conditions

Conditions

if, elseif and else, and the operators that compare and combine, on the swap of a Linux summed up in one word: none, unused, light or heavy.

How to read it

• if (…) { … } elseif (…) { … } else { … }: the first condition that holds wins; else takes the rest. A block is always between braces, even for one line, and one writes elseif, never else if.
• == and != compare in numbers when both sides are numbers, in texts otherwise. <, >, <=, >= compare numbers.
• ||: one side true is enough. &&: both must be true; the right side is only read when the left one has not decided already, so heavy never divides by a total of zero, the first branch having taken it.
• ! turns true into false and false into true: !text.is_number($total).
• fail('misconfigured', …) stops the collector when the answer is not the one expected.

To adapt it

• The two thresholds of heavy (half of the swap, 1 GiB left) are written in the code: they classify, the watch judges. To let the administrator change them, return the figures as numbers and watch them with watch.above.
• The ternary ? : does not exist in Keen: write an if … else.