C# 2005
I am using a background worker to process some login information. However, the background worker has to stop and wait for 2 events to happen. Once these have finished the background worker can complete its job. They are callbacks that will call the Set() method of the AutoResetEvent.
So I am using AutoResetEvent to set when these 2 events have finished. However, I seemed to be getting this error message:
"Exception has been thrown by the target of an invocation."
And Inner exception
Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index".
The exception usually fires when the registration success leaves scope.
Many thanks for any advice
The code for the background worker.
// Waiting for 'Account in use' and 'Register success or failure'
AutoResetEvent[] loginWaitEvents = new AutoResetEvent[]
{
new AutoResetEvent(false),
new AutoResetEvent(false)
};
private void bgwProcessLogin_DoWork(object sender, DoWorkEventArgs e)
{
Console.WriteLine("Wait until event is set or timeout");
loginWaitEvents[0].WaitOne(3000, true);
if (this.accountInUseFlag)
{
if (this.lblRegistering.InvokeRequired)
{
///this.lblRegistering.Invoke(new UpdateRegisterLabelDelegate(this.UpdateRegisterLabel), "Account in use");
}
else
{
///this.lblRegistering.Text = "Account in use";
}
// Failed attemp
e.Cancel = true;
// Reset flag
//this.accountInUseFlag = false;
return;
}
else
{
// Report current progress
//this.bgwProcessLogin.ReportProgress(7, "Account accepted");
}
Console.WriteLine("Just Wait the result of successfull login or not");
loginWaitEvents[1].WaitOne();
Console.WriteLine("Results for login registionSuccess: [ " + registerSuccess + " ]");
if (this.registerSuccess)
{
// Report current progress
//this.bgwProcessLogin.ReportProgress(7, "Register Succesfull");
// Reset flag
//this.registerSuccess = false;
}
else
{
if (this.lblRegistering.InvokeRequired)
{
//this.lblRegistering.Invoke(new UpdateRegisterLabelDelegate(this.UpdateRegisterLabel), "Failed to register");
}
else
{
// this.lblRegistering.Text = "Failed to register";
}
// Failed attemp
e.Cancel = true;
return;
}
}
// Wait for the callback to set the AutoResetEvent
// Error sometimes happens when the function leaves scope.
private void VaxSIPUserAgentOCX_OnSuccessToRegister(object sender, EventArgs e)
{
Console.WriteLine("OnSuccessToRegister() [ Registered successfully ]");
this.registerSuccess = true;
this.loginWaitEvents[1].Set();
}
// If the flag is not set, then just time out after 3 seconds for the first LoginWaitEvent.waitOne(3000, true)
private void VaxSIPUserAgentOCX_OnIncomingDiagnostic(object sender, AxVAXSIPUSERAGENTOCXLib._DVaxSIPUserAgentOCXEvents_OnIncomingDiagnosticEvent e)
{
string messageSip = e.msgSIP;
//Indicates that a user is already logged on (Accout in use).
string sipErrorCode = "600 User Found";
if (messageSip.Contains(sipErrorCode))
{
// Set flag for account in use
this.accountInUseFlag = true;
Console.WriteLine("OnIncomingDiagnostic() WaitEvent.Set() accountInUseFlag: " + this.accountInUseFlag);
loginWaitEvents[0].Set();
}
}
There is most likely an indexing error in the UpdateRegisterLabel method.
Get a Stack Trace from the inner exception, it should point you more closely to where it is.
Related
I am unable to get the reason for this Exception:
private void bwWorker_DoWork(object sender, DoWorkEventArgs e)
{
if (Main.bolDebugMode)
MessageBox.Show("Function DoWork is called");
if (Main.ftpsync(Main.strUsername407, Main.strPassword407, sender as BackgroundWorker) == 0)
e.Result = e.Result + "No error in " + Main.strUsername407;
else
{
if (Main.bolDebugMode)
MessageBox.Show("Errors in " + Main.strUsername407);
e.Cancel = true;
e.Result = e.Result + "Errors in " + Main.strUsername407;
if (Main.bolDebugMode)
MessageBox.Show("Errors marked");
try
{
MessageBox.Show("Next step throws exception");
return;
}
catch (Exception error)
{
if (error.ToString() != null)
MessageBox.Show(error.InnerException.Message);
}
}
}
It throws this exception:An unhandled exception of type 'System.Reflection.TargetInvocationException' occurred in mscorlib.dll
Additional information: Exception has been thrown by the target of an invocation.
