fix: Different ratelimits for the same route (implement discord buckets) (#1546)

* Don't disable when there's no resetTick

Sometimes Discord won't send any ratelimit headers, disabling the semaphore for endpoints that should have them.

* Undo changes and change comment

* Add HttpMethod to BucketIds

* Add X-RateLimit-Bucket

* BucketId changes

- BucketId is it's own class now
- Add WebhookId as a major parameter
- Add shared buckets using the hash and major parameters

* Add webhookId to BucketIds

* Update BucketId and redirect requests

* General bugfixes

* Assign semaphore and follow the same standard as Reset for ResetAfter

src/Discord.Net.Core/Net/BucketId.cs

@@ -0,0 +1,118 @@
+using System;
+using System.Collections.Generic;
+using System.Collections.Immutable;
+using System.Linq;
+
+namespace Discord.Net
+{
+    /// <summary>
+    ///     Represents a ratelimit bucket.
+    /// </summary>
+    public class BucketId : IEquatable<BucketId>
+    {
+        /// <summary>
+        ///     Gets the http method used to make the request if available.
+        /// </summary>
+        public string HttpMethod { get; }
+        /// <summary>
+        ///     Gets the endpoint that is going to be requested if available.
+        /// </summary>
+        public string Endpoint { get; }
+        /// <summary>
+        ///     Gets the major parameters of the route.
+        /// </summary>
+        public IOrderedEnumerable<KeyValuePair<string, string>> MajorParameters { get; }
+        /// <summary>
+        ///     Gets the hash of this bucket.
+        /// </summary>
+        /// <remarks>
+        ///     The hash is provided by Discord to group ratelimits.
+        /// </remarks>
+        public string BucketHash { get; }
+        /// <summary>
+        ///     Gets if this bucket is a hash type.
+        /// </summary>
+        public bool IsHashBucket { get => BucketHash != null; }
+
+        private BucketId(string httpMethod, string endpoint, IEnumerable<KeyValuePair<string, string>> majorParameters, string bucketHash)
+        {
+            HttpMethod = httpMethod;
+            Endpoint = endpoint;
+            MajorParameters = majorParameters.OrderBy(x => x.Key);
+            BucketHash = bucketHash;
+        }
+
+        /// <summary>
+        ///     Creates a new <see cref="BucketId"/> based on the
+        ///     <see cref="HttpMethod"/> and <see cref="Endpoint"/>.
+        /// </summary>
+        /// <param name="httpMethod">Http method used to make the request.</param>
+        /// <param name="endpoint">Endpoint that is going to receive requests.</param>
+        /// <param name="majorParams">Major parameters of the route of this endpoint.</param>
+        /// <returns>
+        ///     A <see cref="BucketId"/> based on the <see cref="HttpMethod"/>
+        ///     and the <see cref="Endpoint"/> with the provided data.
+        /// </returns>
+        public static BucketId Create(string httpMethod, string endpoint, Dictionary<string, string> majorParams)
+        {
+            Preconditions.NotNullOrWhitespace(endpoint, nameof(endpoint));
+            majorParams ??= new Dictionary<string, string>();
+            return new BucketId(httpMethod, endpoint, majorParams, null);
+        }
+
+        /// <summary>
+        ///     Creates a new <see cref="BucketId"/> based on a
+        ///     <see cref="BucketHash"/> and a previous <see cref="BucketId"/>.
+        /// </summary>
+        /// <param name="hash">Bucket hash provided by Discord.</param>
+        /// <param name="oldBucket"><see cref="BucketId"/> that is going to be upgraded to a hash type.</param>
+        /// <returns>
+        ///     A <see cref="BucketId"/> based on the <see cref="BucketHash"/>
+        ///     and <see cref="MajorParameters"/>.
+        /// </returns>
+        public static BucketId Create(string hash, BucketId oldBucket)
+        {
+            Preconditions.NotNullOrWhitespace(hash, nameof(hash));
+            Preconditions.NotNull(oldBucket, nameof(oldBucket));
+            return new BucketId(null, null, oldBucket.MajorParameters, hash);
+        }
+
+        /// <summary>
+        ///     Gets the string that will define this bucket as a hash based one.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="string"/> that defines this bucket as a hash based one.
+        /// </returns>
+        public string GetBucketHash()
+            => IsHashBucket ? $"{BucketHash}:{string.Join("/", MajorParameters.Select(x => x.Value))}" : null;
+
+        /// <summary>
+        ///     Gets the string that will define this bucket as an endpoint based one.
+        /// </summary>
+        /// <returns>
+        ///     A <see cref="string"/> that defines this bucket as an endpoint based one.
+        /// </returns>
+        public string GetUniqueEndpoint()
+            => HttpMethod != null ? $"{HttpMethod} {Endpoint}" : Endpoint;
+
+        public override bool Equals(object obj)
+            => Equals(obj as BucketId);
+
+        public override int GetHashCode()
+            =>  IsHashBucket ? (BucketHash, string.Join("/", MajorParameters.Select(x => x.Value))).GetHashCode() : (HttpMethod, Endpoint).GetHashCode();
+
+        public override string ToString()
+            => GetBucketHash() ?? GetUniqueEndpoint();
+
+        public bool Equals(BucketId other)
+        {
+            if (other is null)
+                return false;
+            if (ReferenceEquals(this, other))
+                return true;
+            if (GetType() != other.GetType())
+                return false;
+            return ToString() == other.ToString();
+        }        
+    }
+}

