Bugfix: initial bottom counts can throw error when a book was moved since Libation was last run

DataLayer/UNTESTED/LibationContext.cs

@@ -64,7 +64,8 @@ namespace DataLayer
 				.Entity<Contributor>()
 				.HasData(Contributor.GetEmpty());
 
-            // views are now supported via "query types" (instead of "entity types"): https://docs.microsoft.com/en-us/ef/core/modeling/query-types
+			// views are now supported via "keyless entity types" (instead of "entity types" or the prev "query types"):
-        }
+			// https://docs.microsoft.com/en-us/ef/core/modeling/keyless-entity-types
-    }
+		}
+	}
 }

DataLayer/UNTESTED/TagPersistenceInterceptor.cs

@@ -4,7 +4,6 @@ using System.Linq;
 using Dinah.Core.Collections.Generic;
 using Dinah.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore;
-using Microsoft.EntityFrameworkCore.ChangeTracking;
 
 namespace DataLayer
 {
@@ -14,24 +13,17 @@ namespace DataLayer
 
         public void Executing(DbContext context)
 		{
-			// persist tags:
+			var tagsCollection
-			var modifiedEntities = context
+				= context
 				.ChangeTracker
 				.Entries()
-				.Where(p => p.State.In(EntityState.Modified, EntityState.Added))
+				.Where(e => e.State.In(EntityState.Modified, EntityState.Added))
-				.ToList();
-
-			persistTags(modifiedEntities);
-		}
-
-		private static void persistTags(List<EntityEntry> modifiedEntities)
-		{
-			var tagsCollection = modifiedEntities
 				.Select(e => e.Entity as UserDefinedItem)
-				// filter by null but NOT by blank. blank is the valid way to show the absence of tags
+				.Where(udi => udi != null)
-				.Where(a => a != null)
+				// do NOT filter out entires with blank tags. blank is the valid way to show the absence of tags
 				.Select(t => (t.Book.AudibleProductId, t.Tags))
 				.ToList();
+
 			FileManager.TagsPersistence.Save(tagsCollection);
 		}
 	}

FileManager/UNTESTED/FilePathCache.cs

@@ -2,11 +2,12 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+using Dinah.Core.Collections.Immutable;
 using Newtonsoft.Json;
 
 namespace FileManager
 {
-    public static class FilePathCache
+	public static class FilePathCache
     {
         internal class CacheEntry
         {
@@ -15,22 +16,25 @@ namespace FileManager
             public string Path { get; set; }
         }
 
-        static List<CacheEntry> inMemoryCache { get; } = new List<CacheEntry>();
+        static Cache<CacheEntry> cache { get; } = new Cache<CacheEntry>();
 
         public static string JsonFile => Path.Combine(Configuration.Instance.LibationFiles, "FilePaths.json");
 
         static FilePathCache()
         {
-            // load json into memory. if file doesn't exist, nothing to do. save() will create if needed
+			// load json into memory. if file doesn't exist, nothing to do. save() will create if needed
-            if (FileUtility.FileExists(JsonFile))
+			if (FileUtility.FileExists(JsonFile))
-                inMemoryCache = JsonConvert.DeserializeObject<List<CacheEntry>>(File.ReadAllText(JsonFile));
+			{
+				var list = JsonConvert.DeserializeObject<List<CacheEntry>>(File.ReadAllText(JsonFile));
+				cache = new Cache<CacheEntry>(list);
+			}
         }
 
         public static bool Exists(string id, FileType type) => GetPath(id, type) != null;
 
         public static string GetPath(string id, FileType type)
         {
-            var entry = inMemoryCache.SingleOrDefault(i => i.Id == id && i.FileType == type);
+            var entry = cache.SingleOrDefault(i => i.Id == id && i.FileType == type);
 
             if (entry == null)
                 return null;
@@ -44,51 +48,47 @@ namespace FileManager
             return entry.Path;
         }
 
-        private static object locker { get; } = new object();
-
         private static void remove(CacheEntry entry)
-        {
+		{
-            lock (locker)
+			cache.Remove(entry);
-            {
+			save();
-                inMemoryCache.Remove(entry);
+		}
-                save();
-            }
-        }
 
         public static void Upsert(string id, FileType type, string path)
         {
             if (!FileUtility.FileExists(path))
                 throw new FileNotFoundException("Cannot add path to cache. File not found");
 
-            lock (locker)
+			var entry = cache.SingleOrDefault(i => i.Id == id && i.FileType == type);
-            {
-                var entry = inMemoryCache.SingleOrDefault(i => i.Id == id && i.FileType == type);
-                if (entry != null)
-                    entry.Path = path;
-                else
-                {
-                    entry = new CacheEntry { Id = id, FileType = type, Path = path };
-                    inMemoryCache.Add(entry);
-                }
-                save();
-            }
-        }
 
-        // ONLY call this within lock()
+			if (entry is null)
-        private static void save()
+				cache.Add(new CacheEntry { Id = id, FileType = type, Path = path });
-        {
+			else
-            // create json if not exists
+				entry.Path = path;
-            void resave() => File.WriteAllText(JsonFile, JsonConvert.SerializeObject(inMemoryCache, Formatting.Indented));
+
-            try { resave(); }
+			save();
-            catch (IOException)
+		}
-            {
+
-                try { resave(); }
+		// cache is thread-safe and lock free. but file saving is not
-                catch (IOException ex)
+		private static object locker { get; } = new object();
+		private static void save()
+		{
+			// create json if not exists
+			static void resave() => File.WriteAllText(JsonFile, JsonConvert.SerializeObject(cache.ToList(), Formatting.Indented));
+
+			lock (locker)
+			{
+				try { resave(); }
+				catch (IOException)
 				{
-					Serilog.Log.Logger.Error(ex, "Error saving FilePaths.json");
+					try { resave(); }
-                    throw;
+					catch (IOException ex)
-                }
+					{
-            }
+						Serilog.Log.Logger.Error(ex, "Error saving FilePaths.json");
+						throw;
+					}
+				}
+			}
         }
     }
 }

LibationWinForm/UNTESTED/Form1.cs

@@ -109,21 +109,9 @@ namespace LibationWinForm
                 .Select(sp => sp.Book)
                 .ToList();
 
-			// will often fail once if book has been moved while libation is closed. just retry once for now
+			setBookBackupCounts(books);
-			// fix actual issue later
+			setPdfBackupCounts(books);
-			//   FilePathCache.GetPath() :: inMemoryCache.SingleOrDefault(i => i.Id == id && i.FileType == type)
+		}
-			try
-			{
-				setBookBackupCounts(books);
-				setPdfBackupCounts(books);
-			}
-			catch (Exception ex)
-			{
-				System.Threading.Thread.Sleep(100);
-				setBookBackupCounts(books);
-				setPdfBackupCounts(books);
-			}
-        }
         enum AudioFileState { full, aax, none }
         private void setBookBackupCounts(IEnumerable<Book> books)
         {