| Message ID | 20240911225449.152928-15-dakr@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Generic `Allocator` support for Rust | expand |
On 12.09.24 00:52, Danilo Krummrich wrote: > Implement `IntoIterator` for `Vec`, `Vec`'s `IntoIter` type, as well as > `Iterator` for `IntoIter`. > > `Vec::into_iter` disassembles the `Vec` into its raw parts; additionally, > `IntoIter` keeps track of a separate pointer, which is incremented > correspondingsly as the iterator advances, while the length, or the count > of elements, is decremented. > > This also means that `IntoIter` takes the ownership of the backing > buffer and is responsible to drop the remaining elements and free the > backing buffer, if it's dropped. > > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Danilo Krummrich <dakr@kernel.org> > --- > rust/kernel/alloc.rs | 1 + > rust/kernel/alloc/kvec.rs | 181 ++++++++++++++++++++++++++++++++++++++ > 2 files changed, 182 insertions(+) One comment below, with that fixed: Reviewed-by: Benno Lossin <benno.lossin@proton.me> --- Cheers, Benno > +impl<T, A> IntoIterator for Vec<T, A> > +where > + A: Allocator, > +{ > + type Item = T; > + type IntoIter = IntoIter<T, A>; > + > + /// Consumes the `Vec<T, A>` and creates an `Iterator`, which moves each value out of the > + /// vector (from start to end). > + /// > + /// # Examples > + /// > + /// ``` > + /// let v = kernel::kvec![1, 2]?; > + /// let mut v_iter = v.into_iter(); > + /// > + /// let first_element: Option<u32> = v_iter.next(); > + /// > + /// assert_eq!(first_element, Some(1)); > + /// assert_eq!(v_iter.next(), Some(2)); > + /// assert_eq!(v_iter.next(), None); > + /// > + /// # Ok::<(), Error>(()) > + /// ``` > + /// > + /// ``` > + /// let v = kernel::kvec![]; > + /// let mut v_iter = v.into_iter(); > + /// > + /// let first_element: Option<u32> = v_iter.next(); > + /// > + /// assert_eq!(first_element, None); > + /// > + /// # Ok::<(), Error>(()) > + /// ``` > + #[inline] > + fn into_iter(self) -> Self::IntoIter { > + let (ptr, len, cap) = self.into_raw_parts(); > + > + IntoIter { > + ptr, > + // SAFETY: `ptr` is either a dangling pointer or a pointer to a valid memory > + // allocation, allocated with `A`. > + buf: unsafe { NonNull::new_unchecked(ptr) }, Instead of this `unsafe` call, you can do let buf = self.ptr; Before the call to `into_raw_parts`. > + len, > + cap, > + _p: PhantomData::<A>, > + } > + } > +} > -- > 2.46.0 >
On Thu, 12 Sep 2024 00:52:50 +0200 Danilo Krummrich <dakr@kernel.org> wrote: > Implement `IntoIterator` for `Vec`, `Vec`'s `IntoIter` type, as well as > `Iterator` for `IntoIter`. > > `Vec::into_iter` disassembles the `Vec` into its raw parts; additionally, > `IntoIter` keeps track of a separate pointer, which is incremented > correspondingsly as the iterator advances, while the length, or the count > of elements, is decremented. > > This also means that `IntoIter` takes the ownership of the backing > buffer and is responsible to drop the remaining elements and free the > backing buffer, if it's dropped. > > Reviewed-by: Alice Ryhl <aliceryhl@google.com> > Signed-off-by: Danilo Krummrich <dakr@kernel.org> A small nit below, with it fixed: Reviewed-by: Gary Guo <gary@garyguo.net> > --- > rust/kernel/alloc.rs | 1 + > rust/kernel/alloc/kvec.rs | 181 ++++++++++++++++++++++++++++++++++++++ > 2 files changed, 182 insertions(+) > > diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs > index 4fb983b63d46..e8fbae2adadb 100644 > --- a/rust/kernel/alloc.rs > +++ b/rust/kernel/alloc.rs > @@ -19,6 +19,7 @@ > pub use self::kbox::KVBox; > pub use self::kbox::VBox; > > +pub use self::kvec::IntoIter; > pub use self::kvec::KVVec; > pub use self::kvec::KVec; > pub use self::kvec::VVec; > diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs > index 631a44e19f35..e91761c5c52d 100644 > --- a/rust/kernel/alloc/kvec.rs > +++ b/rust/kernel/alloc/kvec.rs > @@ -14,6 +14,7 @@ > ops::DerefMut, > ops::Index, > ops::IndexMut, > + ptr, > ptr::NonNull, > slice, > slice::SliceIndex, > @@ -636,3 +637,183 @@ fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] } > impl_slice_eq! { [A: Allocator] [T], Vec<U, A> } > impl_slice_eq! { [A: Allocator, const N: usize] Vec<T, A>, [U; N] } > impl_slice_eq! { [A: Allocator, const N: usize] Vec<T, A>, &[U; N] } > + > +impl<'a, T, A> IntoIterator for &'a Vec<T, A> > +where > + A: Allocator, > +{ > + type Item = &'a T; > + type IntoIter = slice::Iter<'a, T>; > + > + fn into_iter(self) -> Self::IntoIter { > + self.iter() > + } > +} > + > +impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec<T, A> > +where > + A: Allocator, > +{ > + type Item = &'a mut T; > + type IntoIter = slice::IterMut<'a, T>; > + > + fn into_iter(self) -> Self::IntoIter { > + self.iter_mut() > + } > +} > + > +/// An [`Iterator`] implementation for [`Vec`] that moves elements out of a vector. > +/// > +/// This structure is created by the [`Vec::into_iter`] method on [`Vec`] (provided by the > +/// [`IntoIterator`] trait). > +/// > +/// # Examples > +/// > +/// ``` > +/// let v = kernel::kvec![0, 1, 2]?; > +/// let iter = v.into_iter(); > +/// > +/// # Ok::<(), Error>(()) > +/// ``` > +pub struct IntoIter<T, A: Allocator> { > + ptr: *mut T, > + buf: NonNull<T>, > + len: usize, > + cap: usize, > + _p: PhantomData<A>, > +} > + > +impl<T, A> IntoIter<T, A> > +where > + A: Allocator, > +{ > + fn as_raw_mut_slice(&mut self) -> *mut [T] { > + ptr::slice_from_raw_parts_mut(self.ptr, self.len) > + } > +} > + > +impl<T, A> Iterator for IntoIter<T, A> > +where > + A: Allocator, > +{ > + type Item = T; > + > + /// # Examples > + /// > + /// ``` > + /// let v = kernel::kvec![1, 2, 3]?; > + /// let mut it = v.into_iter(); > + /// > + /// assert_eq!(it.next(), Some(1)); > + /// assert_eq!(it.next(), Some(2)); > + /// assert_eq!(it.next(), Some(3)); > + /// assert_eq!(it.next(), None); > + /// > + /// # Ok::<(), Error>(()) > + /// ``` > + fn next(&mut self) -> Option<T> { > + if self.len == 0 { > + return None; > + } > + > + let current = self.ptr; > + > + // SAFETY: We can't overflow; decreasing `self.len` by one every time we advance `self.ptr` > + // by one guarantees that. > + unsafe { self.ptr = self.ptr.add(1) }; > + > + self.len -= 1; > + > + // SAFETY: `current` is guaranteed to point at a valid element within the buffer. > + Some(unsafe { current.read() }) > + } > + > + /// # Examples > + /// > + /// ``` > + /// let v: KVec<u32> = kernel::kvec![1, 2, 3]?; > + /// let mut iter = v.into_iter(); > + /// let size = iter.size_hint().0; > + /// > + /// iter.next(); > + /// assert_eq!(iter.size_hint().0, size - 1); > + /// > + /// iter.next(); > + /// assert_eq!(iter.size_hint().0, size - 2); > + /// > + /// iter.next(); > + /// assert_eq!