If you are opening the file (using e.g. Notepad) while the logger does not
have the file open, it's going to take an exclusive lock on the file (it
assumes you will be writing the file). Your file open will then fail as
noted.
What you need to do is one of two things:
1. On program startup, open the file for exclusive write access (
FileShare.Read) and keep it open until program shutdown (or until logging is
no longer necessary). This will allow you to read the file in another
program without interfering with the logging.
2. Do just as you're doing now, but if you get the System.IO.Exception,
queue up log events and retry the operation periodically until it succeeds,
then write all pending operations to the file. This is probably more complex
and more likely to introduce bugs than (1).
On 2/5/06, Alex Smotritsky <[EMAIL PROTECTED]> wrote:
>
> I'm working on some code to do some asynchronous logging to a text file.
> If
> I open the file (manually) while it's being written to I get a
> System.IO.Exception with the message "The process cannot access the file
> (the path) because it is being used by another process. This happens
> consistently with debug builds and much less with release builds.
>
>
>
> The file io I'm doing is not asynchronous, I say the logging is
> asynchronous
> because I fire an event which a logging function subscribes to.
>
>
>
> I think I should be able to write to a file and not have an exception
> generated when I manually open that file during some write operations but
> I
> haven't figured out how to do that yet. TIA
>
>
>
> Here's the code (running against 1.0 of the framework):
>
>
>
> using System;
>
> using System.IO;
>
>
>
> namespace AsyncLog3
>
> {
>
> class Class1
>
> {
>
> private static object syncObject = new object();
>
> private static int lineNum = 0;
>
>
>
> private delegate void MyDelegate(object sender, DenaliArgs
> args);
>
> private static event MyDelegate MyEvent;
>
>
>
> static void Main()
>
> {
>
> MyEvent += new MyDelegate(WriteLog);
>
>
>
> if (MyEvent != null)
>
> {
>
> object sender = new object();
>
> for (int i=0; i<1000000; i++)
>
> MyEvent(sender, new DenaliArgs("Hello,
> World"));
>
> }
>
> }
>
>
>
> private static void WriteLog(object sender, DenaliArgs args)
>
> {
>
> string fileName = "MyLog.txt";
>
> lock (syncObject)
>
> {
>
> using (FileStream fileStream = new
> FileStream(fileName, FileMode.Append, FileAccess.Write,
> FileShare.ReadWrite)) // System.IO.Exception in debug build
>
> {
> // System.IO.Exception in release, points to disassembly, less frequent
>
> using (StreamWriter writer = new
> StreamWriter(fileStream))
>
> {
>
> writer.WriteLine("{0}: {1}",
> ++lineNum,
> args.Str);
>
> Console.WriteLine("{0}: {1}",
> ++lineNum,
> args.Str);
>
> writer.Flush();
>
> }
>
> }
>
> }
>
> }
>
> }
>
> }
>
>
>
>
>
>
>
>
>
>
>
>
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--
Eric Means
[EMAIL PROTECTED]
http://www.randomtree.org/eric/
===================================
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