title: C# - Waiting for a copy operation to complete
body: <p>I have a program that runs as a Windows Service which is processing files in a specific folder.</p>
  
  <p>Since it's a service, it constantly monitors a folder for new files that have been added. Part of the program's job is to perform comparisons of files in the target folder and flag non-matching files.</p>
  
  <p>What I would like to do is to detect a running copy operation and when it is completed, so that a file is not getting prematurely flagged if it's matching file has not been copied over to the target folder yet.  </p>
  
  <p>What I was thinking of doing was using the <code>FileSystemWatcher</code> to watch the target folder and see if a copy operation is occurring. If there is, I put my program's main thread to sleep until the copy operation has completed, then proceed to perform the operation on the folder like normal.</p>
  
  <p>I just wanted to get some insight on this approach and see if it is valid. If anyone else has any other unique approaches to this problem, it would be greatly appreciated.</p>
  
  <p>UPDATE:</p>
  
  <p>I apologize for the confusion, when I say target directory, I mean the source folder containing all the files I want to process.  A part of the function of my program is to copy the directory structure of the source directory to a destination directory and copy all valid files to that destination directory, preserving the directory structure of the original source directory, i.e. a user may copy folders containing files to the source directory.  I want to prevent errors by ensuring that if a new set of folders containing more subfolders and files is copied to the source directory for processing, my program will not start operating on the target directory until the copy process has completed.</p>