types. Using this new method for `Copy` types is a ~80x performance
improvement over the plain `extend_from_slice` method.
--------------------------------------------------------------------------------
## 3.15.1
Released 2024-02-20.
### Fixed
* Fixed the MSRV listed in `Cargo.toml`, whose update was forgotten when the
MSRV bumped in release 3.15.0.
--------------------------------------------------------------------------------
## 3.15.0
Released 2024-02-15.
### Changed
* The minimum supported Rust version (MSRV) is now 1.73.0.
* `bumpalo::collections::String::push_str` and
`bumpalo::collections::String::from_str_in` received significant performance
improvements.
* Allocator trait methods are now marked `#[inline]`, increasing performance for
some callers.
### Fixed
* Fixed an edge-case bug in the `Allocator::shrink` method.
--------------------------------------------------------------------------------
## 3.14.0
Released 2023-09-14.
### Added
* Added the `std` cargo feature, which enables implementations of `std` traits
for various things. Right now that is just `std::io::Write` for
`bumpalo::collections::Vec`, but could be more in the future.
--------------------------------------------------------------------------------
## 3.13.0
Released 2023-05-22.
### Added
* New `"allocator-api2"` feature enables the use of the allocator API on
stable. This feature uses a crate that mirrors the API of the unstable Rust
`allocator_api` feature. If the feature is enabled, references to `Bump` will
implement `allocator_api2::Allocator`. This allows `Bump` to be used as an
allocator for collection types from `allocator-api2` and any other crates that
support `allocator-api2`.
### Changed
* The minimum supported Rust version (MSRV) is now 1.63.0.
--------------------------------------------------------------------------------
## 3.12.2
Released 2023-05-09.
### Changed
* Added `rust-version` metadata to `Cargo.toml` which helps `cargo` with version
resolution.
--------------------------------------------------------------------------------
## 3.12.1
Released 2023-04-21.
### Fixed
* Fixed a bug where `Bump::try_with_capacity(n)` where `n > isize::MAX` could
lead to attempts to create invalid `Layout`s.
--------------------------------------------------------------------------------
## 3.12.0
Released 2023-01-17.
### Added
* Added the `bumpalo::boxed::Box::bump` and `bumpalo::collections::String::bump`
getters to get the underlying `Bump` that a string or box was allocated into.
### Changed
* Some uses of `Box` that MIRI did not previously consider as UB are now
reported as UB, and `bumpalo`'s internals have been adjusted to avoid the new
UB.
--------------------------------------------------------------------------------
## 3.11.1
Released 2022-10-18.
### Security
* Fixed a bug where when `std::vec::IntoIter` was ported to
`bumpalo::collections::vec::IntoIter`, it didn't get its underlying `Bump`'s
lifetime threaded through. This meant that `rustc` was not checking the
borrows for `bumpalo::collections::IntoIter` and this could result in
use-after-free bugs.
--------------------------------------------------------------------------------
## 3.11.0
Released 2022-08-17.
### Added
* Added support for per-`Bump` allocation limits. These are enforced only in the
slow path when allocating new chunks in the `Bump`, not in the bump allocation
hot path, and therefore impose near zero overhead.
* Added the `bumpalo::boxed::Box::into_inner` method.
### Changed
* Updated to Rust 2021 edition.
* The minimum supported Rust version (MSRV) is now 1.56.0.
--------------------------------------------------------------------------------
## 3.10.0
Released 2022-06-01.
### Added
* Implement `bumpalo::collections::FromIteratorIn` for `Option` and `Result`,
just like `core` does for `FromIterator`.
* Implement `bumpalo::collections::FromIteratorIn` for `bumpalo::boxed::Box<'a,
[T]>`.
* Added running tests under MIRI in CI for additional confidence in unsafe code.
* Publicly exposed `bumpalo::collections::Vec::drain_filter` since the
corresponding `std::vec::Vec` method has stabilized.
### Changed
* `Bump::new` will not allocate a backing chunk until the first allocation
inside the bump arena now.
### Fixed
* Properly account for alignment changes when growing or shrinking an existing
allocation.
* Removed all internal integer-to-pointer casts, to play better with UB checkers
like MIRI.
--------------------------------------------------------------------------------
## 3.9.1
Released 2022-01-06.
### Fixed
* Fixed link to logo in docs and README.md
--------------------------------------------------------------------------------
## 3.9.0
Released 2022-01-05.
### Changed
* The minimum supported Rust version (MSRV) has been raised to Rust 1.54.0.
* `bumpalo::collections::Vec<T>` implements relevant traits for all arrays of
any size `N` via const generics. Previously, it was just arrays up to length
32. Similar for `bumpalo::boxed::Box<[T; N]>`.
--------------------------------------------------------------------------------
## 3.8.0
Released 2021-10-19.
