File concurrent file access

Hi ! I'm developing my new website and I'm worried about concurrent file access. In fact, I want to suppress a maximum database interactions so I keep information in files with faster I/O than databases. But I'm worried by the fact that an error can occur when someone try to access a file being edited by a cron task. Does PHP do all the stuff itself or is there something to do about it ? PS: I only use file_get_contents, file_put_contentsand unlink on files. Best regards. Florian