Apply NRT to MemoryCachingComponent classes

osu.Game/Database/MemoryCachingComponent.cs

@@ -1,13 +1,11 @@
 // 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 disable
-
 using System;
 using System.Collections.Concurrent;
+using System.Diagnostics.CodeAnalysis;
 using System.Threading;
 using System.Threading.Tasks;
-using JetBrains.Annotations;
 using osu.Framework.Extensions.TypeExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Statistics;
@@ -19,8 +17,9 @@ namespace osu.Game.Database
     /// Currently not persisted between game sessions.
     /// </summary>
     public abstract partial class MemoryCachingComponent<TLookup, TValue> : Component
+        where TLookup : notnull
     {
-        private readonly ConcurrentDictionary<TLookup, TValue> cache = new ConcurrentDictionary<TLookup, TValue>();
+        private readonly ConcurrentDictionary<TLookup, TValue?> cache = new ConcurrentDictionary<TLookup, TValue?>();
 
         private readonly GlobalStatistic<MemoryCachingStatistics> statistics;
 
@@ -37,12 +36,12 @@ namespace osu.Game.Database
         /// </summary>
         /// <param name="lookup">The lookup to retrieve.</param>
         /// <param name="token">An optional <see cref="CancellationToken"/> to cancel the operation.</param>
-        protected async Task<TValue> GetAsync([NotNull] TLookup lookup, CancellationToken token = default)
+        protected async Task<TValue?> GetAsync(TLookup lookup, CancellationToken token = default)
         {
-            if (CheckExists(lookup, out TValue performance))
+            if (CheckExists(lookup, out TValue? existing))
             {
                 statistics.Value.HitCount++;
-                return performance;
+                return existing;
             }
 
             var computed = await ComputeValueAsync(lookup, token).ConfigureAwait(false);
@@ -73,7 +72,7 @@ namespace osu.Game.Database
             statistics.Value.Usage = cache.Count;
         }
 
-        protected bool CheckExists([NotNull] TLookup lookup, out TValue value) =>
+        protected bool CheckExists(TLookup lookup, [MaybeNullWhen(false)] out TValue value) =>
             cache.TryGetValue(lookup, out value);
 
         /// <summary>
@@ -82,7 +81,7 @@ namespace osu.Game.Database
         /// <param name="lookup">The lookup to retrieve.</param>
         /// <param name="token">An optional <see cref="CancellationToken"/> to cancel the operation.</param>
         /// <returns>The computed value.</returns>
-        protected abstract Task<TValue> ComputeValueAsync(TLookup lookup, CancellationToken token = default);
+        protected abstract Task<TValue?> ComputeValueAsync(TLookup lookup, CancellationToken token = default);
 
         private class MemoryCachingStatistics
         {

osu.Game/Database/OnlineLookupCache.cs

@@ -1,14 +1,11 @@
 // 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 disable
-
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Extensions;
 using osu.Game.Online.API;
@@ -21,7 +18,7 @@ namespace osu.Game.Database
         where TRequest : APIRequest
     {
         [Resolved]
-        private IAPIProvider api { get; set; }
+        private IAPIProvider api { get; set; } = null!;
 
         /// <summary>
         /// Creates an <see cref="APIRequest"/> to retrieve the values for a given collection of <typeparamref name="TLookup"/>s.
@@ -32,8 +29,7 @@ namespace osu.Game.Database
         /// <summary>
         /// Retrieves a list of <typeparamref name="TValue"/>s from a successful <typeparamref name="TRequest"/> created by <see cref="CreateRequest"/>.
         /// </summary>
-        [CanBeNull]
+        protected abstract IEnumerable<TValue>? RetrieveResults(TRequest request);
-        protected abstract IEnumerable<TValue> RetrieveResults(TRequest request);
 
         /// <summary>
         /// Perform a lookup using the specified <paramref name="id"/>, populating a <typeparamref name="TValue"/>.
@@ -41,8 +37,7 @@ namespace osu.Game.Database
         /// <param name="id">The ID to lookup.</param>
         /// <param name="token">An optional cancellation token.</param>
         /// <returns>The populated <typeparamref name="TValue"/>, or null if the value does not exist or the request could not be satisfied.</returns>
-        [ItemCanBeNull]
+        protected Task<TValue?> LookupAsync(TLookup id, CancellationToken token = default) => GetAsync(id, token);
-        protected Task<TValue> LookupAsync(TLookup id, CancellationToken token = default) => GetAsync(id, token);
 
         /// <summary>
         /// Perform an API lookup on the specified <paramref name="ids"/>, populating a <typeparamref name="TValue"/>.
@@ -50,9 +45,9 @@ namespace osu.Game.Database
         /// <param name="ids">The IDs to lookup.</param>
         /// <param name="token">An optional cancellation token.</param>
         /// <returns>The populated values. May include null results for failed retrievals.</returns>
-        protected Task<TValue[]> LookupAsync(TLookup[] ids, CancellationToken token = default)
+        protected Task<TValue?[]> LookupAsync(TLookup[] ids, CancellationToken token = default)
         {
-            var lookupTasks = new List<Task<TValue>>();
+            var lookupTasks = new List<Task<TValue?>>();
 
             foreach (var id in ids)
             {
@@ -69,18 +64,18 @@ namespace osu.Game.Database
         }
 