### Added
* Added the `CollectIn` and `FromIteratorIn` traits to make building a
collection from an iterator easier. These new traits live in the
`bumpalo::collections` module and are implemented by
`bumpalo::collections::{String,Vec}`.
* Added the `Bump::iter_allocated_chunks_raw` method, which is an `unsafe`, raw
version of `Bump::iter_allocated_chunks`. The new method does not take an
exclusive borrow of the `Bump` and yields raw pointer-and-length pairs for
each chunk in the bump. It is the caller's responsibility to ensure that no
allocation happens in the `Bump` while iterating over chunks and that there
are no active borrows of allocated data if they want to turn any
pointer-and-length pairs into slices.
--------------------------------------------------------------------------------
## 3.7.1
Released 2021-09-17.
### Changed
* The packaged crate uploaded to crates.io when `bumpalo` is published is now
smaller, thanks to excluding unnecessary files.
--------------------------------------------------------------------------------
## 3.7.0
Released 2020-05-28.
### Added
* Added `Borrow` and `BorrowMut` trait implementations for
`bumpalo::collections::Vec` and
### Changed
* When allocating a new chunk fails, don't immediately give up. Instead, try
allocating a chunk that is half that size, and if that fails, then try half of
*that* size, etc until either we successfully allocate a chunk or we fail to
allocate the minimum chunk size and then finally give
--------------------------------------------------------------------------------
## 3.6.1
Released 2020-02-18.
### Added
* Improved performance of `Bump`'s `Allocator::grow_zeroed` trait method
--------------------------------------------------------------------------------
## 3.6.0
Released 2020-01-29.
### Added
* Added a few new flavors of allocation:
* `try_alloc` for fallible, by-value allocation
* `try_alloc_with` for fallible allocation with an infallible initializer
function
* `alloc_try_with` for infallible allocation with a fallible initializer
function
* `try_alloc_try_with` method for fallible allocation with a fallible
initializer function
We already have infallible, by-value allocation (`alloc`) and infallible
allocation with an infallible initializer (`alloc_with`). With these new
methods, we now have every combination covered.
methods!
--------------------------------------------------------------------------------
## 3.5.0
Released 2020-01-22.
### Added
* Added experimental, unstable support for the unstable, nightly Rust
`allocator_api` feature.
The `allocator_api` feature defines an `Allocator` trait and exposes custom
allocators for `std` types. Bumpalo has a matching `allocator_api` cargo
feature to enable implementing `Allocator` and using `Bump` with `std`
collections.
First, enable the `allocator_api` feature in your `Cargo.toml`:
```toml
[dependencies]
bumpalo = { version = "3.5", features = ["allocator_api"] }
```
Next, enable the `allocator_api` nightly Rust feature in your `src/lib.rs` or `src/main.rs`:
```rust
# #[cfg(feature = "allocator_api")]
# {
#![feature(allocator_api)]
# }
```
Finally, use `std` collections with `Bump`, so that their internal heap
allocations are made within the given bump arena:
```
# #![cfg_attr(feature = "allocator_api", feature(allocator_api))]
# #[cfg(feature = "allocator_api")]
# {
#![feature(allocator_api)]
use bumpalo::Bump;
// Create a new bump arena.
let bump = Bump::new();
// Create a `Vec` whose elements are allocated within the bump arena.
let mut v = Vec::new_in(&bump);
v.push(0);
v.push(1);
v.push(2);
# }
```
I'm very excited to see custom allocators in `std` coming along! Thanks to
Arthur Gautier for implementing support for the `allocator_api` feature for
Bumpalo.
--------------------------------------------------------------------------------
## 3.4.0
Released 2020-06-01.
### Added
* Added the `bumpalo::boxed::Box<T>` type. It is an owned pointer referencing a
bump-allocated value, and it runs `T`'s `Drop` implementation on the
referenced value when dropped. This type can be used by enabling the `"boxed"`
cargo feature flag.
--------------------------------------------------------------------------------
## 3.3.0
Released 2020-05-13.
### Added
* Added fallible allocation methods to `Bump`: `try_new`, `try_with_capacity`,
and `try_alloc_layout`.
* Added `Bump::chunk_capacity`
* Added `bumpalo::collections::Vec::try_reserve[_exact]`
--------------------------------------------------------------------------------
## 3.2.1
Released 2020-03-24.
### Security
* When `realloc`ing, if we allocate new space, we need to copy the old
allocation's bytes into the new space. There are `old_size` number of bytes in
the old allocation, but we were accidentally copying `new_size` number of
bytes, which could lead to copying bytes into the realloc'd space from past
the chunk that we're bump allocating out of, from unknown memory.