(iter.size_hint().0, size - 3); > + /// > + /// # Ok::<(), Error>(()) > + /// ``` > + fn size_hint(&self) -> (usize, Option<usize>) { > + (self.len, Some(self.len)) > + } > +} > + > +impl<T, A> Drop for IntoIter<T, A> > +where > + A: Allocator, > +{ > + fn drop(&mut self) { > + // SAFETY: The pointer in `self.0` is guaranteed to be valid by the type invariant. > + unsafe { ptr::drop_in_place(self.as_raw_mut_slice()) }; `as_raw_mut_slice` is only used once? It's better to construct the raw pointer directly so there's no need to refer to some other place when reviewing unsafe code. > + > + // If `cap == 0` we never allocated any memory in the first place. > + if self.cap != 0 { > + // SAFETY: `self.buf` was previously allocated with `A`. > + unsafe { A::free(self.buf.cast()) }; > + } > + } > +} > + > +impl<T, A> IntoIterator for Vec<T, A> > +where > + A: Allocator, > +{ > + type Item = T; > + type IntoIter = IntoIter<T, A>; > + > + /// Consumes the `Vec<T, A>` and creates an `Iterator`, which moves each value out of the > + /// vector (from start to end). > + /// > + /// # Examples > + /// > + /// ``` > + /// let v = kernel::kvec![1, 2]?; > + /// let mut v_iter = v.into_iter(); > + /// > + /// let first_element: Option<u32> = v_iter.next(); > + /// > + /// assert_eq!(first_element, Some(1)); > + /// assert_eq!(v_iter.next(), Some(2)); > + /// assert_eq!(v_iter.next(), None); > + /// > + /// # Ok::<(), Error>(()) > + /// ``` > + /// > + /// ``` > + /// let v = kernel::kvec![]; > + /// let mut v_iter = v.into_iter(); > + /// > + /// let first_element: Option<u32> = v_iter.next(); > + /// > + /// assert_eq!(first_element, None); > + /// > + /// # Ok::<(), Error>(()) > + /// ``` > + #[inline] > + fn into_iter(self) -> Self::IntoIter { > + let (ptr, len, cap) = self.into_raw_parts(); > + > + IntoIter { > + ptr, > + // SAFETY: `ptr` is either a dangling pointer or a pointer to a valid memory > + // allocation, allocated with `A`. > + buf: unsafe { NonNull::new_unchecked(ptr) }, > + len, > + cap, > + _p: PhantomData::<A>, > + } > + } > +}
diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs index 4fb983b63d46..e8fbae2adadb 100644 --- a/rust/kernel/alloc.rs +++ b/rust/kernel/alloc.rs @@ -19,6 +19,7 @@ pub use self::kbox::KVBox; pub use self::kbox::VBox; +pub use self::kvec::IntoIter; pub use self::kvec::KVVec; pub use self::kvec::KVec; pub use self::kvec::VVec; diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs index 631a44e19f35..e91761c5c52d 100644 --- a/rust/kernel/alloc/kvec.rs +++ b/rust/kernel/alloc/kvec.rs @@ -14,6 +14,7 @@ ops::DerefMut, ops::Index, ops::IndexMut, + ptr, ptr::NonNull, slice, slice::SliceIndex, @@ -636,3 +637,183 @@ fn eq(&self, other: &$rhs) -> bool { self[..] == other[..] } impl_slice_eq! { [A: Allocator] [T], Vec<U, A> } impl_slice_eq! { [A: Allocator, const N: usize] Vec<T, A>, [U; N] } impl_slice_eq! { [A: Allocator, const N: usize] Vec<T, A>, &[U; N] } + +impl<'a, T, A> IntoIterator for &'a Vec<T, A> +where + A: Allocator, +{ + type Item = &'a T; + type IntoIter = slice::Iter<'a, T>; + + fn into_iter(self) -> Self::IntoIter { + self.iter() + } +} + +impl<'a, T, A: Allocator> IntoIterator for &'a mut Vec<T, A> +where + A: Allocator, +{ + type Item = &'a mut T; + type IntoIter = slice::IterMut<'a, T>; + + fn into_iter(self) -> Self::IntoIter { + self.iter_mut() + } +} + +/// An [`Iterator`] implementation for [`Vec`] that moves elements out of a vector. +/// +/// This structure is created