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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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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 18 additions and 44 deletions
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50
library/alloc/src/collections/btree/node.rs
View File

@ -112,20 +112,8 @@ unsafe fn new() -> Self {
///
/// 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 @@ pub fn borrow_mut(&mut self) -> NodeRef<marker::Mut<'_>, 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 @@ pub fn push(&mut self, key: K, val: V, edge: Root<K, V>) {
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 @@ fn push_front(&mut self, key: K, val: V, edge: Root<K, V>) {
*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 @@ fn pop(&mut self) -> (K, V, Option<Root<K, V>>) {
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 @@ fn pop_front(&mut self) -> (K, V, Option<Root<K, V>>) {
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 @@ fn insert_fit(&mut self, key: K, val: V, edge: Root<K, V>) {
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 @@ pub fn descend(self) -> NodeRef<BorrowType, K, V, marker::LeafOrInternal> {
// 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 }
}
}

12
src/etc/gdb_providers.py
View File

@ -216,6 +216,10 @@ def children_of_btree_map(map):
internal_type = lookup_type(internal_type_name)
return node.cast(internal_type.pointer())
if node_ptr.type.name.startswith("alloc::collections::btree::node::BoxedNode<"):
# BACKCOMPAT: rust 1.49
node_ptr = node_ptr["ptr"]
node_ptr = unwrap_unique_or_non_null(node_ptr)
leaf = node_ptr.dereference()
keys = leaf["keys"]
vals = leaf["vals"]
@ -224,9 +228,8 @@ def children_of_btree_map(map):
for i in xrange(0, length + 1):
if height > 0:
boxed_child_node = edges[i]["value"]["value"]
child_node = unwrap_unique_or_non_null(boxed_child_node["ptr"])
for child in children_of_node(child_node, height - 1):
child_ptr = edges[i]["value"]["value"]
for child in children_of_node(child_ptr, height - 1):
yield child
if i < length:
# Avoid "Cannot perform pointer math on incomplete type" on zero-sized arrays.
@ -239,9 +242,6 @@ def children_of_btree_map(map):
if root.type.name.startswith("core::option::Option<"):
root = root.cast(gdb.lookup_type(root.type.name[21:-1]))
node_ptr = root["node"]
if node_ptr.type.name.startswith("alloc::collections::btree::node::BoxedNode<"):
node_ptr = node_ptr["ptr"]
node_ptr = unwrap_unique_or_non_null(node_ptr)
height = root["height"]
for child in children_of_node(node_ptr, height):
yield child