feature: Update to .net 5 (#646)

src/Akavache.Core/Akavache.Core.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="MSBuild.Sdk.Extras">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;Xamarin.iOS10;Xamarin.Mac20;MonoAndroid90;tizen40</TargetFrameworks>
-    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net461;uap10.0.16299</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;Xamarin.iOS10;Xamarin.Mac20;MonoAndroid10.0;tizen40;net5.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">$(TargetFrameworks);net461;uap10.0.16299;net5.0-windows</TargetFrameworks>
     <AssemblyName>Akavache.Core</AssemblyName>
     <RootNamespace>Akavache</RootNamespace>
     <Description>An asynchronous, persistent key-value store for desktop and mobile applications on .NET</Description>

src/Akavache.Core/BlobCache/InMemoryBlobCache.cs

@@ -97,7 +97,7 @@ public DateTimeKind? ForcedDateTimeKind
             {
                 _dateTimeKind = value;
 
-                if (_jsonDateTimeContractResolver != null)
+                if (_jsonDateTimeContractResolver is not null)
                 {
                     _jsonDateTimeContractResolver.ForceDateTimeKindOverride = value;
                 }
@@ -198,7 +198,7 @@ public IObservable<byte[]> Get(string key)
                 return ExceptionHelper.ObservableThrowObjectDisposedException<byte[]>("InMemoryBlobCache");
             }
 
-            CacheEntry entry;
+            CacheEntry? entry;
             lock (_cache)
             {
                 if (!_cache.TryGetValue(key, out entry))
@@ -207,7 +207,12 @@ public IObservable<byte[]> Get(string key)
                 }
             }
 
-            if (entry.ExpiresAt != null && Scheduler.Now > entry.ExpiresAt.Value)
+            if (entry is null)
+            {
+                return ExceptionHelper.ObservableThrowKeyNotFoundException<byte[]>(key);
+            }
+
+            if (entry.ExpiresAt is not null && Scheduler.Now > entry.ExpiresAt.Value)
             {
                 lock (_cache)
                 {
@@ -228,7 +233,7 @@ public IObservable<byte[]> Get(string key)
                 return ExceptionHelper.ObservableThrowObjectDisposedException<DateTimeOffset?>("InMemoryBlobCache");
             }
 
-            CacheEntry entry;
+            CacheEntry? entry;
             lock (_cache)
             {
                 if (!_cache.TryGetValue(key, out entry))
@@ -237,6 +242,11 @@ public IObservable<byte[]> Get(string key)
                 }
             }
 
+            if (entry is null)
+            {
+                return ExceptionHelper.ObservableThrowKeyNotFoundException<DateTimeOffset?>(key);
+            }
+
             return Observable.Return<DateTimeOffset?>(entry.CreatedAt, Scheduler);
         }
 
@@ -251,7 +261,7 @@ public IObservable<IEnumerable<string>> GetAllKeys()
             lock (_cache)
             {
                 return Observable.Return(_cache
-                    .Where(x => x.Value.ExpiresAt == null || x.Value.ExpiresAt >= Scheduler.Now)
+                    .Where(x => x.Value.ExpiresAt is null || x.Value.ExpiresAt >= Scheduler.Now)
                     .Select(x => x.Key)
                     .ToList());
             }
@@ -315,7 +325,7 @@ public IObservable<T> GetObject<T>(string key)
                 return ExceptionHelper.ObservableThrowObjectDisposedException<T>("InMemoryBlobCache");
             }
 
-            CacheEntry entry;
+            CacheEntry? entry;
             lock (_cache)
             {
                 if (!_cache.TryGetValue(key, out entry))
@@ -324,7 +334,12 @@ public IObservable<T> GetObject<T>(string key)
                 }
             }
 
-            if (entry.ExpiresAt != null && Scheduler.Now > entry.ExpiresAt.Value)
+            if (entry is null)
+            {
+                return ExceptionHelper.ObservableThrowKeyNotFoundException<T>(key);
+            }
+
+            if (entry.ExpiresAt is not null && Scheduler.Now > entry.ExpiresAt.Value)
             {
                 lock (_cache)
                 {
@@ -357,9 +372,10 @@ public IObservable<IEnumerable<T>> GetAllObjects<T>()
             {
                 return Observable.Return(
                     _cache
-                        .Where(x => x.Value.TypeName == typeof(T).FullName && (x.Value.ExpiresAt == null || x.Value.ExpiresAt >= Scheduler.Now))
+                        .Where(x => x.Value.TypeName == typeof(T).FullName && (x.Value.ExpiresAt is null || x.Value.ExpiresAt >= Scheduler.Now))
                         .Select(x => DeserializeObject<T>(x.Value.Value))
-                        .ToList(), Scheduler);
+                        .ToList(),
+                    Scheduler);
             }
         }
 