The target (to my limited understanding) is the backgroundworker's RunWorkerCompleted function:
private void bwWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (Main.bolDebugMode)
MessageBox.Show("DoWork Completed. Break: " + e.Cancelled + " Error: " + e.Error + " Result: " + e.Result);
// First, handle the case where an exception was thrown.
if (e.Error != null)
{
lStatus.Text = e.Error.Message;
}
else if (e.Cancelled)
lStatus.Text = "Cancelled: " + e.Result.ToString();
}
else
{
lStatus.Text = "Done! " + e.Result;
Thread.Sleep(Convert.ToInt16(Main.strGlobalWaitTime));
pbProgress.Value = 0;
lStatus.Text = "";
}
if (Main.bolDebugMode)
MessageBox.Show("Analysis completed");
// Enable the Start button.
btnStart.Enabled = true;
// Disable the Cancel button.
btnCancel.Enabled = false;
}
public class Main
{
#region Variables
// Variables - FTP Settings
// Reading tons of variables from a appconfig file like so:
private static string StrGlobalWaitTime = ConfigurationManager.AppSettings["program_globalWaitTime"];
private static bool BolDeleteRemoteFiles = Convert.ToBoolean(ConfigurationManager.AppSettings["program_deleteremotefiles"]);
// Configuring the variables to receive and write
public static string strGlobalWaitTime
{
get { return StrGlobalWaitTime; }
set { StrGlobalWaitTime = value; }
}
#endregion
#region Main function
public static int ftpsync(string strUsername, string strPassword, BackgroundWorker bwWorker)
{
if (Directory.EnumerateFiles(strWorkDirectory, "*.pdf").Any())
{
bwWorker.ReportProgress(0, "Files left! Upload not complete");
Thread.Sleep(Convert.ToInt16(Main.strGlobalWaitTime));
return 1;
}
However, it doesn't even reach the first debugging message box. Thus it must be happening between the return and the beginning of the function. Is he background worker not handing over directly to the RunWorkerCompleted function? Can anyone tell me what I am missing or doing wrong?
This is my first question. I will try to provide as much information as possible. Google searches for the most obvious queries have been done.
The thing to look for whenever you encounter a TargetInvocationException is the InnerException property, which will have the "real" exception.
From the look of it, it will most likely have something to do with trying to access the GUI from inside the worker's thread. Remember that when using the DoWork handler, the code executes in a different thread from the main UI's. Therefore, calls to GUI components must be either done via Invoke calls or avoided all together.
I'm working on this program to ping a large number of IP Address simultaneously I tried simply pinging each address one at a time but Once I started pinging 50+ hosts it got insanely long. The problem I'm having is that I am unable to stop the asynchronous thread on the cancel button click and get this error when I try and ping more than 1 host. I've spent 2 days trying to get it figured out and had no luck. The exact error is as follows:
System.InvalidOperationException: An asynchronous call is already in
progress. It must be completed or canceled before you can call this method.
at System.Net.NetworkInformation.Ping.CheckStart(Boolean async)
at System.Net.NetworkInformation.Ping.Send(IPAddress address, Int32 timeout, Byte[] buffer, PingOptions options)
at MultiPing.Form1.backgroundWorker1_DoWork(Object sender, DoWorkEventArgs e) in f:\Dev\tfsMultiPing\Multi Ping\MultiPing\MultiPing\Form1.cs:line 139
private void pingBtn_Click(object sender, EventArgs e)
{
try
{
if (inputBox.Text == "")
{
MessageBox.Show("Please Enter an IP Address to Ping.", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
{
if (backgroundWorker1.IsBusy != true)
{
backgroundWorker1.RunWorkerAsync();
}
else
{
MessageBox.Show("Please Cancel current Ping or wait for it to be completed");
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}
public void backgroundWorker1_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
{
try
{
this.Invoke(new MethodInvoker(delegate { progressBar1.Enabled = true; }));
int i;
//Add each line in the input box to the "allLines" string array
string[] allLines = inputBox.Lines;
Ping pingSender = new Ping();
try
{
//Get an object that will block the main thread
AutoResetEvent waiter = new AutoResetEvent(false);
//When the PingCompleted even is raised,
//The PingCompletedCallback method is called.