src/Discord.Net.Core/RequestOptions.cs

@@ -1,3 +1,4 @@
+using Discord.Net;
 using System.Threading;
 
 namespace Discord
@@ -57,7 +58,7 @@ namespace Discord
 		public bool? UseSystemClock { get; set; }
 
         internal bool IgnoreState { get; set; }
-        internal string BucketId { get; set; }
+        internal BucketId BucketId { get; set; }
         internal bool IsClientBucket { get; set; }
         internal bool IsReactionBucket { get; set; }
 

src/Discord.Net.Rest/BaseDiscordClient.cs

@@ -49,9 +49,9 @@ namespace Discord.Rest
             ApiClient.RequestQueue.RateLimitTriggered += async (id, info) =>
             {
                 if (info == null)
-                    await _restLogger.VerboseAsync($"Preemptive Rate limit triggered: {id ?? "null"}").ConfigureAwait(false);
+                    await _restLogger.VerboseAsync($"Preemptive Rate limit triggered: {id?.ToString() ?? "null"}").ConfigureAwait(false);
                 else
-                    await _restLogger.WarningAsync($"Rate limit triggered: {id ?? "null"}").ConfigureAwait(false);
+                    await _restLogger.WarningAsync($"Rate limit triggered: {id?.ToString() ?? "null"}").ConfigureAwait(false);
             };
             ApiClient.SentRequest += async (method, endpoint, millis) => await _restLogger.VerboseAsync($"{method} {endpoint}: {millis} ms").ConfigureAwait(false);
         }

src/Discord.Net.Rest/DiscordRestApiClient.cs

@@ -24,7 +24,7 @@ namespace Discord.API
 {
     internal class DiscordRestApiClient : IDisposable
     {
-        private static readonly ConcurrentDictionary<string, Func<BucketIds, string>> _bucketIdGenerators = new ConcurrentDictionary<string, Func<BucketIds, string>>();
+        private static readonly ConcurrentDictionary<string, Func<BucketIds, BucketId>> _bucketIdGenerators = new ConcurrentDictionary<string, Func<BucketIds, BucketId>>();
 
         public event Func<string, string, double, Task> SentRequest { add { _sentRequestEvent.Add(value); } remove { _sentRequestEvent.Remove(value); } }
         private readonly AsyncEvent<Func<string, string, double, Task>> _sentRequestEvent = new AsyncEvent<Func<string, string, double, Task>>();
@@ -176,9 +176,9 @@ namespace Discord.API
         //Core
         internal Task SendAsync(string method, Expression<Func<string>> endpointExpr, BucketIds ids,
              ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null, [CallerMemberName] string funcName = null)
-            => SendAsync(method, GetEndpoint(endpointExpr), GetBucketId(ids, endpointExpr, funcName), clientBucket, options);
+            => SendAsync(method, GetEndpoint(endpointExpr), GetBucketId(method, ids, endpointExpr, funcName), clientBucket, options);
         public async Task SendAsync(string method, string endpoint,
-            string bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
+            BucketId bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
         {
             options = options ?? new RequestOptions();
             options.HeaderOnly = true;
@@ -190,9 +190,9 @@ namespace Discord.API
 