@@ -404,7 +420,7 @@ public IObservable<Unit> Vacuum()
 
             lock (_cache)
             {
-                var toDelete = _cache.Where(x => x.Value.ExpiresAt != null && Scheduler.Now > x.Value.ExpiresAt).ToArray();
+                var toDelete = _cache.Where(x => x.Value.ExpiresAt is not null && Scheduler.Now > x.Value.ExpiresAt).ToArray();
                 foreach (var kvp in toDelete)
                 {
                     _cache.Remove(kvp.Key);

src/Akavache.Core/BulkOperationsMixin.cs

@@ -129,12 +129,10 @@ public static IObservable<IDictionary<string, T>> GetObjects<T>(this IBlobCache
             }
 
             return keys.ToObservable()
-                .SelectMany(x =>
-                {
-                    return blobCache.GetObject<T>(x)
-                        .Select(y => new KeyValuePair<string, T>(x, y))
-                        .Catch<KeyValuePair<string, T>, KeyNotFoundException>(_ => Observable.Empty<KeyValuePair<string, T>>());
-                })
+                .SelectMany(x => blobCache.GetObject<T>(x)
+                    .Where(y => y is not null)
+                    .Select(y => new KeyValuePair<string, T>(x, y!))
+                    .Catch<KeyValuePair<string, T>, KeyNotFoundException>(_ => Observable.Empty<KeyValuePair<string, T>>()))
                 .ToDictionary(k => k.Key, v => v.Value);
         }
 

src/Akavache.Core/DependencyResolverMixin.cs

@@ -37,14 +37,19 @@ public static void InitializeAkavache(this IMutableDependencyResolver resolver,
 
             var fdr = typeof(DependencyResolverMixin);
 
-            if (fdr == null || fdr.AssemblyQualifiedName is null)
+            if (fdr is null || fdr.AssemblyQualifiedName is null)
             {
                 throw new Exception($"Cannot find valid assembly name for the {nameof(DependencyResolverMixin)} class.");
             }
 
             var assemblyName = new AssemblyName(
                 fdr.AssemblyQualifiedName.Replace(fdr.FullName + ", ", string.Empty));
 
+            if (assemblyName.Name is null)
+            {
+                throw new InvalidOperationException("Could not find a valid name for assembly");
+            }
+
             foreach (var ns in namespaces)
             {
                 var targetType = ns + ".Registrations";
@@ -56,7 +61,13 @@ public static void InitializeAkavache(this IMutableDependencyResolver resolver,
                     continue;
                 }
 
-                var registerer = (IWantsToRegisterStuff)Activator.CreateInstance(registerTypeClass);
+                var registerer = (IWantsToRegisterStuff?)Activator.CreateInstance(registerTypeClass);
+
+                if (registerer is null)
+                {
+                    continue;
+                }
+
                 registerer.Register(resolver, readonlyDependencyResolver);
             }
         }

src/Akavache.Core/Json/JsonDateTimeContractResolver.cs

@@ -41,7 +41,7 @@ public JsonDateTimeContractResolver(IContractResolver? contractResolver, DateTim
         public override JsonContract ResolveContract(Type type)
         {
             var contract = ExistingContractResolver?.ResolveContract(type);
-            if (contract?.Converter != null)
+            if (contract?.Converter is not null)
             {
                 return contract;
             }

src/Akavache.Core/Json/JsonDateTimeOffsetTickConverter.cs

@@ -22,7 +22,7 @@ public override void WriteJson(JsonWriter writer, object? value, JsonSerializer
 
         public override object? ReadJson(JsonReader reader, Type objectType, object? existingValue, JsonSerializer serializer)
         {
-            if (reader.TokenType == JsonToken.Date && reader.Value != null)
+            if (reader.TokenType == JsonToken.Date && reader.Value is not null)
             {
                 return (DateTimeOffset)reader.Value;
             }

src/Akavache.Core/Json/JsonDateTimeTickConverter.cs

@@ -48,12 +48,12 @@ public override bool CanConvert(Type objectType)
                 return null;
             }
 
-            if (reader.TokenType == JsonToken.Date && reader.Value != null)
+            if (reader.TokenType == JsonToken.Date && reader.Value is not null)
             {
                 return (DateTime)reader.Value;
             }
 
