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Message-ID: <20240603-b4-rbtree-v4-3-308e43d6abfc@google.com>
Date: Mon, 03 Jun 2024 16:05:18 +0000
From: Matt Gilbride <mattgilbride@...gle.com>
To: Miguel Ojeda <ojeda@...nel.org>, Alex Gaynor <alex.gaynor@...il.com>,
Wedson Almeida Filho <wedsonaf@...il.com>, Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>,
"Björn Roy Baron" <bjorn3_gh@...tonmail.com>, Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...sung.com>, Alice Ryhl <aliceryhl@...gle.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Arve Hjønnevåg" <arve@...roid.com>, Todd Kjos <tkjos@...roid.com>, Martijn Coenen <maco@...roid.com>,
Joel Fernandes <joel@...lfernandes.org>, Carlos Llamas <cmllamas@...gle.com>,
Suren Baghdasaryan <surenb@...gle.com>, Christian Brauner <brauner@...nel.org>
Cc: Rob Landley <rob@...dley.net>, Davidlohr Bueso <dave@...olabs.net>,
Michel Lespinasse <michel@...pinasse.org>, rust-for-linux@...r.kernel.org,
linux-kernel@...r.kernel.org, Matt Gilbride <mattgilbride@...gle.com>
Subject: [PATCH v4 3/6] rust: rbtree: add iterator
From: Wedson Almeida Filho <wedsonaf@...il.com>
- Add Iterator implementation for `RBTree`, allowing
iteration over (key, value) pairs in key order.
- Add individual `keys()` and `values()` functions to iterate over keys
or values alone.
- Update doctests to use iteration instead of explicitly getting items.
Iteration is needed by the binder driver to enumerate all values in a
tree for oneway spam detection [1].
Link: https://lore.kernel.org/rust-for-linux/20231101-rust-binder-v1-17-08ba9197f637@google.com/ [1]
Signed-off-by: Wedson Almeida Filho <wedsonaf@...il.com>
Reviewed-by: Alice Ryhl <aliceryhl@...gle.com>
Tested-by: Alice Ryhl <aliceryhl@...gle.com>
Signed-off-by: Matt Gilbride <mattgilbride@...gle.com>
---
rust/kernel/rbtree.rs | 130 +++++++++++++++++++++++++++++++++++++++++++-------
1 file changed, 112 insertions(+), 18 deletions(-)
diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs
index 6c4e259f7516..6ebea833e5a9 100644
--- a/rust/kernel/rbtree.rs
+++ b/rust/kernel/rbtree.rs
@@ -47,14 +47,30 @@
/// assert_eq!(tree.get(&30).unwrap(), &300);
/// }
///
+/// // Iterate over the nodes we just inserted.
+/// {
+/// let mut iter = tree.iter();
+/// assert_eq!(iter.next().unwrap(), (&10, &100));
+/// assert_eq!(iter.next().unwrap(), (&20, &200));
+/// assert_eq!(iter.next().unwrap(), (&30, &300));
+/// assert!(iter.next().is_none());
+/// }
+///
+/// // Print all elements.
+/// for (key, value) in &tree {
+/// pr_info!("{} = {}\n", key, value);
+/// }
+///
/// // Replace one of the elements.
/// tree.try_create_and_insert(10, 1000, flags::GFP_KERNEL)?;
///
/// // Check that the tree reflects the replacement.
/// {
-/// assert_eq!(tree.get(&10).unwrap(), &1000);
-/// assert_eq!(tree.get(&20).unwrap(), &200);
-/// assert_eq!(tree.get(&30).unwrap(), &300);
+/// let mut iter = tree.iter();
+/// assert_eq!(iter.next().unwrap(), (&10, &1000));
+/// assert_eq!(iter.next().unwrap(), (&20, &200));
+/// assert_eq!(iter.next().unwrap(), (&30, &300));
+/// assert!(iter.next().is_none());
/// }
///
/// // Change the value of one of the elements.
@@ -62,9 +78,11 @@
///
/// // Check that the tree reflects the update.
/// {
-/// assert_eq!(tree.get(&10).unwrap(), &1000);
-/// assert_eq!(tree.get(&20).unwrap(), &200);
-/// assert_eq!(tree.get(&30).unwrap(), &3000);
+/// let mut iter = tree.iter();
+/// assert_eq!(iter.next().unwrap(), (&10, &1000));
+/// assert_eq!(iter.next().unwrap(), (&20, &200));
+/// assert_eq!(iter.next().unwrap(), (&30, &3000));
+/// assert!(iter.next().is_none());
/// }
///
/// // Remove an element.
