Shared textfile...threading

[MobileBoy36]

Hi All,

I want to make a LogFile class that is thread safe. I use a Mutex for it.
But the behavior of the class is not that normal.
In a c# guide I read you can achieve it by simply using Mutex.Waitone and
Mutex.ReleaseMutex. Is that right?
What 's wrong with my sub Writelog then?

Best regards,
Mobileboy



Public Class LogFile


Private _LogFile As String
Private _LoggingLevel As Integer = 99

Private Shared _Mutex As System.Threading.Mutex


Public Sub New(ByVal Logfile As String, ByVal LoggingLevel As
Integer)
_LogFile = Logfile
_LoggingLevel = LoggingLevel
If _Mutex Is Nothing Then
_Mutex = New System.Threading.Mutex
End If
End Sub

Public Sub WriteLog(ByVal Text As String, Optional ByVal
LoggingLevelFromThisLogging As Integer = 99)
Dim fsOut As System.IO.FileStream
Dim MyStreamWriter As System.IO.StreamWriter
Dim Datum As DateTime
Dim strDatum As String

_Mutex.WaitOne() ' Waitone wacht tot wanneer hij de mutex kan
verwerven, zolang een ander proces hem niet heeft vrij gegeven

If (_LoggingLevel >= LoggingLevelFromThisLogging) Or
(LoggingLevelFromThisLogging = 99) Then
' tein meegde loggen
Datum = New DateTime
Datum = Now
If System.IO.File.Exists(_LogFile) Then
fsOut = New System.IO.FileStream(_LogFile,
System.IO.FileMode.Append)
Else
fsOut = New System.IO.FileStream(_LogFile,
System.IO.FileMode.Create)
End If
MyStreamWriter = New System.IO.StreamWriter(fsOut)
strDatum = Lzero(CStr(Datum.Day), 2) & "-" & _
Lzero(CStr(Datum.Month), 2) & "-" & _
CStr(Datum.Year) & " " & _
Lzero(CStr(Datum.Hour), 2) & ":" & _
Lzero(CStr(Datum.Minute), 2) & ":" & _
Lzero(CStr(Datum.Second), 2) & " : "
Text = strDatum & Text
Text = FilterText(Text)
MyStreamWriter.WriteLine(Text)
MyStreamWriter.Flush()
MyStreamWriter.Close()
fsOut.Close()
End If
_Mutex.ReleaseMutex() ' De mutex weer vrijgegven, maw aangeven
dat er geen andere thread meer mee bezig is
End Sub

 

[Robinson]

Synclock:



Private m_LockingObject as New String = "My Lock"



Public Sub WriteLog

SyncLock ( m_LockingObject )

.... do stuff

End SyncLock

End Sub


If there are other methods using the log, then wrap those using the same
locking object as well.

 

[Andrew Backer]

Before you go writing something complex, is there a good reason not to
use something like log4net (http://logging.apache.org/log4net/)
instead? It much easier than ms's logging solution, and is safe in
every way you could want.

//Andrew

 

[MobileBoy36]

Hi,

Thanks for the answers.
yes I can use a framework for it. But for this case I prefer to use my own
class. I want to know what I am doing wrong.

I know the the existense of synclock.
Using synclock the way you described it seems not to work ( error on lin:
fsOut = New System.IO.FileStream(_LogFile,System.IO.FileMode.Append)

best regards

 

[MobileBoy36]

No example of a tested and thread safe sub textfilewriter??

best regards,
Mobile boy

 

[Andrew Backer]

Well, if it's really got yer goat I think you could just look at the
source code for log4net?

I always thought that the mutexs = synclock essentially, but here is
some extra locking documentation :
http://everything2.com/index.pl?node_id=1833821&lastnode_id=0

And please post at least some error message. I am not sure you are
actually trying to get help when you just say "it breaks". Please post
some actual error information if you want help debugging.

//Andrew

 

[Herfried K. Wagner [MVP]]

Private m_LockingObject as New String = "My Lock"

I'd use 'Private m_Lock As New Object()'.