code.delx.au - pymsnt/blob - src/throttle.py

   1 # Copyright 2006 James Bunton <james@delx.cjb.net>
   2 # Licensed for distribution under the GPL version 2, check COPYING for details
   3
   4
   5 from twisted.internet import task
   6
   7 class Throttler:
   8         def __init__(self, consumer, speed):
   9                 self.consumer = consumer
  10
  11                 self.buffer = ""
  12                 self.speed = speed # Bytes/second
  13                 self.canClose = False
  14
  15                 self.loopTask = task.LoopingCall(self.loopFunc)
  16                 self.loopTask.start(1.0)
  17
  18         def write(self, data):
  19                 if not self.consumer:
  20                         raise ValueError, "I/O operation on closed 'file'"
  21                 self.buffer += data
  22
  23         def close(self):
  24                 self.canClose = True
  25
  26         def error(self):
  27                 self.consumer.error()
  28                 self.consumer = None
  29                 self.buffer = None
  30                 self.loopTask.stop()
  31
  32         def loopFunc(self):
  33                 if self.canClose and len(self.buffer) == 0:
  34                         self.consumer.close()
  35                         self.consumer = None
  36                         self.loopTask.stop()
  37
  38                 else:
  39                         chunk, self.buffer = self.buffer[:self.speed], self.buffer[self.speed:]
  40                         self.consumer.write(chunk)
  41
  42
  43