@@ -72,9 +90,10 @@
///
/// // Check that the tree reflects the removal.
/// {
-/// assert_eq!(tree.get(&10), None);
-/// assert_eq!(tree.get(&20).unwrap(), &200);
-/// assert_eq!(tree.get(&30).unwrap(), &3000);
+/// let mut iter = tree.iter();
+/// assert_eq!(iter.next().unwrap(), (&20, &200));
+/// assert_eq!(iter.next().unwrap(), (&30, &3000));
+/// assert!(iter.next().is_none());
/// }
///
/// # Ok::<(), Error>(())
@@ -114,9 +133,11 @@
///
/// // Check the nodes we just inserted.
/// {
-/// assert_eq!(tree.get(&10).unwrap(), &100);
-/// assert_eq!(tree.get(&20).unwrap(), &200);
-/// assert_eq!(tree.get(&30).unwrap(), &300);
+/// let mut iter = tree.iter();
+/// assert_eq!(iter.next().unwrap(), (&10, &100));
+/// assert_eq!(iter.next().unwrap(), (&20, &200));
+/// assert_eq!(iter.next().unwrap(), (&30, &300));
+/// assert!(iter.next().is_none());
/// }
///
/// // Remove a node, getting back ownership of it.
@@ -124,9 +145,10 @@
///
/// // Check that the tree reflects the removal.
/// {
-/// assert_eq!(tree.get(&10).unwrap(), &100);
-/// assert_eq!(tree.get(&20).unwrap(), &200);
-/// assert_eq!(tree.get(&30), None);
+/// let mut iter = tree.iter();
+/// assert_eq!(iter.next().unwrap(), (&10, &100));
+/// assert_eq!(iter.next().unwrap(), (&20, &200));
+/// assert!(iter.next().is_none());
/// }
///
/// // Create a preallocated reservation that we can re-use later.
@@ -138,9 +160,11 @@
///
/// // Check that the tree reflect the new insertion.
/// {
-/// assert_eq!(tree.get(&10).unwrap(), &100);
-/// assert_eq!(tree.get(&15).unwrap(), &150);
-/// assert_eq!(tree.get(&20).unwrap(), &200);
+/// let mut iter = tree.iter();
+/// assert_eq!(iter.next().unwrap(), (&10, &100));
+/// assert_eq!(iter.next().unwrap(), (&15, &150));
+/// assert_eq!(iter.next().unwrap(), (&20, &200));
+/// assert!(iter.next().is_none());
/// }
///
/// # Ok::<(), Error>(())
@@ -167,6 +191,26 @@ pub fn new() -> Self {
_p: PhantomData,
}
}
+
+ /// 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.
+ next: unsafe { bindings::rb_first(&self.root) },
+ }
+ }
+
+ /// Returns an iterator over the keys of the nodes in the tree, in sorted order.
+ pub fn keys(&self) -> impl Iterator<Item = &'_ K> {
+ self.iter().map(|(k, _)| k)
+ }
+
+ /// Returns an iterator over the values of the nodes in the tree, sorted by key.
+ pub fn values(&self) -> impl Iterator<Item = &'_ V> {
+ self.iter().map(|(_, v)| v)
+ }
}
impl<K, V> RBTree<K, V>
@@ -358,6 +402,56 @@ fn drop(&mut self) {
}
}
+impl<'a, K, V> IntoIterator for &'a RBTree<K, V> {
+ type Item = (&'a K, &'a V);
+ type IntoIter = Iter<'a, K, V>;
+
+ fn into_iter(self) -> Self::IntoIter {
+ self.iter()
+ }
+}
+
+/// 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,
+}
+
+// SAFETY: The [`Iter`] gives out immutable references to K and V, so it has the same
+// thread safety requirements as immutable references.
+unsafe impl<'a, K: Sync, V: Sync> Send for Iter<'a, K, V> {}
+
+// SAFETY: The [`Iter`] gives out immutable references to K and V, so it has the same
+// thread safety requirements as immutable references.
+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> {
+ if self.next.is_null() {
+ return None;
+ }
+
+ // SAFETY: By the type invariant of `Iter`, `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) };
+
+ // 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) })
+ }
+}
+
/// A memory reservation for a red-black tree node.
///
///
--
2.45.1.288.g0e0cd299f1-goog
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