tokio::io::ReadBuf uses names `new` and `uninit` for its constructors.
For consistency with that, rename recently introduced UninitSlice
constructors to match those names.
Introduce UninitSlice::from_slice and UninitSlice::from_uninit_slice
methods which safely create Uninit slice from provided slice of maybe
uninitialised or initialised memory.
In addition, add `From<&mut [T]>` implementations (for `T=u8` and
`T=MaybeUninit<u8>`) which do conversion from slice to UninitSlice.
Closes: #552
This adds an unsafe method to convert a `&mut UninitSlice` into a
`&mut [MaybeUninit<u8>]`. This method is unsafe because some of the
bytes in the slice may be initialized, and the caller should not
overwrite them with uninitialized bytes.
This came about when auditing [tokio-util's udp frame], where they want
to pass the unitialized portion of a `BytesMut` to [ReadBuf::uninit].
They need to do this unsafe pointer casting in a few places, which
complicates audits. This method lets us document the safety invariants
the caller needs to maintain when doing this conversion.
[tokio-util's udp frame]: https://github.com/tokio-rs/tokio/blob/master/tokio-util/src/udp/frame.rs#L87
[ReadBuf::uninit]: https://docs.rs/tokio/latest/tokio/io/struct.ReadBuf.html#method.uninit
Equivalent to
```
for _ in 0..cnt {
self.put_u8(val);
}
```
but may work faster.
Name and signature is chosen to be consistent with `ptr::write_bytes`.
Include three specializations:
* `Vec<u8>`
* `&mut [u8]`
* `BytesMut`
`BytesMut` and `&mut [u8]` specializations use `ptr::write`, `Vec<u8>`
specialization uses `Vec::resize`.
Avoid allocation when `Take` or `Chain` is composed of `Bytes`
objects.
This works now for `Take`.
`Chain` it works if the requested bytes does not cross boundary
between `Chain` members.
This appears to be the primary cause of significant performance
regressions in the `prost` test suite in the 0.5 to 0.6 transition. See
danburkert/prost#381.
The `bytes()` / `bytes_mut()` name implies the method returns the full
set of bytes represented by `Buf`/`BufMut`. To rectify this, the methods
are renamed to `chunk()` and `chunk_mut()` to reflect the partial nature
of the returned byte slice.
`bytes_vectored()` is renamed `chunks_vectored()`.
Closes#447
This method replaces `Buf::to_bytes()`, providing a method that copies a
subset of the remaining buffer into a `Bytes` value. As this is strictly
more flexible, `to_bytes()` is removed.
Fixes: #129, #398
The way BufMut uses MaybeUninit can lead to unsoundness. This replaces
MaybeUnit with a type owned by bytes so we can ensure the usage patterns
are sound.
Refs: #328
