loop() should have a "never timeout" option

[Ross Burton]

The loop() function has a timeout argument which is good, but there's no way of saying "don't timeout" which is bad for power efficiency. Many applications will be waiting entirely on MQTT messages arriving and whilst there are no messages the process could sit in select() forever, allowing the CPU to sleep. Without the ability to to say "don't timeout", the process is forced to wake up every <whatever> seconds and re-enter the loop.

[Roger Light (roger.light)]

Hi Ross,

In practice in the vast majority of cases you will have a finite
keepalive value set, at which point it is crucial to wake up at least
every keepalive seconds. It can also be important to drop out of the
loop to check on partially delivered messages if you're using a higher
qos, but that is less relevant than the first point.

Not exactly elegant, but you could also set the timeout value to e.g.
86400 if you wanted to ignore the above and only wake up once a day.

Cheers,

Roger

On Tue, Feb 18, 2014 at 11:49 AM, Ross Burton <email address hidden> wrote:
> Public bug reported:
>
> The loop() function has a timeout argument which is good, but there's no
> way of saying "don't timeout" which is bad for power efficiency. Many
> applications will be waiting entirely on MQTT messages arriving and
> whilst there are no messages the process could sit in select() forever,
> allowing the CPU to sleep. Without the ability to to say "don't
> timeout", the process is forced to wake up every <whatever> seconds and
> re-enter the loop.
>
> ** Affects: mosquitto
> Importance: Undecided
> Status: New
>
> --
> You received this bug notification because you are subscribed to
> mosquitto.
> https://bugs.launchpad.net/bugs/1281548
>
> Title:
> loop() should have a "never timeout" option
>
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