Get logging level in Lua script?

Hi guys,

is there a way to get the logging level of the channel in the Lua code?

I’d like to spread a lot of logDebug statements all over the Lua code, but I’m worrying that many statements

iguana.logDebug(<a href="https://github.com/kikito/inspect.lua">inspect</a>.inspect(result))

will slow me down by creating the output even if logDebug is switched off.

The only thing I found was:

   local xml = xml.parse{data=iguana.channelConfig{name='ChannelName'}}
   local loggingLevel = xml.channel.logging_level)

but

• that doesn’t seem to change when I change the logging level in the control panel of the channel… it only reads the setting from IguanaConfiguration.xml?
• parsing the XML might be even slower…

So what I need is either a way to quickly get whether debug logging is enabled, or a logDebug function which accepts a lambda expression, i.e. a function which is then only evaluated if debug log is on.

Is there any possibility for this?

Oh that is funny – I saw a notification for your question and implemented this function:

function LoggingLevel()
if (not Level) then
local X = xml.parse{data=iguana.channelConfig{guid=iguana.channelGuid()}}
Level = tonumber(tostring(X.channel.logging_level))
end
return Level
end

Which is the same type of solution – although it does some caching of the result. The API doesn’t actually hit the disk – it constructs the XML fragment you see from memory so the only impact of this is a little bit of extra CPU usage. On the whole most of the time Iguana tends not to max out CPU – IO (input/output) tends to be where the overhead occurs so I would suspect it won’t make much practical difference if you hit this API every time.

Although I doubt it matters all that much here is a slightly more sophisticated caching scheme. It keeps the API value for 5 seconds:

-- 2 means debug level. 1 is normal and 0 is no logging. This function caches the
-- logging level if found for the last 5 seconds
local LastTime =0
local LogLevel

function LoggingLevel()
if os.ts.time() - 5 > LastTime then -- Check to see last time we looked this up
LastTime = os.ts.time()
local X = xml.parse{data=iguana.channelConfig{guid=iguana.channelGuid()}}
LogLevel = tonumber(tostring(X.channel.logging_level))
end
return LogLevel
end

It’s a reasonable general solution for looking anything up that doesn’t change often but has some overhead in fetching.

I have tested the speed of any of these in production – be curious to see what you find if you have time to try it…

Incidentally it’s a similar optimization we use for some of Iguana’s own internal tracing…enjoy!

Happy Holidays if I don’t hear from you before the season 🙂

Hi Eliot,
OK, so maybe this is indeed the way to go. I think the first solution is good enough, the 5 seconds caching is really really fancy 🙂

Thanks a lot for your help!