System.Threading.Interlocked.Decrement(ref int)

protected virtual void ThreadLoop() {
            try {
                while (Con.IsAlive) {
                    DedupeTimestamp++;

                    int waited = 0;
                    if (Interlocked.CompareExchange(ref QueueCount, 0, 0) == 0)
                        waited = WaitHandle.WaitAny(EventHandles, 1000);

                    if ((waited == WaitHandle.WaitTimeout || DedupeTimestamp % 10 == 0) && LastSent.Count > 0) {
                        for (int i = Dedupes.Count - 1; i >= 0; --i) {
                            DataDedupe slot = Dedupes[i];
                            if (!slot.Update(DedupeTimestamp)) {
                                Dedupes.RemoveAt(i);
                                if (LastSent.TryGetValue(slot.Type, out Dictionary<uint, DataDedupe>? slotByID)) {
                                    slotByID.Remove(slot.ID);
                                    if (slotByID.Count == 0) {
                                        LastSent.Remove(slot.Type);
                                    }
                                }
                            }
                        }
                    }

                    if (!Con.IsAlive)
                        return;

                    DateTime now = DateTime.UtcNow;

                    while (Interlocked.CompareExchange(ref QueueCount, 0, 0) != 0) {
                        DataType? data;
                        lock (QueueLock) {
                            int next = QueueSendNext;
                            data = Queue[next];
                            Queue[next] = null;
                            QueueSendNext = (next + 1) % Queue.Length;
                            Interlocked.Decrement(ref QueueCount);
                        }

                        if (data == null)
                            continue;

                        if (data is DataInternalDisconnect) {
                            Con.Dispose();
                            return;
                        }

                        if ((data.DataFlags & DataFlags.OnlyLatest) == DataFlags.OnlyLatest) {
                            string type = data.GetTypeID(Con.Data);
                            uint id = data.GetDuplicateFilterID();

                            lock (QueueLock) {
                                int next = QueueSendNext;
                                int count = Interlocked.CompareExchange(ref QueueCount, 0, 0);
                                int length = Queue.Length;
                                for (int ii = 0; ii < count; ii++) {
                                    int i = (next + ii) % length;
                                    DataType? d = Queue[i];
                                    if (d != null && d.GetTypeID(Con.Data) == type && d.GetDuplicateFilterID() == id) {
                                        data = d;
                                        Queue[i] = null;
                                    }
                                }
                            }
                        }

                        if ((data.DataFlags & DataFlags.SkipDuplicate) == DataFlags.SkipDuplicate) {
                            string type = data.GetTypeID(Con.Data);
                            uint id = data.GetDuplicateFilterID();

                            if (!LastSent.TryGetValue(type, out Dictionary<uint, DataDedupe>? slotByID))
                                LastSent[type] = slotByID = new();

                            if (slotByID.TryGetValue(id, out DataDedupe? slot)) {
                                if (slot.Data.ConsideredDuplicate(data))
                                    continue;
                                slot.Data = data;
                                slot.Timestamp = DedupeTimestamp;
                                slot.Iterations = 0;
                            } else {
                                Dedupes.Add(slotByID[id] = new(type, id, data, DedupeTimestamp));
                            }

                        }

                        Con.SendRaw(this, data);

                        if ((data.DataFlags & DataFlags.Update) == DataFlags.Update)
                            LastUpdate = now;
                        else
                            LastNonUpdate = now;
                    }

                    if (Con.SendStringMap) {
                        List<Tuple<string, int>> added = Strings.PromoteRead();
                        if (added.Count > 0) {
                            foreach (Tuple<string, int> mapping in added)
                                Con.SendRaw(this, new DataLowLevelStringMapping {
                                    IsUpdate = SendStringMapUpdate,
                                    StringMap = Strings.Name,
                                    Value = mapping.Item1,
                                    ID = mapping.Item2
                                });
                            if (SendStringMapUpdate)
                                LastUpdate = now;
                            else
                                LastNonUpdate = now;
                        }
                    }

                    if (Con.SendKeepAlive) {
                        if (SendKeepAliveUpdate && (now - LastUpdate).TotalSeconds >= 1D) {
                            Con.SendRaw(this, new DataLowLevelKeepAlive {
                                IsUpdate = true
                            });
                            LastUpdate = now;
                        }
                        if (SendKeepAliveNonUpdate && (now - LastNonUpdate).TotalSeconds >= 1D) {
                            Con.SendRaw(this, new DataLowLevelKeepAlive {
                                IsUpdate = false
                            });
                            LastNonUpdate = now;
                        }
                    }

                    Con.SendRawFlush();

                    lock (QueueLock)
                        if (Interlocked.CompareExchange(ref QueueCount, 0, 0) == 0)
                            Event.Reset();
                }

            } catch (ThreadInterruptedException) {

            } catch (ThreadAbortException) {

            } catch (Exception e) {
                if (!(e is IOException) && !(e is ObjectDisposedException))
                    Logger.Log(LogLevel.CRI, "conqueue", $"Failed sending data:\n{e}");

                Con.Dispose();