         internal Task SendJsonAsync(string method, Expression<Func<string>> endpointExpr, object payload, BucketIds ids,
              ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null, [CallerMemberName] string funcName = null)
-            => SendJsonAsync(method, GetEndpoint(endpointExpr), payload, GetBucketId(ids, endpointExpr, funcName), clientBucket, options);
+            => SendJsonAsync(method, GetEndpoint(endpointExpr), payload, GetBucketId(method, ids, endpointExpr, funcName), clientBucket, options);
         public async Task SendJsonAsync(string method, string endpoint, object payload,
-            string bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
+            BucketId bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
         {
             options = options ?? new RequestOptions();
             options.HeaderOnly = true;
@@ -205,9 +205,9 @@ namespace Discord.API
 
         internal Task SendMultipartAsync(string method, Expression<Func<string>> endpointExpr, IReadOnlyDictionary<string, object> multipartArgs, BucketIds ids,
              ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null, [CallerMemberName] string funcName = null)
-            => SendMultipartAsync(method, GetEndpoint(endpointExpr), multipartArgs, GetBucketId(ids, endpointExpr, funcName), clientBucket, options);
+            => SendMultipartAsync(method, GetEndpoint(endpointExpr), multipartArgs, GetBucketId(method, ids, endpointExpr, funcName), clientBucket, options);
         public async Task SendMultipartAsync(string method, string endpoint, IReadOnlyDictionary<string, object> multipartArgs,
-            string bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
+            BucketId bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
         {
             options = options ?? new RequestOptions();
             options.HeaderOnly = true;
@@ -219,9 +219,9 @@ namespace Discord.API
 
         internal Task<TResponse> SendAsync<TResponse>(string method, Expression<Func<string>> endpointExpr, BucketIds ids,
              ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null, [CallerMemberName] string funcName = null) where TResponse : class
-            => SendAsync<TResponse>(method, GetEndpoint(endpointExpr), GetBucketId(ids, endpointExpr, funcName), clientBucket, options);
+            => SendAsync<TResponse>(method, GetEndpoint(endpointExpr), GetBucketId(method, ids, endpointExpr, funcName), clientBucket, options);
         public async Task<TResponse> SendAsync<TResponse>(string method, string endpoint,
-            string bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null) where TResponse : class
+            BucketId bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null) where TResponse : class
         {
             options = options ?? new RequestOptions();
             options.BucketId = bucketId;
@@ -232,9 +232,9 @@ namespace Discord.API
 
         internal Task<TResponse> SendJsonAsync<TResponse>(string method, Expression<Func<string>> endpointExpr, object payload, BucketIds ids,
              ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null, [CallerMemberName] string funcName = null) where TResponse : class
-            => SendJsonAsync<TResponse>(method, GetEndpoint(endpointExpr), payload, GetBucketId(ids, endpointExpr, funcName), clientBucket, options);
+            => SendJsonAsync<TResponse>(method, GetEndpoint(endpointExpr), payload, GetBucketId(method, ids, endpointExpr, funcName), clientBucket, options);
         public async Task<TResponse> SendJsonAsync<TResponse>(string method, string endpoint, object payload,
-            string bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null) where TResponse : class
+            BucketId bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null) where TResponse : class
         {
             options = options ?? new RequestOptions();
             options.BucketId = bucketId;
@@ -246,9 +246,9 @@ namespace Discord.API
 
         internal Task<TResponse> SendMultipartAsync<TResponse>(string method, Expression<Func<string>> endpointExpr, IReadOnlyDictionary<string, object> multipartArgs, BucketIds ids,
              ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null, [CallerMemberName] string funcName = null)
-            => SendMultipartAsync<TResponse>(method, GetEndpoint(endpointExpr), multipartArgs, GetBucketId(ids, endpointExpr, funcName), clientBucket, options);
+            => SendMultipartAsync<TResponse>(method, GetEndpoint(endpointExpr), multipartArgs, GetBucketId(method, ids, endpointExpr, funcName), clientBucket, options);
         public async Task<TResponse> SendMultipartAsync<TResponse>(string method, string endpoint, IReadOnlyDictionary<string, object> multipartArgs,
-            string bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
+            BucketId bucketId = null, ClientBucketType clientBucket = ClientBucketType.Unbucketed, RequestOptions options = null)
         {
             options = options ?? new RequestOptions();
             options.BucketId = bucketId;
@@ -520,7 +520,8 @@ namespace Discord.API
                 throw new ArgumentException(message: $"Message content is too long, length must be less or equal to {DiscordConfig.MaxMessageSize}.", paramName: nameof(args.Content));
             options = RequestOptions.CreateOrClone(options);
 
