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Simplified insert_phase_2 #3

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merged 2 commits into from
Oct 22, 2016
Merged

Simplified insert_phase_2 #3

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a18fd8d
Simplify insert_phase_2
pczarn Oct 22, 2016
ada8d63
Simplify the control flow of VacantEntry insertion
pczarn Oct 22, 2016
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44 changes: 12 additions & 32 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -237,7 +237,6 @@ enum Inserted<V> {
RobinHood {
probe: usize,
old_pos: Pos,
dist: usize,
}
}

Expand Down Expand Up @@ -438,8 +437,6 @@ pub struct VacantEntry<'a, K: 'a, V: 'a, S: 'a = RandomState> {
probe: usize,
#[allow(dead_code)]
index: usize,
dist: usize,
stealing_bucket: bool,
}

impl<'a, K, V, S> VacantEntry<'a, K, V, S> {
Expand All @@ -458,11 +455,8 @@ impl<'a, K, V, S> VacantEntry<'a, K, V, S> {
{
let index = self.map.entries.len();
self.map.entries.push(Bucket { hash: self.hash, key: self.key, value: value });
let old_pos = replace(&mut self.map.indices[self.probe],
Pos::with_hash::<Sz>(index, self.hash));
if self.stealing_bucket {
self.map.insert_phase_2::<Sz>(self.probe, old_pos, self.dist);
}
let old_pos = Pos::with_hash::<Sz>(index, self.hash);
self.map.insert_phase_2::<Sz>(self.probe, old_pos);
&mut {self.map}.entries[index].value
}
}
Expand Down Expand Up @@ -509,9 +503,7 @@ impl<K, V, S> OrderMap<K, V, S>
hash: hash,
key: key,
probe: probe,
stealing_bucket: true,
index: i,
dist: their_dist,
});
} else if entry_hash == hash && self.entries[i].key == key {
return Entry::Occupied(OccupiedEntry {
Expand All @@ -529,9 +521,7 @@ impl<K, V, S> OrderMap<K, V, S>
hash: hash,
key: key,
probe: probe,
stealing_bucket: false,
index: 0,
dist: 0,
});
}
dist += 1;
Expand Down Expand Up @@ -574,11 +564,9 @@ impl<K, V, S> OrderMap<K, V, S>
if their_dist < dist {
// robin hood: steal the spot if it's better for us
let index = self.entries.len();
let old_pos = replace(pos, Pos::with_hash::<Sz>(index, hash));
insert_kind = Inserted::RobinHood {
probe: probe,
old_pos: old_pos,
dist: their_dist,
old_pos: Pos::with_hash::<Sz>(index, hash),
};
break;
} else if entry_hash == hash && self.entries[i].key == key {
Expand Down Expand Up @@ -688,17 +676,17 @@ impl<K, V, S> OrderMap<K, V, S>
match self.insert_phase_1::<u64>(key, value) {
Inserted::Swapped { prev_value } => Some(prev_value),
Inserted::Done => None,
Inserted::RobinHood { probe, old_pos, dist } => {
self.insert_phase_2::<u64>(probe, old_pos, dist);
Inserted::RobinHood { probe, old_pos } => {
self.insert_phase_2::<u64>(probe, old_pos);
None
}
}
} else {
match self.insert_phase_1::<u32>(key, value) {
Inserted::Swapped { prev_value } => Some(prev_value),
Inserted::Done => None,
Inserted::RobinHood { probe, old_pos, dist } => {
self.insert_phase_2::<u32>(probe, old_pos, dist);
Inserted::RobinHood { probe, old_pos } => {
self.insert_phase_2::<u32>(probe, old_pos);
None
}
}
Expand Down Expand Up @@ -902,26 +890,18 @@ impl<K, V, S> OrderMap<K, V, S> {
self.remove_found(probe, found)
}

/// phase 2 is post-insert where we swap `Pos` in the indices around to
/// adjust after a bucket was stolen.
fn insert_phase_2<Sz>(&mut self, mut probe: usize, mut old_pos: Pos, mut dist: usize)
/// phase 2 is post-insert where we forward-shift `Pos` in the indices.
fn insert_phase_2<Sz>(&mut self, mut probe: usize, mut old_pos: Pos)
where Sz: Size
{
probe_loop!(probe < self.indices.len(), {
let pos = &mut self.indices[probe];
if let Some((i, hash_proxy)) = pos.resolve::<Sz>() {
let entry_hash = hash_proxy.get_short_hash(&self.entries, i);
// if existing element probed less than us, swap
let their_dist = probe_distance(self.mask, entry_hash.into_hash(), probe);
if their_dist < dist {
swap(&mut old_pos, pos);
dist = their_dist;
}
} else {
if pos.is_none() {
*pos = old_pos;
break;
} else {
old_pos = replace(pos, old_pos);
}
dist += 1;
});
}

Expand Down