            } finally {
                Event.Dispose();
            }
        }

public void Dispose()
            {
#if DEBUG
                Debug.replacedert(!_disposed);
                _disposed = true;
#endif
                lock (_parent._reentrancy)
                {
                    Interlocked.Decrement(ref _parent._reentrances);
                    if (_parent._reentrances == 0)
                    {
                        //the owning thread is always the same so long as we are in a nested stack call
                        //we reset the owning id to null only when the lock is fully unlocked
                        _parent._owningId = UnlockedThreadId;
                        if (_parent._retry.CurrentCount == 0)
                        {
                            _parent._retry.Release();
                        }
                    }
                }
            }

internal void ResetSentinel()
            {
                if (ResetSentinelFlag != 0) return;
                if (Interlocked.Increment(ref ResetSentinelFlag) != 1)
                {
                    Interlocked.Decrement(ref ResetSentinelFlag);
                    return;
                }
                string masterhostEnd = _masterHost;
                var allkeys = _ib.GetKeys().ToList();

                for (int i = 0; i < _sentinels.Count; i++)
                {
                    if (i > 0)
                    {
                        var first = _sentinels.First;
                        _sentinels.RemoveFirst();
                        _sentinels.AddLast(first.Value);
                    }

                    try
                    {
                        using (var sentinelcli = new RedisSentinelClient(_sentinels.First.Value))
                        {
                            var masterhost = sentinelcli.GetMasterAddrByName(_connectionString.Host);
                            var masterConnectionString = localTestHost(masterhost, RoleType.Master);
                            if (masterConnectionString == null) continue;
                            masterhostEnd = masterhost;

                            if (_rw_splitting)
                            {
                                foreach (var slave in sentinelcli.Salves(_connectionString.Host))
                                {
                                    ConnectionStringBuilder slaveConnectionString = localTestHost($"{slave.ip}:{slave.port}", RoleType.Slave);
                                    if (slaveConnectionString == null) continue;
                                }
                            }

                            foreach (var sentinel in sentinelcli.Sentinels(_connectionString.Host))
                            {
                                var remoteSentinelHost = $"{sentinel.ip}:{sentinel.port}";
                                if (_sentinels.Contains(remoteSentinelHost)) continue;
                                _sentinels.AddLast(remoteSentinelHost);
                            }
                        }
                        break;
                    }
                    catch { }
                }

                foreach (var spkey in allkeys) _ib.TryRemove(spkey, true);
                Interlocked.Exchange(ref _masterHost, masterhostEnd);
                Interlocked.Decrement(ref ResetSentinelFlag);

                ConnectionStringBuilder localTestHost(string host, RoleType role)
                {
                    ConnectionStringBuilder connectionString = _connectionString.ToString();
                    connectionString.Host = host;
                    connectionString.MinPoolSize = 1;
                    connectionString.MaxPoolSize = 1;
                    using (var cli = new RedisClient(connectionString))
                    {
                        if (cli.Role().role != role)
                            return null;

                        if (role == RoleType.Master)
                        {
                            //test set/get
                        }
                    }
                    connectionString.MinPoolSize = _connectionString.MinPoolSize;
                    connectionString.MaxPoolSize = _connectionString.MaxPoolSize;

                    _ib.TryRegister(host, () => new RedisClientPool(connectionString, null, TopOwner));
                    allkeys.Remove(host);

                    return connectionString;
                }
            }

private void DoClient(ConnectClient client)
        {
            SessionServer session = null;
            string addrIP = ((IPEndPoint)client.Client.Client.RemoteEndPoint).Address.ToString();
            try
            {
                try
                {
                    if (Repository.CheckIsBanIP(addrIP))
                    {
                        Loger.Log("Abort connect BanIP " + addrIP);
                    }
                    else
                    {
                        Loger.Log($"New connect {addrIP} (connects: {ActiveClientCount})");
                        session = new SessionServer();
                        lock (Sessions)
                        {
                            Sessions.Add(session);
                        }
                        session.Do(client, SessionsAction);
                    }
                }
                catch (ObjectDisposedException)
                {
                    Loger.Log("Abort connect Relogin " + addrIP);
                }
                catch (Transfer.ConnectClient.ConnectSilenceTimeOutException)
                {
                    Loger.Log("Abort connect TimeOut " + addrIP);
                }
                catch (Exception e)
                {
                    if (!(e is SocketException) && !(e.InnerException is SocketException)
                        && !(e is Transfer.ConnectClient.ConnectNotConnectedException) && !(e.InnerException is Transfer.ConnectClient.ConnectNotConnectedException))
                    {
                        ExceptionUtil.ExceptionLog(e, "Server Exception");
                    }
                }
                //if (LogMessage != null) LogMessage("End connect");
            }
            finally
            {
                Interlocked.Decrement(ref _ActiveClientCount);
                Loger.Log($"Close connect {addrIP}{(session == null ? "" : " " + session?.GetNameWhoConnect())} (connects: {ActiveClientCount})");
                try
                {
                    if (session != null)
                    {
                        session.Dispose();
                    }
                }
                catch
                { }
            }
        }

private void StartReadStream(StreamReader reader, ConcurrentQueue<string> dataBuffer)
        {
            Task.Run(() =>
            {
                while (!reader.EndOfStream)
                {
                    string line = reader.ReadLine();
                    if (line != null)
                    {
                        dataBuffer.Enqueue(line);
                        _outputProcessEvent.Set();
                    }
                }

