Am 23.09.2015 um 20:14 schrieb Colin Reese:
> Is there a way to set the cache delay?
>
IIRC temperature values are cached as set in settings/timeout/volatile,
in seconds.
> There is the case where you
> don't want sensors read every second (for power consumption, load, or
> other reasons), but want values instantly. Setting the cache delay
> would address this, and the shell script could read this value and
> adjust accordingly. Also, is the time of the cache reading available?
>
I think there is a chance for misunderstanding here.
When you start a simultaneous conversion, you create a valid sensor
value in all sensors after at most one second. Owlib remembers for each
sensor it has a valid conversion value inside. That means reading that
single sensor *once* will *never* trigger another conversion.
So if you synchronize the simultaneous conversion and the readout
action, you don't need the cache ever. Same if you don't synchronize but
do the simultaneous conversion at least twice as often as the readout.
The cache is never used if these provisions are met.
However, if you have owhttpd or similar as the client, you cannot be
sure if the readout is more often than that. That's the only reason you
need the cache in that setup. Set it's timeout to a value twice as long
as the simultaneous conversion cycle and you are fine.
> The above are issues also solved with the database approach.
>
Sure, you could always build a secondary cache if you just want to get
rid of the delay. Then again, you could always change your client
program to do asynchronous reads and build the "cache" into the client
by doing so.
I had the impression Alex wanted to avoid that. KISS, something like that.
Kind regards
Jan
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