接收MSMQ消息作为列表

Question

Just a small question that whether a list would be able to store large amount of messages.

My code is like this, there are 50,000 queue messages which I am receiving and assigning to messages list.

var msgEnumerator = msgQueue.GetMessageEnumerator2();
var messages = new List<System.Messaging.Message>();
while(msgEnumerator.MoveNext(new TimeSpan(0, 0, 1))) {
    var msg = msgQueue.ReceiveById(msgEnumerator.Current.Id, new TimeSpan(0, 0, 1));
    messages.Add(msg);
 }

foreach(var k in messages) {
    MailMessage mailM = (k.Body as SerializeableMailMessage).GetMailMessage();

    try {
        SmtpClient sp = new SmtpClient(smtpip, 25);
        sp.EnableSsl = false;
        sp.Send(mailM);
    }   
    catch (Exception ex) {
        logger.ErrorException("General error sending email.", ex);
    }
}

Is this the correct way, or is there an alternative for this? Let me know your suggestions and help!

Answer 1

Seems all fine... It gives often multiple ways to programm the exact same thing, but yours is already pretty good ;)

I personally would rather prefer to use a for loop, but my know league isnt so high msmq, soooo...

Next level of this is programming a Keylogger-Bypass-injection or how it is called... (I hope i didnt missunderstood your intention with this code).

Answer 2

First of all, when you are doing RecieveById, you remove the message from the queue. And if your software crashes after reading all the messages from the queue, they are gone forever.

You should be using BeginPeek and create event handler OnPeekCompleted to handle new messages from the queue. This way you only handle 1 message at a time and are not that susceptible to such errors when just reading all and then handling them.

private static void Main()
{
    var queue = new MessageQueue("myQueue");
    queue.PeekCompleted += new PeekCompletedEventHandler(OnPeekCompleted);

    // Start listening to queue
    queue.BeginPeek();
}

private void OnPeekCompleted(object sender, PeekCompletedEventArgs e)
{
    var cmq = (MessageQueue)sender;
    try
    {
        var msmqMessage = cmq.EndPeek(e.AsyncResult);

        msmqMessage.Formatter = new XmlMessageFormatter(typeof(messagetypehere));

        var message = msmqMessage.Body;

        // Do logic for the message
        {
            // Send mail or what ever

        }

        cmq.Receive(); // Remove the message from the queue
    }
    catch (Exception ex) 
    {
        // Log or other
    }

    // Refresh queue
    cmq.Refresh();

    // Start listening to queue
    cmq.BeginPeek();
}