                Trace.Info("STDOUT/STDERR stream read finished.");

                if (Interlocked.Decrement(ref _asyncStreamReaderCount) == 0 && _waitingOnStreams)
                {
                    _processExitedCompletionSource.TrySetResult(true);
                    _processStandardInWriteCancellationTokenSource.Cancel();
                }
            });
        }

public int Release()
			{
				return Interlocked.Decrement(ref _count);
			}

private void ThreadFunc() {
            for (;;) {
                m_semapreplaced.WaitOne();
                int nCurrentPointer, nNextPointer;
                do {
                    nCurrentPointer = m_nGetPointer;
                    nNextPointer = nCurrentPointer + 1;
                    if (nNextPointer == m_taskQueue.Length) {
                        nNextPointer = 0;
                    }
                } while (Interlocked.CompareExchange(ref m_nGetPointer, nNextPointer, nCurrentPointer) != nCurrentPointer);
                TaskInfo task = m_taskQueue[nCurrentPointer];
                if (Interlocked.Decrement(ref m_numTasks) == m_taskQueue.Length - 1) {
                    m_getNotification.Set();
                }
                task.callback(task.args);
            }
        }

private void SingleThreadFunc() {
            for (;;) {
                while (m_numTasks == 0) {
                    m_putNotification.WaitOne();
                }
                TaskInfo task = m_taskQueue[m_nGetPointer++];
                if (m_nGetPointer == m_taskQueue.Length) {
                    m_nGetPointer = 0;
                }
                if (Interlocked.Decrement(ref m_numTasks) == m_taskQueue.Length - 1) {
                    m_getNotification.Set();
                }
                task.callback(task.args);
            }
        }

private void ThreadExecutionLoop()
            {
                //Perform any initialization requested.
                if (threadStart != null)
                    threadStart();
                TaskEntry task;

                while (true)
                {
                    resetEvent.WaitOne();
                    while (true)
                    {
                        if (!taskData.TryDequeueFirst(out task))
                        {
                            bool gotSomething = false;
                            for (int i = 1; i < manager.workers.Count; i++)
                            {
                                if (TrySteal((index + i) % manager.workers.Count, out task))
                                {
                                    gotSomething = true;
                                    break;
                                }
                            }
                            if (!gotSomething)
                                break; //Nothing to steal and I'm broke! Guess I'll mosey on out
                        }
                        try
                        {
                            if (task.Task != null)
                                task.Task(task.Info);
                            if (Interlocked.Decrement(ref manager.tasksRemaining) == 0)
                            {
                                manager.allThreadsIdleNotifier.Set();
                            }
                            if (task.Task == null)
                                return;
                        }
                        catch (ArithmeticException arithmeticException)
                        {
                            throw new ArithmeticException(
                                "Some internal mulreplacedhreaded arithmetic has encountered an invalid state.  Check for invalid enreplacedy momentums, velocities, and positions; propagating NaN's will generally trigger this exception in the getExtremePoint function.",
                                arithmeticException);
                        }
                    }
                }
            }

private void ShutDownThread()
            {
                //Let the manager know that it is done with its 'task'!
                if (Interlocked.Decrement(ref manager.tasksRemaining) == 0)
                {
                    if (!manager.disposed) //Don't mess with the handle if it's already disposed.
                        manager.allThreadsIdleNotifier.Set();
                }
                //Dump out any remaining tasks in the queue.
                for (int i = 0; i < taskQueue.Count; i++) //This is still safe since shutDownThread is called from within a lock(taskQueue) block.
                {
                    taskQueue.Dequeue();
                    if (Interlocked.Decrement(ref manager.tasksRemaining) == 0)
                    {
                        if (!manager.disposed) //Don't mess with the handle if it's already disposed.
                            manager.allThreadsIdleNotifier.Set();
                    }
                }

                lock (manager.workers)
                    manager.workers.Remove(this);
            }

internal void OnWorkerFinish()
        {
            if (Interlocked.Decrement(ref workerCount) == 0)
                loopFinished.Set();
        }

private void ThreadExecutionLoop()
            {
                //Perform any initialization requested.
                if (threadStart != null)
                    threadStart(initializationInformation);
                object information = null;

                while (true)
                {
                    Action<object> task = null;
                    lock (taskQueue)
                    {
                        if (taskQueue.Count > 0)
                        {
                            task = taskQueue.Dequeue();
                            if (task == null)
                            {
                                Dispose();
                                return;
                            }

                            information = taskInformationQueue.Dequeue();
                        }
                    }
                    if (task != null)
                    {
                        //Perform the task!
                        try
                        {
                            task(information);
                        }
                        catch (ArithmeticException arithmeticException)
                        {
                            throw new ArithmeticException(
                                "Some internal mulreplacedhreaded arithmetic has encountered an invalid state.  Check for invalid enreplacedy momentums, velocities, and positions; propagating NaN's will generally trigger this exception in the getExtremePoint function.",
                                arithmeticException);
                        }
                        if (Interlocked.Decrement(ref manager.tasksRemaining) == 0)
                        {
                            manager.allThreadsIdleNotifier.Set();
                            resetEvent.WaitOne();
                        }
                    }
                    else
                        resetEvent.WaitOne();
                }
            }

void BecameNonDeactivationCandidate(SimulationIslandMember member)
        {
            Interlocked.Decrement(ref deactivationCandidateCount);
        }

public void WaitForTaskCompletion()
        {
            //TODO: Try a WAITALL version of this
            if (Interlocked.Decrement(ref tasksRemaining) == 0)
            {
                allThreadsIdleNotifier.Set();
            }
            allThreadsIdleNotifier.WaitOne();

