Re: Problem with negative number - C# Discussion Boards

14-Aug-07 1:19

Hello everyone,

I have a problem with one application which should run permanently to transfer some output from a serial port to a database. This application crashes about every 17 hours once which should not happen because of loosing data when the application is not running.

I located the error in this code:

if (tmp.Length > 0) {<br />
                        while (_conn.State != ConnectionState.Open) {<br />
                            _conn.Open();<br />
                            Thread.Sleep(100);<br />
                        }<br />
                        cmd.Connection = _conn;<br />
                        cmd.ExecuteNonQuery();<br />
                    }

* tmp is a string which contains the edited output of the serial port.
* _conn is an MySQL-Connection made through the MySQL-.NET-Connector 5.0
* cmd is a simple INSERT-Command (MySQLCommand)

So in this context i got the following error:

<br />
exception.source == mscorlib<br />
<br />
exception.message == Non-negative number required.\nParameter name: count<br />

My problem is: I cant see any parameter named count where the exception can happen. Might it be that the MySQL-Connector itself causes that exception? If this is the reason i'll try to rewrite the code for an ODBC-Connection.

I hope i provided all needed information to pass a hint to me.

With best regards,
K. Ahlers

plastio14-Aug-07 1:37

plastio

14-Aug-07 1:37

You haven't posted the query that you are executing towards the DB
anyway try to set on nocount in the query string

Just
Set NOCOUNT ON
and at the end
SET NOCOUNT OFF

maybe it will help
I am not sure
by the way you can use a
DB profiler to check whether your problem emerges from the DB layer

K. Ahlers14-Aug-07 1:40

14-Aug-07 1:40

My query is as I said a simple insert:

string now = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");<br />
MySqlCommand cmd = new MySqlCommand("INSERT INTO log (datelogged, logentry) VALUES ('" + now + "', '" + tmp + "')");

tmp is here equal to the tmp in my first posting a string from the serial output.

The table is a InnoDB table with the fields id(INT), datelogged(DATETIME), logentry(VARCHAR(200)

With best regards,
K. Ahlers

Luc Pattyn14-Aug-07 1:42

14-Aug-07 1:42

Hi,

"parameter named count" refers to a method that has count in it's documentation
(actually its reflected parm list); it does not refer to one of your app's
variables named count. Yhere are many candidates including:

public int SerialPort.Read (
byte[] buffer,
int offset,
int count
)

some suggestions:

- look at the entire exception, that is use exception.ToString(), it will
show all available information including line numbers, message details, and
inner exceptions if any
- have Visual show line numbers (see my sig)
- put a try-catch and have it show all relevant variables when it catches this
or some other exception, including cmd, tmp, ...

and ideas:

- a 16-bit number counting seconds would overflow after 18.2 hours
- you might have a memory leak (or a disk full; logging?) resulting in a
systematic failure; if exceptions are not handled correctly, that might
result in just about any symptom

final comment:
if all the above dont help, show us all available info and some complete methods.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

this weeks tips:
- make Visual display line numbers: Tools/Options/TextEditor/...
- show exceptions with ToString() to see all information
- before you ask a question here, search CodeProject, then Google

K. Ahlers14-Aug-07 1:45

14-Aug-07 1:45

Okay. I added the .ToString() but we have to wait for the next crash to execute...

With best regards,
K. Ahlers

J4amieC14-Aug-07 3:24

J4amieC

14-Aug-07 3:24

[quote]make Visual display line numbers: Tools/Options/TextEditor/..[/quote]

Thanks for that... i gave up looking last time I tried.

ps. Another quality response. Out of interest, where are you from Luc?

---

How to get answers to your questions[^]

Luc Pattyn14-Aug-07 6:06

14-Aug-07 6:06

Hi,

J4amieC wrote:
make Visual display line numbers: Tools/Options/TextEditor/...

it is a shame Microsoft did not turn that on by default; posters ignore line numnbers
in exceptions since they don't show in source files anyway, making them look for
problems everywhere except where they really are.

J4amieC wrote:
where are you from

Belgium, a little south of where you are Laugh | :laugh:

See profile page.

