diff --git a/osu.Game/Database/UserLookupCache.cs b/osu.Game/Database/UserLookupCache.cs index c85ad6d651..05d6930992 100644 --- a/osu.Game/Database/UserLookupCache.cs +++ b/osu.Game/Database/UserLookupCache.cs @@ -1,7 +1,6 @@ // Copyright (c) ppy Pty Ltd . Licensed under the MIT Licence. // See the LICENCE file in the repository root for full licence text. -using System; using System.Collections.Generic; using System.Linq; using System.Threading; @@ -15,103 +14,93 @@ namespace osu.Game.Database { public class UserLookupCache : MemoryCachingComponent { - private readonly HashSet nextTaskIDs = new HashSet(); - [Resolved] private IAPIProvider api { get; set; } - private readonly object taskAssignmentLock = new object(); - - private Task> pendingRequest; - - /// - /// Whether has already grabbed its IDs. - /// - private bool pendingRequestConsumedIDs; - public Task GetUserAsync(int userId, CancellationToken token = default) => GetAsync(userId, token); protected override async Task ComputeValueAsync(int lookup, CancellationToken token = default) - { - var users = await getQueryTaskForUser(lookup); - return users.FirstOrDefault(u => u.Id == lookup); - } + => await queryUser(lookup); - /// - /// Return the task responsible for fetching the provided user. - /// This may be part of a larger batch lookup to reduce web requests. - /// - /// The user to lookup. - /// The task responsible for the lookup. - private Task> getQueryTaskForUser(int userId) + private readonly Queue<(int id, TaskCompletionSource)> pendingUserTasks = new Queue<(int, TaskCompletionSource)>(); + private Task pendingRequestTask; + private readonly object taskAssignmentLock = new object(); + + private Task queryUser(int userId) { lock (taskAssignmentLock) { - nextTaskIDs.Add(userId); + var tcs = new TaskCompletionSource(); - // if there's a pending request which hasn't been started yet (and is not yet full), we can wait on it. - if (pendingRequest != null && !pendingRequestConsumedIDs && nextTaskIDs.Count < 50) - return pendingRequest; + // Add to the queue. + pendingUserTasks.Enqueue((userId, tcs)); - return queueNextTask(nextLookup); + // Create a request task if there's not already one. + if (pendingRequestTask == null) + createNewTask(); + + return tcs.Task; } + } - List nextLookup() + private void performLookup() + { + // contains at most 50 unique user IDs from userTasks, which is used to perform the lookup. + var userTasks = new Dictionary>>(); + + // Grab at most 50 unique user IDs from the queue. + lock (taskAssignmentLock) { - int[] lookupItems; - - lock (taskAssignmentLock) + while (pendingUserTasks.Count > 0 && userTasks.Count < 50) { - pendingRequestConsumedIDs = true; - lookupItems = nextTaskIDs.ToArray(); - nextTaskIDs.Clear(); + (int id, TaskCompletionSource task) next = pendingUserTasks.Dequeue(); - if (lookupItems.Length == 0) + // Perform a secondary check for existence, in case the user was queried in a previous batch. + if (CheckExists(next.id, out var existing)) + next.task.SetResult(existing); + else { - queueNextTask(null); - return new List(); + if (userTasks.TryGetValue(next.id, out var tasks)) + tasks.Add(next.task); + else + userTasks[next.id] = new List> { next.task }; } } - - var request = new GetUsersRequest(lookupItems); - - // rather than queueing, we maintain our own single-threaded request stream. - api.Perform(request); - - return request.Result?.Users; } - } - /// - /// Queues new work at the end of the current work tasks. - /// Ensures the provided work is eventually run. - /// - /// The work to run. Can be null to signify the end of available work. - /// The task tracking this work. - private Task> queueNextTask(Func> work) - { + // Query the users. + var request = new GetUsersRequest(userTasks.Keys.ToArray()); + + // rather than queueing, we maintain our own single-threaded request stream. + api.Perform(request); + + // Create a new request task if there's still more users to query. lock (taskAssignmentLock) { - if (work == null) - { - pendingRequest = null; - pendingRequestConsumedIDs = false; - } - else if (pendingRequest == null) - { - // special case for the first request ever. - pendingRequest = Task.Run(work); - pendingRequestConsumedIDs = false; - } - else - { - // append the new request on to the last to be executed. - pendingRequest = pendingRequest.ContinueWith(_ => work()); - pendingRequestConsumedIDs = false; - } + pendingRequestTask = null; + if (pendingUserTasks.Count > 0) + createNewTask(); + } - return pendingRequest; + foreach (var user in request.Result.Users) + { + if (userTasks.TryGetValue(user.Id, out var tasks)) + { + foreach (var task in tasks) + task.SetResult(user); + + userTasks.Remove(user.Id); + } + } + + // if any tasks remain which were not satisfied, return null. + foreach (var tasks in userTasks.Values) + { + foreach (var task in tasks) + task.SetResult(null); } } + + private void createNewTask() => pendingRequestTask = Task.Run(performLookup); } }