c# signalr是什么 通过使用BookSleeve的ConnectionUtils.Connect(),使用SignalR和Redis messagebus进行故障转移



signalr是什么 (1)

SignalR团队现在已经实现了对使用StackExchange.Redis的自定义连接工厂的支持,BookSleeve的继任者通过ConnectionMultiplexer支持冗余Redis连接。

遇到的最初问题是,尽管在BookSleeve中创建了自己的扩展方法来接受服务器集合,但无法进行故障切换。

现在,随着BookSleeve发展到StackExchange.Redis,我们现在可以在Connect初始化中正确configure服务器/端口的集合。

新创建的实现比创建UseRedisCluster方法的道路要简单得多,而后端UseRedisCluster现在支持真正的故障切换:

var conn = ConnectionMultiplexer.Connect("redisServer1:6380,redisServer2:6380,redisServer3:6380,allowAdmin=true");

StackExchange.Redis还允许进行附加的手动配置,如文档的“ Automatic and Manual Configuration部分所述:

ConfigurationOptions config = new ConfigurationOptions
{
    EndPoints =
    {
        { "redis0", 6379 },
        { "redis1", 6380 }
    },
    CommandMap = CommandMap.Create(new HashSet<string>
    { // EXCLUDE a few commands
        "INFO", "CONFIG", "CLUSTER",
        "PING", "ECHO", "CLIENT"
    }, available: false),
    KeepAlive = 180,
    DefaultVersion = new Version(2, 8, 8),
    Password = "changeme"
};

实质上,现在通过一系列服务器来初始化我们的SignalR横向扩展环境的能力现在解决了最初的问题。

我正在尝试使用SignalR应用程序创建Redis消息总线故障切换方案。

起初,我们尝试了一种简单的硬件负载平衡器故障切换,它只监视两台Redis服务器。 SignalR应用程序指向单一的HLB端点。 然后,我失败了一台服务器,但无法在第二台Redis服务器上成功获取任何消息,而无需再次使用SignalR应用程序池。 大概这是因为它需要将设置命令发布到新的Redis消息总线上。

从SignalR RC1开始, Microsoft.AspNet.SignalR.Redis.RedisMessageBus使用Booksleeve的RedisConnection()连接到单个Redis for pub / sub。

我创建了一个新类RedisMessageBusCluster() ,它使用Booksleeve的ConnectionUtils.Connect()连接到Redis服务器集群中的一个。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using BookSleeve;
using Microsoft.AspNet.SignalR.Infrastructure;

namespace Microsoft.AspNet.SignalR.Redis
{
    /// <summary>
    /// WIP:  Getting scaleout for Redis working
    /// </summary>
    public class RedisMessageBusCluster : ScaleoutMessageBus
    {
        private readonly int _db;
        private readonly string[] _keys;
        private RedisConnection _connection;
        private RedisSubscriberConnection _channel;
        private Task _connectTask;

        private readonly TaskQueue _publishQueue = new TaskQueue();

        public RedisMessageBusCluster(string serverList, int db, IEnumerable<string> keys, IDependencyResolver resolver)
            : base(resolver)
        {
            _db = db;
            _keys = keys.ToArray();

            // uses a list of connections
            _connection = ConnectionUtils.Connect(serverList);

            //_connection = new RedisConnection(host: server, port: port, password: password);

            _connection.Closed += OnConnectionClosed;
            _connection.Error += OnConnectionError;


            // Start the connection - TODO:  can remove this Open as the connection is already opened, but there's the _connectTask is used later on
            _connectTask = _connection.Open().Then(() =>
            {
                // Create a subscription channel in redis
                _channel = _connection.GetOpenSubscriberChannel();

                // Subscribe to the registered connections
                _channel.Subscribe(_keys, OnMessage);

                // Dirty hack but it seems like subscribe returns before the actual
                // subscription is properly setup in some cases
                while (_channel.SubscriptionCount == 0)
                {
                    Thread.Sleep(500);
                }
            });
        }


        protected override Task Send(Message[] messages)
        {
            return _connectTask.Then(msgs =>
            {
                var taskCompletionSource = new TaskCompletionSource<object>();

                // Group messages by source (connection id)
                var messagesBySource = msgs.GroupBy(m => m.Source);