pingSender.PingCompleted += new PingCompletedEventHandler(PingCompletedCallback);
//Create a buffer of 32 bytes of data to be transmitted.
string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
byte[] buffer = Encoding.ASCII.GetBytes(data);
//Wait 2 seconds for a reply.
int timeout = 2000;
//Set Options for transmission:
//The data can go through 64 gateways or routers
//before it is destroyed, and the data packet
//cannot be fragmented
PingOptions options = new PingOptions(64, true);
//Check if Cancel Button was clicked
if (backgroundWorker1.CancellationPending == true)
{
e.Cancel = true;
return;
}
else
{
//Begin Loop to ping each given IP Address
for (i = 0; i < allLines.Length; i++)
{
//Check if Cancel Button was clicked
if (backgroundWorker1.CancellationPending == true)
{
e.Cancel = true;
return;
}
else
{
//Convert each line from the input box to an IP address
IPAddress address = IPAddress.Parse(allLines[i]);
//Send ping Asynchronously
//Use the waiter as the user token.
//When the callback complets, it can wake up this thread.
pingSender.SendAsync(address, timeout, buffer, options, waiter);
PingReply reply = pingSender.Send(address, timeout, buffer, options);
waiter.WaitOne();
//If a replay is recieved Print "IP Address" is up in the output box.
if (reply.Status == IPStatus.Success)
{
this.Invoke(new MethodInvoker(delegate { outputBoxLive.AppendText(address + " is up" + Environment.NewLine); }));
}
//If no reply is recieved then print "IP Address" is down in the output box.
else if (reply.Status == IPStatus.TimedOut)
{
this.Invoke(new MethodInvoker(delegate { outputBoxDown.AppendText(address + " is down" + Environment.NewLine); }));
pingSender.Dispose();
}
pingSender.Dispose();
}
}
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
}
public void pingStuff()
{
}
private static void PingCompletedCallback(object sender, PingCompletedEventArgs e)
{
//If the operation was cancelled, Display a message to the user
if (e.Cancelled)
{
MessageBox.Show("Ping Cancelled");
//Let the main thread resume.
//User token is the AutoResetEvent object that the main thread is waiting for
((AutoResetEvent)e.UserState).Set();
}
//If an error occurred, Display the exception to the user.
if (e.Error != null)
{
MessageBox.Show("Ping Failed: " + e.Error.ToString());
//Let the main thread resume.
((AutoResetEvent)e.UserState).Set();
}
PingReply reply = e.Reply;
DisplayReply(reply);
//Let the main thread resume.
((AutoResetEvent)e.UserState).Set();
}
public static void DisplayReply(PingReply reply)
{
if (reply == null)
return;
Console.WriteLine("ping status: [0]", reply.Status);
if (reply.Status == IPStatus.Success)
{
Console.WriteLine("Address: {0}", reply.Address.ToString());
Console.WriteLine("RoundTrip time: {0}", reply.RoundtripTime);
Console.WriteLine("Time to live: {0}", reply.Options.Ttl);
Console.WriteLine("Don't fragment: {0}", reply.Options.DontFragment);
Console.WriteLine("Buffer size: {0}", reply.Buffer.Length);
}
}
public void button2_Click(object sender, EventArgs e)
{
try
{
backgroundWorker1.CancelAsync();
}
catch (Exception exc)
{
Console.WriteLine(exc);
}
}
}
}
The immediate issue with your code (i.e. the cause of the exception) is that you are calling both Ping.Send() and Ping.SendAsync() in your loop. Once you have called Ping.SendAsync(), any subsequent call to Send() or SendAsync() is illegal until the first SendAsync() operation has completed.
It's not clear why you even have both. Given that you appear to want to make the call synchronously, the simplest thing is to simply remove the call to SendAsync() and anything related to it (i.e. the waiter object). Alternatively, since you seem to want to be able to interrupt the operation, you may prefer to remove the call to Send(), so that you can use the SendAsyncCancel() method to interrupt an outstanding operation.
