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Cache finalised attributes to avoid conversion overhead every usage #282

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merged 2 commits into from
Oct 21, 2024
Merged

Cache finalised attributes to avoid conversion overhead every usage #282

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Cache finalised attributes to avoid conversion overhead every usage
peppy Oct 18, 2024
1238149
Merge branch 'master' into cache-finalised-attribs
bdach Oct 21, 2024
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41 changes: 23 additions & 18 deletions osu.Server.Queues.ScoreStatisticsProcessor/Stores/BeatmapStore.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ public class BeatmapStore
private static readonly string beatmap_download_path = Environment.GetEnvironmentVariable("BEATMAP_DOWNLOAD_PATH") ?? "https://osu.ppy.sh/osu/{0}";

private readonly ConcurrentDictionary<uint, Beatmap?> beatmapCache = new ConcurrentDictionary<uint, Beatmap?>();
private readonly ConcurrentDictionary<DifficultyAttributeKey, BeatmapDifficultyAttribute[]?> attributeCache = new ConcurrentDictionary<DifficultyAttributeKey, BeatmapDifficultyAttribute[]?>();
private readonly ConcurrentDictionary<DifficultyAttributeKey, DifficultyAttributes?> attributeCache = new ConcurrentDictionary<DifficultyAttributeKey, DifficultyAttributes?>();
private readonly IReadOnlyDictionary<BlacklistEntry, byte> blacklist;

private BeatmapStore(IEnumerable<KeyValuePair<BlacklistEntry, byte>> blacklist)
Expand Down Expand Up @@ -82,29 +82,34 @@ public static async Task<BeatmapStore> CreateAsync(MySqlConnection connection, M
return calculator.Calculate(mods);
}

BeatmapDifficultyAttribute[]? rawDifficultyAttributes;

LegacyMods legacyModValue = getLegacyModsForAttributeLookup(beatmap, ruleset, mods);

DifficultyAttributeKey key = new DifficultyAttributeKey(beatmap.beatmap_id, (uint)ruleset.RulesetInfo.OnlineID, (uint)legacyModValue);

if (!attributeCache.TryGetValue(key, out rawDifficultyAttributes))
{
rawDifficultyAttributes = attributeCache[key] = (await connection.QueryAsync<BeatmapDifficultyAttribute>(
"SELECT * FROM osu_beatmap_difficulty_attribs WHERE `beatmap_id` = @BeatmapId AND `mode` = @RulesetId AND `mods` = @ModValue", new
{
key.BeatmapId,
key.RulesetId,
key.ModValue
}, transaction: transaction)).ToArray();
}
if (attributeCache.TryGetValue(key, out DifficultyAttributes? difficultyAttributes))
return difficultyAttributes;

if (rawDifficultyAttributes == null || rawDifficultyAttributes.Length == 0)
return null;
BeatmapDifficultyAttribute[] dbAttribs = (await connection.QueryAsync<BeatmapDifficultyAttribute>(
"SELECT * FROM osu_beatmap_difficulty_attribs WHERE `beatmap_id` = @BeatmapId AND `mode` = @RulesetId AND `mods` = @ModValue", new
{
key.BeatmapId,
key.RulesetId,
key.ModValue
}, transaction: transaction)).ToArray();

DifficultyAttributes difficultyAttributes = LegacyRulesetHelper.CreateDifficultyAttributes(ruleset.RulesetInfo.OnlineID);
difficultyAttributes.FromDatabaseAttributes(rawDifficultyAttributes.ToDictionary(a => (int)a.attrib_id, a => (double)a.value), beatmap);
try
{
if (dbAttribs.Length == 0)
return difficultyAttributes;

return difficultyAttributes;
difficultyAttributes = LegacyRulesetHelper.CreateDifficultyAttributes(ruleset.RulesetInfo.OnlineID);
difficultyAttributes.FromDatabaseAttributes(dbAttribs.ToDictionary(a => (int)a.attrib_id, a => (double)a.value), beatmap);
return difficultyAttributes;
}
finally
{
attributeCache[key] = difficultyAttributes;
}
Comment on lines +100 to +112
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I believe all of this works but it's intricate enough to be pushing my limits of how much subtlety I'm willing to accept in code, what with all of the juggling of difficultyAttributes, implicit null returns of TryGetValue(), and finally used to coalesce return paths in order to populate attributeCache...

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Hmm, this is the standard way I'd write any caching code (I believe it's done this was elsewhere) but I'm neutral to approaching it differently. Would be be more understandable if the early return did the null-caching inline?

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The general pattern is standard yes, I'm more talking about the mechanics here.

Would be be more understandable if the early return did the null-caching inline?

To a degree, but it would also make it mechanically uglier, so I decided I would just put up with this as is.

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@smoogipoo smoogipoo Oct 21, 2024 •
edited
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One thing to keep in mind is that this will cache attributes even if they fail, and then they will pass as if nothing went wrong the next time around. There's two places that can fail - either the attributes are not present in the DB which I can't immediately think of a situation in which it should be allowed (and it previously returned null too), or the deserialisation fails which is always a bad sign.

Exercise is left up to the reader to determine what this means for scores computed using the "actually failed but cached" attribs.

}

/// <remarks>
Expand Down