            //When it gets here, it means things are successfully idle'd.
            tasksRemaining = 1;
            allThreadsIdleNotifier.Reset();
        }

public void WaitForTaskCompletion()
        {
            if (Interlocked.Decrement(ref tasksRemaining) == 0)
            {
                allThreadsIdleNotifier.Set();
            }
            allThreadsIdleNotifier.WaitOne();

            //When it gets here, it means things are successfully idle'd.
            tasksRemaining = 1;
            allThreadsIdleNotifier.Reset();
        }

private static void WriteRecordLoop()
        {
            bool success = true;
            try
            {
                if (Interlocked.Increment(ref BackIsRuning) > 1)
                {
                    return;
                }

                SystemTrace(LogLevel.System, "日志开始");
                int cnt = 0;
                while (State != LogRecorderStatus.Shutdown)
                {
                    //Thread.Sleep(10);//让子弹飞一会
                    if (State < LogRecorderStatus.Initialized || !BaseRecorder.IsInitialized || !Recorder.IsInitialized)
                    {
                        Thread.Sleep(50);
                        continue;
                    }

                    var array = RecordInfos.Switch();
                    if (array.Count == 0)
                    {
                        Thread.Sleep(50);
                        continue;
                    }

                    foreach (var info in array)
                    {
                        if (info == null)
                            continue;
                        try
                        {
                            info.Index = ++_id;
                            if (_id == ulong.MaxValue)
                                _id = 1;
                            if (!_isTextRecorder && (info.Type >= LogType.System || info.Local))
                                BaseRecorder.RecordLog(info);
                            if (Listener != null || TraceToConsole)
                                DoTrace(info);

                        }
                        catch (Exception ex)
                        {
                            SystemTrace(LogLevel.Error, "日志写入发生错误", ex);
                        }
                    }

                    try
                    {
                        Recorder.RecordLog(array.ToList());
                    }
                    catch (Exception ex)
                    {
                        SystemTrace(LogLevel.Error, "日志写入发生错误", ex);
                    }

                    if (++cnt < 1024)
                        continue;
                    GC.Collect();
                    cnt = 0;
                }
                _syncSlim.Release();
            }
            catch (Exception e)
            {
                success = false;
                Console.WriteLine(e);
            }
            finally
            {
                Interlocked.Decrement(ref BackIsRuning);
                SystemTrace(LogLevel.System, "日志结束");
            }
            if (!success)
                NewRecorderThread();
        }

void Async()
        {
            Interlocked.Increment(ref WaitCount);
            GlobalContext.SetRequestContext(ZeroApplication.Config.ServiceName, Guid.NewGuid().ToString("N"));
            DateTime s = DateTime.Now;

            DoAsync();

            Interlocked.Decrement(ref WaitCount);
            var sp = (DateTime.Now - s);
            Interlocked.Add(ref RunTime, sp.Ticks);
            if (sp.TotalMilliseconds > 500)
                Interlocked.Increment(ref TmError);
            if ((Interlocked.Increment(ref ExCount) % 100) == 0)
                Count();
        }

private void ApiCall(ref ZSocket socket, ApiCallItem item)
        {
            using (IocScope.CreateScope())
            {
                Interlocked.Increment(ref CallCount);
                try
                {
                    if (LogRecorder.LogMonitor)
                        ApiCallByMonitor(ref socket, item);
                    else
                        ApiCallNoMonitor(ref socket, item);
                }
                catch (Exception ex)
                {
                    ZeroTrace.WriteException(StationName, ex, "ApiCall", item.ApiName);
                    item.Result = ApiResult.InnerErrorJson;
                    SendResult(ref socket, item, ZeroOperatorStateType.Error);
                }
                finally
                {
                    Interlocked.Decrement(ref waitCount);
                }
            }
        }

void OnTestEnd()
        {
            if (Interlocked.Decrement(ref testerCount) == 0)
            {
                Cancel.Dispose();
                Cancel = null;
            }
        }

internal async Task OnHeartbeatAckAsync()
        {
            Interlocked.Decrement(ref this._skippedHeartbeats);

            var ping = (int)(DateTime.Now - this._lastHeartbeat).TotalMilliseconds;

            this.Logger.LogTrace(LoggerEvents.WebSocketReceive, "Received HEARTBEAT_ACK (OP11, {0}ms)", ping);

            Volatile.Write(ref this._ping, ping);

            var args = new HeartbeatEventArgs(this.ServiceProvider)
            {
                Ping = this.Ping,
                Timestamp = DateTimeOffset.Now
            };

            await this._heartbeated.InvokeAsync(this, args).ConfigureAwait(false);
        }

private async Task ExecuteRequestAsync(BaseRestRequest request, RateLimitBucket bucket, TaskCompletionSource<bool> ratelimitTcs)
        {
            if (this._disposed)
                return;

            HttpResponseMessage res = default;

            try
            {
                await this.GlobalRateLimitEvent.WaitAsync().ConfigureAwait(false);

                if (bucket == null)
                    bucket = request.RateLimitBucket;

                if (ratelimitTcs == null)
                    ratelimitTcs = await this.WaitForInitialRateLimit(bucket).ConfigureAwait(false);

                if (ratelimitTcs == null) // ckeck rate limit only if we are not the probe request
                {
                    var now = DateTimeOffset.UtcNow;

                    await bucket.TryResetLimitAsync(now).ConfigureAwait(false);

