Question

I wrote a Rhythmbox plugin and I’m trying to add some code to download some JSON asynchronously. Callbacks are registered in the do_activate function:

def do_activate(self):
    shell = self.object
    sp = shell.props.shell_player
    self.db = shell.get_property('db')
    self.qm = RB.RhythmDBQueryModel.new_empty(self.db)
    self.pec_id = sp.connect('playing-song-changed', self.playing_entry_changed)
    self.pc_id = sp.connect('playing-changed', self.playing_changed)
    self.sc_id = sp.connect('playing-source-changed', self.source_changed)
    self.current_entry = None

    ...

I’m trying to download some content when playing_changed is triggered. It currently uses urllib2 to download the content synchronously, but this has the potential to block the UI for a short while. I’d like to use Twisted to solve the problem, but all the examples I’ve seen use reactor.run(), which blocks indefinitely.

I’m pretty new to Twisted and I was wondering, is there some way to handle this case asynchronously without blocking the main thread?

The full code is here

Answer 1

There isn’t any way in twisted to do asynchronous http requests without running IO-loop (reactor.run). Running reactor enables you to use async features not present in python by default. However if your only reason to use twisted is to make async http calls it might be an overkill. Use simple threading instead and make your thread wait for http response.