[Ovmsdev] Duktape handling of blank metrics?

[Greg D.]

So, now it's failing at my desk, too.  Good - a lot easier to grab a
backtrace...   But, it's also happening whether the metrics are set or
not.  I've updated the code to the current (including your housekeeping
changes); not sure if that made a difference.

OVMS> vfs cat /store/obd2ecu/10
ret1=OvmsMetricFloat("v.p.speed");
ret2=OvmsMetricFloat("v.b.power");
out = 0.0;
if(ret1 > 0) { out=ret2/ret1; }
out;
OVMS> obdii ecu list
  PID             Type        Value    Metric
0   (0x00)       internal     0.000000
4   (0x04)       internal     0.000000 v.b.soc
5   (0x05)         metric     0.000000 v.e.temp
***ERROR*** A stack overflow in task AsyncConsole has been detected.
abort() was called at PC 0x4008ecc4 on core 1

Backtrace: 0x4008ead4:0x3fff2f50 0x4008ecab:0x3fff2f70
0x4008ecc4:0x3fff2f90 0x4008ab6b:0x3fff2fb0 0x4008cd94:0x3fff2fd0
0x4008cd4a:0x3fff600c

Rebooting...




Mark Webb-Johnson wrote:
> Need to see a backtrace. Perhaps you are just on the borderline of stack usage, or something going crazy?
>
> Looking at DukOvmsMetricFloat(), it just return the metric AsFloat(), and for float type metrics that should just be zero if not defined.
>
> Regards, Mark.
>
>> On 29 Mar 2018, at 8:58 AM, Greg D. <gregd2350 at gmail.com> wrote:
>>
>> Hi folks,
>>
>> Does anyone know how DukTape scripting handles math with a metric that
>> hasn't been updated yet? 
>>
>> I have a short example script in the OBDII ECU documentation which
>> (should) calculate a power-per-speed metric for display on a HUD.  Seems
>> like it would be a useful example, and wanted to verify that it actually
>> works. 
>>
>> OVMS> vfs cat /store/obd2ecu/10
>> ret1=OvmsMetricFloat("v.p.speed");
>> ret2=OvmsMetricFloat("v.b.power");
>> out = 0.0;
>> if(ret1 > 0) { out=ret2/ret1; }
>> out;
>>
>> I have the module in the my Roadster, and the v.p.speed metric comes up
>> as 0 kph (that's good - it's parked), but the power metric isn't
>> provided by the car, so is blank when listing the metrics.  I expected
>> the code to return zero.
>>
>> Instead, executing the script by asking for 'obdii ecu list' causes an
>> immediate crash with a stack overflow in task AsyncConsole.  If I
>> initialize the power metric by hand (metric set v.b.power 0), the script
>> runs just fine, returning 0 for the metric.
>>
>> Oddly, when I first set it up on the desk (sans vehicle), so both of the
>> metrics were blank, executing the script didn't cause crash.
>>
>> Is there a way to make the code "Roadster safe", without dummying up the
>> metric in, say, a startup script?  Better, is there a fix for DukTape to
>> handle this, or should I just increase the stack size in AsyncConsole?
>>
>> Thanks,
>>
>> Greg
>>
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