when new email is received, the idle stop method is ran and there it says Imap client is currently busy processing in another thread. i assume its because idle command is still running in the background thread ?
even tho i called thread.Join() method, it wont end. i am sturck here for quite some time, and the example demo on MailKit github only shows how to handle it with help from manual user input such as Console.ReadKey().
i am pretty sure i am missing some major point or the code have major flaws but i have searched many times for an answer and there doesnt seem to be any major results other than the github example
protocol logger when idle start and message recevied until the exception occurs
S: * OK [UIDNEXT 21641] Predicted next UID.
S: * OK [HIGHESTMODSEQ 881089]
S: A00000006 OK [READ-WRITE] INBOX selected. (Success)
C: A00000007 IDLE
S: + idling
S: * 21512 EXISTS
C: DONE
method which starts idle
IdleClient.Inbox.MessageExpunged += OnMessageExpunged;
IdleClient.Inbox.CountChanged += OnInboxCountChanged;
ImapToken = new CancellationTokenSource();
SetTokenValues(ImapToken.Token);
ImapToken.Token.ThrowIfCancellationRequested();
ImapThreadInfo = Helpers.InBackgroundThread(ImapIdleLoop, UniqueAccountId, true);
declarations related to idle
private (int, Thread) ImapThreadInfo;
private CancellationToken CancellationToken { get; set; }
private CancellationToken DoneToken { get; set; }
private CancellationTokenSource ImapToken { get; set; }
private CancellationTokenSource Timeout { get; set; }
private bool IsCancellationRequested => CancellationToken.IsCancellationRequested || DoneToken.IsCancellationRequested;
private readonly object Mutex = new object();
private void CancelTimeout() {
lock (Mutex) {
Timeout?.Cancel();
}
}
private void SetTimeoutSource(CancellationTokenSource source) {
lock (Mutex) {
Timeout = source;
if (Timeout != null && IsCancellationRequested) {
Timeout.Cancel();
}
}
}
private void SetTokenValues(CancellationToken doneToken, CancellationToken cancellationToken = default) {
CancellationToken = cancellationToken;
DoneToken = doneToken;
doneToken.Register(CancelTimeout);
}
stop idle method
public void StopImapIdle(bool clientDisconnect) {
ImapToken.Cancel();
try {
Task.Factory.StartNew(() => {
ImapThreadInfo.Item2?.Join();
});
ImapToken.Dispose();
if (!clientDisconnect) {
return;
}
if (IdleClient.IsConnected && IdleClient.IsIdle) {
while (true) {
if (!IdleClient.IsIdle) {
BotLogger.Log("Idling has been stopped.", LogLevels.Trace);
break;
}
BotLogger.Log("Waiting for idle client to stop idling...", LogLevels.Trace);
}
}
lock (IdleClient.SyncRoot) {
//Error here
IdleClient.Disconnect(true);
BotLogger.Log("Imap client has been disconnected.", LogLevels.Trace);
}
}
catch (NullReferenceException) {
BotLogger.Log("There is no thread with the specified uniqueID", LogLevels.Warn);
}
IsAccountLoaded = false;
}
idle loop method
private void ImapIdleLoop() {
while (!IsCancellationRequested) {
Timeout = new CancellationTokenSource(new TimeSpan(0, 9, 0));
try {
SetTimeoutSource(Timeout);
if (IdleClient.Capabilities.HasFlag(ImapCapabilities.Idle)) {
lock (IdleClient.SyncRoot) {
IdleClient.Idle(Timeout.Token, CancellationToken);
}
}
else {
lock (IdleClient.SyncRoot) {
IdleClient.NoOp(CancellationToken);
}
WaitHandle.WaitAny(new[] { Timeout.Token.WaitHandle, CancellationToken.WaitHandle });
}
}
catch (OperationCanceledException) {
// This means that idle.CancellationToken was cancelled, not the DoneToken nor the timeout.
break;
}
catch (ImapProtocolException) {
// The IMAP server sent garbage in a response and the ImapClient was unable to deal with it.
// This should never happen in practice, but it's probably still a good idea to handle it.
//
// Note: an ImapProtocolException almost always results in the ImapClient getting disconnected.
