Topic: Armory - Discussion Thread - page 92. (Read 521829 times)

class PyBackgroundThread(threading.Thread):
   """
   Wraps a function in a threading.Thread object which will run
   that function in a separate thread.  Calling self.start() will
   return immediately, but will start running that function in
   separate thread.  You can check its progress later by using
   self.isRunning() or self.isFinished().  If the function returns
   a value, use self.getOutput().  Use self.getElapsedSeconds()
   to find out how long it took.
   """
  
   def __init__(self, *args, **kwargs):
      threading.Thread.__init__(self)

      self.output     = None
      self.startedAt  = UNINITIALIZED
      self.finishedAt = UNINITIALIZED

      if len(args)==0:
         self.func  = lambda: ()
      else:
         if not hasattr(args[0], '__call__'):
            raise TypeError, ('PyBkgdThread constructor first arg '
                              '(if any) must be a function')
         else:
            self.setThreadFunction(args[0], *args[1:], **kwargs)

   def setThreadFunction(self, thefunc, *args, **kwargs):
      def funcPartial():
         return thefunc(*args, **kwargs)
      self.func = funcPartial

   def isFinished(self):
      return not (self.finishedAt==UNINITIALIZED)

   def isStarted(self):
      return not (self.startedAt==UNINITIALIZED)

   def isRunning(self):
      return (self.isStarted() and not self.isFinished())

   def getElapsedSeconds(self):
      if not self.isFinished():
         LOGERROR('Thread is not finished yet!')
         return None
      else:
         return self.finishedAt - self.startedAt

   def getOutput(self):
      if not self.isFinished():
         if self.isRunning():
            LOGERROR('Cannot get output while thread is running')
         else:
            LOGERROR('Thread was never .start()ed')
         return None

      return self.output


   def start(self):
      # The prefunc is blocking.  Probably preparing something
      # that needs to be in place before we start the thread
      self.startedAt = RightNow()
      super(PyBackgroundThread, self).start()

   def run(self):
      # This should not be called manually.  Only call start()
      self.output     = self.func()
      self.finishedAt = RightNow()


# Define a decorator that allows the function to be called asynchronously
def AllowAsync(func):
   def wrappedFunc(*args, **kwargs):

      if not 'async' in kwargs or not kwargs['async']==True:
         # Run the function normally
         if 'async' in kwargs:
            del kwargs['async']
         return func(*args, **kwargs)
      else:
         # Run the function as a background thread
         del kwargs['async']
         thr = PyBackgroundThread(func, *args, **kwargs)
         thr.start()
         return thr

   return wrappedFunc

def myFunc(...):
   doSomething()

@AllowAsync
def myFunc(...):
   doSomething()

thr = myFunc(..., async=True)

while not thr.isFinished():
   doOtherStuff()

# It must be finished to have gotten here
data = thr.getOutput()
print "myFunc took %f seconds" % thr.getElapsedSeconds()

thr = myFunc(..., async=True)

doOtherStuffInParallel()

thr.join()  # will wait for it to finish