spawn/__init__.py

   1 # __init__.py
   2 # 14 Aug 2007
   3
   4 import time, thread, weakref, gc
   5
   6 class Process:
   7     def __init__(self, computation, stopper):
   8         self.container = [None]
   9         self.computation = computation
  10         self.stopper = stopper
  11
  12     def run(self):
  13         try:
  14             self.container[0] = self.computation()
  15         except Exception, e:
  16             self.container[0] = repr(e)
  17
  18 class MyList(list):
  19     def __init__(self, x):
  20         list.__init__(self)
  21         self.append(x)
  22
  23 class MyObject: pass
  24
  25 def spawn(computation, stopper):
  26     proc = Process(computation, stopper)
  27
  28     token = MyObject()
  29     wref = weakref.ref(token, lambda arg: stopper())
  30
  31     class Retriever:
  32         def __init__(self):
  33             self.children = []
  34
  35         def __call__(self):
  36             x = proc.container[0]
  37             if x is None: return ('working', None)
  38             else:   return ('done', x)
  39
  40         def __repr__(self):
  41             return '<Retriever holding value %s>' % str(self())
  42
  43         def stop(self):
  44             stopper()
  45             for kid in self.children:
  46                 kid.stop()
  47
  48         def spawn(self, comp, stopr):
  49             p = globals().spawn(comp, stopr)
  50             self.children.append(p)
  51
  52         def start(self):
  53             thread.start_new_thread(proc.run, ())
  54
  55     r = Retriever()
  56     r.saving_ref = token
  57     del token
  58     return r
  59
  60 def fib(n, go):
  61     if not go[0]:
  62         raise Exception, "Cancelled"
  63     elif n <= 2:
  64         return 1
  65     else:
  66         return fib(n - 1, go) + fib(n - 2, go)
  67
  68 def test(n):
  69     go = [True]
  70     def stop(): go[0] = False
  71     return spawn(lambda: fib(n, go), stop)
  72