pppy/osu-global-rank-lookup-cache repository overview

⁠osu-global-rank-lookup-cache

A memory-based caching layer for beatmap-rank lookups which cannot be easily optimised as a database/SQL level.

Intended to handle queries which iterate over large sections of (already indexed) scores, where the overhead of counting rows becomes an issue.

⁠Query API

/ranklookup?beatmapId={$beatmapId}&score={$score}&rulesetId={$mode}

$beatmapId - The beatmap ID to lookup $score - The achieved total score value $mode - The ruleset ID (0..3)

⁠Response

An zero-index integer denoting the rank in the leaderboard for the provided score.

⁠TODO

• Currently this is only useful for global leaderboards. Mod filters cannot be applied, for instance.
• After an initial query, the queried beatmap will be tracked permanently. There is no cache expiry, so the potential of saturating available memory is real. LRU expiry should be implemented.
• More correctly handling top 50 lookups where score collisions are feasible (need to fallback to ID).