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pythonqtpyqtqthreadlibtorrent

How to use QThreads with libtorrent in PyQt?


I want to write some simple PyQt torrent client, but I've got some snag with that. I would like to run some loop which takes care of downloading files (simple code using libtorrent) in a PyQt code. Although, when the torrent downloading works, the UI doesn't show up and when I change the order of called functions, the UI shows but downloading doesn't work. I read about QThreads but it's a bit hard for me - could anyone explain how does QThread work and how to use it with libtorrent? Here's some example of torrent client code:

import libtorrent as lt
import time
import sys

ses = lt.session()
ses.listen_on(6881, 6891)

info = lt.torrent_info(sys.argv[1])
h = ses.add_torrent({'ti': info, 'save_path': './'})
print 'starting', h.name()

while (not h.is_seed()):
   s = h.status()

   state_str = ['queued', 'checking', 'downloading metadata', \
      'downloading', 'finished', 'seeding', 'allocating', 'checking fastresume']
   print '\r%.2f%% complete (down: %.1f kb/s up: %.1f kB/s peers: %d) %s' % \
      (s.progress * 100, s.download_rate / 1000, s.upload_rate / 1000, \
      s.num_peers, state_str[s.state]),
   sys.stdout.flush()

   time.sleep(1)

print h.name(), 'complete'

Solution

  • I would imagine QT runs a message loop that doesn't return until the application is terminated.

    What I believe you want to do is to move the loop body (that polls the libtorrent status) into a message handler that's called regularly by QT. Say, a timer function.