rust: rbtree: add mutable iterator (cf5397d1) · Commits · git / linux-nf

rust/kernel/rbtree.rs

+89 −14

Original line number	Diff line number	Diff line
		@@ -12,7 +12,7 @@
		cmp::{Ord, Ordering},
		marker::PhantomData,
		mem::MaybeUninit,
		ptr::{addr_of_mut, NonNull},
		ptr::{addr_of_mut, from_mut, NonNull},
		};

		/// A red-black tree with owned nodes.
		@@ -194,11 +194,31 @@ pub fn new() -> Self {

		/// Returns an iterator over the tree nodes, sorted by key.
		pub fn iter(&self) -> Iter<'_, K, V> {
		// INVARIANT: `bindings::rb_first` returns a valid pointer to a tree node given a valid pointer to a tree root.
		Iter {
		_tree: PhantomData,
		// SAFETY: `self.root` is a valid pointer to the tree root.
		// INVARIANT:
		// - `self.root` is a valid pointer to a tree root.
		// - `bindings::rb_first` produces a valid pointer to a node given `root` is valid.
		iter_raw: IterRaw {
		// SAFETY: by the invariants, all pointers are valid.
		next: unsafe { bindings::rb_first(&self.root) },
		_phantom: PhantomData,
		},
		}
		}

		/// Returns a mutable iterator over the tree nodes, sorted by key.
		pub fn iter_mut(&mut self) -> IterMut<'_, K, V> {
		IterMut {
		_tree: PhantomData,
		// INVARIANT:
		// - `self.root` is a valid pointer to a tree root.
		// - `bindings::rb_first` produces a valid pointer to a node given `root` is valid.
		iter_raw: IterRaw {
		// SAFETY: by the invariants, all pointers are valid.
		next: unsafe { bindings::rb_first(from_mut(&mut self.root)) },
		_phantom: PhantomData,
		},
		}
		}

		@@ -211,6 +231,11 @@ pub fn keys(&self) -> impl Iterator<Item = &'_ K> {
		pub fn values(&self) -> impl Iterator<Item = &'_ V> {
		self.iter().map(\|(_, v)\| v)
		}

		/// Returns a mutable iterator over the values of the nodes in the tree, sorted by key.
		pub fn values_mut(&mut self) -> impl Iterator<Item = &'_ mut V> {
		self.iter_mut().map(\|(_, v)\| v)
		}
		}

		impl<K, V> RBTree<K, V>
		@@ -414,13 +439,9 @@ fn into_iter(self) -> Self::IntoIter {
		/// An iterator over the nodes of a [`RBTree`].
		///
		/// Instances are created by calling [`RBTree::iter`].
		///
		/// # Invariants
		/// - `self.next` is a valid pointer.
		/// - `self.next` points to a node stored inside of a valid `RBTree`.
		pub struct Iter<'a, K, V> {
		_tree: PhantomData<&'a RBTree<K, V>>,
		next: *mut bindings::rb_node,
		iter_raw: IterRaw<K, V>,
		}

		// SAFETY: The [`Iter`] gives out immutable references to K and V, so it has the same
		@@ -434,21 +455,75 @@ unsafe impl<'a, K: Sync, V: Sync> Sync for Iter<'a, K, V> {}
		impl<'a, K, V> Iterator for Iter<'a, K, V> {
		type Item = (&'a K, &'a V);

		fn next(&mut self) -> Option<Self::Item> {
		// SAFETY: Due to `self._tree`, `k` and `v` are valid for the lifetime of `'a`.
		self.iter_raw.next().map(\|(k, v)\| unsafe { (&k, &v) })
		}
		}

		impl<'a, K, V> IntoIterator for &'a mut RBTree<K, V> {
		type Item = (&'a K, &'a mut V);
		type IntoIter = IterMut<'a, K, V>;

		fn into_iter(self) -> Self::IntoIter {
		self.iter_mut()
		}
		}

		/// A mutable iterator over the nodes of a [`RBTree`].
		///
		/// Instances are created by calling [`RBTree::iter_mut`].
		pub struct IterMut<'a, K, V> {
		_tree: PhantomData<&'a mut RBTree<K, V>>,
		iter_raw: IterRaw<K, V>,
		}

		// SAFETY: The [`IterMut`] has exclusive access to both `K` and `V`, so it is sufficient to require them to be `Send`.
		// The iterator only gives out immutable references to the keys, but since the iterator has excusive access to those same
		// keys, `Send` is sufficient. `Sync` would be okay, but it is more restrictive to the user.
		unsafe impl<'a, K: Send, V: Send> Send for IterMut<'a, K, V> {}

		// SAFETY: The [`IterMut`] gives out immutable references to K and mutable references to V, so it has the same
		// thread safety requirements as mutable references.
		unsafe impl<'a, K: Sync, V: Sync> Sync for IterMut<'a, K, V> {}

		impl<'a, K, V> Iterator for IterMut<'a, K, V> {
		type Item = (&'a K, &'a mut V);

		fn next(&mut self) -> Option<Self::Item> {
		self.iter_raw.next().map(\|(k, v)\|
		// SAFETY: Due to `&mut self`, we have exclusive access to `k` and `v`, for the lifetime of `'a`.
		unsafe { (&k, &mut v) })
		}
		}

		/// A raw iterator over the nodes of a [`RBTree`].
		///
		/// # Invariants
		/// - `self.next` is a valid pointer.
		/// - `self.next` points to a node stored inside of a valid `RBTree`.
		struct IterRaw<K, V> {
		next: *mut bindings::rb_node,
		_phantom: PhantomData<fn() -> (K, V)>,
		}

		impl<K, V> Iterator for IterRaw<K, V> {
		type Item = (mut K, mut V);

		fn next(&mut self) -> Option<Self::Item> {
		if self.next.is_null() {
		return None;
		}

		// SAFETY: By the type invariant of `Iter`, `self.next` is a valid node in an `RBTree`,
		// SAFETY: By the type invariant of `IterRaw`, `self.next` is a valid node in an `RBTree`,
		// and by the type invariant of `RBTree`, all nodes point to the links field of `Node<K, V>` objects.
		let cur = unsafe { container_of!(self.next, Node<K, V>, links) };
		let cur = unsafe { container_of!(self.next, Node<K, V>, links) }.cast_mut();

		// SAFETY: `self.next` is a valid tree node by the type invariants.
		self.next = unsafe { bindings::rb_next(self.next) };

		// SAFETY: By the same reasoning above, it is safe to dereference the node. Additionally,
		// it is ok to return a reference to members because the iterator must outlive it.
		Some(unsafe { (&(cur).key, &(cur).value) })
		// SAFETY: By the same reasoning above, it is safe to dereference the node.
		Some(unsafe { (addr_of_mut!((cur).key), addr_of_mut!((cur).value)) })
		}
		}