Use Twisted Anywhere!¶
Crochet is an MIT-licensed library that makes it easier for blocking and threaded applications like Flask or Django to use the Twisted networking framework.
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.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 ip = gethostbyname(name) print(name, "->", ip)
Run on the command line:
$ python blockingdns.py twistedmatrix.com twistedmatrix.com -> 126.96.36.199
Table of Contents¶
- The API
- Best Practices
- Known Issues and Workarounds
- What’s New