PyKQueue

IMPORTANT -- PLEASE READ

I no longer maintain this software or the associated FreeBSD port (devel/py-kqueue).  Work is going on to locate a new maintainer and update the software to work with current Python versions.  Please don't email me asking to take over maintainership or offer updates, I've had plenty enough, thanks :-) 

I will update this page when the maintainership change is official.

What is PyKQueue?

PyKQueue is a Python module that provides an object-oriented interface to the FreeBSD syscalls kqueue(2) and kevent(2).

The kqueue system provides a more robust and less compute-intensive way to monitor system and file events. Instead of slinging huge arrays as needed with select(2), kevent(2) takes a list of KEvents to monitor, and keeps watching them until they're explicitly deleted -- no need to keep passing in the same objects over and over again. This methodology promotes the construction of large asynchronous frameworks, such as the one used in the asyncore Python module.

Where can I get PyKQueue?

The current version is 1.2, available at

ftp://ftp.freebsd.org/pub/FreeBSD/ports/local-distfiles/dwhite/

How do I use PyKQueue?

PyKQueue provides fairly direct access to the kqueue and kevent calls, so reading the kqueue(2) and kevent(2) manpages is a must.

You will want to import all the symbols from the KQueue module to make accessing the functions easier: use 'from KQueue import *' in the beginning of your Python program.

The available constructors are:

• KQueue() -- Creates a new kernel queue and returns an integer describing it.
  Example use:
  kq = KQueue()
• KEvent(ident, filter=EVFILT_READ, flags=EV_ADD, fflags=None, data=None, udata=None) -- Creates a new KEvent object, which tracks events on a particular object. Ident is usually a file descriptor but can be any object supported by kevent(2).
  Example use:
  kev = KEvent(file.fileno()) # Create a KEvent that triggers when the file object file is ready for reading


The available methods of a KQueue are:

• event(kevs, wantEvents, timeout): Wait for an event to trigger, adding the list of KEvents in kevs to the set of filters. Retrieve up to wantEvents events and wait up to timeout milliseconds for an event to show up. Triggered events are returned as a list of KEvents; if the timeout expires, an empty list is returned. Filters that detect an error will return a KEvent with the EV_ERROR flag set. kevs should be an empty list if there are no changes to the event watch list.

What if I have suggestions or improvements for PyKQueue?

Please email them to dwhite@freebsd.org.