by the [`Vec::into_iter`] method on [`Vec`] (provided by the +/// [`IntoIterator`] trait). +/// +/// # Examples +/// +/// ``` +/// let v = kernel::kvec![0, 1, 2]?; +/// let iter = v.into_iter(); +/// +/// # Ok::<(), Error>(()) +/// ``` +pub struct IntoIter<T, A: Allocator> { + ptr: *mut T, + buf: NonNull<T>, + len: usize, + cap: usize, + _p: PhantomData<A>, +} + +impl<T, A> IntoIter<T, A> +where + A: Allocator, +{ + fn as_raw_mut_slice(&mut self) -> *mut [T] { + ptr::slice_from_raw_parts_mut(self.ptr, self.len) + } +} + +impl<T, A> Iterator for IntoIter<T, A> +where + A: Allocator, +{ + type Item = T; + + /// # Examples + /// + /// ``` + /// let v = kernel::kvec![1, 2, 3]?; + /// let mut it = v.into_iter(); + /// + /// assert_eq!(it.next(), Some(1)); + /// assert_eq!(it.next(), Some(2)); + /// assert_eq!(it.next(), Some(3)); + /// assert_eq!(it.next(), None); + /// + /// # Ok::<(), Error>(()) + /// ``` + fn next(&mut self) -> Option<T> { + if self.len == 0 { + return None; + } + + let current = self.ptr; + + // SAFETY: We can't overflow; decreasing `self.len` by one every time we advance `self.ptr` + // by one guarantees that. + unsafe { self.ptr = self.ptr.add(1) }; + + self.len -= 1; + + // SAFETY: `current` is guaranteed to point at a valid element within the buffer. + Some(unsafe { current.read() }) + } + + /// # Examples + /// + /// ``` + /// let v: KVec<u32> = kernel::kvec![1, 2, 3]?; + /// let mut iter = v.into_iter(); + /// let size = iter.size_hint().0; + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 1); + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 2); + /// + /// iter.next(); + /// assert_eq!(iter.size_hint().0, size - 3); + /// + /// # Ok::<(), Error>(()) + /// ``` + fn size_hint(&self) -> (usize, Option<usize>) { + (self.len, Some(self.len)) + } +} + +impl<T, A> Drop for IntoIter<T, A> +where + A: Allocator, +{ + fn drop(&mut self) { + // SAFETY: The pointer in `self.0` is guaranteed to be valid by the type invariant. + unsafe { ptr::drop_in_place(self.as_raw_mut_slice()) }; + + // If `cap == 0` we never allocated any memory in the first place. + if self.cap != 0 { + // SAFETY: `self.buf` was previously allocated with `A`. + unsafe { A::free(self.buf.cast()) }; + } + } +} + +impl<T, A> IntoIterator for Vec<T, A> +where + A: Allocator, +{ + type Item = T; + type IntoIter = IntoIter<T, A>; + + /// Consumes the `Vec<T, A>` and creates an `Iterator`, which moves each value out of the + /// vector (from start to end). + /// + /// # Examples + /// + /// ``` + /// let v = kernel::kvec![1, 2]?; + /// let mut v_iter = v.into_iter(); + /// + /// let first_element: Option<u32> = v_iter.next(); + /// + /// assert_eq!(first_element, Some(1)); + /// assert_eq!(v_iter.next(), Some(2)); + /// assert_eq!(v_iter.next(), None); + /// + /// # Ok::<(), Error>(()) + /// ``` + /// + /// ``` + /// let v = kernel::kvec![]; + /// let mut v_iter = v.into_iter(); + /// + /// let first_element: Option<u32> = v_iter.next(); + /// + /// assert_eq!(first_element, None); + /// + /// # Ok::<(), Error>(()) + /// ``` + #[inline] + fn into_iter(self) -> Self::IntoIter { + let (ptr, len, cap) = self.into_raw_parts(); + + IntoIter { + ptr, + // SAFETY: `ptr` is either a dangling pointer or a pointer to a valid memory + // allocation, allocated with `A`. + buf: unsafe { NonNull::new_unchecked(ptr) }, + len, + cap, + _p: PhantomData::<A>, + } + } +}