I'm developing a sample program to connect multiple device using backgroundworker. Each device connected will be add to the list as new object. After finished connecting all the devices, i wanted to add an event handler for each connected devices. The problem that i'm facing now is the event handler doesn't firing at all. Below are the sample codes.
The Connect click button event :
private void btnConnect_Click(object sender, EventArgs e)
{
using (BackgroundWorker m_oWorker = new BackgroundWorker())
{
m_oWorker.DoWork += delegate (object s, DoWorkEventArgs args)
{
int iIpStart = 0;
int iIpEnd = 0;
string strIp1 = string.Empty;
string strIp2 = string.Empty;
list.Clear();
string[] sIP1 = txtIpStart.Text.Trim().ToString().Split('.');
string[] sIP2 = txtIpEnd.Text.Trim().ToString().Split('.');
iIpStart = Convert.ToInt32(sIP1[3]);
iIpEnd = Convert.ToInt32(sIP2[3]);
strIp1 = sIP1[0] + "." + sIP1[1] + "." + sIP1[2] + ".";
strIp2 = sIP2[0] + "." + sIP2[1] + "." + sIP2[2] + ".";
Ping ping = new Ping();
PingReply reply = null;
int iIncre = 0;
int iVal = (100 / (iIpEnd - iIpStart));
for (int i = iIpStart; i <= iIpEnd; i++)
{
Thread.Sleep(100);
string strIpconnect = strIp1 + i.ToString();
Console.Write("ip address : " + strIpconnect + ", status: ");
reply = ping.Send(strIpconnect);
if (reply.Status.ToString() == "Success")
{
if (ConnectDevice(strIpconnect))
{
strLastDevice = strIpconnect + " Connected";
isconnected = true;
}
else
{
isconnected = false;
}
}
else
{
isconnected = false;
}
m_oWorker.ReportProgress(iIncre);
iIncre = iIncre + iVal;
}
m_oWorker.ReportProgress(100);
};
m_oWorker.ProgressChanged += new ProgressChangedEventHandler(m_oWorker_ProgressChanged);
m_oWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(m_oWorker_RunWorkerCompleted);
m_oWorker.WorkerReportsProgress = true;
m_oWorker.WorkerSupportsCancellation = true;
m_oWorker.RunWorkerAsync();
}
}
ConnectDevice function method. Connected device will be added to the list :
protected bool ConnectDevice(string sIP)
{
try
{
NewSDK sdk = new NewSDK();
if (sdk.Connect() == true)
{
list.Add(new objSDK { sdk = sdk, ipaddress = sIP });
return true;
}
else
{
}
}
catch() {}
return false;
}
the Backgroundworker :
void m_oWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
//If it was cancelled midway
if (e.Cancelled)
{
lblStatus.Text = "Task Cancelled.";
}
else if (e.Error != null)
{
lblStatus.Text = "Error while performing background operation.";
}
else
{
lblStatus.Text = "Task Completed...";
btnListen.Enabled = true;
}
}
void m_oWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
//Here you play with the main UI thread
progressBar1.Value = e.ProgressPercentage;
lblStatus.Text = "Processing......" + progressBar1.Value.ToString() + "%";
if (isconnected)
{
listBox2.Items.Add(strLastDevice);
string[] ssplit = sDeviceInfo.Split(';');
foreach (string sword in ssplit)
{
listBox1.Items.Add(sword);
}
}
}
The function to attached event :
private void RegisterEvent()
{
foreach (objSDK obj in list)
{
obj.sdk.OnTransaction += () =>
{
listBox1.Items.Add("ip : " + obj.IP + " transaction");
};
}
}
You have declared m_oWorker as a local variable. I'm guessing this was a mistake ( the m_ prefix should only be used for class member variables)?
Also, you declared it within a using statement, meaning that it that the framework will call Dispose() on it at the end of the using block. Even if you held on to a reference to it (and I don't think you do) it still means its resources will be deallocated, which is probably why it isn't handling any events.
I try another workaround by using thread and task and work perfectly. Thanks for all response
Related
My problem is that I have multiple Forms Controls that I need to make visible/invisible/change text, based on the output of my code.
Obviously this is very easy to achieve but the code is ridiculously long due to how I've set it up.
I have 3 image boxes containing a red, green and orange 'light'.