If an attacker can cause `realloc`s, and can read the `realoc`ed data back,
this could allow them to read things from other regions of memory that they
shouldn't be able to. For example, if some crypto keys happened to live in
memory right after a chunk we were bump allocating out of, this could allow
the attacker to read the crypto keys.
Beyond just fixing the bug and adding a regression test, I've also taken two
additional steps:
1. While we were already running the testsuite under `valgrind` in CI, because
`valgrind` exits with the same code that the program did, if there are
invalid reads/writes that happen not to trigger a segfault, the program can
still exit OK and we will be none the wiser. I've enabled the
`--error-exitcode=1` flag for `valgrind` in CI so that tests eagerly fail
in these scenarios.
2. I've written a quickcheck test to exercise `realloc`. Without the bug fix
in this patch, this quickcheck immediately triggers invalid reads when run
under `valgrind`. We didn't previously have quickchecks that exercised
`realloc` because `realloc` isn't publicly exposed directly, and instead
can only be indirectly called. This new quickcheck test exercises `realloc`
via `bumpalo::collections::Vec::resize` and
`bumpalo::collections::Vec::shrink_to_fit` calls.
This bug was introduced in version 3.0.0.
--------------------------------------------------------------------------------
## 3.2.0
Released 2020-02-07.
### Added
* Added the `bumpalo::collections::Vec::into_bump_slice_mut` method to turn a
`bumpalo::collections::Vec<'bump, T>` into a `&'bump mut [T]`.
--------------------------------------------------------------------------------
## 3.1.2
Released 2020-01-07.
### Fixed
* The `bumpalo::collections::format!` macro did not used to accept a trailing
comma like `format!(in bump; "{}", 1,)`, but it does now.
--------------------------------------------------------------------------------
## 3.1.1
Released 2020-01-03.
### Fixed
* The `bumpalo::collections::vec!` macro did not used to accept a trailing
comma like `vec![in bump; 1, 2,]`, but it does now.
--------------------------------------------------------------------------------
## 3.1.0
Released 2019-12-27.
### Added
* Added the `Bump::allocated_bytes` diagnostic method for counting the total
number of bytes a `Bump` has allocated.
--------------------------------------------------------------------------------
# 3.0.0
Released 2019-12-20.
## Added
* Added `Bump::alloc_str` for copying string slices into a `Bump`.
* Added `Bump::alloc_slice_copy` and `Bump::alloc_slice_clone` for copying or
cloning slices into a `Bump`.
* Added `Bump::alloc_slice_fill_iter` for allocating a slice in the `Bump` from
an iterator.
* Added `Bump::alloc_slice_fill_copy` and `Bump::alloc_slice_fill_clone` for
creating slices of length `n` that are filled with copies or clones of an
initial element.
* Added `Bump::alloc_slice_fill_default` for creating slices of length `n` with
the element type's default instance.
* Added `Bump::alloc_slice_fill_with` for creating slices of length `n` whose
elements are initialized with a function or closure.
* Added `Bump::iter_allocated_chunks` as a replacement for the old
`Bump::each_allocated_chunk`. The `iter_allocated_chunks` version returns an
iterator, which is more idiomatic than its old, callback-taking counterpart.
Additionally, `iter_allocated_chunks` exposes the chunks as `MaybeUninit`s
instead of slices, which makes it usable in more situations without triggering
undefined behavior. See also the note about bump direction in the "changed"
section; if you're iterating chunks, you're likely affected by that change!
* Added `Bump::with_capacity` so that you can pre-allocate a chunk with the
requested space.
### Changed
* **BREAKING:** The direction we allocate within a chunk has changed. It used to
be "upwards", from low addresses within a chunk towards high addresses. It is
now "downwards", from high addresses towards lower addresses.
Additionally, the order in which we iterate over allocated chunks has changed!
We used to iterate over chunks from oldest chunk to youngest chunk, and now we
do the opposite: the youngest chunks are iterated over first, and the oldest
chunks are iterated over last.
If you were using `Bump::each_allocated_chunk` to iterate over data that you
had previously allocated, and *you want to iterate in order of
oldest-to-youngest allocation*, you need to reverse the chunks iterator and
also reverse the order in which you loop through the data within a chunk!
For example, if you had this code:
```rust
unsafe {
bump.each_allocated_chunk(|chunk| {
for byte in chunk {
// Touch each byte in oldest-to-youngest allocation order...
}
});
}
```
It should become this code:
```rust
let mut chunks: Vec<_> = bump.iter_allocated_chunks().collect();
chunks.reverse();
for chunk in chunks {
for byte in chunk.iter().rev() {
let byte = unsafe { byte.assume_init() };
// Touch each byte in oldest-to-youngest allocation order...
}
}
```
The good news is that this change yielded a *speed up in allocation throughput
of 3-19%!*
* **BREAKING:** The `collections` cargo feature is no longer on by default. You
must explicitly turn it on if you intend to use the `bumpalo::collections`
module.
