Variable error handling (defaults/substitutes)

[gbakeman]

The WinNUT variable update system has a design that causes it to substitute in default/fallback values for when there's an error retrieving a variable. This is a problem because the user may be unaware of when a variable is being substituted, and when it is a true value.

Examples

• Missing battery.voltage
  

• UPS data retrieval subroutine
  

  WinNUT-Client/WinNUT_V2/WinNUT-Client_Common/UPS_Device.vb

  Lines 265 to 268 in 1d9fe47

  	With UPS_Datas.UPS_Value
  	.Batt_Charge = Double.Parse(GetUPSVar("battery.charge", 255), ciClone)
  	.Batt_Voltage = Double.Parse(GetUPSVar("battery.voltage", 12), ciClone)
  	.Batt_Runtime = Double.Parse(GetUPSVar("battery.runtime", 86400), ciClone)

Solution

First, the concept of having fallback values should be removed. When an error is encountered retrieving a variable, that error (exception) should be passed along to the calling method. It will be up to the variables management system to handle errors. Most likely, an error will occur due to a variable not being available on the NUT server. In which case, the variable should be marked so that WinNUT knows how to handle it, and the variable is no longer fetched during periodic update calls.

Items

• Alert user if battery condition is not available (Crashes relating to bad/out-of-range values reported by NUT server #129) when stop conditions are active
• Modify gauge displays to indicate that the value is invalid or not available (precludes larger change to gauges and how they're displayed or added?)

Pull Requests

• Standard Exception logging subroutine, variable error handling, misc. bugfixes #131
• Enhanced GetUPSVar to support variable name arrays #215

Related

• Autodetect value ranges and gauge settings from UPS values #24
• UPS Power out showing wrong Wattage #41
• Ability to overwrite UPS value (Enhancement) #69
• Win NUT Client shows wrong values and stock at wrong value #74
• CPS wrong output voltage #101