When the ping action is started (button click or a timer) all the controls need to be set like so:
// ping 1
redLight1.Visible = true;
greenLight1.Visible = false;
orangeLight1.Visible = false;
status_Lbl1.Text = "Initiated...";
I need to do this 9 times, and the code looks a bit meh to me having this repeated this many times.
I have a ping object that sends a ping every second for x amount of time. If all of the pings are sent and received successfully then an imagebox containing a green circle becomes visible greenLight1.Visible = true, while all others are set redLight1.Visible = false, orangeLight1.Visible = false, etc.
I have 9 of these sets of 'traffic lights', with a different IP being pinged and a different outcome for each.
I feel there must be a way to iteratively change the values of each of these boxes using the fact they all follow the same naming convention with just a different number on the end corresponding to the ping object they represent.
Here's a more visual idea of what I want to achieve.
private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
// int counter = 0
if (e.Cancelled == true)
{
status_Lbl1.Text = "Cancelled";
}
else if (e.Error != null)
{
status_Lbl1.Text = "Error: " + e.Error.Message;
}
else
{
foreach (Ping pingObj in pings)
{
if (pingObj.SuccessfulPings == 0)
{
Debug.WriteLine("Ping Object: " + pingObj.Fqdn + " failed to successfully ping");
// greenLight[i].Visible = false;
// orangeLight[i].Visible = false;
// redLight[i].Visible = true;
// counter++
}
else if (pingObj.FailedPings != 0)
{
Debug.WriteLine("Ping Object: " + pingObj.Fqdn + " failed to successfully ping: " + pingObj.FailedPings + " times.");
// greenLight[i].Visible = false;
// orangeLight[i].Visible = true;
// redLight[i].Visible = false;
// counter++
}
else
{
Debug.WriteLine("Ping Object: " + pingObj.Fqdn + " succesfully pinged: " + pingObj.SuccessfulPings + " times.");
// greenLight[i].Visible = false;
// orangeLight[i].Visible = false;
// redLight[i].Visible = false;
// counter++
}
}
}
}
Here's the method that creates/uses the ping objects just in case that is necessary
private async void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
try
{
// Create background worker
BackgroundWorker worker = (BackgroundWorker)sender;
// Write to log file
await file.WriteAsync("Starting job...\n");
await file.WriteAsync("Requested amount of pings: " + count + "\n");
// Create date object for logs
DateTime localDate = DateTime.Now;
for (int i = 0; i < count; i++)
{
// Create ping objects
System.Net.NetworkInformation.Ping pinger = new System.Net.NetworkInformation.Ping();
PingReply pingReply;
try
{
foreach (Ping pingObj in pings)
{
try
{
pingReply = pinger.Send(pingObj.IpAddress);
// Write log file
await file.WriteLineAsync(localDate.TimeOfDay + " | Friendly Name " + pingObj.FriendlyName + " | Ping: " + pingReply.Address + " | Status " + pingReply.Status + " | Time: " + pingReply.RoundtripTime);
if (pingReply.Status.ToString().Contains("Success"))
{
pingObj.SuccessfulPings += 1;
}
else // Unsuccessful ping has been sent
{
pingObj.FailedPings += 1;
}
}
catch (Exception ex)
{
Debug.WriteLine(ex.ToString());
}
}
wait(1000);
}
catch (Exception b)
{
Debug.WriteLine(b.ToString());
}
}
}
catch (Exception a)
{
Debug.WriteLine(a.ToString());
}
}
You can use Controls.Find() and "search by name" with the recurse option:
Control ctl = this.Controls.Find("greenLight" + counter, true).FirstOrDefault() as Control;
if (ctl != null) {
ctl.Visible = false;
}
I have a simple work to do, On button click it will get all Network IP addresses from a range, loop through them and put the active in a list. While performing the process a panel will be shown on which ip address will be displayed that is being checked. Code runs fine but form hangs up, application go to not responding and ip address not displayed even panel is not shown. how to do that?
my code is:
private void btnAutoSearch_Click(object sender, EventArgs e)
{
panel_Search.Visible = true; // Not Working
Cursor.Current = Cursors.WaitCursor;
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = p.Send(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
lblConnecting.Text = ip; // Not Working
}
}
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (obj.ConnectToHostServer())
{
obj.SendConnectionMessage();
obj.ReceiveConnectionMessage();
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Visible = false;
}
The issue is that the UI must be updated from the 'Main' thread (always called UI thread), but if you do other processing on this thread then the UI itself will lock up. So you should put long running process onto another thread.
