Method prune_subnets

ipld/resolver/src/provider_cache.rs:149–175

Ensure we don't have more than `max_subnets` number of subnets in the cache. Returns the removed subnet IDs.

(&mut self)

    ///
    /// Returns the removed subnet IDs.
    fn prune_subnets(&mut self) -> HashSet<SubnetID> {
        let mut removed_subnet_ids = HashSet::new();

        let to_prune = self.subnet_providers.len().saturating_sub(self.max_subnets);
        if to_prune > 0 {
            let mut counts = self
                .subnet_providers
                .iter()
                .map(|(id, ps)| (id.clone(), ps.len()))
                .collect::<Vec<_>>();

            counts.sort_by_key(|(_, count)| *count);

            for (subnet_id, _) in counts {
                if self.pinned_subnets.contains(&subnet_id) {
                    continue;
                }
                self.subnet_providers.remove(&subnet_id);
                removed_subnet_ids.insert(subnet_id);
                if removed_subnet_ids.len() == to_prune {
                    break;
                }
            }
        }

        removed_subnet_ids
    }

    /// Prune any provider which hasn't provided an update since a cutoff timestamp.
    ///