* `Bump::reset` will now retain only the last allocated chunk (the biggest),
rather than only the first allocated chunk (the smallest). This should enable
`Bump` to better adapt to workload sizes and quickly reach a steady state
where new chunks are not requested from the global allocator.
### Removed
* The `Bump::each_allocated_chunk` method is removed in favor of
`Bump::iter_allocated_chunks`. Note that its safety requirements for reading
from the allocated chunks are slightly different from the old
`each_allocated_chunk`: only up to 16-byte alignment is supported now. If you
allocate anything with greater alignment than that into the bump arena, there
might be uninitialized padding inserted in the chunks, and therefore it is no
longer safe to read them via `MaybeUninit::assume_init`. See also the note
about bump direction in the "changed" section; if you're iterating chunks,
you're likely affected by that change!
* The `std` cargo feature has been removed, since this crate is now always
no-std.
## Fixed
* Fixed a bug involving potential integer overflows with large requested
allocation sizes.
--------------------------------------------------------------------------------
# 2.6.0
Released 2019-08-19.
* Implement `Send` for `Bump`.
--------------------------------------------------------------------------------
# 2.5.0
Released 2019-07-01.
* Add `alloc_slice_copy` and `alloc_slice_clone` methods that allocate space for
slices and either copy (with bound `T: Copy`) or clone (with bound `T: Clone`)
the provided slice's data into the newly allocated space.
--------------------------------------------------------------------------------
# 2.4.3
Released 2019-05-20.
* Fixed a bug where chunks were always deallocated with the default chunk
layout, not the layout that the chunk was actually allocated with (i.e. if we
started growing larger chunks with larger layouts, we would deallocate those
chunks with an incorrect layout).
--------------------------------------------------------------------------------
# 2.4.2
Released 2019-05-17.
* Added an implementation `Default` for `Bump`.
* Made it so that if bump allocation within a chunk overflows, we still try to
allocate a new chunk to bump out of for the requested allocation. This can
avoid some OOMs in scenarios where the chunk we are currently allocating out
of is very near the high end of the address space, and there is still
available address space lower down for new chunks.
--------------------------------------------------------------------------------
# 2.4.1
Released 2019-04-19.
* Added readme metadata to Cargo.toml so it shows up on crates.io
--------------------------------------------------------------------------------
# 2.4.0
Released 2019-04-19.
* Added support for `realloc`ing in-place when the pointer being `realloc`ed is
the last allocation made from the bump arena. This should speed up various
`String`, `Vec`, and `format!` operations in many cases.
--------------------------------------------------------------------------------
# 2.3.0
Released 2019-03-26.
* Add the `alloc_with` method, that (usually) avoids stack-allocating the
allocated value and then moving it into the bump arena. This avoids potential
stack overflows in release mode when allocating very large objects, and also
some `memcpy` calls. This is similar to the `copyless` crate. Read [the
`alloc_with` doc comments][alloc-with-doc-comments] and [the original issue
proposing this API][issue-proposing-alloc-with] for more.
[alloc-with-doc-comments]: https://github.com/fitzgen/bumpalo/blob/9f47aee8a6839ba65c073b9ad5372aacbbd02352/src/lib.rs#L436-L475
--------------------------------------------------------------------------------
# 2.2.2
Released 2019-03-18.
* Fix a regression from 2.2.1 where chunks were not always aligned to the chunk
footer's alignment.
--------------------------------------------------------------------------------
# 2.2.1
Released 2019-03-18.
* Fix a regression in 2.2.0 where newly allocated bump chunks could fail to have
capacity for a large requested bump allocation in some corner cases.
--------------------------------------------------------------------------------
# 2.2.0
Released 2019-03-15.
* Chunks in an arena now start out small, and double in size as more chunks are
requested.
--------------------------------------------------------------------------------
# 2.1.0
Released 2019-02-12.
* Added the `into_bump_slice` method on `bumpalo::collections::Vec<T>`.
--------------------------------------------------------------------------------
# 2.0.0
Released 2019-02-11.
* Removed the `BumpAllocSafe` trait.
* Correctly detect overflows from large allocations and panic.
--------------------------------------------------------------------------------
# 1.2.0
Released 2019-01-15.
* Fixed an overly-aggressive `debug_assert!` that had false positives.
* Ported to Rust 2018 edition.
--------------------------------------------------------------------------------
# 1.1.0
Released 2018-11-28.
* Added the `collections` module, which contains ports of `std`'s collection
types that are compatible with backing their storage in `Bump` arenas.
* Lifted the limits on size and alignment of allocations.
--------------------------------------------------------------------------------
# 1.0.2
--------------------------------------------------------------------------------
# 1.0.1
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# 1.0.0