Stale entries in cache after upgrade to 0.12.13 #575
Description
After an upgrade to 0.12.13 from 0.12.12 we started seeing stale entries returned from the cache, that should already be evicted.
We're using sync Cache and a custom Expiry implementation with only expire_after_create overridden:
/// Extracts TTL from the Entry
struct Expirer;
impl Expiry<Key, Arc<Entry>> for Expirer {
fn expire_after_create(
&self,
_key: &Key,
value: &Arc<Entry>,
created_at: Instant,
) -> Option<Duration> {
Some(value.expires - created_at)
}
}
value.expires is filled as current Instant plus some TTL when an entry is inserted into a cache:
self.cache.insert(
key,
Arc::new(Entry {
...
expires: now + ttl,
}),
);
From the docs on the Expiry trait I see that this method is only called when the key wasn't found in the cache, as it should be I guess.
It all worked fine, but after a crate upgrade I'm getting Entry-ies from the cache where expires is earlier than current time. When I pin the crate to 0.12.12 the problem goes away.
I couldn't find the exact commit which introduced it and I don't have a concise repro yet, will add it if I can manage.