                    // Decrement the remaining number of requests as there can be other concurrent requests before this one finishes and has a chance to update the bucket
                    if (Interlocked.Decrement(ref bucket._remaining) < 0)
                    {
                        this.Logger.LogDebug(LoggerEvents.RatelimitDiag, "Request for {0} is blocked", bucket.ToString());
                        var delay = bucket.Reset - now;
                        var resetDate = bucket.Reset;

                        if (this.UseResetAfter)
                        {
                            delay = bucket.ResetAfter.Value;
                            resetDate = bucket.ResetAfterOffset;
                        }

                        if (delay < new TimeSpan(-TimeSpan.TicksPerMinute))
                        {
                            this.Logger.LogError(LoggerEvents.RatelimitDiag, "Failed to retrieve ratelimits - giving up and allowing next request for bucket");
                            bucket._remaining = 1;
                        }

                        if (delay < TimeSpan.Zero)
                            delay = TimeSpan.FromMilliseconds(100);

                        this.Logger.LogWarning(LoggerEvents.RatelimitPreemptive, "Pre-emptive ratelimit triggered - waiting until {0:yyyy-MM-dd HH:mm:ss zzz} ({1:c}).", resetDate, delay);
                        Task.Delay(delay)
                            .ContinueWith(_ => this.ExecuteRequestAsync(request, null, null))
                            .LogTaskFault(this.Logger, LogLevel.Error, LoggerEvents.RestError, "Error while executing request");

                        return;
                    }
                    this.Logger.LogDebug(LoggerEvents.RatelimitDiag, "Request for {0} is allowed", bucket.ToString());
                }
                else
                    this.Logger.LogDebug(LoggerEvents.RatelimitDiag, "Initial request for {0} is allowed", bucket.ToString());

                var req = this.BuildRequest(request);

                if(this.Debug)
                    this.Logger.LogTrace(LoggerEvents.Misc, await req.Content.ReadreplacedtringAsync());

                var response = new RestResponse();
                try
                {
                    if (this._disposed)
                        return;

                    res = await this.HttpClient.SendAsync(req, HttpCompletionOption.ResponseContentRead, CancellationToken.None).ConfigureAwait(false);

                    var bts = await res.Content.ReadAsByteArrayAsync().ConfigureAwait(false);
                    var txt = Utilities.UTF8.GetString(bts, 0, bts.Length);

                    this.Logger.LogTrace(LoggerEvents.RestRx, txt);

                    response.Headers = res.Headers.ToDictionary(xh => xh.Key, xh => string.Join("\n", xh.Value), StringComparer.OrdinalIgnoreCase);
                    response.Response = txt;
                    response.ResponseCode = (int)res.StatusCode;
                }
                catch (HttpRequestException httpex)
                {
                    this.Logger.LogError(LoggerEvents.RestError, httpex, "Request to {0} triggered an HttpException", request.Url);
                    request.SetFaulted(httpex);
                    this.FailInitialRateLimitTest(request, ratelimitTcs);
                    return;
                }

                this.UpdateBucket(request, response, ratelimitTcs);

                Exception ex = null;
                switch (response.ResponseCode)
                {
                    case 400:
                    case 405:
                        ex = new BadRequestException(request, response);
                        break;

                    case 401:
                    case 403:
                        ex = new UnauthorizedException(request, response);
                        break;

                    case 404:
                        ex = new NotFoundException(request, response);
                        break;

                    case 413:
                        ex = new RequestSizeException(request, response);
                        break;

                    case 429:
                        ex = new RateLimitException(request, response);

                        // check the limit info and requeue
                        this.Handle429(response, out var wait, out var global);
                        if (wait != null)
                        {
                            if (global)
                            {
                                this.Logger.LogError(LoggerEvents.RatelimitHit, "Global ratelimit hit, cooling down");
                                try
                                {
                                    this.GlobalRateLimitEvent.Reset();
                                    await wait.ConfigureAwait(false);
                                }
                                finally
                                {
                                    // we don't want to wait here until all the blocked requests have been run, additionally Set can never throw an exception that could be suppressed here
                                    _ = this.GlobalRateLimitEvent.SetAsync();
                                }
                                this.ExecuteRequestAsync(request, bucket, ratelimitTcs)
                                    .LogTaskFault(this.Logger, LogLevel.Error, LoggerEvents.RestError, "Error while retrying request");
                            }
                            else
                            {
                                this.Logger.LogError(LoggerEvents.RatelimitHit, "Ratelimit hit, requeueing request to {0}", request.Url);
                                await wait.ConfigureAwait(false);
                                this.ExecuteRequestAsync(request, bucket, ratelimitTcs)
                                    .LogTaskFault(this.Logger, LogLevel.Error, LoggerEvents.RestError, "Error while retrying request");
                            }

                            return;
                        }
                        break;

                    case 500:
                    case 502:
                    case 503:
                    case 504:
                        ex = new ServerErrorException(request, response);
                        break;
                }

                if (ex != null)
                    request.SetFaulted(ex);
                else
                    request.SetCompleted(response);
            }
            catch (Exception ex)
            {
                this.Logger.LogError(LoggerEvents.RestError, ex, "Request to {0} triggered an exception", request.Url);