IsAccountLoaded = false;
break;
}
catch (ImapCommandException) {
// The IMAP server responded with "NO" or "BAD" to either the IDLE command or the NOOP command.
// This should never happen... but again, we're catching it for the sake of completeness.
break;
}
catch (SocketException) {
}
catch (ServiceNotConnectedException) {
}
catch (IOException) {
}
finally {
// We're about to Dispose() the timeout source, so set it to null.
SetTimeoutSource(null);
}
Timeout?.Dispose();
}
}
The problem is that you are waiting for the thread to join from within the ImapClient's event callback which means you are blocking the ImapClient from continuing.
The solution is: don't do that.
MailKit's IMAP events are emitted while the IMAP command processor is still processing the server responses, so you cannot invoke more commands on the same ImapClient within those event handlers.
What you need to do instead is to implement some sort of command queue in your program and then, within the CountChanged event handler (or whatever handler you are handling), queue the next command(s) to invoke once the current command completes.
An easy way to do this is to keep a System.Threading.Tasks.Task somewhere where your event handler has access to it and can then do:
task = task.ContinueWith (...);
That's a simple way of implementing a command queue.
Related
I have implemented a rabbitMQ listener, which essentially just sits in a loop waiting for messages to arrive. When the message arrives I wish to fire an event and run some code.
However I don't always seem to receive this event, and I am wondering if this is because I am running the queue polling part of the code on a different thread.
It does seem to work initially though, so it is possible that the threading is not the problem. Can anyone give me an opinion on this?
QueueListener:
public void CreateQueueListener<T>() where T : IPubSubEvent
{
var mqServer = new RabbitMqServer(m_RabbitMqAddress);
var mqClient = (RabbitMqQueueClient)mqServer.MessageFactory.CreateMessageQueueClient();
var channel = mqClient.Channel;
string queueName = mqClient.GetTempQueueName();
channel.QueueBind(queueName, m_EventExchange, routingKey: QueueNames<T>.In);
var consumer = new RabbitMqBasicConsumer(channel);
channel.BasicConsume(queue: queueName, autoAck: true, consumer: consumer);
Task.Run(() =>
{
while (true)
{
BasicGetResult basicGetResult;
try
{
basicGetResult = consumer.Queue.Dequeue();
}
catch (Exception ex)
{
throw;
}
var message = basicGetResult.ToMessage<T>();
PublishEvent?.Invoke(this, new PubSubEventArgs { EventData = message.GetBody().EventName });
}
});
}
Consuming Class
public class MyClass
{
public MyClass(IEventClient eventClient)
{
eventClient.CreateQueueListener<AuthoriseEvent>();
eventClient.PublishEvent += OnPublishEvent;
}
private async void OnPublishEvent(object sender, PubSubEventArgs e)
{
if (e.EventData == "AuthoriseEvent")
//dostuff
}
}
I am running the queue polling part of the code on a different thread
As far as I know, this isn't supported by the .NET client.
NOTE: the RabbitMQ team monitors the rabbitmq-users mailing list and only sometimes answers questions on StackOverflow.
I want to make connection conformation
what I have now is
internal bool connect(remoteIP)
{
if ( network.startping(RemoteIP))
{
peer1.write("Hello!") ---> waits for "connected" until time out
if (Isconnected) return true
}
else
{
try again after few sec with finite number of repeats
}
return false
}
1) what can I do to wait
I saw a way with Task wait = new task.factory(()=> doDwaiting())
with I think can work , but I I'm missing some logic here
2) how can I make the return
i think I can Do it with int Counter and goto but it deosnt look like the "good" way to go
what can I do?
I've used the BeginConnect from the TcpClient class to verify the connection is valid. A System.Timer object would be used to reconnect if the connection failed. An example of a connection method would be as follows:
public void Connect(IPAddress ipAddress, int port, double reconnectInterval)
{
_reconnectTimer = new Timer { Interval = _reconnectInterval, Enabled = false, AutoReset = false };
_reconnectTimer.Elapsed += ReconnectTimer_Elapsed;
_tcpClient = new TcpClient();
try
{
_tcpClient.BeginConnect(ipAddress, port, ConnectionRequestCallback, null);
}
catch (Exception exception)
{
LostConnection(exception.Message);
}
}
The LostConnection method is called when there is any type of connection failure. The responsibility of the LostConenction method is to start the timer.
