System.IO.FileSystemWatcher

[John Talli]

System.IO.FileSystemWatcher

When a user copies and pastes a file from one directory to a directory that is monitored
by the FileSystemWatcher, the FileSystemWatcher executes twice, once for a CREATED file
event and once for a CHANGED file event.

I think I understand why. First the monitored file is created and then contents are
inserted into it. (Although the file datetime remains the same.)

This is not what I require. If there is a new file created in a monitored directoy, I
only want TRUELY CREATED event raised, not the default of CREATED event raised & CHANGED
event raised.

Is there anyway I can turn-off the second event (CHANGED event raise) ?

Thanks

 

[Nicolas]

Hi this is a bug from Microsoft in this Obj

''' <remarks>Implementing a trick to stop double call from the onChange
FileSystemWatcher event bug</remarks>
Protected Sub OnChanged(ByVal source As Object, ByVal e As
FileSystemEventArgs)
Try

If lastChange <>
TimeSpan.FromTicks(Now.Ticks).TotalMilliseconds Then
'DO YOUR STUFF HERE
End If

lastChange =
TimeSpan.FromTicks(Now.Ticks).TotalMilliseconds

Catch ex As Exception
errorHandler(ex, Me.GetType.ToString & ".onChanged")

Finally
End Try

End Sub

Hope this help

Nicolas

 

[John Talli]

Thanks!!! I'll play with this and let everyone know the outcome. This double call is
an interesting feature from MS.

 

[John Talli]

Thanks again Nicolas.

It does appear MS is logging multiple events for a file copy. (ugh) Nicolas's
workaround of utilizing TimeSpan.FromTicks(Now.Ticks).TotalMilliseconds is wonderful
when monitoring a single directory. ( watchfolder.IncludeSubdirectories = False ).

But another problem popped-up when setting :
watchfolder.IncludeSubdirectories = True

Example of the "another" problem :
Folder Setup
C:\temp\FSW
C:\temp\FSW\FSW2

watchfolder.Path = "C:\temp\FSW"
watchfolder.IncludeSubdirectories = True


Now I copy & pasted a file into "C:\temp\FSW\FSW2" called "testDoc1.txt"
I would have expected Nicolas's solution to also work here. But no, MS has another
surprise in store.

The output of my log file shows:
#1 File C:\temp\FSW\FSW2\testDoc1.txt has been created by SYSTEM from OWNER-PC
#2 File C:\temp\FSW\FSW2 has been changed by SYSTEM from OWNER-PC
#3 File C:\temp\FSW\FSW2\testDoc1.txt has been changed by SYSTEM from OWNER-PC

Notice MS's surprise of #2. It is telling us that that the "Folder" has been modified
before continuing with #3.

If watchfolder.IncludeSubdirectories = False
the order is:
#1 File C:\temp\FSW\FSW2\testDoc1.txt has been created by SYSTEM from OWNER-PC
#2 File C:\temp\FSW\FSW2\testDoc1.txt has been changed by SYSTEM from OWNER-PC

The solution to watchfolder.IncludeSubdirectories = True
is to monitor for #2 File C:\temp\FSW\FSW2 has been changed by SYSTEM from OWNER-PC
which means a FOLDER was changed and just skip any processing for that.

To do this I had to increase the difference (CurrentTime - PreviousTime)
in Milliseconds = 400 to Milliseconds = 800.