Cache BestForTags briefly for better performance when processing releases

src/NzbDrone.Core/Profiles/Delay/DelayProfileService.cs

@@ -1,5 +1,7 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
+using NzbDrone.Common.Cache;
 using NzbDrone.Common.Extensions;
 
 namespace NzbDrone.Core.Profiles.Delay
@@ -20,22 +22,29 @@ namespace NzbDrone.Core.Profiles.Delay
     public class DelayProfileService : IDelayProfileService
     {
         private readonly IDelayProfileRepository _repo;
+        private readonly ICached<DelayProfile> _bestForTagsCache;
 
-        public DelayProfileService(IDelayProfileRepository repo)
+        public DelayProfileService(IDelayProfileRepository repo, ICacheManager cacheManager)
         {
             _repo = repo;
+            _bestForTagsCache = cacheManager.GetCache<DelayProfile>(GetType(), "best");
         }
 
         public DelayProfile Add(DelayProfile profile)
         {
             profile.Order = _repo.Count();
 
-            return _repo.Insert(profile);
+            var result = _repo.Insert(profile);
+            _bestForTagsCache.Clear();
+
+            return result;
         }
 
         public DelayProfile Update(DelayProfile profile)
         {
-            return _repo.Update(profile);
+            var result = _repo.Update(profile);
+            _bestForTagsCache.Clear();
+            return result;
         }
 
         public void Delete(int id)
@@ -52,6 +61,7 @@ namespace NzbDrone.Core.Profiles.Delay
             }
 
             _repo.UpdateMany(all);
+            _bestForTagsCache.Clear();
         }
 
         public List<DelayProfile> All()
@@ -77,8 +87,15 @@ namespace NzbDrone.Core.Profiles.Delay
 
         public DelayProfile BestForTags(HashSet<int> tagIds)
         {
-            return _repo.All().Where(r => r.Tags.Intersect(tagIds).Any() || r.Tags.Empty())
-                        .OrderBy(d => d.Order).First();
+            var key = "-" + tagIds.Select(v => v.ToString()).Join(",");
+            return _bestForTagsCache.Get(key, () => FetchBestForTags(tagIds), TimeSpan.FromSeconds(30));
+        }
+
+        private DelayProfile FetchBestForTags(HashSet<int> tagIds)
+        {
+            return _repo.All()
+                .Where(r => r.Tags.Intersect(tagIds).Any() || r.Tags.Empty())
+                .OrderBy(d => d.Order).First();
         }
 
         public List<DelayProfile> Reorder(int id, int? afterId)