-            if ((objectType == typeof(DateTime) || objectType == typeof(DateTime?)) && reader.Value != null)
+            if ((objectType == typeof(DateTime) || objectType == typeof(DateTime?)) && reader.Value is not null)
             {
                 var ticks = (long)reader.Value;
 

src/Akavache.Core/Json/JsonSerializationMixin.cs

@@ -80,7 +80,7 @@ public static IObservable<Unit> InsertAllObjects<T>(this IBlobCache blobCache, I
         /// <param name="key">The key to look up in the cache
         /// modified key name. If this is true, GetAllObjects will not find this object.</param>
         /// <returns>A Future result representing the object in the cache.</returns>
-        public static IObservable<T> GetObject<T>(this IBlobCache blobCache, string key)
+        public static IObservable<T?> GetObject<T>(this IBlobCache blobCache, string key)
         {
             if (blobCache is null)
             {
@@ -122,7 +122,7 @@ public static IObservable<IEnumerable<T>> GetAllObjects<T>(this IBlobCache blobC
                     .Where(y =>
                         y.StartsWith(GetTypePrefixedKey(string.Empty, typeof(T)), StringComparison.InvariantCulture))
                     .ToObservable())
-                .SelectMany(x => blobCache.GetObject<T>(x)
+                .SelectMany(x => blobCache.GetObject<T>(x).Where(x => x is not null).Select(x => x!)
                     .Catch(Observable.Empty<T>()))
                 .ToList();
         }
@@ -147,14 +147,14 @@ public static IObservable<IEnumerable<T>> GetAllObjects<T>(this IBlobCache blobC
         /// <typeparam name="T">The type of item to get.</typeparam>
         /// <returns>A Future result representing the deserialized object from
         /// the cache.</returns>
-        public static IObservable<T> GetOrFetchObject<T>(this IBlobCache blobCache, string key, Func<IObservable<T>> fetchFunc, DateTimeOffset? absoluteExpiration = null)
+        public static IObservable<T?> GetOrFetchObject<T>(this IBlobCache blobCache, string key, Func<IObservable<T>> fetchFunc, DateTimeOffset? absoluteExpiration = null)
         {
             if (blobCache is null)
             {
                 throw new ArgumentNullException(nameof(blobCache));
             }
 
-            return blobCache.GetObject<T>(key).Catch<T, Exception>(ex =>
+            return blobCache.GetObject<T>(key).Catch<T?, Exception>(ex =>
             {
                 var prefixedKey = blobCache.GetHashCode().ToString(CultureInfo.InvariantCulture) + key;
 
@@ -184,7 +184,7 @@ public static IObservable<T> GetOrFetchObject<T>(this IBlobCache blobCache, stri
         /// <param name="absoluteExpiration">An optional expiration date.</param>
         /// <returns>A Future result representing the deserialized object from
         /// the cache.</returns>
-        public static IObservable<T> GetOrFetchObject<T>(this IBlobCache blobCache, string key, Func<Task<T>> fetchFunc, DateTimeOffset? absoluteExpiration = null)
+        public static IObservable<T?> GetOrFetchObject<T>(this IBlobCache blobCache, string key, Func<Task<T>> fetchFunc, DateTimeOffset? absoluteExpiration = null)
         {
             if (blobCache is null)
             {
@@ -210,7 +210,7 @@ public static IObservable<T> GetOrFetchObject<T>(this IBlobCache blobCache, stri
         /// <param name="absoluteExpiration">An optional expiration date.</param>
         /// <returns>A Future result representing the deserialized object from
         /// the cache.</returns>
-        public static IObservable<T> GetOrCreateObject<T>(this IBlobCache blobCache, string key, Func<T> fetchFunc, DateTimeOffset? absoluteExpiration = null)
+        public static IObservable<T?> GetOrCreateObject<T>(this IBlobCache blobCache, string key, Func<T> fetchFunc, DateTimeOffset? absoluteExpiration = null)
         {
             if (blobCache is null)
             {
@@ -275,7 +275,7 @@ public static IObservable<T> GetOrCreateObject<T>(this IBlobCache blobCache, str
         /// <returns>An Observable stream containing either one or two
         /// results (possibly a cached version, then the latest version).</returns>
         [SuppressMessage("Design", "CA2000: call dispose", Justification = "Disposed by member")]
-        public static IObservable<T> GetAndFetchLatest<T>(
+        public static IObservable<T?> GetAndFetchLatest<T>(
             this IBlobCache blobCache,
             string key,
             Func<IObservable<T>> fetchFunc,
@@ -291,7 +291,7 @@ public static IObservable<T> GetAndFetchLatest<T>(
 
