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[backend/core] Improve heuristics query performance, move timeline-related extensions into its own file

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This commit is contained in:
Laura Hausmann 2024-06-26 17:14:46 +02:00
parent 2858f66ad4
commit 7a57862048
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GPG key ID: D044E84C5BE01605
4 changed files with 54 additions and 41 deletions
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2
Iceshrimp.Backend/Controllers/Mastodon/TimelineController.cs
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@ -31,7 +31,7 @@ public class TimelineController(DatabaseContext db, NoteRenderer noteRenderer, C
public async Task<IActionResult> GetHomeTimeline(MastodonPaginationQuery query)
{
var user = HttpContext.GetUserOrFail();
var heuristic = await QueryableExtensions.GetHeuristic(user, db, cache);
var heuristic = await QueryableTimelineExtensions.GetHeuristic(user, db, cache);
var res = await db.Notes
.IncludeCommonProperties()

2
Iceshrimp.Backend/Controllers/TimelineController.cs
View file

@ -29,7 +29,7 @@ public class TimelineController(DatabaseContext db, CacheService cache, NoteRend
public async Task<IActionResult> GetHomeTimeline(PaginationQuery pq)
{
var user = HttpContext.GetUserOrFail();
var heuristic = await QueryableExtensions.GetHeuristic(user, db, cache);
var heuristic = await QueryableTimelineExtensions.GetHeuristic(user, db, cache);
var notes = await db.Notes.IncludeCommonProperties()
.FilterByFollowingAndOwn(user, db, heuristic)
.EnsureVisibleFor(user)

39
Iceshrimp.Backend/Core/Extensions/QueryableExtensions.cs
View file

@ -259,45 +259,6 @@ public static class QueryableExtensions
return query.Where(note => note.Visibility == visibility);
}
/// <summary>
/// Runs the most efficient following query for the user in question.
/// The different queries are identical but nudge the query planner towards the smartest query plan available.
/// </summary>
public static IQueryable<Note> FilterByFollowingAndOwn(
this IQueryable<Note> query, User user, DatabaseContext db, int heuristic
)
{
// Determined empirically in 2023. Ask zotan for the spreadsheet if you're curious.
const int cutoff = 250;
return heuristic < cutoff
? query.Where(note => db.Users
.First(p => p == user)
.Following
.Select(p => p.Id)
.Concat(new[] { user.Id })
.Contains(note.UserId))
: query.Where(note => note.User == user || note.User.IsFollowedBy(user));
}
//TODO: move this into another class where it makes more sense
public static async Task<int> GetHeuristic(User user, DatabaseContext db, CacheService cache)
{
return await cache.FetchValueAsync($"following-query-heuristic:{user.Id}",
TimeSpan.FromHours(24), FetchHeuristic);
[SuppressMessage("ReSharper", "EntityFramework.UnsupportedServerSideFunctionCall")]
async Task<int> FetchHeuristic()
{
var lastDate = await db.Notes.AnyAsync()
? await db.Notes.OrderByDescending(p => p.Id).Select(p => p.CreatedAt).FirstOrDefaultAsync()
: DateTime.UtcNow;
return await db.Notes.CountAsync(p => p.CreatedAt > lastDate - TimeSpan.FromDays(7) &&
(p.User.IsFollowedBy(user) || p.User == user));
}
}
public static IQueryable<Note> FilterByUser(this IQueryable<Note> query, User user)
{
return query.Where(note => note.User == user);

52
Iceshrimp.Backend/Core/Extensions/QueryableTimelineExtensions.cs Normal file
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@ -0,0 +1,52 @@
using System.Diagnostics.CodeAnalysis;
using Iceshrimp.Backend.Core.Database;
using Iceshrimp.Backend.Core.Database.Tables;
using Iceshrimp.Backend.Core.Services;
using Microsoft.EntityFrameworkCore;
namespace Iceshrimp.Backend.Core.Extensions;
public static class QueryableTimelineExtensions
{
// Determined empirically in 2023. Ask zotan for the spreadsheet if you're curious.
private const int Cutoff = 250;
public static IQueryable<Note> FilterByFollowingAndOwn(
this IQueryable<Note> query, User user, DatabaseContext db, int heuristic
)
{
return heuristic < Cutoff
? query.FollowingAndOwnLowFreq(user, db)
: query.Where(note => note.User == user || note.User.IsFollowedBy(user));
}
private static IQueryable<Note> FollowingAndOwnLowFreq(this IQueryable<Note> query, User user, DatabaseContext db)
=> query.Where(note => db.Followings
.Where(p => p.Follower == user)
.Select(p => p.FolloweeId)
.Concat(new[] { user.Id })
.Contains(note.UserId));
public static async Task<int> GetHeuristic(User user, DatabaseContext db, CacheService cache)
{
return await cache.FetchValueAsync($"following-query-heuristic:{user.Id}",
TimeSpan.FromHours(24), FetchHeuristic);
[SuppressMessage("ReSharper", "EntityFramework.UnsupportedServerSideFunctionCall")]
async Task<int> FetchHeuristic()
{
var latestNote = await db.Notes.OrderByDescending(p => p.Id)
.Select(p => new { p.CreatedAt })
.FirstOrDefaultAsync() ??
new { CreatedAt = DateTime.UtcNow };
//TODO: maybe we should express this as a ratio between matching and non-matching posts
return await db.Notes
.Where(p => p.CreatedAt > latestNote.CreatedAt - TimeSpan.FromDays(7))
.FollowingAndOwnLowFreq(user, db)
//.Select(p => new { })
.Take(Cutoff + 1)
.CountAsync();
}
}
}