Move beatmap processing tasks to new BeatmapUpdater class

osu.Game/Beatmaps/BeatmapUpdater.cs

@@ -0,0 +1,78 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+#nullable enable
+
+using System.Linq;
+using System.Threading.Tasks;
+using osu.Framework.Extensions;
+using osu.Game.Database;
+using osu.Game.Rulesets.Objects;
+
+namespace osu.Game.Beatmaps
+{
+    /// <summary>
+    /// Handles all processing required to ensure a local beatmap is in a consistent state with any changes.
+    /// </summary>
+    public class BeatmapUpdater
+    {
+        private readonly BeatmapManager beatmapManager;
+        private readonly BeatmapOnlineLookupQueue onlineLookupQueue;
+        private readonly BeatmapDifficultyCache difficultyCache;
+
+        public BeatmapUpdater(BeatmapManager beatmapManager, BeatmapOnlineLookupQueue onlineLookupQueue, BeatmapDifficultyCache difficultyCache)
+        {
+            this.beatmapManager = beatmapManager;
+            this.onlineLookupQueue = onlineLookupQueue;
+            this.difficultyCache = difficultyCache;
+        }
+
+        /// <summary>
+        /// Queue a beatmap for background processing.
+        /// </summary>
+        public void Queue(Live<BeatmapSetInfo> beatmap)
+        {
+            // For now, just fire off a task.
+            // TODO: Add actual queueing probably.
+            Task.Factory.StartNew(() => beatmap.PerformRead(Process));
+        }
+
+        /// <summary>
+        /// Run all processing on a beatmap immediately.
+        /// </summary>
+        public void Process(BeatmapSetInfo beatmapSet)
+        {
+            beatmapSet.Realm.Write(() =>
+            {
+                onlineLookupQueue.Update(beatmapSet);
+
+                foreach (var beatmap in beatmapSet.Beatmaps)
+                {
+                    var working = beatmapManager.GetWorkingBeatmap(beatmap);
+
+                    // Because we aren't guaranteed all processing will happen on this thread, it's very hard to use the live realm object.
+                    // This can be fixed by adding a synchronous flow to `BeatmapDifficultyCache`.
+                    var detachedBeatmap = beatmap.Detach();
+
+                    beatmap.StarRating = difficultyCache.GetDifficultyAsync(detachedBeatmap).GetResultSafely()?.Stars ?? 0;
+                    beatmap.Length = calculateLength(working.Beatmap);
+                    beatmap.BPM = 60000 / working.Beatmap.GetMostCommonBeatLength();
+                }
+            });
+        }
+
+        private double calculateLength(IBeatmap b)
+        {
+            if (!b.HitObjects.Any())
+                return 0;
+
+            var lastObject = b.HitObjects.Last();
+
+            //TODO: this isn't always correct (consider mania where a non-last object may last for longer than the last in the list).
+            double endTime = lastObject.GetEndTime();
+            double startTime = b.HitObjects.First().StartTime;
+
+            return endTime - startTime;
+        }
+    }
+}