How to handle threads in an eventhandler

[eddy147]

For Sharepoint 2003 (SP2) I wrote an eventhandler wich assigns an unique number to a document when the INSERT event fires.

To avoid locking exceptions, the code loops until the file is no longer locked. Otherwise the document doesnt get a number.

This works OK, until someone locks a file, because all the other threads are waiting (with different documents) for the thread with the locked file.

I thought the threading mechanism for eventhandlers is parallel, but clearly it works like a stack.



How to avoid this? Do I have to write threading code?

Here's a snippet from the code:



try

{

System.Security.Principal.WindowsImpersonationContext wic = null;

wic = System.Security.Principal.WindowsIdentity.GetCurrent().Impersonate();

string _uniqueField = ReadSetting("RefUniqueField");

using (SPSite _site = new SPSite(EventInfo.Site.Url))

{

using (SPWeb _web = _site.OpenWeb())

{

System.Int64 _uniqueId = this.GetUniqueId();

bool _error = true;

int _nrOfTries = 0;

while (_error && (_nrOfTries <= 1800) )

{

_error = false;

_nrOfTries++;

try

{

SPFile _file = _web.GetFile(EventInfo.UrlAfter);

_file = _web.GetFile(EventInfo.UrlAfter);

Debug("processing file " + _file.Name);

SPListItem _item = _file.Item;

_item[_uniqueField] = _uniqueId;

_item.Update();

}

catch (Exception e)

{

EventLog.WriteEntry(_source, e.Message + "\n" + e.StackTrace,EventLogEntryType.Error);

_error = true;

Thread.Sleep(1000);

}

}

}

wic.Undo();

}

}

catch (Exception e)

{

EventLog.WriteEntry(_source + " ", e.Message + "\n" + e.StackTrace, EventLogEntryType.Error);

}