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Rollup merge of #79354 - ssomers:btree_bereave_BoxedNode, r=Mark-Simulacrum

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BTreeMap: cut out the ceremony around BoxedNode

The opposite direction of #79093.

r? ``@Mark-Simulacrum``
This commit is contained in:
Jonas Schievink 2020-11-24 13:17:45 +01:00 • committed by GitHub
commit 012d5fd8d7
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2 changed files with 18 additions and 44 deletions
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50
library/alloc/src/collections/btree/node.rs
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@ -112,20 +112,8 @@ impl<K, V> InternalNode<K, V> {
///
/// However, `BoxedNode` contains no information as to which of the two types
/// of nodes it actually contains, and, partially due to this lack of information,
/// has no destructor.
struct BoxedNode<K, V> {
ptr: NonNull<LeafNode<K, V>>,
}
impl<K, V> BoxedNode<K, V> {
fn from_owned(ptr: NonNull<LeafNode<K, V>>) -> Self {
BoxedNode { ptr }
}
fn as_ptr(&self) -> NonNull<LeafNode<K, V>> {
self.ptr
}
}
/// is not a separate type and has no destructor.
type BoxedNode<K, V> = NonNull<LeafNode<K, V>>;
/// An owned tree.
///
@ -168,11 +156,6 @@ impl<K, V, Type> NodeRef<marker::Owned, K, V, Type> {
pub fn borrow_valmut(&mut self) -> NodeRef<marker::ValMut<'_>, K, V, Type> {
NodeRef { height: self.height, node: self.node, _marker: PhantomData }
}
/// Packs the reference, aware of type and height, into a type-agnostic pointer.
fn into_boxed_node(self) -> BoxedNode<K, V> {
BoxedNode::from_owned(self.node)
}
}
impl<K, V> NodeRef<marker::Owned, K, V, marker::LeafOrInternal> {
@ -181,7 +164,7 @@ impl<K, V> NodeRef<marker::Owned, K, V, marker::LeafOrInternal> {
/// and is the opposite of `pop_internal_level`.
pub fn push_internal_level(&mut self) -> NodeRef<marker::Mut<'_>, K, V, marker::Internal> {
let mut new_node = Box::new(unsafe { InternalNode::new() });
new_node.edges[0].write(BoxedNode::from_owned(self.node));
new_node.edges[0].write(self.node);
let mut new_root = NodeRef::from_new_internal(new_node, self.height + 1);
new_root.borrow_mut().first_edge().correct_parent_link();
*self = new_root.forget_type();
@ -288,13 +271,6 @@ unsafe impl<'a, K: Send + 'a, V: Send + 'a, Type> Send for NodeRef<marker::Mut<'
unsafe impl<'a, K: Send + 'a, V: Send + 'a, Type> Send for NodeRef<marker::ValMut<'a>, K, V, Type> {}
unsafe impl<K: Send, V: Send, Type> Send for NodeRef<marker::Owned, K, V, Type> {}
impl<BorrowType, K, V> NodeRef<BorrowType, K, V, marker::LeafOrInternal> {
/// Unpack a node reference that was packed by `Root::into_boxed_node`.
fn from_boxed_node(boxed_node: BoxedNode<K, V>, height: usize) -> Self {
NodeRef { height, node: boxed_node.as_ptr(), _marker: PhantomData }
}
}
impl<BorrowType, K, V> NodeRef<BorrowType, K, V, marker::Internal> {
/// Unpack a node reference that was packed as `NodeRef::parent`.
fn from_internal(node: NonNull<InternalNode<K, V>>, height: usize) -> Self {
@ -695,7 +671,7 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::Internal> {
unsafe {
self.reborrow_mut().into_key_area_mut_at(idx).write(key);
self.reborrow_mut().into_val_area_mut_at(idx).write(val);
self.reborrow_mut().into_edge_area_mut_at(idx + 1).write(edge.into_boxed_node());
self.reborrow_mut().into_edge_area_mut_at(idx + 1).write(edge.node);
Handle::new_edge(self.reborrow_mut(), idx + 1).correct_parent_link();
}
}
@ -710,7 +686,7 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::Internal> {
*self.reborrow_mut().into_len_mut() += 1;
slice_insert(self.reborrow_mut().into_key_area_slice(), 0, key);
slice_insert(self.reborrow_mut().into_val_area_slice(), 0, val);
slice_insert(self.reborrow_mut().into_edge_area_slice(), 0, edge.into_boxed_node());
slice_insert(self.reborrow_mut().into_edge_area_slice(), 0, edge.node);
}
self.correct_all_childrens_parent_links();
@ -732,8 +708,8 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
let edge = match self.reborrow_mut().force() {
ForceResult::Leaf(_) => None,
ForceResult::Internal(internal) => {
let boxed_node = ptr::read(internal.reborrow().edge_at(idx + 1));
let mut edge = Root::from_boxed_node(boxed_node, internal.height - 1);
let node = ptr::read(internal.reborrow().edge_at(idx + 1));
let mut edge = Root { node, height: internal.height - 1, _marker: PhantomData };
// In practice, clearing the parent is a waste of time, because we will
// insert the node elsewhere and set its parent link again.
edge.borrow_mut().clear_parent_link();
@ -760,9 +736,8 @@ impl<'a, K: 'a, V: 'a> NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal> {
let edge = match self.reborrow_mut().force() {
ForceResult::Leaf(_) => None,
ForceResult::Internal(mut internal) => {
let boxed_node =
slice_remove(internal.reborrow_mut().into_edge_area_slice(), 0);
let mut edge = Root::from_boxed_node(boxed_node, internal.height - 1);
let node = slice_remove(internal.reborrow_mut().into_edge_area_slice(), 0);
let mut edge = Root { node, height: internal.height - 1, _marker: PhantomData };
// In practice, clearing the parent is a waste of time, because we will
// insert the node elsewhere and set its parent link again.
edge.borrow_mut().clear_parent_link();
@ -1041,12 +1016,11 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
debug_assert!(self.node.len() < CAPACITY);
debug_assert!(edge.height == self.node.height - 1);
let boxed_node = edge.into_boxed_node();
unsafe {
*self.node.reborrow_mut().into_len_mut() += 1;
slice_insert(self.node.reborrow_mut().into_key_area_slice(), self.idx, key);
slice_insert(self.node.reborrow_mut().into_val_area_slice(), self.idx, val);
slice_insert(self.node.reborrow_mut().into_edge_area_slice(), self.idx + 1, boxed_node);
slice_insert(self.node.reborrow_mut().into_edge_area_slice(), self.idx + 1, edge.node);
self.node.correct_childrens_parent_links((self.idx + 1)..=self.node.len());
}
@ -1135,8 +1109,8 @@ impl<BorrowType, K, V> Handle<NodeRef<BorrowType, K, V, marker::Internal>, marke
// reference (Rust issue #73987) and invalidate any other references
// to or inside the array, should any be around.
let parent_ptr = NodeRef::as_internal_ptr(&self.node);
let boxed_node = unsafe { (*parent_ptr).edges.get_unchecked(self.idx).assume_init_read() };
NodeRef::from_boxed_node(boxed_node, self.node.height - 1)
let node = unsafe { (*parent_ptr).edges.get_unchecked(self.idx).assume_init_read() };
NodeRef { node, height: self.node.height - 1, _marker: PhantomData }
}
}