Lacking a good, complete code example (this code example doesn't show the full context, including where you get the addresses to ping), it's hard to know exactly what is wrong in your scenario. But I can offer a couple of observations about the code you did post:
You are calling the Ping.Dispose() method in each iteration of your loop. This means only in the first iteration of the loop should you expect to succeed. In the next iteration, you should be getting an ObjectDisposedException, terminating the work!
If you want to cancel an in-progress call to Ping.SendAsync(), you should call the Ping.SendAsyncCancel() method. This will cause the current ping operation to complete with cancellation status. Of course, to do this you will need to expose the pingSender reference to the form's code somehow, so that the button2_Click() method has access to it.
I have a test web connection form in c#. I want to show a loading window while my connection is being checked, and then show the result of checking.
This is my code for testing the web connection:
public bool ConnectionAvailable(string strServer)
{
try
{
HttpWebRequest reqFP = (HttpWebRequest)HttpWebRequest.Create(strServer);
HttpWebResponse rspFP = (HttpWebResponse)reqFP.GetResponse();
if (HttpStatusCode.OK == rspFP.StatusCode)
{
// HTTP = 200 - Internet connection available, server online
rspFP.Close();
return true;
}
else
{
// Other status - Server or connection not available
rspFP.Close();
return false;
}
}
catch (WebException)
{
// Exception - connection not available
return false;
}
}
And this:
private void button1_Click(object sender, EventArgs e)
{
string url = "Web-url";
label1.Text = "Checking ...";
button1.Enabled = false;
if (ConnectionAvailable(url))
{
WebClient w = new WebClient();
w.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
label1.Text = w.UploadString(url, "post", "SN=" + textBox1.Text);
button1.Enabled = true;
}
else
{
label1.Text = "Conntion fail";
button1.Enabled = true;
}
}
On a windows forms application the user interface runs on one thread, if you try to run a long running process, which checking the web connection might end up being this will cause the form to freeze until it completes the work.
So, I'd start a new thread that does the check. then raise an event to return the result. while all that's happening you can do what you like with the user interface, such as a loading graphic, or even allow the user to continue using features that don't require the internet connection.
Create EventArgs class of your own so you can pass back the result:
public class ConnectionResultEventArgs : EventArgs
{
public bool Available { get; set; }
}
Then in your form class, create your event, handlers and the method to action when the event arrives
//Create Event and Handler
public delegate void ConnectionResultEventHandler(object sender, ConnectionResultEventArgs e);
public event ConnectionResultEventHandler ConnectionResultEvent;
//Method to run when the event has been receieved, include a delegate in case you try to interact with the UI thread
delegate void ConnectionResultDelegate(object sender, ConnectionResultEventArgs e);
void ConnectionResultReceived(object sender, ConnectionResultEventArgs e)
{
//Check if the request has come from a seperate thread, if so this will raise an exception unless you invoke.
if (InvokeRequired)
{
BeginInvoke(new ConnectionResultDelegate(ConnectionResultReceived), new object[] { this, e });
return;
}
//Do Stuff
if (e.Available)
{
label1.Text = "Connection Good!";
return;
}
label1.Text = "Connection Bad";
}
Subscribe to the event when your form loads:
private void Form1_Load(object sender, EventArgs e)
{
//Subscribe to the the results event.
ConnectionResultEvent += ConnectionResultReceived;
}
and then setup the worker thread:
//Check the connection
void BeginCheck()
{
try
{
HttpWebRequest reqFP = (HttpWebRequest)HttpWebRequest.Create("http://google.co.uk");
HttpWebResponse rspFP = (HttpWebResponse)reqFP.GetResponse();
if (HttpStatusCode.OK == rspFP.StatusCode)
{
// HTTP = 200 - Internet connection available, server online
rspFP.Close();
ConnectionResultEvent(this, new ConnectionResultEventArgs {Available = true});
}
else
{
// Other status - Server or connection not available
rspFP.Close();
ConnectionResultEvent(this, new ConnectionResultEventArgs { Available = false });
}
}
catch (WebException)
{
// Exception - connection not available
//Raise the Event - Connection False
ConnectionResultEvent(this, new ConnectionResultEventArgs { Available = false });
}
}
private void button1_Click(object sender, EventArgs e)
{
//loading graphic, screen or whatever
label1.Text = "Checking Connection...";
//Begin the checks - Start this in a new thread
Thread t = new Thread(BeginCheck);
t.Start();
}
I am thinking of threading! One thread checks the connection while the other one is showing the loading window. If for example the connection has been established you can notify the other thread and show the result.