This will cause the problem however that this thread cannot update the UI, as it is not the Main/UI thread. So then you have to invoke the UI thread yourself to update it.
Luckily there is simple way of doing this using the BackgroundWorker class in C# which can help you a lot. But you need to separate out your UI and background tasks.
//Define worker
BackgroundWorker myBGWorker;
//Initalise worker and start it from your button
private void btnAutoSearch_Click(object sender, EventArgs e)
{
panel_Search.Visible = true; // Not Working
Cursor.Current = Cursors.WaitCursor;
myBGWorker = new BackgroundWorker()
//This method will execute your processing on a background thread
myBGWorker.DoWork += new DoWorkEventHandler(bgw_DoWork);
//This method will execute when your background worker finishes
//It runs on the Main/UI thread
myBGWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgw_RunWorkerCompleted);
//This method will execute when the background thread wants to update the progress
//It runs on the Main/UI Thread
myBGWorker.ProgressChanged += new ProgressChangedEventHandler(bgw_ProgressChanged);
//Tell it we will be reporting progress
myBGWorker.WorkerReportsProgress = true;
//Start!
myBGWorker.RunWorkerAsync()
}
private void bgw_DoWork(object sender, DoWorkEventArgs e)
{
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = p.Send(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
//Below reports the progress. The number shouuld represent the percentage of process, the object can be anything you want
double percentDone = (100.0 / 255.0) * i;
e.ReportProgress(Convert.ToInt32(percentDone), ip);
}
}
}
private void bgw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
lblConnecting.Text = e.UserState as string;
}
private void bgw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
if (e.Cancelled)
MessageBox.Show("Operation was canceled");
else if (e.Error != null)
MessageBox.Show(e.Error.Message);
else
{
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (obj.ConnectToHostServer())
{
obj.SendConnectionMessage();
obj.ReceiveConnectionMessage();
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Visible = false;
}
}
Desktop applications use one single thread to handle UI, and event handlers run synchronously on the UI thread, that is why form hangs, because it cannot handle other UI interactions while the event handler is running.
Best practice is that event handlers take UI thread for very short time.
When you need to perform long running tasks because of user interaction, you should perform the task in another thread, you should not use the UI thread for long running tasks.
You can use BackgroundWorker to move the task to another thread, but it is better to use asynchronous event handlers.
For example:
private async void myButton_Click(object sender, EventArgs e)
{
await PerformLongRunningTaskAsync();
//TODO: update UI after completing task
await Task.Run(() => PerformLongRunningTaskSynchronously());
//TODO: update UI after completing task;
}
private async Task PerformLongRunnigTaskAsync() {
//TODO: implement this async method
}
private void PerformLongRunningTaskSynchronously() {
//TODO: implement this synchronus method
}
Your code should be something like this:
private async void btnAutoSearch_Click(object sender, EventArgs e)
{
panel_Search.Visible = true; // Not Working
Cursor.Current = Cursors.WaitCursor;
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = await p.SendPingAsync(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
lblConnecting.Text = ip; // Not Working
}
}
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (await Task.Run(() => obj.ConnectToHostServer())
{
await Task.Run(() => obj.SendConnectionMessage());
await Task.Run(() => obj.ReceiveConnectionMessage());
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Visible = false;
}
Here is how i did the work thanks to Brian Rogers,
private void btnAutoSearch_Click(object sender, EventArgs e)
{
backgroundWorker1.WorkerSupportsCancellation = true;
if (backgroundWorker1.IsBusy != true)
{
// Start the asynchronous operation.
backgroundWorker1.RunWorkerAsync();
}
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
BackgroundWorker worker = sender as BackgroundWorker;
for (int j = 1; j <= 10; j++)
{
if (worker.CancellationPending == true)
{
e.Cancel = true;
break;
}
else
{
Cursor.Current = Cursors.WaitCursor;
panel_Search.Location = new Point(380, 72);
// Perform a time consuming operation and report progress.