Luc Pattyn [Forum Guidelines] [My Articles]

K. Ahlers14-Aug-07 10:57

14-Aug-07 10:57

Okay NOW i have a complete error-message:

System.ArgumentOutOfRangeException: Non-negative number required.<br />
Parameter name: count<br />
   at System.IO.BufferedStream.Read(Byte[] array, Int32 offset, Int32 count)<br />
   at MySql.Data.MySqlClient.MySqlStream.Read(Byte[] buffer, Int32 offset, Int32 count)<br />
   at MySql.Data.MySqlClient.MySqlStream.ReadString(Int64 length)<br />
   at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData41()<br />
   at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData()<br />
   at MySql.Data.MySqlClient.NativeDriver.ReadColumnMetadata(Int32 count)<br />
   at MySql.Data.MySqlClient.MySqlDataReader.NextResult()<br />
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)<br />
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()<br />
   at Cisco2Mysql.Form1.serialPort1_DataReceived(Object sender, SerialDataReceivedEventArgs e)<br />

So it seems to be really a buggy .NET-Connector or can anyone there a mistake by me?

With best regards,
K. Ahlers

Luc Pattyn14-Aug-07 13:31

14-Aug-07 13:31

OK, seems the problem is in your serialPort1_DataReceived method.
Will you find it yourself, or do you plan on showing us the entire method's source code ?

For some reason, we did not get line numbers. Is this release code ?

And this seemed like an 9-hour run, not a 17-hour one ?

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

K. Ahlers14-Aug-07 23:14

14-Aug-07 23:14

Good morning Luc,

here is the complete method:

        private void serialPort1_DataReceived(object sender, System.IO.Ports.SerialDataReceivedEventArgs e) {<br />
            try {<br />
                // Read out existing chars into _buffer<br />
                _buffer += serialPort1.ReadExisting();<br />
<br />
                // If there is a complete line availiable process it<br />
                int posofbreak = _buffer.IndexOf('\n');<br />
                if (posofbreak > -1) {<br />
                    // Get the line<br />
                    string tmp = _buffer.Substring(0, posofbreak).Trim();<br />
<br />
                    // If there is more code than this line put it back into the buffer<br />
                    if (posofbreak < _buffer.Length - 1)<br />
                        _buffer = _buffer.Substring(posofbreak + 1);<br />
<br />
                    // If there is a command-prompt before the log-text remove it<br />
                    while (tmp.IndexOf('>') > -1)<br />
                        tmp = tmp.Substring(tmp.IndexOf('>') + 1).Trim();<br />
<br />
                    // Get a database-readable date<br />
                    string now = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");<br />
<br />
                    // Create insert-command for the database<br />
                    MySqlCommand cmd = new MySqlCommand("INSERT INTO cisco_log (datelogged, logentry) VALUES ('" + now + "', '" + tmp + "')");<br />
<br />
                    // If the textbox with every logoutput is too long shorten it<br />
                    if(box.Text.Length > 5000) <br />
                        box.Text = box.Text.Substring(0, 5000);<br />
<br />
                    // Add the new line before the old logtext<br />
                    box.Text = tmp + "\r\n" + box.Text;<br />
<br />
                    // If there is a call with both lines connected free one line for that call<br />
                    if (tmp.Contains("L11  0")) {<br />
                        serialPort1.WriteLine("CD EWE");<br />
                        serialPort1.WriteLine("DISCO 2");<br />
                        LogWrite("Call detected, disconnecting second line.");<br />
                    }<br />
<br />
                    // If there is a line error reconnect the line<br />
                    if (tmp.Contains("L67  2")) {<br />
                        Thread.Sleep(2000);<br />
                        serialPort1.WriteLine("CD EWE");<br />
                        serialPort1.WriteLine("CALL 2");<br />
                        LogWrite("Line Integrity Violation detected, reconnecting second line.");<br />
                    }<br />
<br />
                    // Check whether the second line is connected, if not connect it and execute the insert-command<br />
                    if (tmp.Length > 0) {<br />
                        while (_conn.State != ConnectionState.Open) {<br />
                            _conn.Open();<br />
                            Thread.Sleep(100);<br />
                        }<br />
                        cmd.Connection = _conn;<br />
                        // MARKER<br />
                        cmd.ExecuteNonQuery();<br />
                    }<br />
<br />
                }<br />
<br />
                // Write the content of _buffer to a textbox for debug view<br />
                buff.Text = _buffer;<br />
            }<br />
            catch (Exception ex) {<br />
                LogWrite("Exception at serialPort1_DataReceived: "+ex.ToString());<br />
            }<br />
        }

After the "MARKER" the exception is thrown. (Yes it is a release-binary)

With best regards,
K. Ahlers

Luc Pattyn15-Aug-07 2:43

15-Aug-07 2:43

Hi,

I looked at your code and have some comments:

1.
you did not follow my advice "put a try-catch and have it show all relevant variables
when it catches this or some other exception, including cmd, tmp, ..."

