eventlet/eventlet/twistedutil/__init__.py

   1 from eventlet.hubs import get_hub
   2 from eventlet import spawn, getcurrent
   3
   4 def block_on(deferred):
   5     cur = [getcurrent()]
   6     synchronous = []
   7     def cb(value):
   8         if cur:
   9             if getcurrent() is cur[0]:
  10                 synchronous.append((value, None))
  11             else:
  12                 cur[0].switch(value)
  13         return value
  14     def eb(fail):
  15         if cur:
  16             if getcurrent() is cur[0]:
  17                 synchronous.append((None, fail))
  18             else:
  19                 fail.throwExceptionIntoGenerator(cur[0])
  20     deferred.addCallbacks(cb, eb)
  21     if synchronous:
  22         result, fail = synchronous[0]
  23         if fail is not None:
  24             fail.raiseException()
  25         return result
  26     try:
  27         return get_hub().switch()
  28     finally:
  29         del cur[0]
  30
  31 def _putResultInDeferred(deferred, f, args, kwargs):
  32     try:
  33         result = f(*args, **kwargs)
  34     except:
  35         from twisted.python import failure
  36         f = failure.Failure()
  37         deferred.errback(f)
  38     else:
  39         deferred.callback(result)
  40
  41 def deferToGreenThread(func, *args, **kwargs):
  42     from twisted.internet import defer
  43     d = defer.Deferred()
  44     spawn(_putResultInDeferred, d, func, args, kwargs)
  45     return d
  46
  47 def callInGreenThread(func, *args, **kwargs):
  48     return spawn(func, *args, **kwargs)
  49
  50
  51 if __name__=='__main__':
  52     import sys
  53     try:
  54         num = int(sys.argv[1])
  55     except:
  56         sys.exit('Supply number of test as an argument, 0, 1, 2 or 3')
  57     from twisted.internet import reactor
  58     def test():
  59         print(block_on(reactor.resolver.getHostByName('www.google.com')))
  60         print(block_on(reactor.resolver.getHostByName('###')))
  61     if num==0:
  62         test()
  63     elif num==1:
  64         spawn(test)
  65         from eventlet.api import sleep
  66         print('sleeping..')
  67         sleep(5)
  68         print('done sleeping..')
  69     elif num==2:
  70         from eventlet.twistedutil import join_reactor
  71         spawn(test)
  72         reactor.run()
  73     elif num==3:
  74         from eventlet.twistedutil import join_reactor
  75         print("fails because it's impossible to use block_on from the mainloop")
  76         reactor.callLater(0, test)
  77         reactor.run()
  78