Add usage lib

[KyleBonnes]

Same concept as TorQ's logusage script.
Basic by-hand testing for kdb+ 3.0 and above on Linux

[jonathonmcmurray]

a few style tweaks to bring this in line with other packages please

[jonnypress]

@jmlemay could we pull out the unit test framework parts of this package and merge them separately to the main code base so that we all the packages can use the same framework code please?

[jonnypress]

I think this looks good generally as first version.

Question (which we can follow up in second pass). Does it handle very long input query strings, i.e. greater than whatever \c is set to? In the TorQ version they get truncated in the log file. I don't know a good solution but I guess there probably is one (there are pros and cons to the truncation).

[jonnypress]

Approved (sorry meant to hit approve on the last update)

[jmlemay]

I think this looks good generally as first version.

Question (which we can follow up in second pass). Does it handle very long input query strings, i.e. greater than whatever \c is set to? In the TorQ version they get truncated in the log file. I don't know a good solution but I guess there probably is one (there are pros and cons to the truncation).

It handles long query strings in that it will execute them, but they will be truncated in the logs to whatever \c is. E.g.

// Remote process.
q)`::5000(::;til 100000)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42..

// Logged usage.
q)\c 2000 2000
q)@[;`cmd].usage.usage -2+count .usage.usage
"(::;0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41
42 43 44 45 46 47 48 49 50.."

I suppose the best solution is probably to make this configurable? Could be done in a second version. At the moment it's configurable simply by setting \c, with the only limitation being the max console size.