Here's DoWork:
private void uploadWorker_DoWork(object sender, DoWorkEventArgs e)
{
uploadWorker.ReportProgress(20);
int tiffError = 0;
finalFiles = Directory.GetFiles(AppVars.FinalPolicyImagesFolder);
foreach (string file in finalFiles)
{
if (!file.EndsWith(".tiff"))
{
tiffError = 1;
break;
}
}
uploadWorker.ReportProgress(50);
if (tiffError == 1)
{
MessageBox.Show("There are files in this folder that are not .tiff. Please ensure only .tiff files are in this folder.", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
{
if (finalFiles.Length == 0)
{
MessageBox.Show("There are no TIFF files to be uploaded. Please generate files first.", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
pbUpload.Value = 0;
EnableAllButtons();
}
else
{
double count = finalFiles.Length;
int current = 0;
int pbValue = 0;
uploadWorker.ReportProgress(70);
foreach (string file in finalFiles)
{
current = current + 2;
if (file.Contains(".tiff") == true)
{
PolicyNumber = Path.GetFileName(file).Split('_')[0];
basePolicyNumber = PolicyNumber.Remove(PolicyNumber.Length - 2);
basePolicyNumber = basePolicyNumber + "00";
finalPolicyName = Path.GetFileName(file);
PolicyUUID = Transporter.GetPolicyUUID(AppVars.pxCentralRootURL, basePolicyNumber);
if (PolicyUUID == "")
{
MessageBox.Show("The InsightPolicyID for the policy you are trying to upload does not exist in ixLibrary. Please ensure the policy number is correct. If you are sure it should be in ixLibray, please contact IT.", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
{
ixLibrarySourceFileURL = AppVars.ixLibraryPolicyAttachmentsURL + finalPolicyName;
UploadToixLibraryErrorCode = Transporter.UploadFileToixLibrary(AppVars.ixLibraryPolicyAttachmentsURL, file);
if (UploadToixLibraryErrorCode != 0)
{
MessageBox.Show("There was an error uploading the file to ixLibrary. Please contact IT about this problem.", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
{
GeneratePayLoadErrorCode = Transformer.GeneratePayLoad(ixLibrarySourceFileURL, finalPolicyName);
if (GeneratePayLoadErrorCode != 0)
{
MessageBox.Show("There was an error generating the XML for pxCentral. Please contact IT about this problem.", "Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
else
{
pxCentralPOSTErrorCode = Transporter.pxCentralPOST(AppVars.pxCentralRootURL + PolicyUUID, AppVars.pxCentralXMLPayloadFilePath);
pbValue = Convert.ToInt32(((current / count) * 30) + 70);
uploadWorker.ReportProgress(pbValue);
}
}
}
}
}
}
}
}
As soon as it hits the last }, I get the TargetInvocationException was unhandled error here (see comment in code):
static class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
bool createdNew = false;
Mutex mutex = new Mutex(true, "MyApplicationMutex", out createdNew);
if (createdNew == true)
{
//error happens here
Application.Run(new frmMain());
}
else
{
MessageBox.Show("The application is already running.", Application.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
}
}
I'm not sure why this started happening all of the sudden. Does anyone know why?
Finally, here's RunWorkerCompleted:
private void uploadWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Error == null)
{
DeleteFinalFiles(finalFiles);
MessageBox.Show("Upload process complete.", "Complete!", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
EnableAllButtons();
}
You are calling EnableAllButtons in your DoWork handler. this, presumably, changes the Enabled state of buttons on the form. that is not legal from any other thread than the UI thread. You should make the call to EnableAllButtons in your ProgressChanged event handler or in your RunWorkerCompleted event handler. You're also calling ProgressBar.Value in the DoWork with the code pbUpload.Value = 0.
