Is it possible to dedicate a mutex to a specific name ?

[eran otzar]

hello,
on my server iv'e got an xml file for each client witch holds the packets witch the client had not received.

i need to access multiple client files on a server side ,this happens from multiple background threads

i'm looking for a way to create mutual Exclusion an a specific file

for example lets say iv'e got tow clients john and tom
and the method running in the background (_AppendToUnsen t)

now lets say john as 2 packets to append ,and tom as 3

2 threads would be dispatched for john and three for tom

i don't want to block a thread writing to tom.xml because a different thread is writing to john.xml

i would how ever want to block a second thread trying to access john.xml while a different one is already writing to the file

private static void _AppendToUnSent (object obj)
{
append_packets_ mutex.WaitOne() ; // this will block all threads no matter if the writing to the same file or not
// holds the name and the packet
KeyValuePair<St ring, byte[]> _pair = (KeyValuePair<S tring, byte[]>)obj;

XmlDocument _doc = new XmlDocument();
// build the path of the file
StringBuilder _builder = new StringBuilder() ;
_builder.Append (_path);
_builder.Append (_pair.Key);
_builder.Append (".xml");
if (!File.Exists(_ builder.ToStrin g()))
{ // if the file dosent exist create it
XmlDeclaration xmlDeclaration = _doc.CreateXmlD eclaration("1.0 ", "utf-8", null);
XmlElement rootNode = _doc.CreateElem ent(_pair.Value .ToString());
_doc.InsertBefo re(xmlDeclarati on, _doc.DocumentEl ement);
_doc.AppendChil d(rootNode);
XmlElement _packets_node = _doc.CreateElem ent("Packets");
rootNode.Append Child(_packets_ node);

_doc.Save(_buil der.ToString()) ;
}

try
{
_doc.Load(_buil der.ToString()) ;
}
catch (Exception es)
{
Console.WriteLi ne("Could Not save packet for " + _pair.Key);
return;
}
// create and save a new <Packet> Node
XmlNode declarition_nod e = _doc.FirstChild ;// <Xml......>
XmlNode packets_node = declarition_nod e.NextSibling;// <Messages>

XmlElement _packet_node = _doc.CreateElem ent("Packet");// <Packet>

_packet_node.In nerText = Convert.ToBase6 4String(_pair.V alue);//43rg43g43yt42g. ... // Encode to base64
_packet_node.Ap pendChild(_pack et_node);// <Packet>43rg43g 43yt42g....</Packet>
try
{
_doc.Save(_buil der.ToString()) ;
}
catch (Exception es)
{
Console.WriteLi ne("Could Not save packet from " + _pair.Key);
}
append_packets_ mutex.ReleaseMu tex(); // realese the genrel mutex for this operaition

} // end _AppendToUnsent e here

[Leito]

First, paste your code into [ code ] tags, it helps the reader.

For your problem, I think you should use a switch{ case: } loop, and have a different process depending on the file you have to treat.
For example:

private static void _AppendToUnSent(object obj){
    switch (file_name ){
        case "john.xml":
            append_packets_mutex_john.WaitOne();
        case "tom.xml":
            append_packets_mutex_tom.WaitOne();
    }
}