loops

Loops

The three loops of Keen, foreach, for and while, and the two words that steer them, continue and break, on the processes of a Linux counted by state.

How to read it

• foreach ($states as $state): one turn per element of the list. foreach ($list as $key => $value) gives the key too (see examples/watches/deviate).
• continue goes straight to the next turn: the zombies are counted by skipping every other state.
• for ($i = 0; $i < list.count($states); $i = $i + 1): a counter, its start, its condition, its step. $i++ and $i += 1 do not exist: write $i = $i + 1.
• while (…): turns as long as the condition holds. break leaves the loop at once: once one stopped process is found, the others need not be read.
• text.like($state, 'Z*'): does the text follow the pattern, * standing for any characters.
• A loop never turns forever: the poller counts the turns and stops the collector at its ceiling, saying so.

To adapt it

• The states of ps are documented in man ps, under "PROCESS STATE CODES": D (waiting for a disk) is often worth counting too.
• The watch on stopped processes is not checked by default ('enabled' => false): the administrator checks it on the probe.