mirrors/salsa
1
0
Fork 0
mirror of https://github.com/salsa-rs/salsa.git synced 2024-10-23 20:59:51 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Fix race condition in interned data

Browse source 
In some scenarios the `InternedIngredient` could return two different
ids for the same data if called in parallel.
This commit is contained in:
Jack Rickard 2022-09-13 00:47:07 +01:00
parent f0fe691d3f
commit 61e3bdfc81
No known key found for this signature in database
GPG key ID: 88084D7D08A72C8A
1 changed files with 18 additions and 13 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

31
components/salsa-2022/src/interned.rs
View file

@ -83,23 +83,28 @@ where
self.reset_at,
);
// Optimisation to only get read lock on the map if the data has already
// been interned.
if let Some(id) = self.key_map.get(&data) {
return *id;
}
loop {
let next_id = self.counter.fetch_add(1);
let next_id = Id::from_id(crate::id::Id::from_u32(next_id));
match self.value_map.entry(next_id) {
// If we already have an entry with this id...
dashmap::mapref::entry::Entry::Occupied(_) => continue,
// Otherwise...
dashmap::mapref::entry::Entry::Vacant(entry) => {
self.key_map.insert(data.clone(), next_id);
entry.insert(Box::new(data));
return next_id;
}
match self.key_map.entry(data.clone()) {
// Data has already been interned, just use the existing ID
dashmap::mapref::entry::Entry::Occupied(entry) => *entry.get(),
// Insert the new value at the next available id
// This holds a lock on the entry so other can't attempt to insert
// at the same time.
dashmap::mapref::entry::Entry::Vacant(entry) => {
let next_id = self.counter.fetch_add(1);
let next_id = Id::from_id(crate::id::Id::from_u32(next_id));
let old_value = self.value_map.insert(next_id, Box::new(data));
assert!(
old_value.is_none(),
"next_id is guaranteed to be unique, bar overflow"
);
entry.insert(next_id);
next_id
}
}
}