title: Non-blocking file access with Twisted
body: <p>I'm trying to figure out if there is a defacto pattern for file access using twisted. Lots of examples I've looked at (twisted.python.log, twisted.persisted.dirdbm, twisted.web.static) actually don't seem to worry about blocking for file access. </p>
  
  <p>It seems like there should be some obvious interface, probably inheriting from abstract.FileDescriptor, that all file access should be going through it as a producer/consumer.</p>
  
  <p>Have I missed something or is it just that the primary use for twisted in asynchronous programming is for networking and it hasn't really been worked out for other file descriptor operations, not worrying about the purity of non-blocking IO ?</p>