string ipBase = getIPAddress();
string[] ipParts = ipBase.Split('.');
ipBase = ipParts[0] + "." + ipParts[1] + "." + ipParts[2] + ".";
for (int i = 1; i < 255; i++)
{
string ip = ipBase + i.ToString();
Ping p = new Ping();
PingReply pingresult = p.Send(ip, 100);
if (pingresult.Status == IPStatus.Success)
{
lstIPs.Add(ip);
lblConnecting.Text = ip;
//listBox1.Items.Add(ip);
}
}
GridConn.Rows.Clear();
foreach (string s in lstIPs)
{
Device obj = new Device();
obj.IPAddress = s;
lblConnecting.Text = s;
int vSMSLimit = 0;
int.TryParse(txtSMSLimit.Text, out vSMSLimit);
obj.SMSLimit = 0;
if (obj.ConnectToHostServer())
{
obj.SendConnectionMessage();
obj.ReceiveConnectionMessage();
MyDevices.lst.Add(obj);
GridConn.Rows.Add(true, obj.IPAddress, obj.PhoneModel, obj.PhoneStatus, obj.SoftwareVersion);
}
}
Cursor.Current = Cursors.Default;
panel_Search.Location = new Point(333, 252);
}
}
}
I am working on this GUI for serial port application. I recently added stop and wait protocols to the application. Surprisingly my disconnect button stopped working. I have thought through the logic and I have not been able to find the problem.
namespace WindowsFormsApplication5
{
public partial class Form1 : Form
{
public bool packetreceived = false;
private SerialPort sp = null; //<---- serial port at form level
public delegate void AddDataDelegate(String myString);
public AddDataDelegate myDelegate;
//delegate variable to disconnect
public AddDataDelegate disconnectDelegate = null;
public void AddDataMethod(String myString)
{
richTextBox1.AppendText(myString);
}
/**
* Takes byte array and returns a string representation
*
*/
public String parseUARTData(byte[] data)
{
if (data.Length == 11)
{
String rv = "";
DataFields d = new DataFields();
if (!packetreceived)
{
d = mainLogic.parseData(data);
packetreceived = true;
}
//TODO
System.Threading.Thread.Sleep(5000);
if (d.sequence == 0)
{
sp.Write("1\r\n");
}
else
{
sp.Write("0\r\n");
}
packetreceived = false;
//now display it as a string
rv += STR_OPCODE + " = " + d.opcode + "\n";
rv += STR_CRC + " = " + d.crc + "\n";
rv += STR_SEQ + " = " + d.sequence + "\n";
rv += STR_FLAGS + " = " + d.flags + "\n";
rv += STR_TEMP + " = " + d.temperature + "\n";
rv += STR_HUMID + " = " + d.humidity + "\n";
rv += STR_PH + " = " + d.ph + "\n";
return rv + "\n\n";
}
else
{
return Encoding.ASCII.GetString(data);
}
}
private void sp_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
SerialPort sp = (SerialPort)sender;
string s = sp.ReadExisting();
if (disconnectDelegate != null)
{
disconnectDelegate.Invoke(s);
}
richTextBox1.Invoke(this.myDelegate, new Object[] { parseUARTData(Encoding.ASCII.GetBytes(s)) });
}
private void button1_Click(object sender, EventArgs e)
{
connect.Enabled = false;
try
{
// open port if not already open
// Note: exception occurs if Open when already open.
if (!sp.IsOpen)
{
//sp.PortName = this.comboBox1.SelectedItem.ToString();
sp.Open();
}
// send data to port
sp.Write("####,###########\r\n");
disconnect.Enabled = true;
}
catch (Exception)
{
// report exception to user
Console.WriteLine(e.ToString());
}
}
private void button2_Click(object sender, EventArgs e)
{
connect.Enabled = true;
try
{
// open port if not already open
// Note: exception occurs if Open when already open.
if (sp.IsOpen)
{
// send data to port
sp.Write("+++\r\n");
//add the delegate
disconnectDelegate = new AddDataDelegate(onDisconnect);
//sp.WriteTimeout = 500;
// sp.Write("####,0\r\n");
}
}
catch (Exception)
{
Console.WriteLine(e.ToString());
}
finally
{
disconnect.Enabled = false;
}
}
public void OnApplicationExit(object sender, EventArgs e)
{
sp.Close();
}
private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
//foreach (string port in ports)
//{
// comboBoxSerialPorts.Items.Add(port);
//}
}
private void onDisconnect(string msg)
{
string trimmedMsg = msg.Trim();
if (trimmedMsg.Equals("OK"))
{
//send the second time
sp.Write("##,0\r\n");
//null the object
disconnectDelegate = null;
}
}
private void comPort_Click(object sender, EventArgs e)
{
try
{
if (sp.IsOpen)
{
//send data to port
sp.Write("1\r\n");
MessageBox.Show("bluetooth is transmitting data...");
//message box telling user that you are asking for data.
