How do you want to save the info? MySfQL? Text file?
Also, your httpd log should contain access information, you may not even want this function to be coded, but configured by your server. I think by defaul the second to last number in the apache log indicates what happened to the file, 200 or 300 or something is a simple access and the number following is the by bytes transfered. You can parse the log file for successfull accesses to your file with the full amount of bytes transfered.