                SendImpl(messagesBySource.GetEnumerator(), taskCompletionSource);

                return taskCompletionSource.Task;
            },
            messages);
        }

        private void SendImpl(IEnumerator<IGrouping<string, Message>> enumerator, TaskCompletionSource<object> taskCompletionSource)
        {
            if (!enumerator.MoveNext())
            {
                taskCompletionSource.TrySetResult(null);
            }
            else
            {
                IGrouping<string, Message> group = enumerator.Current;

                // Get the channel index we're going to use for this message
                int index = Math.Abs(group.Key.GetHashCode()) % _keys.Length;

                string key = _keys[index];

                // Increment the channel number
                _connection.Strings.Increment(_db, key)
                                   .Then((id, k) =>
                                   {
                                       var message = new RedisMessage(id, group.ToArray());

                                       return _connection.Publish(k, message.GetBytes());
                                   }, key)
                                   .Then((enumer, tcs) => SendImpl(enumer, tcs), enumerator, taskCompletionSource)
                                   .ContinueWithNotComplete(taskCompletionSource);
            }
        }

        private void OnConnectionClosed(object sender, EventArgs e)
        {
            // Should we auto reconnect?
            if (true)
            {
                ;
            }
        }

        private void OnConnectionError(object sender, BookSleeve.ErrorEventArgs e)
        {
            // How do we bubble errors?
            if (true)
            {
                ;
            }
        }

        private void OnMessage(string key, byte[] data)
        {
            // The key is the stream id (channel)
            var message = RedisMessage.Deserialize(data);

            _publishQueue.Enqueue(() => OnReceived(key, (ulong)message.Id, message.Messages));
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (_channel != null)
                {
                    _channel.Unsubscribe(_keys);
                    _channel.Close(abort: true);
                }

                if (_connection != null)
                {
                    _connection.Close(abort: true);
                }                
            }

            base.Dispose(disposing);
        }
    }
}

Booksleeve具有自己的机制来确定主机,并自动故障切换到另一台服务器,现在我们用SignalR.Chat测试它。

web.config ,我设置了可用服务器的列表:

<add key="redis.serverList" value="dbcache1.local:6379,dbcache2.local:6379"/>

然后在Application_Start()

        // Redis cluster server list
        string redisServerlist = ConfigurationManager.AppSettings["redis.serverList"];

        List<string> eventKeys = new List<string>();
        eventKeys.Add("SignalR.Redis.FailoverTest");
        GlobalHost.DependencyResolver.UseRedisCluster(redisServerlist, eventKeys);

我向Microsoft.AspNet.SignalR.Redis.DependencyResolverExtensions添加了两个附加方法:

public static IDependencyResolver UseRedisCluster(this IDependencyResolver resolver, string serverList, IEnumerable<string> eventKeys)
{
    return UseRedisCluster(resolver, serverList, db: 0, eventKeys: eventKeys);
}

public static IDependencyResolver UseRedisCluster(this IDependencyResolver resolver, string serverList, int db, IEnumerable<string> eventKeys)
{
    var bus = new Lazy<RedisMessageBusCluster>(() => new RedisMessageBusCluster(serverList, db, eventKeys, resolver));
    resolver.Register(typeof(IMessageBus), () => bus.Value);

    return resolver;
}

现在的问题是,当我启用了多个断点时,直到添加了用户名后,然后禁用所有断点,应用程序才按预期工作。 但是,从一开始就禁用断点,在连接过程中似乎会出现一些可能失败的竞争条件。

因此,在RedisMessageCluster()

    // Start the connection
    _connectTask = _connection.Open().Then(() =>
    {
        // Create a subscription channel in redis
        _channel = _connection.GetOpenSubscriberChannel();

        // Subscribe to the registered connections
        _channel.Subscribe(_keys, OnMessage);

        // Dirty hack but it seems like subscribe returns before the actual
        // subscription is properly setup in some cases
        while (_channel.SubscriptionCount == 0)
        {
            Thread.Sleep(500);
        }
    });

我尝试添加一个Task.Wait ,甚至还有一个额外的Sleep() (上面没有显示) - 正在等待/等,但仍然出现错误。

经常出现的错误似乎在Booksleeve.MessageQueue.cs 71:

