Struct SortedViewCache 

pub struct SortedViewCache { /* private fields */ }

Sorted view cache maintaining entities in sort order.

Bounding

The cache holds every entity it has been given. It shares an entity’s fields with whoever gave it (see SharedEntity) rather than copying them, but it keeps them alive, so callers that feed it from a bounded source (the projector and snapshot restore feed it from the LRU-capped EntityCache) should use upsert_bounded or trim_to_max_entries with that source’s cap.

Entries are evicted from the bottom of the sort order, not by recency. Evicting the least-recently-updated entries (mirroring the entity cache) would drop a top-ranked entity that simply has not updated recently and break leaderboard-style sort + take views. Evicting everything beyond position max_entries keeps every window with skip + take <= max_entries exact. An evicted entity re-enters on its next update, because the projector re-reads the full entity from the entity cache before upserting.

Known edge: after entities are removed from (or move down out of) the top of the order, a previously evicted entity that has not updated since is missing from the cache until it next updates, so a window near the cap can under-fill or show a lower-ranked entity in its place until then.

Implementations

impl SortedViewCache

pub fn new(view_id: String, sort_field: Vec<String>, order: SortOrder) -> Self

pub fn view_id(&self) -> &str

pub fn len(&self) -> usize

pub fn is_empty(&self) -> bool

pub fn upsert( &mut self, entity_key: String, entity: impl Into<SharedEntity>, ) -> UpsertResult

Insert or update an entity, returns the position where it was inserted

An update merges into the entity held, keeping fields the update lacks. When it lacks none, which is the case for a whole entity, the cache shares the update’s fields instead of copying them.

pub fn would_keep<E: EntityFields + ?Sized>( &self, entity_key: &str, entity: &E, max_entries: usize, ) -> bool

Whether upserting entity under entity_key into a cache bounded at max_entries would keep it: the cache already holds the key, has room, or the entity sorts before its current last entry.

Lets a caller skip copying an entity that Self::upsert_bounded would evict straight away, which in a busy view is most of them.

pub fn upsert_bounded( &mut self, entity_key: String, entity: impl Into<SharedEntity>, max_entries: usize, ) -> UpsertResult

Upsert an entity, then evict from the bottom of the sort order so the cache holds at most max_entries entities.

If the upserted entity itself sorts beyond max_entries it is evicted immediately and the returned position is >= max_entries.

pub fn trim_to_max_entries(&mut self, max_entries: usize) -> usize

Evict entities from the bottom of the sort order until at most max_entries remain. Returns the number of evicted entities.

Each eviction is an O(log n) pop from the end of the ordered index, so a batch of evictions (e.g. after a bulk rebuild) costs no more than the inserts that caused it. The ordered-keys cache is truncated in place when it is current, so trimming does not force a full rebuild.

pub fn clear(&mut self)

Remove an entity, returns the position it was at

pub fn remove(&mut self, entity_key: &str) -> Option<usize>

pub fn get(&self, entity_key: &str) -> Option<&SharedEntity>

Get entity by key

pub fn ordered_keys(&mut self) -> &[String]

Get ordered keys (rebuilds cache if dirty)

pub fn get_window(&mut self, skip: usize, take: usize) -> Vec<(String, Value)>

Get a window of entities, as copies.

pub fn get_all_ordered(&mut self) -> Vec<(String, Value)>

Copies of every entity in deterministic sort order.

pub fn ordered_entities(&mut self) -> Vec<(String, SharedEntity)>

Every entity in deterministic sort order for query-side filtering, sharing their fields with the cache rather than copying them.

pub fn compute_window_deltas( &mut self, old_window_keys: &[String], skip: usize, take: usize, ) -> Vec<ViewDelta>

Compute deltas for a client with a specific window

Trait Implementations

impl Debug for SortedViewCache

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.