         // cannot be sealed due to test usages (see TestUserLookupCache).
-        protected override async Task<TValue> ComputeValueAsync(TLookup lookup, CancellationToken token = default)
+        protected override async Task<TValue?> ComputeValueAsync(TLookup lookup, CancellationToken token = default)
             => await queryValue(lookup).ConfigureAwait(false);
 
-        private readonly Queue<(TLookup id, TaskCompletionSource<TValue>)> pendingTasks = new Queue<(TLookup, TaskCompletionSource<TValue>)>();
+        private readonly Queue<(TLookup id, TaskCompletionSource<TValue?>)> pendingTasks = new Queue<(TLookup, TaskCompletionSource<TValue?>)>();
-        private Task pendingRequestTask;
+        private Task? pendingRequestTask;
         private readonly object taskAssignmentLock = new object();
 
-        private Task<TValue> queryValue(TLookup id)
+        private Task<TValue?> queryValue(TLookup id)
         {
             lock (taskAssignmentLock)
             {
-                var tcs = new TaskCompletionSource<TValue>();
+                var tcs = new TaskCompletionSource<TValue?>();
 
                 // Add to the queue.
                 pendingTasks.Enqueue((id, tcs));
@@ -96,14 +91,14 @@ namespace osu.Game.Database
         private async Task performLookup()
         {
             // contains at most 50 unique IDs from tasks, which is used to perform the lookup.
-            var nextTaskBatch = new Dictionary<TLookup, List<TaskCompletionSource<TValue>>>();
+            var nextTaskBatch = new Dictionary<TLookup, List<TaskCompletionSource<TValue?>>>();
 
             // Grab at most 50 unique IDs from the queue.
             lock (taskAssignmentLock)
             {
                 while (pendingTasks.Count > 0 && nextTaskBatch.Count < 50)
                 {
-                    (TLookup id, TaskCompletionSource<TValue> task) next = pendingTasks.Dequeue();
+                    (TLookup id, TaskCompletionSource<TValue?> task) next = pendingTasks.Dequeue();
 
                     // Perform a secondary check for existence, in case the value was queried in a previous batch.
                     if (CheckExists(next.id, out var existing))
@@ -113,7 +108,7 @@ namespace osu.Game.Database
                         if (nextTaskBatch.TryGetValue(next.id, out var tasks))
                             tasks.Add(next.task);
                         else
-                            nextTaskBatch[next.id] = new List<TaskCompletionSource<TValue>> { next.task };
+                            nextTaskBatch[next.id] = new List<TaskCompletionSource<TValue?>> { next.task };
                     }
                 }
             }

osu.Game/Database/UserLookupCache.cs

@@ -1,13 +1,10 @@
 // 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 disable
-
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using JetBrains.Annotations;
 using osu.Game.Online.API.Requests;
 using osu.Game.Online.API.Requests.Responses;
 
@@ -21,8 +18,7 @@ namespace osu.Game.Database
         /// <param name="userId">The user to lookup.</param>
         /// <param name="token">An optional cancellation token.</param>
         /// <returns>The populated user, or null if the user does not exist or the request could not be satisfied.</returns>
-        [ItemCanBeNull]
+        public Task<APIUser?> GetUserAsync(int userId, CancellationToken token = default) => LookupAsync(userId, token);
-        public Task<APIUser> GetUserAsync(int userId, CancellationToken token = default) => LookupAsync(userId, token);
 
         /// <summary>
         /// Perform an API lookup on the specified users, populating a <see cref="APIUser"/> model.
@@ -30,10 +26,10 @@ namespace osu.Game.Database
         /// <param name="userIds">The users to lookup.</param>
         /// <param name="token">An optional cancellation token.</param>
         /// <returns>The populated users. May include null results for failed retrievals.</returns>
-        public Task<APIUser[]> GetUsersAsync(int[] userIds, CancellationToken token = default) => LookupAsync(userIds, token);
+        public Task<APIUser?[]> GetUsersAsync(int[] userIds, CancellationToken token = default) => LookupAsync(userIds, token);
 
         protected override GetUsersRequest CreateRequest(IEnumerable<int> ids) => new GetUsersRequest(ids.ToArray());
 
-        protected override IEnumerable<APIUser> RetrieveResults(GetUsersRequest request) => request.Response?.Users;
+        protected override IEnumerable<APIUser>? RetrieveResults(GetUsersRequest request) => request.Response?.Users;
     }
 }

osu.Game/Online/API/Requests/GetUsersRequest.cs

@@ -1,8 +1,6 @@
 // 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 disable
-
 using System;
 
 namespace osu.Game.Online.API.Requests