}
}
catch (Exception)
{
// report exception to user
Console.WriteLine(e.ToString());
}
}
My error
Cross-thread operation not
valid: Control 'MailTree' accessed
from a thread other than the thread it
was created on.
with my code
My idea is when SaveMail method has finish store 1 mes then add this mes to listview.
private delegate int SaveMailDelegate(ImapX.Message mes);
public int SaveMail(ImapX.Message mess)
{
if (!File.Exists("D:\\" + Username + "\\" + MailTree.SelectedNode.Text + "\\" + mes.MessageUid.ToString() + ".eml"))
{
mess.Process();
mess.SaveAsEmlToFile("D:\\" + Username + "\\" + MailTree.SelectedNode.Text + "\\", mes.MessageUid.ToString()); //Store messages to a Location
}
// mes.MessageUid=mess.MessageUid;
return 1;
}
Mime EncodingMail(string NodeName,string focusitem)
{
Mime m = new Mime();
m=Mime.Parse("D:\\" + Username+ "\\"+NodeName+"\\"+focusitem+".eml");
return m;
}
private void AddMesToMailList()
{
ListViewItem item = new ListViewItem();
Mime m = EncodingMail(MailTree.SelectedNode.Text, mes);
item.Text = mes.MessageUid.ToString();
item.SubItems.Add(m.MainEntity.Subject);
ReturnMime(m);
if (mailfromname != null)
item.SubItems.Add(mailfromname);
else item.SubItems.Add(mailfrom);
item.SubItems.Add(m.MainEntity.Date.ToString());
item.SubItems.Add(mailfrom);
MailList.Items.Add(item);
}
private void SaveMailDone(IAsyncResult iar)
{
SaveMailDelegate del = iar.AsyncState as SaveMailDelegate;
if (del != null)
{
int result = del.EndInvoke(iar);
AddMesToMailList();
}
}
private void MailTree_AfterSelect(object sender, System.Windows.Forms.TreeViewEventArgs e)
{
MailList.Items.Clear();
for (int i = 0; i < client.Folders.Count; i++)
{
(ContextMenuListView.Items[1] as ToolStripMenuItem).DropDownItems[i].Click += new EventHandler(MainForm_Click);
}
if (MailTree.SelectedNode.Text == Username)
{
webBrowser1.Visible = false;//webBrowser1.DocumentText = "Hello Baby";
AttachmentList.Visible = false;
groupBox1.Visible = false;
}
else
{
webBrowser1.Visible = true;
groupBox1.Visible = true;
try
{
messages = client.Folders[MailTree.SelectedNode.Text].Search("ALL", false); // Search mail in your choossen Folder
AmoutOfMail = messages.Count(); //Amout of Mail in this Folder
for (int i = 0; i < AmoutOfMail; i++)
{
mes=messages[i];
SaveMailDelegate del = new SaveMailDelegate(this.SaveMail);
del.BeginInvoke(mes, new AsyncCallback(this.SaveMailDone), del);
}
}
catch (Exception)
{ }
}
}
You cannot directly access a control from another thread, you will have to invoke it.
private delegate void ControlCallback(string s);
public void CallControlMethod(string text)
{
if (control.InvokeRequired)
{
ControlCallback call = new ControlCallback((s) =>
{
// do control stuff
});
control.Invoke(call, new object[] { text });
}
else
{
// do control stuff
}
}
you can't access the UI on a different thread than what it was created on. From inside your secondary thread (the one that runs your callback handler) you will need to call Form.BeginInvoke to register a method that will be run on the UI thread. From that method you can update your UI controls
I think AddMesToMailList() is trying to modify the view elements but it is on a wrong thread.
Try something like this
void AddMesToMailList()
{
if (this.InvokeRequired)
{
this.BeginInvoke(new Action(AddMesToMailList));
return;
}
// do stuff that original AddMesToMailList() did.