-            return await SendJsonAsync<Message>("POST", () => $"webhooks/{webhookId}/{AuthToken}?wait=true", args, new BucketIds(), clientBucket: ClientBucketType.SendEdit, options: options).ConfigureAwait(false);
+            var ids = new BucketIds(webhookId: webhookId);
+            return await SendJsonAsync<Message>("POST", () => $"webhooks/{webhookId}/{AuthToken}?wait=true", args, ids, clientBucket: ClientBucketType.SendEdit, options: options).ConfigureAwait(false);
         }
         /// <exception cref="ArgumentOutOfRangeException">Message content is too long, length must be less or equal to <see cref="DiscordConfig.MaxMessageSize"/>.</exception>
         public async Task<Message> UploadFileAsync(ulong channelId, UploadFileParams args, RequestOptions options = null)
@@ -559,7 +560,8 @@ namespace Discord.API
                     throw new ArgumentOutOfRangeException($"Message content is too long, length must be less or equal to {DiscordConfig.MaxMessageSize}.", nameof(args.Content));
             }
 
-            return await SendMultipartAsync<Message>("POST", () => $"webhooks/{webhookId}/{AuthToken}?wait=true", args.ToDictionary(), new BucketIds(), clientBucket: ClientBucketType.SendEdit, options: options).ConfigureAwait(false);
+            var ids = new BucketIds(webhookId: webhookId);
+            return await SendMultipartAsync<Message>("POST", () => $"webhooks/{webhookId}/{AuthToken}?wait=true", args.ToDictionary(), ids, clientBucket: ClientBucketType.SendEdit, options: options).ConfigureAwait(false);
         }
         public async Task DeleteMessageAsync(ulong channelId, ulong messageId, RequestOptions options = null)
         {
@@ -1466,21 +1468,39 @@ namespace Discord.API
         {
             public ulong GuildId { get; internal set; }
             public ulong ChannelId { get; internal set; }
+            public ulong WebhookId { get; internal set; }
+            public string HttpMethod { get; internal set; }
 
-            internal BucketIds(ulong guildId = 0, ulong channelId = 0)
+            internal BucketIds(ulong guildId = 0, ulong channelId = 0, ulong webhookId = 0)
             {
                 GuildId = guildId;
                 ChannelId = channelId;
+                WebhookId = webhookId;
             }
+
             internal object[] ToArray()
-                => new object[] { GuildId, ChannelId };
+                => new object[] { HttpMethod, GuildId, ChannelId, WebhookId };
+
+            internal Dictionary<string, string> ToMajorParametersDictionary()
+            {
+                var dict = new Dictionary<string, string>();
+                if (GuildId != 0)
+                    dict["GuildId"] = GuildId.ToString();
+                if (ChannelId != 0)
+                    dict["ChannelId"] = ChannelId.ToString();
+                if (WebhookId != 0)
+                    dict["WebhookId"] = WebhookId.ToString();
+                return dict;
+            }
 
             internal static int? GetIndex(string name)
             {
                 switch (name)
                 {
-                    case "guildId": return 0;
-                    case "channelId": return 1;
+                    case "httpMethod": return 0;
+                    case "guildId": return 1;
+                    case "channelId": return 2;
+                    case "webhookId": return 3;
                     default:
                         return null;
                 }
@@ -1491,18 +1511,19 @@ namespace Discord.API
         {
             return endpointExpr.Compile()();
         }
-        private static string GetBucketId(BucketIds ids, Expression<Func<string>> endpointExpr, string callingMethod)
+        private static BucketId GetBucketId(string httpMethod, BucketIds ids, Expression<Func<string>> endpointExpr, string callingMethod)
         {
+            ids.HttpMethod ??= httpMethod;
             return _bucketIdGenerators.GetOrAdd(callingMethod, x => CreateBucketId(endpointExpr))(ids);
         }
 
-        private static Func<BucketIds, string> CreateBucketId(Expression<Func<string>> endpoint)
+        private static Func<BucketIds, BucketId> CreateBucketId(Expression<Func<string>> endpoint)
         {
             try
             {
                 //Is this a constant string?
                 if (endpoint.Body.NodeType == ExpressionType.Constant)
-                    return x => (endpoint.Body as ConstantExpression).Value.ToString();
+                    return x => BucketId.Create(x.HttpMethod, (endpoint.Body as ConstantExpression).Value.ToString(), x.ToMajorParametersDictionary());
 
                 var builder = new StringBuilder();
                 var methodCall = endpoint.Body as MethodCallExpression;
@@ -1539,7 +1560,7 @@ namespace Discord.API
 
                     var mappedId = BucketIds.GetIndex(fieldName);
 