2.
I don't see why you have the test in
if(posofbreak < _buffer.Length - 1) _buffer = _buffer.Substring(posofbreak + 1);

With it, if _buffer contains just one line ending on \n, that line remains in
_buffer and will be processed again next time DataReceived fires.

3.
while(tmp.IndexOf('>') > -1) tmp = tmp.Substring(tmp.IndexOf('>') + 1).Trim();
could have been handled more elegantly with ListIndexOf

4.
I am not sure the Thread.Sleeps, especially the one with 2000, are a good idea
inside DataReceived; they make your code not react for 2 seconds on the next
data; if for some reason "L67 2\n" comes in every second, you will never
catch up.

5.
I don't know what value serialport1.ReceivedBytesThreshold has; if it is
much larger than 1, chances are you receive more than one line of text every
time, but you only process one line at a time.
Actually, there should have been a while loop: as long as entire lines are
available, process it.

6.
if buffer contains only one line of the form
sometext > \n
then tmp will be an empty string; not sure SQL will like that

I strongly suggest you follow my advice (see 1); I don't understand how you
did not do this from the beginning: when something goes wrong, the more information
you have about it, the easier it is to pinpoint the problem...

Hope this helps.

Luc Pattyn [Forum Guidelines] [My Articles]

K. Ahlers15-Aug-07 3:29

15-Aug-07 3:29

1) How can I do that? In the try-catch these variables are not longer availiable. How to access them without declaring them global? Or did you mean to define a try-catch inside my existing try-catch?

2) Solved.

4) It must sleep about 2 seconds because the router have to clean up the line before reconnecting. This error can appear only if the line is connected - so not multiple times before reconnecting.

5) Solved.

6) If tmp.lenght is not greater than 0 the SQL-Command will not be executed.

With best regards,
K. Ahlers

Luc Pattyn15-Aug-07 3:57

15-Aug-07 3:57

Hi
1.
declare and initialize the var before the try statement (or as a class
member, see _buffer)

6.
sorry, my mistake

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

K. Ahlers17-Aug-07 0:35

17-Aug-07 0:35

Okay - This time it took really long to the next crash.

So I cant find any timing in there.

Here is the debug-output:

<br />
Content of tmp: """Connection 2 Add     Link 2 Channel 2"""<br />
MySQL-Command: """INSERT INTO cisco_log (datelogged, logentry) VALUES ('2007-08-17 11:47:38', 'Connection 2 Add  Link 2 Channel 2')"""<br />
Buffer-Content: """CISCO:EWE> """<br />
PosOfBreak: 50<br />
<br />
Exception: System.ArgumentOutOfRangeException: Non-negative number required.<br />
Parameter name: count<br />
   at System.IO.BufferedStream.Read(Byte[] array, Int32 offset, Int32 count)<br />
   at MySql.Data.MySqlClient.MySqlStream.Read(Byte[] buffer, Int32 offset, Int32 count)<br />
   at MySql.Data.MySqlClient.MySqlStream.ReadString(Int64 length)<br />
   at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData41()<br />
   at MySql.Data.MySqlClient.NativeDriver.GetFieldMetaData()<br />
   at MySql.Data.MySqlClient.NativeDriver.ReadColumnMetadata(Int32 count)<br />
   at MySql.Data.MySqlClient.MySqlDataReader.NextResult()<br />
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)<br />
   at MySql.Data.MySqlClient.MySqlCommand.ExecuteNonQuery()<br />
   at Cisco2Mysql.Form1.serialPort1_DataReceived(Object sender, SerialDataReceivedEventArgs e)<br />

The only constant in there is the exception. Every time it's raised by the ExecuteNonQuery()-method.

I do not have any idea why this happens - so if you can help me it would be fine. If you don't have any idea too i'll have to try the ODBC-connector. Might be that it will not crash with this error...

With best regards,
K. Ahlers

Luc Pattyn17-Aug-07 5:43