iowait

iowait -- Platform-independent module for I/O completion events

Different operating systems provide different ways to wait for I/O completion events: there's select(), poll(), epoll() and kqueue(). For cross-platform applications it can be a pain to support all this system functions, especially because each one provides a different interface.

IOWait solves this problem by providing a unified interface and using always the best and faster function available in the platform. Its only limitation is that, on Windows, it only works for sockets.

This library is compatible both with Python 2 and 3.

Example

Here is an usage example. First, we need to create a pair of sockets:

>>> import socket
>>> a, b = socket.socketpair()

Then we create a IOWait object. This object is essentially a wrapper around a system function (such as select() or poll()), but exposes always the same methods and behaves always the same.

>>> from iowait import IOWait
>>> waitobj = IOWait()

Now we can watch the first socket for read events in this way:

>>> waitobj.watch(a, read=True)

We send some data over the other socket:

>>> b.sendall('this is a test')

Calling wait() on the IOWait object will tell us that the socket a is ready to be read:

>>> events = waitobj.wait()
>>> events #doctest:+ELLIPSIS
[IOEvent(fileobj=<socket object, ...>, read=True, write=False)]

The return value of wait() is a list of three-tuples in the format: (file, read, write), where file is a file-like object, read and write tell respectively whether the file is ready to be read or written.

Once all the data has been read, the next call to wait() will block forever, unless a timeout is specified. The timeout can be zero:

>>> a.recv(14)
'this is a test'
>>> waitobj.wait(0)
[]

Documentation

The documentation is stored in the module's doc string. To read it, use the Python interactive interpreter:

>>> import iowait
>>> help(iowait) #doctest:+SKIP