 #pragma warning disable CS8604 // Possible null reference argument.
             var fetch = Observable.Defer(() => blobCache.GetObjectCreatedAt<T>(key))
-                .Select(x => fetchPredicate == null || x == null || fetchPredicate(x.Value))
+                .Select(x => fetchPredicate is null || x is null || fetchPredicate(x.Value))
                 .Where(x => x)
                 .SelectMany(_ =>
                 {
@@ -305,23 +305,28 @@ public static IObservable<T> GetAndFetchLatest<T>(
 
                     return fetchObs
                         .SelectMany(x =>
-                            cacheValidationPredicate != null && !cacheValidationPredicate(x)
+                            cacheValidationPredicate is not null && !cacheValidationPredicate(x)
                                 ? Observable.Return(default(T))
                                 : blobCache.InvalidateObject<T>(key).Select(__ => x))
                         .SelectMany(x =>
-                            cacheValidationPredicate != null && !cacheValidationPredicate(x)
+                            cacheValidationPredicate is not null && !cacheValidationPredicate(x)
                                 ? Observable.Return(default(T))
                                 : blobCache.InsertObject(key, x, absoluteExpiration).Select(__ => x));
                 });
 
-            var result = blobCache.GetObject<T>(key).Select(x => new Tuple<T, bool>(x, true))
-                .Catch(Observable.Return(new Tuple<T, bool>(default(T), false)));
+            if (fetch is null)
+            {
+                return Observable.Throw<T>(new Exception("Could not find a valid way to fetch the value"));
+            }
+
+            var result = blobCache.GetObject<T>(key).Select(x => (x, true))
+                .Catch(Observable.Return((default(T), false)));
 
 #pragma warning restore CS8604 // Possible null reference argument.
 
             return result.SelectMany(x => x.Item2 ? Observable.Return(x.Item1) : Observable.Empty<T>())
                 .Concat(fetch)
-                .Multicast(new ReplaySubject<T>())
+                .Multicast(new ReplaySubject<T?>())
                 .RefCount();
         }
 
@@ -356,7 +361,7 @@ public static IObservable<T> GetAndFetchLatest<T>(
         /// if the fetched value should be cached.</param>
         /// <returns>An Observable stream containing either one or two
         /// results (possibly a cached version, then the latest version).</returns>
-        public static IObservable<T> GetAndFetchLatest<T>(
+        public static IObservable<T?> GetAndFetchLatest<T>(
             this IBlobCache blobCache,
             string key,
             Func<Task<T>> fetchFunc,
@@ -447,7 +452,7 @@ internal static byte[] SerializeObject<T>(T value)
             return Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(value, settings));
         }
 
-        internal static IObservable<T> DeserializeObject<T>(byte[] x)
+        internal static IObservable<T?> DeserializeObject<T>(byte[] x)
         {
             var settings = Locator.Current.GetService<JsonSerializerSettings>();
 

src/Akavache.Core/KeyedOperations/KeyedOperationQueue.cs

@@ -102,7 +102,7 @@ public IObservable<Unit> ShutdownQueue()
         {
             lock (_queuedOps)
             {
-                if (_shutdownObs != null)
+                if (_shutdownObs is not null)
                 {
                     return _shutdownObs;
                 }
@@ -113,7 +113,7 @@ public IObservable<Unit> ShutdownQueue()
                 var sub = _resultObs.Materialize()
                     .Where(x => x.Kind != NotificationKind.OnNext)
                     .SelectMany(x =>
-                        (x.Kind == NotificationKind.OnError) ?
+                        (x.Kind == NotificationKind.OnError && x.Exception is not null) ?
                             Observable.Throw<Unit>(x.Exception) :
                             Observable.Return(Unit.Default))
                     .Multicast(_shutdownObs);
@@ -156,19 +156,20 @@ private IObservable<T> SafeStart<T>(Func<T> calculationFunc)
             var ret = new AsyncSubject<T>();
             Observable.Start(
                 () =>
-            {
-                try
-                {
-                    var val = calculationFunc();
-                    ret.OnNext(val);
-                    ret.OnCompleted();
-                }
-                catch (Exception ex)
                 {
-                    this.Log().Warn(ex, "Failure running queued op");
-                    ret.OnError(ex);
-                }
-            }, _scheduler);
+                    try
+                    {
+                        var val = calculationFunc();
+                        ret.OnNext(val);
+                        ret.OnCompleted();
+                    }
+                    catch (Exception ex)
+                    {
+                        this.Log().Warn(ex, "Failure running queued op");
+                        ret.OnError(ex);
+                    }
+                },
+                _scheduler);
 
             return ret;
         }