Also, you should call MessageBox.Show from your UI thread (i.e. in ProgressChanged or RunworkerCompleted handler) so that the MessageBox can be associated with your forms message pump propertly. You should pass a form object to MessageBox.Show to associate the message box with the form so you can't bring the form to the foreground while the message box is shown. e.g.:
MessageBox.Show(this,
"There are files in this folder that are not .tiff. Please ensure only .tiff files are in this folder.",
"Error!", MessageBoxButtons.OK, MessageBoxIcon.Error);
In WinForms, you must only access a control on the thread that created the control. Your DoWork event handler is not running on the thread that created the form (which, of course, is the point). Therefore, you must not access any of the controls on the form in the DoWork handler. Doing so can create unpredictable results.
I had exactly the same problem with TargetInvocation Exception raised after the completion of the background process. Inside the backgroundWorker ProgressChanges Event I have references to controls as shown below`private void m_oWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
// This function fires on the UI thread so it's safe to edit
// the UI control directly, no funny business with Control.Invoke :)
CurrentState state =
(CurrentState)e.UserState;
txtProgress.Text = state.CrawlStatus;
lblStatus2.Text = state.sStatus;
txtItemsStored.Text = state.TotItems.ToString() + " items";
txtLastRunTime.Text = state.MostRecentGatherDate.ToString();
AppNameKey.SetValue("LastCrawlTime", txtLastRunTime.Text);
}`
The DoWork event reads from a control
private void m_oWorker_DoWork(object sender, DoWorkEventArgs e)
{
DateTime LastCrawlTime;
try
{
LastCrawlTime = Convert.ToDateTime(txtLastRunTime.Text);
if (lblStatus2.Text != "Status: Running" || (!cmdRunNow.Enabled && cmdStopRun.Enabled)) // run is not currently running or cmdRunNow clicked
{
//lblStatus2.Text = "Status: Running";
GetUpdated(LastCrawlTime,e);
}
}
catch (Exception Ex)
{
MessageBox.Show(Ex.Message);
}
}
The RunWorkedrCompleted Event writes to a control:
void m_oWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Cancelled)
{
lblStatus2.Text = "Status: Stopped";
cmdStopRun.Enabled = false;
}
// Check to see if an error occurred in the background process.
else if (e.Error != null)
{
lblStatus2.Text = "Fatal Error while processing.";
}
else
{
// Everything completed normally.
//CurrentState state = (CurrentState)e.UserState;
lblStatus2.Text = "Status: Finished";
}
}
None of these caused problems. What did cause the problem was the attempt to reference e.UserState in the RunWorker_Completed event (commented out above)
I figured out the issue.
The progress bar was exceeding its maximum allowed (of 100).
The problem was that in the code, I was incrementing the progress bar as such:
current = current + 2;
I replaced it with:
current++;
The reason why I was incrementing by 2 was simply for testing purposes.
So I am trying to create a basic WinForm Application that uses SNMP, from snmpsharpnet.
I have two buttons 'Eye' and 'Jitter' that when one is pressed a timer starts which executes SNMP code inside the timer handler every minute.
I am trying to write the SNMP output to a textbox from the timer handler but everything I try either leads to thread exceptions or a continuous running process when I exit the program.
I have tried so many different things to fix those two errors that I may be screwing everything up but here is the code I have:
using System;
using System.Net;
using SnmpSharpNet;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
public static bool stop = false;
static bool min = false, sec = false, eye = false, jitter = false;
static string ipAdd = "";
static System.Windows.Forms.Timer timer = new System.Windows.Forms.Timer();
static int alarmCounter = 1;
static bool exitFlag = false;
static TextBox textbox;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
textbox = outputBox;
}
private void IPtext_TextChanged(object sender, EventArgs e)
{
ipAdd = IPtext.Text;
}
private void stopButton_Click(object sender, EventArgs e)
{
stop = true;
timer.Stop();
}
// This is the method to run when the timer is raised.
private static void TimerEventProcessor(Object myObject,
EventArgs myEventArgs)
{
timer.Stop();
// If stop button has not been pressed then continue timer.