-                    if(!mappedId.HasValue && rightIndex != endIndex && format.Length > rightIndex + 1 && format[rightIndex + 1] == '/') //Ignore the next slash
+                    if (!mappedId.HasValue && rightIndex != endIndex && format.Length > rightIndex + 1 && format[rightIndex + 1] == '/') //Ignore the next slash
                         rightIndex++;
 
                     if (mappedId.HasValue)
@@ -1552,7 +1573,7 @@ namespace Discord.API
 
                 format = builder.ToString();
 
-                return x => string.Format(format, x.ToArray());
+                return x => BucketId.Create(x.HttpMethod, string.Format(format, x.ToArray()), x.ToMajorParametersDictionary());
             }
             catch (Exception ex)
             {

src/Discord.Net.Rest/Net/Queue/ClientBucket.cs

@@ -10,14 +10,14 @@ namespace Discord.Net.Queue
     internal struct ClientBucket
     {
         private static readonly ImmutableDictionary<ClientBucketType, ClientBucket> DefsByType;
-        private static readonly ImmutableDictionary<string, ClientBucket> DefsById;
+        private static readonly ImmutableDictionary<BucketId, ClientBucket> DefsById;
 
         static ClientBucket()
         {
             var buckets = new[]
             {
-                new ClientBucket(ClientBucketType.Unbucketed, "<unbucketed>", 10, 10),
-                new ClientBucket(ClientBucketType.SendEdit, "<send_edit>", 10, 10)
+                new ClientBucket(ClientBucketType.Unbucketed, BucketId.Create(null, "<unbucketed>", null), 10, 10),
+                new ClientBucket(ClientBucketType.SendEdit, BucketId.Create(null, "<send_edit>", null), 10, 10)
             };
 
             var builder = ImmutableDictionary.CreateBuilder<ClientBucketType, ClientBucket>();
@@ -25,21 +25,21 @@ namespace Discord.Net.Queue
                 builder.Add(bucket.Type, bucket);
             DefsByType = builder.ToImmutable();
 
-            var builder2 = ImmutableDictionary.CreateBuilder<string, ClientBucket>();
+            var builder2 = ImmutableDictionary.CreateBuilder<BucketId, ClientBucket>();
             foreach (var bucket in buckets)
                 builder2.Add(bucket.Id, bucket);
             DefsById = builder2.ToImmutable();
         }
 
         public static ClientBucket Get(ClientBucketType type) => DefsByType[type];
-        public static ClientBucket Get(string id) => DefsById[id];
+        public static ClientBucket Get(BucketId id) => DefsById[id];
         
         public ClientBucketType Type { get; }
-        public string Id { get; }
+        public BucketId Id { get; }
         public int WindowCount { get; }
         public int WindowSeconds { get; }
 
-        public ClientBucket(ClientBucketType type, string id, int count, int seconds)
+        public ClientBucket(ClientBucketType type, BucketId id, int count, int seconds)
         {
             Type = type;
             Id = id;

src/Discord.Net.Rest/Net/Queue/RequestQueue.cs

@@ -12,9 +12,9 @@ namespace Discord.Net.Queue
 {
     internal class RequestQueue : IDisposable
     {
-        public event Func<string, RateLimitInfo?, Task> RateLimitTriggered;
+        public event Func<BucketId, RateLimitInfo?, Task> RateLimitTriggered;
 
-        private readonly ConcurrentDictionary<string, RequestBucket> _buckets;
+        private readonly ConcurrentDictionary<BucketId, object> _buckets;
         private readonly SemaphoreSlim _tokenLock;
         private readonly CancellationTokenSource _cancelTokenSource; //Dispose token
         private CancellationTokenSource _clearToken;
@@ -34,7 +34,7 @@ namespace Discord.Net.Queue
             _requestCancelToken = CancellationToken.None;
             _parentToken = CancellationToken.None;
 
-            _buckets = new ConcurrentDictionary<string, RequestBucket>();
+            _buckets = new ConcurrentDictionary<BucketId, object>();
 
             _cleanupTask = RunCleanup();
         }
@@ -82,7 +82,7 @@ namespace Discord.Net.Queue
             else
                 request.Options.CancelToken = _requestCancelToken;
 
-            var bucket = GetOrCreateBucket(request.Options.BucketId, request);
+            var bucket = GetOrCreateBucket(request.Options, request);
             var result = await bucket.SendAsync(request).ConfigureAwait(false);
             createdTokenSource?.Dispose();
             return result;
@@ -110,14 +110,32 @@ namespace Discord.Net.Queue
             _waitUntil = DateTimeOffset.UtcNow.AddMilliseconds(info.RetryAfter.Value + (info.Lag?.TotalMilliseconds ?? 0.0));
         }
 
