functions

Functions

A function written once and called four times, and another called twice, on the memory and the swap of a Linux.

How to read it

• function kilobytes($meminfo, $name) { … }: a name without a point, its parameters, its body. It is written at the first level of the code, never inside a block, before or after its calls.
• A function sees only its parameters: the text of /proc/meminfo is passed to it, it does not read $meminfo of the body.
• return gives back a value and leaves the function; percent returns 0 for a host without swap, rather than divide by zero.
• fail works inside a function as everywhere: a line missing from /proc/meminfo stops the collector.
• A function never calls itself, directly or through another: the validation refuses it.

To adapt it

• kilobytes reads any line of /proc/meminfo: Cached, Dirty, HugePages_Total…
• A function name cannot be a word of Keen (value, fail…) nor the name of a domain (text, http…).