_reconnectTimer.Start();
Finally the timer's callback calls the same code shown above to attempt a new connection to the remote host.
Connect(_endPoint.Address, _endPoint.Port, _reconnectTimer.Interval);
}
i have a windows service that runs every 10 seconds to execute the read method. The Read method connects to remote server with the connection url provided in the constructor.
if the remote server fails to respond, it throws error and goes to catch. How do we make the thread to start again?
class PMTicketsService
{
private Timer _serviceTimer;
private TimerCallback _timerDelegate;
public PMTicketsService()
{
InitializeComponent();
}
protected override void OnStart(string[] args)
{
// Set the method to execute when the timer executes.
_timerDelegate = new TimerCallback(Receive);
// Create timer and attach our method delegate to it
_serviceTimer = new Timer(_timerDelegate, null, 1000, 10000);
}
public void Receive(object state)
{
ABC abc = new ABC(Url);
ABC abc1 = new ABC(Url1);
/* Create the thread object, passing in the abc.Read() method
via a ThreadStart delegate. This does not start the thread. */
Thread oThread = new Thread(new ThreadStart(abc.Read());
Thread oThread1 = new Thread(new ThreadStart(abc1.Read());
// Start the thread
oThread.Start();
oThread1.Start();
oThread.Join();
oThread1.Join();
}
}
class ABC
{
public string strUrl;
public ABC(string url)
{
strUrl = url;
}
public void Read()
{
try
{
// Code to use the connectionurl to access a remote server
}
catch (Exception ex)
{
// If the connection url fails to respond, how do we make thread start again?
}
}
}
In the future, you should submit sample code that actually compiles. I took what you had and cleaned it up, removed the unnecessary timer and structured it in a way that should give you what you need. In the code below, your Read method will continue running until you set done to true.
protected override void OnStart(string[] args)
{
try
{
ABC abc = new ABC("www.abc.com");
// Create the thread object, passing in the abc.Read() method
Thread oThread = new Thread(new ThreadStart(abc.Read));
// Start the thread
oThread.Start();
}
catch (Exception)
{
}
}
public class ABC
{
string strUrl = "";
public ABC(string url)
{
strUrl = url;
}
public void Read()
{
bool done = false;
while (!done)
{
try
{
//Code to use the connectionurl to access a remote server
//Use strUrl in here
}
catch (Exception)
{
//Wait 10 seconds before trying again
Thread.Sleep(10000);
}
//On success, set done to true
done = true;
}
}
}
Why do you want to start another thread? Starting/stopping threads is an expensive operation, you're far better off just keeping the existing thread open and continually trying to connect (possibly with a sleep in between). You already have the try/catch to keep the thread from crashing. Just wrap the try/catch in a while(!done) and set done to be true once you successfully connect.
You might also want to add some code so that if you can't connect X times in a row (maybe 5?) then you'll stop trying, or increase the timeout between connection attempts.
I'm writing a C# program that runs two IRC connections at once.
The connections are threaded, and each thread starts like so:
MainThread = new Thread(new ThreadStart(StartMainProcessor));
MainThread.IsBackground = false;
MainThread.Start();
private void StartMainProcessor() {
MainProcessor.Bot.Connect();
//while (true) { }
}
Bot.Connect() looks like this (somewhat abridged version):
public void Connect() {
try {
Client.Connect(IRCHelper.SERVER, IRCHelper.PORT);
}
catch (CouldNotConnectException e) {
Reconnect(true);
return;
}
try {
Client.Listen();
}
catch (Exception e) {
Reconnect(false);
return;
}
}
This works fine until the bot disconnects (which will always happen eventually, it's the nature of IRC).
When it disconnects, Reconnect() is called, which starts a timer. When that timer expires the bot is meant to then call Connect() again. The reason for the timer is that an IRC server will refuse an immediate reconnection sometimes.
However, once the Connect() method has ended, the Thread ends, and the program (console application) exits. (Client.Listen() is blocking)
I had previously overcome this problem by adding while (true) { } in StartMainProcessor()... But this eats up 100% CPU, and I'd really prefer a different solution.