                // if something went wrong and we couldn't get rate limits for the first request here, allow the next request to run
                if (bucket != null && ratelimitTcs != null && bucket._limitTesting != 0)
                    this.FailInitialRateLimitTest(request, ratelimitTcs);

                if (!request.TrySetFaulted(ex))
                    throw;
            }
            finally
            {
                res?.Dispose();

                // Get and decrement active requests in this bucket by 1.
                _ = this.RequestQueue.TryGetValue(bucket.BucketId, out var count);
                this.RequestQueue[bucket.BucketId] = Interlocked.Decrement(ref count);

                // If it's 0 or less, we can remove the bucket from the active request queue,
                // along with any of its past routes.
                if (count <= 0)
                {
                    foreach (var r in bucket.RouteHashes)
                    {
                        if (this.RequestQueue.ContainsKey(r))
                        {
                            _ = this.RequestQueue.TryRemove(r, out _);
                        }
                    }
                }
            }
        }

internal async Task<bool> DecrementUseAsync()
        {
            await this.UsageSemapreplaced.WaitAsync().ConfigureAwait(false);

            // if we're past reset time...
            var now = DateTimeOffset.UtcNow;
            if (now >= this.ResetsAt)
            {
                // ...do the reset and set a new reset time
                Interlocked.Exchange(ref this._remaining_uses, this.MaxUses);
                this.ResetsAt = now + this.Reset;
            }

            // check if we have any uses left, if we do...
            var success = false;
            if (this.RemainingUses > 0)
            {
                // ...decrement, and return success...
                Interlocked.Decrement(ref this._remaining_uses);
                success = true;
            }

            // ...otherwise just fail
            this.UsageSemapreplaced.Release();
            return success;
        }

internal bool CheckDisposed()
            {
                return Interlocked.Decrement(ref _disposeWip) != 0;
            }

private bool TryDisposeSource()
            {
                if (Interlocked.Decrement(ref _sourceDisposeWip) != 0)
                {
                    Dispose(_source);
                    return false;
                }
                return true;
            }

private bool TryDisposeOther()
            {
                if (Interlocked.Decrement(ref _otherDisposeWip) != 0)
                {
                    Dispose(_other);
                    return false;
                }
                return true;
            }

private bool TryDispose()
                {
                    if (Interlocked.Decrement(ref _disposeWip) != 0)
                    {
                        _parent.Dispose(_source);
                        return false;
                    }
                    return true;
                }

private bool TryDispose()
            {
                if (Interlocked.Decrement(ref _sourceDisposeWip) != 0)
                {
                    Dispose(_source);
                    return false;
                }
                return true;
            }

private void NextHandler(Task<bool> t)
            {
                if (t.IsCanceled)
                {
                    ExceptionHelper.AddException(ref _error, new OperationCanceledException());
                    _sourceDone = true;
                    if (TryDispose())
                    {
                        ResumeHelper.Resume(ref _resume);
                    }
                } else
                if (t.IsFaulted)
                {
                    ExceptionHelper.AddException(ref _error, ExceptionHelper.Extract(t.Exception));
                    _sourceDone = true;
                    if (TryDispose())
                    {
                        ResumeHelper.Resume(ref _resume);
                    }
                }
                else if (t.Result)
                {
                    var cts = CancellationTokenSource.CreateLinkedTokenSource(_sourceCTS.Token);
                    IAsyncEnumerator<TResult> src;
                    try
                    {
                        src = _mapper(_source.Current).GetAsyncEnumerator(cts.Token);
                    }
                    catch (Exception ex)
                    {
                        ExceptionHelper.AddException(ref _error, ex);
                        _sourceDone = true;
                        src = null;
                        if (TryDispose())
                        {
                            ResumeHelper.Resume(ref _resume);
                            return;
                        }
                    }

                    if (src != null)
                    {
                        Interlocked.Increment(ref _disposeWip);
                        var inner = new InnerHandler(src, this, cts);
                        _inners.Enqueue(inner);

                        if (_disposeRequested)
                        {
                            while (_inners.TryDequeue(out var inner2))
                            {
                                inner2.Dispose();
                            }
                        }

                        if (TryDispose())
                        {
                            inner.MoveNext();
                            if (Interlocked.Decrement(ref _sourceOutstanding) != 0)
                            {
                                MoveNextSource();
                            }
                            ResumeHelper.Resume(ref _resume);
                        }
                    }
                }
                else
                {
                    _sourceDone = true;
                    if (TryDispose())
                    {
                        ResumeHelper.Resume(ref _resume);
                    }
                }
            }

private void InnerNextHandler(Task<bool> t)
                {
                    if (t.IsCanceled)
                    {
                        ExceptionHelper.AddException(ref _parent._error, new OperationCanceledException());
                        Done = true;
                        if (TryDispose())
                        {
                            ResumeHelper.Resume(ref _parent._resume);
                        }
                    } else if (t.IsFaulted)
                    {
                        ExceptionHelper.AddException(ref _parent._error, ExceptionHelper.Extract(t.Exception));
                        Done = true;
                        if (TryDispose())
                        {
                            ResumeHelper.Resume(ref _parent._resume);
                        }
                    }
                    else if (t.Result)
                    {
                        Queue.Enqueue(_source.Current);
                        if (TryDispose())
                        {
                            if (Interlocked.Decrement(ref _outstanding) != 0)
                            {
                                MoveNext();
                            }
                            ResumeHelper.Resume(ref _parent._resume);
                        }
                    }
                    else
                    {
                        Done = true;
                        if (TryDispose())
                        {
                            ResumeHelper.Resume(ref _parent._resume);
                        }
                    }
                }

