mirror of https://github.com/rust-lang/rust.git
BTreeMap: better way to postpone root access in DrainFilter
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119d2a1a98
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85a7879341
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@ -1697,10 +1697,9 @@ impl<'a, K: 'a, V: 'a> DrainFilterInner<'a, K, V> {
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let (k, v) = kv.kv_mut();
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let (k, v) = kv.kv_mut();
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if pred(k, v) {
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if pred(k, v) {
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*self.length -= 1;
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*self.length -= 1;
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let RemoveResult { old_kv, pos, emptied_internal_root } = kv.remove_kv_tracking();
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let (kv, pos) = kv.remove_kv_tracking(|_| self.emptied_internal_root = true);
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self.cur_leaf_edge = Some(pos);
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self.cur_leaf_edge = Some(pos);
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self.emptied_internal_root |= emptied_internal_root;
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return Some(kv);
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return Some(old_kv);
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}
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}
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self.cur_leaf_edge = Some(kv.next_leaf_edge());
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self.cur_leaf_edge = Some(kv.next_leaf_edge());
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}
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}
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@ -2645,35 +2644,28 @@ impl<'a, K: Ord, V> OccupiedEntry<'a, K, V> {
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fn remove_kv(self) -> (K, V) {
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fn remove_kv(self) -> (K, V) {
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*self.length -= 1;
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*self.length -= 1;
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let RemoveResult { old_kv, pos, emptied_internal_root } = self.handle.remove_kv_tracking();
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let (old_kv, _) =
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let root = pos.into_node().into_root_mut();
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self.handle.remove_kv_tracking(|root| root.into_root_mut().pop_internal_level());
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if emptied_internal_root {
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root.pop_internal_level();
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}
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old_kv
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old_kv
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}
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}
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}
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}
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struct RemoveResult<'a, K, V> {
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// Key and value removed.
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old_kv: (K, V),
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// Unique location at the leaf level that the removed KV lopgically collapsed into.
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pos: Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>,
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// Whether the remove left behind and empty internal root node, that should be removed
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// using `pop_internal_level`.
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emptied_internal_root: bool,
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}
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impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV> {
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impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInternal>, marker::KV> {
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/// Removes a key/value-pair from the tree, and returns that pair, as well as
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/// Removes a key/value-pair from the tree, and returns that pair, as well as
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/// the leaf edge corresponding to that former pair. It's possible this leaves
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/// the leaf edge corresponding to that former pair. It's possible this leaves
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/// an empty internal root node, which the caller should subsequently pop from
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/// an empty internal root node, which the caller should subsequently pop from
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/// the map holding the tree. The caller should also decrement the map's length.
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/// the map holding the tree. The caller should also decrement the map's length.
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fn remove_kv_tracking(self) -> RemoveResult<'a, K, V> {
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fn remove_kv_tracking<F>(
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let (mut pos, old_key, old_val, was_internal) = match self.force() {
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self,
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handle_emptied_internal_root: F,
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) -> ((K, V), Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>)
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where
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F: FnOnce(NodeRef<marker::Mut<'a>, K, V, marker::Internal>),
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{
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let (old_kv, mut pos, was_internal) = match self.force() {
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Leaf(leaf) => {
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Leaf(leaf) => {
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let (hole, old_key, old_val) = leaf.remove();
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let (old_kv, pos) = leaf.remove();
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(hole, old_key, old_val, false)
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(old_kv, pos, false)
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}
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}
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Internal(mut internal) => {
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Internal(mut internal) => {
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// Replace the location freed in the internal node with the next KV,
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// Replace the location freed in the internal node with the next KV,
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@ -2688,17 +2680,16 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInter
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let to_remove = internal.left_edge().descend().last_leaf_edge().left_kv().ok();
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let to_remove = internal.left_edge().descend().last_leaf_edge().left_kv().ok();
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let to_remove = unsafe { unwrap_unchecked(to_remove) };
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let to_remove = unsafe { unwrap_unchecked(to_remove) };
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let (hole, key, val) = to_remove.remove();
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let (kv, pos) = to_remove.remove();
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let old_key = unsafe { mem::replace(&mut *key_loc, key) };
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let old_key = unsafe { mem::replace(&mut *key_loc, kv.0) };
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let old_val = unsafe { mem::replace(&mut *val_loc, val) };
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let old_val = unsafe { mem::replace(&mut *val_loc, kv.1) };
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(hole, old_key, old_val, true)
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((old_key, old_val), pos, true)
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}
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}
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};
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};
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// Handle underflow
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// Handle underflow
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let mut emptied_internal_root = false;
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let mut cur_node = unsafe { ptr::read(&pos).into_node().forget_type() };
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let mut cur_node = unsafe { ptr::read(&pos).into_node().forget_type() };
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let mut at_leaf = true;
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let mut at_leaf = true;
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while cur_node.len() < node::MIN_LEN {
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while cur_node.len() < node::MIN_LEN {
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@ -2719,8 +2710,10 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInter
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let parent = edge.into_node();
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let parent = edge.into_node();
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if parent.len() == 0 {
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if parent.len() == 0 {
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// This empty parent must be the root, and should be popped off the tree.
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// The parent that was just emptied must be the root,
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emptied_internal_root = true;
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// because nodes on a lower level would not have been
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// left underfull. It has to be popped off the tree soon.
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handle_emptied_internal_root(parent);
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break;
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break;
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} else {
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} else {
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cur_node = parent.forget_type();
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cur_node = parent.forget_type();
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@ -2747,7 +2740,7 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::LeafOrInter
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pos = unsafe { unwrap_unchecked(pos.next_kv().ok()).next_leaf_edge() };
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pos = unsafe { unwrap_unchecked(pos.next_kv().ok()).next_leaf_edge() };
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}
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}
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RemoveResult { old_kv: (old_key, old_val), pos, emptied_internal_root }
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(old_kv, pos)
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}
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}
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}
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}
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@ -1083,12 +1083,12 @@ impl<'a, K, V> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::KV>
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/// between the now adjacent key/value pairs (if any) to the left and right of this handle.
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/// between the now adjacent key/value pairs (if any) to the left and right of this handle.
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pub fn remove(
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pub fn remove(
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mut self,
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mut self,
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) -> (Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>, K, V) {
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) -> ((K, V), Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, marker::Edge>) {
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unsafe {
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unsafe {
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let k = slice_remove(self.node.keys_mut(), self.idx);
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let k = slice_remove(self.node.keys_mut(), self.idx);
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let v = slice_remove(self.node.vals_mut(), self.idx);
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let v = slice_remove(self.node.vals_mut(), self.idx);
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(*self.node.as_leaf_mut()).len -= 1;
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(*self.node.as_leaf_mut()).len -= 1;
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(self.left_edge(), k, v)
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((k, v), self.left_edge())
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}
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}
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}
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}
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}
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}
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