A first chance exception of type 'System.InvalidOperationException' occurred in BookSleeve.dll
iisexpress.exe Error: 0 : SignalR exception thrown by Task: System.AggregateException: One or more errors occurred. ---> System.InvalidOperationException: The queue is closed
   at BookSleeve.MessageQueue.Enqueue(RedisMessage item, Boolean highPri) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\MessageQueue.cs:line 71
   at BookSleeve.RedisConnectionBase.EnqueueMessage(RedisMessage message, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\RedisConnectionBase.cs:line 910
   at BookSleeve.RedisConnectionBase.ExecuteInt64(RedisMessage message, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\RedisConnectionBase.cs:line 826
   at BookSleeve.RedisConnection.IncrementImpl(Int32 db, String key, Int64 value, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\IStringCommands.cs:line 277
   at BookSleeve.RedisConnection.BookSleeve.IStringCommands.Increment(Int32 db, String key, Int64 value, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\IStringCommands.cs:line 270
   at Microsoft.AspNet.SignalR.Redis.RedisMessageBusCluster.SendImpl(IEnumerator`1 enumerator, TaskCompletionSource`1 taskCompletionSource) in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Redis\RedisMessageBusCluster.cs:line 90
   at Microsoft.AspNet.SignalR.Redis.RedisMessageBusCluster.<Send>b__2(Message[] msgs) in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Redis\RedisMessageBusCluster.cs:line 67
   at Microsoft.AspNet.SignalR.TaskAsyncHelper.GenericDelegates`4.<>c__DisplayClass57.<ThenWithArgs>b__56() in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Core\TaskAsyncHelper.cs:line 893
   at Microsoft.AspNet.SignalR.TaskAsyncHelper.TaskRunners`2.<>c__DisplayClass42.<RunTask>b__41(Task t) in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Core\TaskAsyncHelper.cs:line 821
   --- End of inner exception stack trace ---
---> (Inner Exception #0) System.InvalidOperationException: The queue is closed
   at BookSleeve.MessageQueue.Enqueue(RedisMessage item, Boolean highPri) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\MessageQueue.cs:line 71
   at BookSleeve.RedisConnectionBase.EnqueueMessage(RedisMessage message, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\RedisConnectionBase.cs:line 910
   at BookSleeve.RedisConnectionBase.ExecuteInt64(RedisMessage message, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\RedisConnectionBase.cs:line 826
   at BookSleeve.RedisConnection.IncrementImpl(Int32 db, String key, Int64 value, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\IStringCommands.cs:line 277
   at BookSleeve.RedisConnection.BookSleeve.IStringCommands.Increment(Int32 db, String key, Int64 value, Boolean queueJump) in c:\Projects\Frameworks\BookSleeve-1.2.0.5\BookSleeve\IStringCommands.cs:line 270
   at Microsoft.AspNet.SignalR.Redis.RedisMessageBusCluster.SendImpl(IEnumerator`1 enumerator, TaskCompletionSource`1 taskCompletionSource) in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Redis\RedisMessageBusCluster.cs:line 90
   at Microsoft.AspNet.SignalR.Redis.RedisMessageBusCluster.<Send>b__2(Message[] msgs) in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Redis\RedisMessageBusCluster.cs:line 67
   at Microsoft.AspNet.SignalR.TaskAsyncHelper.GenericDelegates`4.<>c__DisplayClass57.<ThenWithArgs>b__56() in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Core\TaskAsyncHelper.cs:line 893
   at Microsoft.AspNet.SignalR.TaskAsyncHelper.TaskRunners`2.<>c__DisplayClass42.<RunTask>b__41(Task t) in c:\Projects\Frameworks\SignalR\SignalR.1.0RC1\SignalR\src\Microsoft.AspNet.SignalR.Core\TaskAsyncHelper.cs:line 821<---



public void Enqueue(RedisMessage item, bool highPri)
{
    lock (stdPriority)
    {
        if (closed)
        {
            throw new InvalidOperationException("The queue is closed");
        }

在哪里抛出一个封闭的队列异常。

我预见到另一个问题:由于Redis连接是在Application_Start()因此在“重新连接”到另一台服务器时可能会出现一些问题。 不过,我认为在使用单数RedisConnection()时这是有效的,在这里只有一个连接可供选择。 但是,通过ConnectionUtils.Connect()的引入,我想从@dfowler或其他SignalR家伙听到SignalR中如何处理这种情况。





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