How to monitor a directory for files in C++?

Question

I need to monitor a directory which contains many files and a process reads and deletes the .txt files from the directory; once all the .txt files are consumed, the consuming process needs to be killed. How do I check if all the .txt files are consumed using C++? I am developing my application on Visual Studio on windows platform.

Answer 1

To get callbacks of when the contents of the directory changed, use the ReadDirectoryChangesW and FindFirstChangeNotification Win32 API.

You can see examples from this question.

Answer 2

Use FindFirstChangeNotification to register a notification callback.

Answer 3

Since it was not required to perform action on each txt file deletion. I came up with following code:

{
  intptr_t hFile;
  struct _finddata_t c_file;
  string searchSpec;
  for (size_t i = 0; i < dataPathVec.size(); ++i)
  {
    searchSpec = dataPathVec.at(i) + DIRECTORY_SEPERATOR + "*" + TXT_FILE_EXT;
    hFile = 0;
    while((hFile != -1L) || (ret != 0))
    {
        hFile = _findfirst(searchSpec.c_str(), &c_file);
        Sleep(500);
        if (hFile != -1L)
        {
            ret = _findclose(hFile);
        }
    }
  }
}

It can monitor many folders and wait till all the txt files are deleted from all the monitored folders.