Need program to poll directory and run CLI on new files

Hello, can somebody please refer me to a windows program (preferably free) that will poll a directory every 30 seconds or so and whenever a new file appears it will run a command line for that file?

It would need the following features:

- Specify which extensions to trigger the command line execution.
- Recursive ability so that files in sub-folders will work as well.
- Ability to detect when the file is unlocked. For example a file may be created but is locked because it is still being created. Therefore it should be able to wait until the file is unlocked, and finished being created, before it runs the command line program.

Anything out there to do this? Thanks!