private bool TryDispose()
            {
                if (Interlocked.Decrement(ref _disposeWip) != 0)
                {
                    if (_emitLast)
                    {
                        _emitLasreplacedem = default;
                    }
                    ResumeHelper.Complete(ref _disposeTask, _source.DisposeAsync());
                    return false;
                }
                return true;
            }

private void Handle(Task<bool> task)
            {
                if (task.IsCanceled)
                {
                    AddException(new OperationCanceledException());
                    _done = true;
                    if (TryDispose())
                    {
                        Signal();
                    }
                }
                else if (task.IsFaulted)
                {
                    AddException(task.Exception);
                    _done = true;
                    if (TryDispose())
                    {
                        Signal();
                    }
                }
                else
                {
                    if (task.Result)
                    {
                        var v = _source.Current;

                        if (TryDispose())
                        {
                            var cts = CancellationTokenSource.CreateLinkedTokenSource(_sourceCTS.Token);
                            IAsyncEnumerator<TResult> innerSource;
                            try
                            {
                                innerSource = _mapper(v)
                                    .GetAsyncEnumerator(cts.Token);
                            }
                            catch (Exception ex)
                            {
                                _source.DisposeAsync();

                                AddException(ex);
                                _done = true;
                                Signal();
                                return;
                            }

                            var handler = new InnerHandler(this, innerSource, _prefetch, cts);
                            Interlocked.Increment(ref _allDisposeWip);
                            if (Add(handler))
                            {
                                handler.MoveNext();

                                if (Interlocked.Decrement(ref _outstanding) != 0)
                                {
                                    MoveNext();
                                }
                            }
                            else
                            {
                                // This will decrement _allDisposeWip so
                                // that the DisposeAsync() can be released eventually
                                DisposeOne();
                            }
                        }
                    }
                    else
                    {
                        _done = true;
                        if (TryDispose())
                        {
                            Signal();
                        }
                    }
                }
            }

private bool TryDispose()
            {
                if (Interlocked.Decrement(ref _dispose) != 0)
                {
                    _parent.Dispose(_source);
                    return false;
                }
                return true;
            }

private void Handle(Task<bool> task)
            {
                if (task.IsCanceled)
                {
                    if (TryDispose())
                    {
                        _parent.InnerError(this, new OperationCanceledException());
                    }
                }
                else if (task.IsFaulted)
                {
                    if (TryDispose())
                    {
                        _parent.InnerError(this, task.Exception);
                    }
                }
                else
                {
                    if (task.Result)
                    {
                        var v = _source.Current;
                        if (TryDispose())
                        {
                            _parent.InnerNext(this, v);
                            if (Interlocked.Decrement(ref _outstanding) != 0)
                            {
                                MoveNext();
                            }
                        }
                    }
                    else
                    {
                        if (TryDispose())
                        {
                            _parent.InnerComplete(this);
                        }
                    }
                }
            }

public async ValueTask DisposeAsync()
            {
                if (!_done)
                {
                    for (; ; )
                    {
                        try
                        {
                            if (_groups.IsEmpty)
                            {
                                break;
                            }
                            if (await _source.MoveNextAsync())
                            {
                                var t = _source.Current;
                                var k = _keySelector(t);

                                var found = _groups.TryGetValue(k, out var g);

                                if (found)
                                {
                                    await g.Next(_valueSelector(t));
                                }
                            }
                            else
                            {
                                foreach (var gr in _groups)
                                {
                                    await gr.Value.Complete();
                                }
                                break;
                            }
                        }
                        catch (Exception ex)
                        {
                            foreach (var gr in _groups)
                            {
                                await gr.Value.Error(ex);
                            }

                            throw;
                        }
                    }
                }
                if (Interlocked.Decrement(ref _active) == 0)
                {
                    await _source.DisposeAsync();
                }
            }

private async ValueTask Remove(Group g)
            {
                _groups.TryRemove(g.Key, out _);
                if (Interlocked.Decrement(ref _active) == 0)
                {
                    await _source.DisposeAsync();
                }
            }

private bool TryDispose()
            {
                if (Interlocked.Decrement(ref _disposeWip) != 0)
                {
                    ResumeHelper.Complete(ref _disposeTask, _source.DisposeAsync());
                    return false;
                }
                return true;
            }

private void InnerError(Exception ex)
            {
                ExceptionHelper.AddException(ref _error, ex);
                Interlocked.Decrement(ref _done);
                Signal();
            }

private void InnerComplete()
            {
                Interlocked.Decrement(ref _done);
                Signal();
            }

private void MoveNextSource()
        {
            if (Interlocked.Increment(ref _sourceWip) == 1)
            {
                do
                {
                    if (Interlocked.Increment(ref _sourceDisposeWip) == 1)
                    {
                        _source.MoveNextAsync()
                            .AsTask()
                            .ContinueWith(HandleSourceAction, this);
                    }
                    else
                    {
                        break;
                    }
                }
                while (Interlocked.Decrement(ref _sourceWip) != 0);
            }
        }

private bool TryDisposeSource()
        {
            if (Interlocked.Decrement(ref _sourceDisposeWip) != 0)
            {
                Dispose(_source);
                return false;
            }
            return true;
        }

private void SourceHandler(Task<bool> t)
            {
                var next = false;
                if (t.IsFaulted)
                {
                    _error = ExceptionHelper.Extract(t.Exception);
                    _done = true;
                }
                else if (t.IsCanceled)
                {
                    _error = new OperationCanceledException();
                    _done = true;
                }
                else if (t.Result)
                {
                    _queue.Enqueue(_source.Current);
                    next = true;
                }
                else
                {
                    _done = true;
                }
                // release the MoveNext, just in case
                if (Interlocked.Decrement(ref _disposeWip) != 0)
                {
                    ResumeHelper.Complete(ref _disposeTask, _source.DisposeAsync());
                }
                else
                {
                    if (next && Interlocked.Decrement(ref _outstanding) != 0)
                    {
                        MoveNext();
                    }

