Crochet is an MIT-licensed library that makes it easier to use Twisted
from regular blocking code. Some use cases include:
* Easily use Twisted from a blocking framework like Django or Flask.
* Write a library that provides a blocking API, but uses Twisted for
its implementation.
* Port blocking code to Twisted more easily, by keeping a backwards
compatibility layer.
* Allow normal Twisted programs that use threads to interact with
Twisted more cleanly from their threaded parts. For example this can
be useful when using Twisted as a WSGI container.
This is a bugfix release, recommended for all users of Crochet.
Crochet can be downloaded from https://pypi.python.org/pypi/crochet or
by running:
$ pip install crochet
Documentation can be found at http://crochet.readthedocs.org
<https://crochet.readthedocs.org/>
Bugs and feature requests should be filed at the project
https://github.com/itamarst/crochet
Here’s an example of a program using Crochet. Notice that you get a
completely blocking interface to Twisted and do not need to run the
Twisted reactor, the event loop, yourself.
#!/usr/bin/python
"""
Do a DNS lookup using Twisted's APIs.
"""
from __future__ import print_function
# The Twisted code we'll be using:
from twisted.names import client
from crochet import setup, wait_for
setup()
# Crochet layer, wrapping Twisted's DNS library in a blocking call.
@wait_for(timeout=5.0)
def gethostbyname(name):
"""Lookup the IP of a given hostname.
Unlike socket.gethostbyname() which can take an arbitrary amount of time
to finish, this function will raise crochet.TimeoutError if more than 5
seconds elapse without an answer being received.
"""
d = client.lookupAddress(name)
d.addCallback(lambda result: result[0][0].payload.dottedQuad())
return d
if __name__ == '__main__':
# Application code using the public API - notice it works in a normal
# blocking manner, with no event loop visible:
import sys
name = sys.argv[1]
ip = gethostbyname(name)
print(name, "->", ip)
Run on the command line:
$ python blockingdns.py twistedmatrix.com
twistedmatrix.com -> 66.35.39.66
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