Concurrency

We got Both Kinds

I/O Bound
Compute Bound

Waiting For Answers

Just Wait... wasn't doing nothin' anyway
Spawn Process
Spawn Thread
Non-blocking calls and "a plan"

Non-Blocking Calls

   1 O.registerCallback(fn, *args, **kargs) # fn can be function or method
   2 
   3 def fn(result, *args, **kargs)
   4   print "important message: ", result

Use Deferreds

   1 d = O.doComplicatedLengthyCalc(a, b, c) # returns deferred
   2 def gotResult(result)
   3   print "important message: ", result
   4   return "a more important message"
   5 d.addCallback(gotResult)             # first callback
   6 def gotResult2(result, i2, s2, specialLabel)
   7    print "gotResult2 returns: ", result # will print "a more important message"
   8    print i2, s2, specialLabel               # will print "2, string2, special"
   9 d.addCallback(gotResult2, 2, "string2", specialLabel="special")
  10 d.addErrback(errfn,...)    # exception handling for deferreds

This is a very important passage... but don't hurt your brain!!

If you need to call a method that returns a deferred within your callback chain, just return that deferred, and the result of the secondary deferred's processing chain will become the result that gets passed to the next callback of the primary deferreds processing chain

DsageNg/TwistedTalk/100_Twisted_Deconstructed (last edited 2008-11-14 13:41:51 by anonymous)