if (stop == false)
{
textbox.Clear();
// Restarts the timer and increments the counter.
alarmCounter += 1;
timer.Enabled = true;
/*
textbox.Invoke(
new MethodInvoker(
delegate { textbox.AppendText("fsjdaò"); }));
*/
System.IO.StreamWriter file;
if (eye == true)
{
file = new System.IO.StreamWriter("c:/Users/bshellnut/Desktop/Eye.txt", true);
}
else
{
file = new System.IO.StreamWriter("c:/Users/bshellnut/Desktop/Jitter.txt", true);
}
// SNMP community name
OctetString community = new OctetString("public");
// Define agent parameters class
AgentParameters param = new AgentParameters(community);
// Set SNMP version to 2 (GET-BULK only works with SNMP ver 2 and 3)
param.Version = SnmpVersion.Ver2;
// Construct the agent address object
// IpAddress class is easy to use here because
// it will try to resolve constructor parameter if it doesn't
// parse to an IP address
IpAddress agent = new IpAddress(ipAdd);
// Construct target
UdpTarget target = new UdpTarget((IPAddress)agent, 161, 2000, 1);
// Define Oid that is the root of the MIB
// tree you wish to retrieve
Oid rootOid;
if (eye == true)
{
rootOid = new Oid("1.3.6.1.4.1.128.5.2.10.14"); // ifDescr
}
else
{
rootOid = new Oid("1.3.6.1.4.1.128.5.2.10.15");
}
// This Oid represents last Oid returned by
// the SNMP agent
Oid lastOid = (Oid)rootOid.Clone();
// Pdu class used for all requests
Pdu pdu = new Pdu(PduType.GetBulk);
// In this example, set NonRepeaters value to 0
pdu.NonRepeaters = 0;
// MaxRepetitions tells the agent how many Oid/Value pairs to return
// in the response.
pdu.MaxRepetitions = 5;
// Loop through results
while (lastOid != null)
{
// When Pdu class is first constructed, RequestId is set to 0
// and during encoding id will be set to the random value
// for subsequent requests, id will be set to a value that
// needs to be incremented to have unique request ids for each
// packet
if (pdu.RequestId != 0)
{
pdu.RequestId += 1;
}
// Clear Oids from the Pdu class.
pdu.VbList.Clear();
// Initialize request PDU with the last retrieved Oid
pdu.VbList.Add(lastOid);
// Make SNMP request
SnmpV2Packet result;
try
{
result = (SnmpV2Packet)target.Request(pdu, param);
//textbox.Text = "";
}
catch (SnmpSharpNet.SnmpException)
{
textbox.Invoke(
new MethodInvoker(
delegate { textbox.AppendText("Could not connect to the IP Provided."); }));
timer.Stop();
//outputBox.Text += "Could not connect to the IP Provided.";
break;
}
// You should catch exceptions in the Request if using in real application.
// If result is null then agent didn't reply or we couldn't parse the reply.
if (result != null)
{
// ErrorStatus other then 0 is an error returned by
// the Agent - see SnmpConstants for error definitions
if (result.Pdu.ErrorStatus != 0)
{
// agent reported an error with the request
/*Console.WriteLine("Error in SNMP reply. Error {0} index {1}",
result.Pdu.ErrorStatus,
result.Pdu.ErrorIndex);*/
textbox.Invoke(
new MethodInvoker(
delegate { textbox.AppendText("Error in SNMP reply. " + "Error " + result.Pdu.ErrorStatus + " index " + result.Pdu.ErrorIndex); }));
//outputBox.Text = "Error in SNMP reply. " + "Error " + result.Pdu.ErrorStatus + " index " + result.Pdu.ErrorIndex;
lastOid = null;
break;
}
else
{
// Walk through returned variable bindings
foreach (Vb v in result.Pdu.VbList)
{
// Check that retrieved Oid is "child" of the root OID
if (rootOid.IsRootOf(v.Oid))
{
/*Console.WriteLine("{0} ({1}): {2}",
v.Oid.ToString(),
SnmpConstants.GetTypeName(v.Value.Type),
v.Value.ToString());*/
textbox.Invoke(
new MethodInvoker(
delegate { textbox.AppendText(v.Oid.ToString() + " " + SnmpConstants.GetTypeName(v.Value.Type) +
" " + v.Value.ToString() + Environment.NewLine); }));
//outputBox.Text += v.Oid.ToString() + " " + SnmpConstants.GetTypeName(v.Value.Type) +
//" " + v.Value.ToString() + Environment.NewLine;
file.WriteLine(v.Oid.ToString() + " " + SnmpConstants.GetTypeName(v.Value.Type) +
" " + v.Value.ToString(), true);
if (v.Value.Type == SnmpConstants.SMI_ENDOFMIBVIEW)
lastOid = null;
else
lastOid = v.Oid;
}
else
{
// we have reached the end of the requested
// MIB tree. Set lastOid to null and exit loop
lastOid = null;
}
}
}
}
else
{
//Console.WriteLine("No response received from SNMP agent.");
textbox.Invoke(
new MethodInvoker(
delegate { textbox.AppendText("No response received from SNMP agent."); }));
//outputBox.Text = "No response received from SNMP agent.";
}
}
target.Close();
file.Close();
}
else
{
// Stops the timer.