                    Signal();
                }
            }

private bool TryDispose()
            {
                if (Interlocked.Decrement(ref _disposeWip) != 0)
                {
                    Interlocked.Exchange(ref _timerLatest, EmptyHelper.EmptyIndicator);
                    ResumeHelper.Complete(ref _disposeTask, _source.DisposeAsync());
                    return false;
                }
                return true;
            }

internal override void Drain()
            {
                if (Interlocked.Increment(ref wip) == 1)
                {
                    for (; ; )
                    {
                        var srcs = sources;
                        var n = srcs.Length;
                        if (DisposableHelper.IsDisposed(ref upstream))
                        {
                            for (int i = index; i < n; i++)
                            {
                                srcs[i] = null;
                            }
                        }
                        else
                        {
                            var i = index;
                            if (i == n)
                            {
                                DisposableHelper.WeakDispose(ref upstream);

                                var ex = Volatile.Read(ref errors);
                                if (ex != null)
                                {
                                    downstream.OnError(ex);
                                }
                                else
                                {
                                    downstream.OnCompleted();
                                }
                            } else
                            {
                                var src = srcs[i];
                                if (src == null)
                                {
                                    DisposableHelper.WeakDispose(ref upstream);

                                    ExceptionHelper.AddException(ref errors, new NullReferenceException("The " + i + "th ICompletableSource is null"));
                                    var ex = Volatile.Read(ref errors);
                                    downstream.OnError(ex);
                                    continue;
                                }
                                else
                                {
                                    srcs[i] = null;
                                    index = i + 1;

                                    src.Subscribe(this);
                                }
                            }
                        }

                        if (Interlocked.Decrement(ref wip) == 0)
                        {
                            break;
                        }
                    }
                }
            }

void InnerCompleted(MergeInnerObserver sender)
        {
            Remove(sender);
            Interlocked.Decrement(ref active);
            Drain();
        }

void InnerError(MergeInnerObserver sender, Exception ex)
        {
            Remove(sender);
            if (delayErrors)
            {
                ExceptionHelper.AddException(ref errors, ex);
                Interlocked.Decrement(ref active);
                Drain();
            }
            else
            {
                if (Interlocked.CompareExchange(ref errors, ex, null) == null)
                {
                    Drain();
                }
            }
        }

internal void SubscribeAll(IEnumerable<ICompletableSource> sources)
            {
                Interlocked.Increment(ref active);
                try
                {
                    foreach (var src in sources)
                    {
                        var inner = new MergeInnerObserver(this);
                        if (!Add(inner))
                        {
                            break;
                        }
                        Interlocked.Increment(ref active);
                        src.Subscribe(inner);
                    }
                }
                catch (Exception ex)
                {
                    if (delayErrors)
                    {
                        ExceptionHelper.AddException(ref errors, ex);
                    }
                    else
                    {
                        Interlocked.CompareExchange(ref errors, ex, null);
                    }
                }
                Interlocked.Decrement(ref active);
                Drain();
            }

internal void Drain()
        {
            if (Interlocked.Increment(ref wip) == 1)
            {
                for (; ; )
                {
                    if (!DisposableHelper.IsDisposed(ref upstream))
                    {
                        source.Subscribe(this);
                    }

                    if (Interlocked.Decrement(ref wip) == 0)
                    {
                        break;
                    }
                }
            }
        }

internal void HandlerNext()
        {
            if (Interlocked.Increment(ref trampoline) == 1)
            {
                do
                {
                    if (Interlocked.CompareExchange(ref once, 1, 0) == 0)
                    {
                        source.Subscribe(this);
                    }
                }
                while (Interlocked.Decrement(ref trampoline) != 0);
            }
        }

private bool TryDisposeMain()
            {
                if (Interlocked.Decrement(ref _sourceDisposeWip) != 0)
                {
                    Dispose(_source);
                    return false;
                }
                return true;
            }

[Fact]
        public async void Race()
        {
            for (var i = 0; i < 10_000; i++)
            {
                var rsm = new SlimResume();

                var wip = 2;

                var t1 = Task.Factory.StartNew(() =>
                {
                    if (Interlocked.Decrement(ref wip) != 0)
                    {
                        while (Volatile.Read(ref wip) != 0) { }
                    }

                    rsm.Signal();
                }, TaskCreationOptions.LongRunning);

                var t2 = Task.Factory.StartNew(async () =>
                {
                    if (Interlocked.Decrement(ref wip) != 0)
                    {
                        while (Volatile.Read(ref wip) != 0) { }
                    }

                    await rsm;
                }, TaskCreationOptions.LongRunning);

                await t1;

                await t2;
            }
        }