-        private RequestBucket GetOrCreateBucket(string id, RestRequest request)
+        private RequestBucket GetOrCreateBucket(RequestOptions options, RestRequest request)
         {
-            return _buckets.GetOrAdd(id, x => new RequestBucket(this, request, x));
+            var bucketId = options.BucketId;
+            object obj = _buckets.GetOrAdd(bucketId, x => new RequestBucket(this, request, x));
+            if (obj is BucketId hashBucket)
+            {
+                options.BucketId = hashBucket;
+                return (RequestBucket)_buckets.GetOrAdd(hashBucket, x => new RequestBucket(this, request, x));
+            }
+            return (RequestBucket)obj;
         }
-        internal async Task RaiseRateLimitTriggered(string bucketId, RateLimitInfo? info)
+        internal async Task RaiseRateLimitTriggered(BucketId bucketId, RateLimitInfo? info)
         {
             await RateLimitTriggered(bucketId, info).ConfigureAwait(false);
         }
+        internal (RequestBucket, BucketId) UpdateBucketHash(BucketId id, string discordHash)
+        {
+            if (!id.IsHashBucket)
+            {
+                var bucket = BucketId.Create(discordHash, id);
+                var hashReqQueue = (RequestBucket)_buckets.GetOrAdd(bucket, _buckets[id]);
+                _buckets.AddOrUpdate(id, bucket, (oldBucket, oldObj) => bucket);
+                return (hashReqQueue, bucket);
+            }
+            return (null, null);
+        }
 
         private async Task RunCleanup()
         {
@@ -126,10 +144,15 @@ namespace Discord.Net.Queue
                 while (!_cancelTokenSource.IsCancellationRequested)
                 {
                     var now = DateTimeOffset.UtcNow;
-                    foreach (var bucket in _buckets.Select(x => x.Value))
+                    foreach (var bucket in _buckets.Where(x => x.Value is RequestBucket).Select(x => (RequestBucket)x.Value))
                     {
                         if ((now - bucket.LastAttemptAt).TotalMinutes > 1.0)
+                        {
+                            if (bucket.Id.IsHashBucket)
+                                foreach (var redirectBucket in _buckets.Where(x => x.Value == bucket.Id).Select(x => (BucketId)x.Value))
+                                    _buckets.TryRemove(redirectBucket, out _); //remove redirections if hash bucket
                             _buckets.TryRemove(bucket.Id, out _);
+                        }
                     }
                     await Task.Delay(60000, _cancelTokenSource.Token).ConfigureAwait(false); //Runs each minute
                 }

src/Discord.Net.Rest/Net/Queue/RequestQueueBucket.cs

@@ -19,12 +19,13 @@ namespace Discord.Net.Queue
         private readonly RequestQueue _queue;
         private int _semaphore;
         private DateTimeOffset? _resetTick;
+        private RequestBucket _redirectBucket;
 
-        public string Id { get; private set; }
+        public BucketId Id { get; private set; }
         public int WindowCount { get; private set; }
         public DateTimeOffset LastAttemptAt { get; private set; }
 
-        public RequestBucket(RequestQueue queue, RestRequest request, string id)
+        public RequestBucket(RequestQueue queue, RestRequest request, BucketId id)
         {
             _queue = queue;
             Id = id;
@@ -32,7 +33,7 @@ namespace Discord.Net.Queue
             _lock = new object();
 
             if (request.Options.IsClientBucket)
-                WindowCount = ClientBucket.Get(request.Options.BucketId).WindowCount;
+                WindowCount = ClientBucket.Get(Id).WindowCount;
             else
                 WindowCount = 1; //Only allow one request until we get a header back
             _semaphore = WindowCount;
@@ -52,6 +53,8 @@ namespace Discord.Net.Queue
             {
                 await _queue.EnterGlobalAsync(id, request).ConfigureAwait(false);
                 await EnterAsync(id, request).ConfigureAwait(false);
+                if (_redirectBucket != null)
+                    return await _redirectBucket.SendAsync(request);
 
 #if DEBUG_LIMITS
                 Debug.WriteLine($"[{id}] Sending...");
@@ -160,6 +163,9 @@ namespace Discord.Net.Queue
 
             while (true)
             {
+                if (_redirectBucket != null)
+                    break;
+
                 if (DateTimeOffset.UtcNow > request.TimeoutAt || request.Options.CancelToken.IsCancellationRequested)
                 {
                     if (!isRateLimited)
@@ -175,7 +181,8 @@ namespace Discord.Net.Queue
                 }
 
