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treemap: cut down on swap_unwrap in remove

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Performance before:

    std::treemap::TreeMap
                   sequential_ints 0.083971 s
                       random_ints 0.095861 s
                       delete_ints 0.083931 s
                sequential_strings 0.278272 s
                    random_strings 0.240286 s
                    delete_strings 0.173581 s

Performance after:

    std::treemap::TreeMap
                   sequential_ints 0.083297 s
                       random_ints 0.097644 s
                       delete_ints 0.052602 s
                sequential_strings 0.287326 s
                    random_strings 0.242372 s
                    delete_strings 0.142269 s
This commit is contained in:
Daniel Micay 2013-02-10 22:03:26 -05:00
parent b0f58f6e68
commit f9c7ba009b
1 changed files with 21 additions and 15 deletions
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36
src/libstd/treemap.rs
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@ -626,7 +626,7 @@ fn insert<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: K,
}
fn remove<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: &K) -> bool {
fn heir_swap<K: Ord, V>(node: &mut TreeNode<K, V>,
fn heir_swap<K: Ord, V>(node: &mut ~TreeNode<K, V>,
child: &mut Option<~TreeNode<K, V>>) {
// *could* be done without recursion, but it won't borrow check
do child.mutate |mut child| {
@ -640,15 +640,15 @@ fn remove<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: &K) -> bool {
}
}
if node.is_none() {
match *node {
None => {
return false // bottom of tree
} else {
let mut save = node.swap_unwrap();
let removed = if save.key < *key {
remove(&mut save.right, key)
}
Some(ref mut save) => {
let (removed, this) = if save.key < *key {
(remove(&mut save.right, key), false)
} else if *key < save.key {
remove(&mut save.left, key)
(remove(&mut save.left, key), false)
} else {
if save.left.is_some() {
if save.right.is_some() {
@ -662,16 +662,22 @@ fn remove<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: &K) -> bool {
save.left = Some(left);
remove(&mut save.left, key);
} else {
save = save.left.swap_unwrap();
*save = save.left.swap_unwrap();
}
(true, false)
} else if save.right.is_some() {
save = save.right.swap_unwrap();
*save = save.right.swap_unwrap();
(true, false)
} else {
return true // leaf
(true, true)
}
true
};
if this {
*node = None;
return true;
}
let left_level = save.left.map_default(0, |x| x.level);
let right_level = save.right.map_default(0, |x| x.level);
@ -683,7 +689,7 @@ fn remove<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: &K) -> bool {
do save.right.mutate |mut x| { x.level = save.level; x }
}
skew(&mut save);
skew(save);
match save.right {
Some(ref mut right) => {
@ -696,15 +702,15 @@ fn remove<K: Ord, V>(node: &mut Option<~TreeNode<K, V>>, key: &K) -> bool {
None => ()
}
split(&mut save);
split(save);
match save.right {
Some(ref mut x) => { split(x) },
None => ()
}
}
*node = Some(save);
removed
}
}
}