}
EDIT:
SaveMail is a little complicated as it has a return value but you can try this
public int SaveMail(ImapX.Message mess)
{
if(this.InvokeRequired)
{
return (int) this.Invoke(
new Func<ImapX.Message, int>( m => SaveMail(mess)) );
}
else
{
if (!File.Exists(#"D:\" + Username + "\\" + MailTree.SelectedNode.Text + "\\" + mes.MessageUid.ToString() + ".eml"))
{
mess.Process();
mess.SaveAsEmlToFile(#"D:\" + Username + "\\" + MailTree.SelectedNode.Text + "\\", mes.MessageUid.ToString()); //Store messages to a Location
}
// mes.MessageUid=mess.MessageUid;
return 1;
}
}
I am writing a c# program to let me know when a file has been added or deleted. I run it on my Windows 7 machine and watch an FTP server on our network.
It works fine but will suddenly stop catching any events. I'm guessing that it might be losing connection to the server or there is a glitch in the network.
How can I handle this situation in the code. Is there some exception I can watch for and try to restart the FileSystemWatcher object.
Any suggestions and code samples would be appreciated.
I needed to add an error handler for the FileSystemWatcher
fileSystemWatcher.Error += new ErrorEventHandler(OnError);
And then add this code:
private void OnError(object source, ErrorEventArgs e)
{
if (e.GetException().GetType() == typeof(InternalBufferOverflowException))
{
txtResults.Text += "Error: File System Watcher internal buffer overflow at " + DateTime.Now + "\r\n";
}
else
{
txtResults.Text += "Error: Watched directory not accessible at " + DateTime.Now + "\r\n";
}
NotAccessibleError(fileSystemWatcher ,e);
}
Here is how I reset the SystemFileWatcher object:
static void NotAccessibleError(FileSystemWatcher source, ErrorEventArgs e)
{
source.EnableRaisingEvents = false;
int iMaxAttempts = 120;
int iTimeOut = 30000;
int i = 0;
while (source.EnableRaisingEvents == false && i < iMaxAttempts)
{
i += 1;
try
{
source.EnableRaisingEvents = true;
}
catch
{
source.EnableRaisingEvents = false;
System.Threading.Thread.Sleep(iTimeOut);
}
}
}
I think this code should do what I want it to do.
The previous answer does not fix it completely, I had to reset the watcher not just turn it on and off.
I use filesystemwatcher on a window service
void NotAccessibleError(FileSystemWatcher source, ErrorEventArgs e)
{
int iMaxAttempts = 120;
int iTimeOut = 30000;
int i = 0;
while ((!Directory.Exists(source.Path) || source.EnableRaisingEvents == false) && i < iMaxAttempts)
{
i += 1;
try
{
source.EnableRaisingEvents = false;
if (!Directory.Exists(source.Path))
{
MyEventLog.WriteEntry("Directory Inaccessible " + source.Path + " at " + DateTime.Now.ToString("HH:mm:ss"));
System.Threading.Thread.Sleep(iTimeOut);
}
else
{
// ReInitialize the Component
source.Dispose();
source = null;
source = new System.IO.FileSystemWatcher();
((System.ComponentModel.ISupportInitialize)(source)).BeginInit();
source.EnableRaisingEvents = true;
source.Filter = "*.tif";
source.Path = #"\\server\dir";
source.NotifyFilter = System.IO.NotifyFilters.FileName;
source.Created += new System.IO.FileSystemEventHandler(fswCatchImages_Changed);
source.Renamed += new System.IO.RenamedEventHandler(fswCatchImages_Renamed);
source.Error += new ErrorEventHandler(OnError);
((System.ComponentModel.ISupportInitialize)(source)).EndInit();
MyEventLog.WriteEntry("Try to Restart RaisingEvents Watcher at " + DateTime.Now.ToString("HH:mm:ss"));
}
}
catch (Exception error)
{
MyEventLog.WriteEntry("Error trying Restart Service " + error.StackTrace + " at " + DateTime.Now.ToString("HH:mm:ss"));
source.EnableRaisingEvents = false;
System.Threading.Thread.Sleep(iTimeOut);
}
}
}
You can create a method that initiates the FileSystemWatcher, and in case of an error, just restart it.
private void WatchFile()
{
try
{
fsw = new FileSystemWatcher(path, filter)
{
EnableRaisingEvents = true
};
fsw.Changed += Fsw_Changed;
fsw.Error += Fsw_Error;
}
catch (Exception e)
{
Console.WriteLine(e.Message);
}
}
private void Fsw_Error(object sender, ErrorEventArgs e)
{
Thread.Sleep(1000);
fsw.Changed -= Fsw_Changed;
fsw.Error -= Fsw_Error;
WatchFile();
}