exitFlag = true;
}
}
private void eyeButton_Click(object sender, EventArgs e)
{
outputBox.Text = "Connecting...";
eye = true;
jitter = false;
stop = false;
timer.Tick += new EventHandler(TimerEventProcessor);
// Sets the timer interval to 5 seconds.
timer.Interval = 5000;
timer.Start();
// Runs the timer, and raises the event.
while (exitFlag == false)
{
// Processes all the events in the queue.
Application.DoEvents();
}
}
private void jitterButton_Click(object sender, EventArgs e)
{
outputBox.Text = "Connecting...";
eye = false;
jitter = true;
stop = false;
timer.Tick += new EventHandler(TimerEventProcessor);
// Sets the timer interval to 5 seconds.
timer.Interval = 5000;
timer.Start();
// Runs the timer, and raises the event.
while (exitFlag == false)
{
// Processes all the events in the queue.
Application.DoEvents();
}
}
private void Seconds_CheckedChanged(object sender, EventArgs e)
{
min = false;
sec = true;
}
private void Minutes_CheckedChanged(object sender, EventArgs e)
{
min = true;
sec = false;
}
}
}
I believe you are running into a deadlock on the UI thread.
TimerEventProcessor() is called by your instance of System.Windows.Forms.Timer, which runs on the UI thread. When the timer goes off, I believe it puts a message into the UI thread's message queue to call your TimerEventProcessor() method. That method in turn calls textbox.Invoke(), which puts another message into the queue and then waits for it to be processed.
Your UI thread is now stuck, as it is in the middle of processing a message, but must wait until another message is processed before it can continue. The calls to Application.DoEvents() do you no good, as they are not being called once your program enters TimerEventProcessor(). (They're also unnecessary, since your button click handlers wouldn't be blocking the UI thread anyway.)
Since the timer runs on the UI thread, you can get rid of the textbox.Invoke() calls and just access textbox directly.
Summary:
Replace your calls to textbox.Invoke() with direct access to textbox
Remove your calls to Application.DoEvents()
Note: if you got the Application.DoEvents() logic from the MSDN example for using a timer, they put it there so that the application doesn't quit once the Main function completes.
Update: You can see if this is truly the issue by replacing your calls to textbox.Invoke with the following code. If this code works, then you definitely have a UI message queue deadlocking issue. Also, if this does resolve the issue, I would not recommend keeping this as the solution, but rather, addressing the deadlocking as suggested above.
// Make the request asynchronously
System.IAsyncResult asyncResult = textbox.BeginInvoke(
new MethodInvoker(
delegate { /* insert delegate code here */ }));
// Process the message queue until this request has been completed
while(!asyncResult.IsCompleted) Application.DoEvents();
// Clean up our async request
textbox.EndInvoke(asyncResult);
Since you seem to have your code working, you can ignore the above test code.
Your problem is not related to the timer and all the Invoke statements you use are not necessary. The System.Windows.Forms.Timer class operates in the UI thread. Look here: http://msdn.microsoft.com/en-us/library/system.windows.forms.timer.aspx