Thank you for your help. :)
Sounds like you need a signaling construct. For example, you could use something like an AutoResetEvent to block the thread calling Reconnect, i.e. call Reconnect, start the timer and then block the thread. Then set the auto reset event in the timer expired event handler to allow the thread to continue (unblock) and call Connect.
I'm not a fan of spinning the processor - wastes huge amounts of CPU resources when you add infinite loops or sleeps in loops.
Why don't you just Thread.Sleep inside Bot.Reconnect? That would keep your thread alive and wake it up when ready to call Bot.Connect again.
You might want to try something like that
private bool canExitThread;
private void StartMainProcessor()
{
while (canExitThread)
{
//do the magic here
System.Threading.Thread.Sleep(1); //make sure you allow thread to do the job, otherwise you will get 100 cpu usage
//do the connecting, disconnecting, listening
}
}
Also can you check if Client is connected? if so then you should be checking that within the main loop and if it's disconnected - call the connect method.
Hope that gives you an idea how to do it.
Also have a look the the article below, which might explain things a little bit more.
http://msdn.microsoft.com/en-us/library/aa645740(v=vs.71).aspx
how about something like this
using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;
namespace Server
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Starting server..");
foreach (var connection in new[] {new Connection(TimeSpan.FromSeconds(1)), new Connection(TimeSpan.FromSeconds(1))})
ThreadPool.QueueUserWorkItem(connection.Connect);
Console.WriteLine("Server running. Press Enter to quit.");
Console.ReadLine();
}
}
public class Connection //might be good to implement IDisposable and disconnect on Dipose()
{
private readonly TimeSpan _reConnectionPause;
public Connection(TimeSpan reConnectionPause)
{
_reConnectionPause = reConnectionPause;
}
//You probably need a Disconnect too
public void Connect(object state)
{
try
{
//for testing assume connection success Client.Connect(IRCHelper.SERVER, IRCHelper.PORT);
Debug.WriteLine("Open Connection");
}
catch (Exception)
{
//You might want a retry limit here
Connect(state);
}
try
{
//Client.Listen();
//Simulate sesison lifetime
Thread.Sleep(1000);
throw new Exception();
}
catch (Exception)
{
Debug.WriteLine("Session end");
Thread.Sleep(_reConnectionPause);
Connect(state);
}
}
}
}
I presume you have a Main method, so why don't we start there:
private static readonly MAX_NUM_BOTS = 2;
static void Main(string[] args)
{
List<Thread> ircBotThreads = new List<Thread>();
for(int numBots = 0; numBots < MAX_NUM_BOTS; numButs++)
{
Thread t = new Thread(()=>{StartMainProcessor();});
t.IsBackground = false;
t.Start();
ircBotThreads.Add(t);
}
// Block until all of your threads are done
foreach(Thread t in ircBotThreads)
{
t.Join();
}
Console.WriteLine("Goodbye!");
}
private static void StartMainProcessor()
{
MainProcessor.Bot.Connect();
}
Then you can do something like this:
// 30 second time out (or whatever you want)
private static readonly TimeSpan TIMEOUT = TimeSpan.FromSeconds(30.0);
// specify the maximum number of connection attempts
private static readonly int MAX_RECONNECTS = 10;
public void Connect()
{
bool shouldListen = false;
// This is your connect and re-connect loop
for(int i = 0; i < MAX_RECONNECTS; i++)
{
try
{
Client.Connect(IRCHelper.SERVER, IRCHelper.PORT);
shouldListen = true;
}
catch (CouldNotConnectException e)
{
// It's OK to sleep here, because you know exactly
// how long you need to wait before you try and
// reconnect
Thread.Sleep((long)TIMEOUT.TotalMilliseconds);
shouldListen = false;
}
}
while(shouldListen)
{
try
{
Client.Listen();
}
catch (Exception e)
{
// Handle the exception
}
}
}
This is a very rough draft, but the concept is that you keep trying to reconnect until you fail. Once you connect, then you listen (I presume you listen for something in IRC) and you process the data until you decide that you no longer need to be doing that work.
