Question

I have the following code in a class:

def __setattr__(self, key, value):
    self.__dict__['d'][key] = value
    ...
    self.saveToIni()

The saveToIni function saves all the dict’s items to an ini file at every object’s setattr call. If 80 setattr calls are made in the last 120ms, then the file will be written from scratch every time. The function also orders and sometimes deletes data from the dictonary, so I don’t want to change it.

I want to limit the calls to once in, let’s say, 5 seconds:

1. When the first setattr is triggered, a timer starts asynchronicly, still not running saveToIni.
2. If any calls are made to setattr and the timer is still counting, it will nor fire a timer nor run saveToIni.
3. When the timer times out, the saveToIni should launch.

Now, I’m not sure how to achieve this behavoir. I’ve thought about messing with threads, but still didn’t found the idea about how to do it.

Answer 1

The way I would go, is to create a Timer Thread which runs a timedSaveToIni function once every 5 sec.
I would also have a tag isSaveRequested telling this function if it should actually write data to the disk or not.

The _setattr_ function would simply set this tag to true.

Your code would look like this:

class Dict:

  def __init__(self):
    ...
    self.isSaveRequested = False
    self.timedSaveToIni()

  def timedSaveToIni(self):
    threading.Timer(5.0, self.timedSaveToIni).start()
    if self.isSaveRequested:
      self.saveToIni()
      self.isSaveRequested = False


  def __setattr__(self, key, value):
    self.__dict__['d'][key] = value
    ...
    self.isSaveRequested = True

  def saveToInit()
    ...