                 DateTimeOffset? timeoutAt = request.TimeoutAt;
-                if (windowCount > 0 && Interlocked.Decrement(ref _semaphore) < 0)
+                int semaphore = Interlocked.Decrement(ref _semaphore);
+                if (windowCount > 0 && semaphore < 0)
                 {
                     if (!isRateLimited)
                     {
@@ -210,20 +217,52 @@ namespace Discord.Net.Queue
                 }
 #if DEBUG_LIMITS
                 else
-                    Debug.WriteLine($"[{id}] Entered Semaphore ({_semaphore}/{WindowCount} remaining)");
+                    Debug.WriteLine($"[{id}] Entered Semaphore ({semaphore}/{WindowCount} remaining)");
 #endif
                 break;
             }
         }
 
-        private void UpdateRateLimit(int id, RestRequest request, RateLimitInfo info, bool is429)
+        private void UpdateRateLimit(int id, RestRequest request, RateLimitInfo info, bool is429, bool redirected = false)
         {
             if (WindowCount == 0)
                 return;
 
             lock (_lock)
             {
+                if (redirected)
+                {
+                    Interlocked.Decrement(ref _semaphore); //we might still hit a real ratelimit if all tickets were already taken, can't do much about it since we didn't know they were the same
+#if DEBUG_LIMITS
+                    Debug.WriteLine($"[{id}] Decrease Semaphore");
+#endif
+                }
                 bool hasQueuedReset = _resetTick != null;
+
+                if (info.Bucket != null && !redirected)
+                {
+                    (RequestBucket, BucketId) hashBucket = _queue.UpdateBucketHash(Id, info.Bucket);
+                    if (!(hashBucket.Item1 is null) && !(hashBucket.Item2 is null))
+                    {
+                        if (hashBucket.Item1 == this) //this bucket got promoted to a hash queue
+                        {
+                            Id = hashBucket.Item2;
+#if DEBUG_LIMITS
+                            Debug.WriteLine($"[{id}] Promoted to Hash Bucket ({hashBucket.Item2})");
+#endif
+                        }
+                        else
+                        {
+                            _redirectBucket = hashBucket.Item1; //this request should be part of another bucket, this bucket will be disabled, redirect everything
+                            _redirectBucket.UpdateRateLimit(id, request, info, is429, redirected: true); //update the hash bucket ratelimit
+#if DEBUG_LIMITS
+                            Debug.WriteLine($"[{id}] Redirected to {_redirectBucket.Id}");
+#endif
+                            return;
+                        }
+                    }
+                }
+
                 if (info.Limit.HasValue && WindowCount != info.Limit.Value)
                 {
                     WindowCount = info.Limit.Value;
@@ -233,7 +272,6 @@ namespace Discord.Net.Queue
 #endif
                 }
 
-                var now = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
                 DateTimeOffset? resetTick = null;
 
                 //Using X-RateLimit-Remaining causes a race condition
@@ -250,16 +288,18 @@ namespace Discord.Net.Queue
                     Debug.WriteLine($"[{id}] Retry-After: {info.RetryAfter.Value} ({info.RetryAfter.Value} ms)");
 #endif
                 }
-				else if (info.ResetAfter.HasValue && (request.Options.UseSystemClock.HasValue ? !request.Options.UseSystemClock.Value : false))
-				{
-					resetTick = DateTimeOffset.UtcNow.Add(info.ResetAfter.Value);
-				}
+                else if (info.ResetAfter.HasValue && (request.Options.UseSystemClock.HasValue ? !request.Options.UseSystemClock.Value : false))
+                {
+                    resetTick = DateTimeOffset.UtcNow.Add(info.ResetAfter.Value);
+#if DEBUG_LIMITS
+                    Debug.WriteLine($"[{id}] Reset-After: {info.ResetAfter.Value} ({info.ResetAfter?.TotalMilliseconds} ms)");
+#endif
+                }
                 else if (info.Reset.HasValue)
                 {
                     resetTick = info.Reset.Value.AddSeconds(info.Lag?.TotalSeconds ?? 1.0);
 
