Skip to main content

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [List Home]
Re: [paho-dev] non blocking sleep

opps, sorry, I thought this list was specifically for python-paho. 

I'm using Python.

> You basically have to avoid calling sleep and use timers instead.

this sounds funny asking, but What is a timer?

Years ago I used a gui desktop database app designer,  I dragged a "timer widget" onto the form and type in the function it should call every X amount of time.
I understand what that did, I understand i need something like that, but in this context I have no idea how I should implement it. 

I have a few guesses, like check for events in a loop.  maybe add a sleep so the cpu has some cycles to do other things (no sure what other things are needed, pretty sure incoming network traffic will take priority? also pretty sure this is not a problem I should be trying to solve.   I am sure it has been solved  100's of times.

I also guess "event loop" is a thing I need.  Which I also comprehend and could implement one from scratch if I needed to, but I hope I don't need to.

On Sat, Oct 5, 2019 at 7:32 AM Greg Troxel <gdt@xxxxxxxxxx> wrote:
Carl Karsten <carl@xxxxxxxxxxxxxxxx> writes:

> When the door opens, the light should stay on for 60 seconds.
> or if the button is pressed, turn the light off 30 seconds later.
> every door open resets the 60 seconds.
> (this is the simplified version that I think is the root of my problem)

This is not an MQTT issue, but I can see it comes up often in things
that want to use MQTT.

> I can't do "on, sleep(60), off" because that will block the on_button
> (right?)

If the main control program calls sleep, it will ignore all other inputs
for that time.  So don't do that :-)

> and when the button is pressed, if the door opens again that should disable
> the "off in 30" thing.

A further complexity is humans asking for lights to be in certain states
and automatic rules at the same time.  In this case I think you want a
virtual light controlled by the human and a virtual light controlled by
the rules and the real light to be the OR of those.

> Is there a tutorial page or something I should be reading?

This is really a fundamental programming issue; you are constructing a
finite state machine with timers.

There are arguably two approaches to this sort of thing, usually called
threads and async.   It will seems that threads are easier, but really
they just look easier and async is actually easier, when you define that
as "work to get a 100% reliable system".

Frameworks that are set up for your problem include (but this is Lua on ESP8266,
  probably not where you should run the controller)

but really you sound like you are starting down the path of slowly
reinventing a home automation system, so have a look at

Yes, but this system is 'special' otherwise we wouldn't be making it :p
We might be right. not my call.  What I am sure of is someone will make something better some day.  might be me!

Is this what I should be doing?
async def main():
    print('Hello ...')
    await asyncio.sleep(1)
    print('... World!')

Carl K

Back to the top