csharp active log parsing question

[takeru]

trying to find some examples on parsing active (constantly updating) log files. there are a lot of examples on parsing static text files yeah, but none that i can find that shows how to parse active log files (which can grow fairly large too). anyone have links to some examples?

 

[Merad]

Haven't tried it, but the File class has a method to see when the last write happened, and FileStream lets you get and set the read position within the file. Rough pseudo code for what should work:

lastReadTime = File.GetCreationTime
lastReadPos = 0

while program is running {
  if File.GetLastWriteTime is newer than lastReadTime {
    open file
    FileStream.Position = lastReadPos
    read to end of file and store in buffer
    lastReadPost = FileStream.Position
    lastReadTime = now
    close file
  }

  do things with the data in the buffer
}

 

[ejjpi]

This is how you do it:

Stream stream = File.Open(@"c:\mylog.log", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);             
StreamReader streamReader = new StreamReader(stream);             
string str = streamReader.ReadToEnd();

In this way you'll avoid the error "The process cannot access the file xxxxx because it is being used by another process"

If you're parsing huge log files use the BufferedStream for better performance (http://msdn.microsoft.com/en-us/library/system.io.bufferedstream%28v=vs.110%29.aspx)

If you want to make only incremental reads just save somewhere the last read line and start from there the next time.