-					/* millisecond precision makes this unnecessary, retaining in case of regression
-
+                    /* millisecond precision makes this unnecessary, retaining in case of regression
                     if (request.Options.IsReactionBucket)
                         resetTick = DateTimeOffset.Now.AddMilliseconds(250);
 					*/
@@ -269,17 +309,17 @@ namespace Discord.Net.Queue
                     Debug.WriteLine($"[{id}] X-RateLimit-Reset: {info.Reset.Value.ToUnixTimeSeconds()} ({diff} ms, {info.Lag?.TotalMilliseconds} ms lag)");
 #endif
                 }
-                else if (request.Options.IsClientBucket && request.Options.BucketId != null)
+                else if (request.Options.IsClientBucket && Id != null)
                 {
-                    resetTick = DateTimeOffset.UtcNow.AddSeconds(ClientBucket.Get(request.Options.BucketId).WindowSeconds);
+                    resetTick = DateTimeOffset.UtcNow.AddSeconds(ClientBucket.Get(Id).WindowSeconds);
 #if DEBUG_LIMITS
-                    Debug.WriteLine($"[{id}] Client Bucket ({ClientBucket.Get(request.Options.BucketId).WindowSeconds * 1000} ms)");
+                    Debug.WriteLine($"[{id}] Client Bucket ({ClientBucket.Get(Id).WindowSeconds * 1000} ms)");
 #endif
                 }
 
                 if (resetTick == null)
                 {
-                    WindowCount = 0; //No rate limit info, disable limits on this bucket (should only ever happen with a user token)
+                    WindowCount = 0; //No rate limit info, disable limits on this bucket
 #if DEBUG_LIMITS
                     Debug.WriteLine($"[{id}] Disabled Semaphore");
 #endif

src/Discord.Net.Rest/Net/RateLimitInfo.cs

@@ -11,7 +11,8 @@ namespace Discord.Net
         public int? Remaining { get; }
         public int? RetryAfter { get; }
         public DateTimeOffset? Reset { get; }
-		    public TimeSpan? ResetAfter { get; }
+        public TimeSpan? ResetAfter { get; }
+        public string Bucket { get; }
         public TimeSpan? Lag { get; }
 
         internal RateLimitInfo(Dictionary<string, string> headers)
@@ -26,8 +27,9 @@ namespace Discord.Net
                 double.TryParse(temp, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out var reset) ? DateTimeOffset.FromUnixTimeMilliseconds((long)(reset * 1000)) : (DateTimeOffset?)null;
             RetryAfter = headers.TryGetValue("Retry-After", out temp) &&
                 int.TryParse(temp, NumberStyles.None, CultureInfo.InvariantCulture, out var retryAfter) ? retryAfter : (int?)null;
-			      ResetAfter = headers.TryGetValue("X-RateLimit-Reset-After", out temp) && 
-				        float.TryParse(temp, out var resetAfter) ? TimeSpan.FromMilliseconds((long)(resetAfter * 1000)) : (TimeSpan?)null;
+			ResetAfter = headers.TryGetValue("X-RateLimit-Reset-After", out temp) &&
+                double.TryParse(temp, NumberStyles.AllowDecimalPoint, CultureInfo.InvariantCulture, out var resetAfter) ? TimeSpan.FromMilliseconds((long)(resetAfter * 1000)) : (TimeSpan?)null;
+            Bucket = headers.TryGetValue("X-RateLimit-Bucket", out temp) ? temp : null;
             Lag = headers.TryGetValue("Date", out temp) &&
                 DateTimeOffset.TryParse(temp, CultureInfo.InvariantCulture, DateTimeStyles.None, out var date) ? DateTimeOffset.UtcNow - date : (TimeSpan?)null;
         }

src/Discord.Net.Webhook/DiscordWebhookClient.cs

@@ -77,9 +77,9 @@ namespace Discord.Webhook
             ApiClient.RequestQueue.RateLimitTriggered += async (id, info) =>
             {
                 if (info == null)
-                    await _restLogger.VerboseAsync($"Preemptive Rate limit triggered: {id ?? "null"}").ConfigureAwait(false);
+                    await _restLogger.VerboseAsync($"Preemptive Rate limit triggered: {id?.ToString() ?? "null"}").ConfigureAwait(false);
                 else
-                    await _restLogger.WarningAsync($"Rate limit triggered: {id ?? "null"}").ConfigureAwait(false);
+                    await _restLogger.WarningAsync($"Rate limit triggered: {id?.ToString() ?? "null"}").ConfigureAwait(false);
             };
             ApiClient.SentRequest += async (method, endpoint, millis) => await _restLogger.VerboseAsync($"{method} {endpoint}: {millis} ms").ConfigureAwait(false);
         }