.net/c# RabbitMQ 鏈接斷開處理-斷線重連（轉載）

Rabbitmq 官方給的NET consumer示例代碼以下，但使用過程，會遇到connection斷開的問題，一旦斷開，這個代碼就會報錯，就會致使消費者或者生產者掛掉。

下圖是生產者發送消息，我手動中止了rabbitmq，而後又從新啓動了rabbitmq，大概等啓動成功之後，爲了防止服務沒有徹底啓動，我又等待了10秒鐘

服務徹底啓動成功之後，我嘗試從新發送一些消息，報錯，以下：
html

************** 異常文本 **************
RabbitMQ.Client.Exceptions.AlreadyClosedException: Already closed: The AMQP operation was interrupted: AMQP close-reason, initiated by Peer, code=320, text="CONNECTION_FORCED - broker forced connection closure with reason 'shutdown'", classId=0, methodId=0, cause=
在 RabbitMQ.Client.Impl.SessionBase.Transmit(Command cmd)
在 RabbitMQ.Client.Impl.ModelBase.ModelSend(MethodBase method, ContentHeaderBase header, Byte[] body)
在 RabbitMQ.Client.Impl.ModelBase.BasicPublish(String exchange, String routingKey, Boolean mandatory, IBasicProperties basicProperties, Byte[] body)
在 RabbitMQ.Client.Impl.ModelBase.BasicPublish(String exchange, String routingKey, IBasicProperties basicProperties, Byte[] body)
在 rabbitMQ_Publish.Form1.button1_Click(Object sender, EventArgs e) 位置 C:\project\my\RabbitMQ-demo\rabbitMQ-Publish\Form1.cs:行號 37
在 System.Windows.Forms.Control.OnClick(EventArgs e)
在 System.Windows.Forms.Button.OnClick(EventArgs e)
在 System.Windows.Forms.Button.PerformClick()
在 System.Windows.Forms.Form.ProcessDialogKey(Keys keyData)
在 System.Windows.Forms.TextBoxBase.ProcessDialogKey(Keys keyData)
在 System.Windows.Forms.Control.PreProcessMessage(Message& msg)
在 System.Windows.Forms.Control.PreProcessControlMessageInternal(Control target, Message& msg)
在 System.Windows.Forms.Application.ThreadContext.PreTranslateMessage(MSG& msg)

那麼如何會異常恢復呢？或者說斷線重連呢？

RabbitMQ NET Client的源碼，研究發現一種自動的錯誤恢復機制 AutomaticRecoveryEnabled = true 使用方式以下

ide

var factory = new ConnectionFactory() { HostName = "localhost", AutomaticRecoveryEnabled = true };

複製代碼

具體的恢復機制以下

1.在AutoRecoveringConnection初始化時，在連接關閉事件委託上增長斷開處理

this

public void init()
{
m_delegate = new Connection(m_factory, false, m_factory.CreateFrameHandler());
AutorecoveringConnection self = this;
EventHandler<ShutdownEventArgs> recoveryListener = (_, args) =>
{
lock (recoveryLockTarget)
{
if (ShouldTriggerConnectionRecovery(args))
{
try
{
self.BeginAutomaticRecovery();
}
catch (Exception e)
{
// TODO: logging
Console.WriteLine("BeginAutomaticRecovery() failed: {0}", e);
}
}
}
};
lock (m_eventLock)
{
ConnectionShutdown += recoveryListener;
if (!m_recordedShutdownEventHandlers.Contains(recoveryListener))
{
m_recordedShutdownEventHandlers.Add(recoveryListener);
}
}
}

複製代碼

觀察調用的方式BeginAutomaticRecovery，能夠看到這個方法內部調用了PerformAutomaticRecovery方法。咱們直接看這個方法的內容，其中第一個調用的是方法RecoverConnectionDelegate
spa

protected void PerformAutomaticRecovery()
{
lock (recoveryLockTarget)
{
RecoverConnectionDelegate();
RecoverConnectionShutdownHandlers();
RecoverConnectionBlockedHandlers();
RecoverConnectionUnblockedHandlers();
RecoverModels();
if (m_factory.TopologyRecoveryEnabled)
{
RecoverEntities();
RecoverConsumers();
}
RunRecoveryEventHandlers();
}
}

複製代碼

這個方法中調用的是
code

protected void RecoverConnectionDelegate()
{
bool recovering = true;
while (recovering)
{
try
{
m_delegate = new Connection(m_factory, false, m_factory.CreateFrameHandler());
recovering = false;
}
catch (Exception)
{
// TODO: exponential back-off
Thread.Sleep(m_factory.NetworkRecoveryInterval);
// TODO: provide a way to handle these exceptions
}
}
}

複製代碼

能夠看出，它是執行了死循環，直到鏈接從新打開，固然，若是遇到異常，它會調用Thread.Sleep來等待一下，而後再次執行鏈接恢復。orm

轉載自： https://www.itsvse.com/thread-4636-1-1.htmlhtm