i have a simple windows service which runs and starts a thread which listen/receive heartbeat via tcp/ip. i'm having a hard time finding ways to sync between getting information from the tcp thread and using that value to update something in the main thread.
i try to use a thread.sleep method and keep on looping it for a few times while awaiting the answer back from the thread and then getting the value, but that method seems to be a bit volatile with the method sometimes working and sometimes not.
so what's a good way to sync between these two?
basically what i want to do is to start the listening tcp thread, get specific value and the update the main program.
attached are the receive function and the function which i used to start the thread.
p.s: i'm a totally noobie when it comes to tcp/ip and c# so any comments on any part of the code or the design is more than welcome :)
public virtual void Receive()
{
string eventMessage = string.Empty;
int bytesRcvd = 0;
int totalBytesRcvd = 0;
byte[] byteBuffer = new byte[maxBufferSize];
NetworkStream listenStream;
try
{
if (client.Connected)
{
listenStream = client.GetStream();
}
else
{
return;
}
while (true)
{
//message that is slot in from the object will get sent here.
if (!string.IsNullOrEmpty(MessageToSend))
{
Send(MessageToSend);
MessageToSend = string.Empty;
}
// must convert it back and look for the delimiter, cannot wait for the three heartbeat to pass
string leftoverMsg = string.Empty;
bytesRcvd = listenStream.Read(byteBuffer, totalBytesRcvd, maxBufferSize - totalBytesRcvd);
totalBytesRcvd += bytesRcvd;
//if more than heart beat size, can process to see if it's a heartbeat and proceed to send
if (totalBytesRcvd > msgHeartbeatSize)
{
eventMessage = Encoding.ASCII.GetString(byteBuffer, 0, totalBytesRcvd);
ProcessMessage(eventMessage, ref leftoverMsg, ref totalBytesRcvd, ref byteBuffer);
}
}
}
catch (ThreadAbortException thEx)
{
//do nothing as main thread has aborted and waiting to close
logger.Info(Thread.CurrentThread.Name + " is stopped. ");
}
catch (Exception exce)
{
bIsActive = false;
logger.Error(exce);
CleanUp();
}
finally
{
logger.Info(String.Format("Thread {0} Exiting. ", Thread.CurrentThread.Name));
}
}
public virtual void StartReceivingThread()
{
Thread thrReceive = new Thread(Receive);
try
{
if (!bIsActive && Connect())
{
//NOTE: exception thrown by a thread can only be captured by that thread itself
//start a listen thread
//wait until heartbeat message is accepted
thrReceive.Name = "thr" + serviceType.Name;
thrReceive.Start();
bIsActive = true;
//wait to get the heartbeat message
for (int i = 0; i < maxRetry; i++)
{
Thread.Sleep(maxTimeOutValue);
if (bIsReceivingHeartbeat)
break;
}
//if nothing happens close the connection and try again
if (!bIsReceivingHeartbeat)
{
bIsActive = false;
CleanUp();
logger.Info("Closing receiver thread - " + thrReceive.Name);
}
else
{
logger.Info("Starting receiver thread - " + thrReceive.Name);
}
}
}
catch(Exception ex)
{
logger.Error(ex);
}
//finally
//{
// logger.Info("Exiting receiver thread - " + thrReceive.Name);
//}
}
I assume bIsReceivingHeartbeat is a bool member variable of the class. If the value changed in one thread (receiver) is not visible in the other thread this is most likely due to memory barrier. I am saying this from my Java background but this is most likely true in .net as well.
Try declaring the variables volatile or use a property and make the getter and setter synchronized:
private bool bIsReceivingHeartbeat;
public bool IsReceivingHeartbeat
{
[MethodImpl(MethodImplOptions.Synchronized)]
get { return bIsReceivingHeartbeat; }
[MethodImpl(MethodImplOptions.Synchronized)]
set { bIsReceivingHeartbeat = value; }
}
And in the calling code:
if (!IsReceivingHeartbeat) ....
I am writing from Java background but the situation most likely similar
(Looks like you also posted this code in refactormycode.com.)
Anyway, instead of the loop with a sleep delay, I recommend using an Event object that pulsed by the code that sets IsReceivingHeartbeat. See the ManualResetEvent and AutoResetEvent classes in MSDN.