fix(folders): honour folder_N_refresh instead of walking every cycle

[ntdatt812]

The bug

FolderList.update() guards the per-folder timer like this:

if not self.first_grab and i in self.timer_folders and not self.timer_folders[i].finished():
    continue

i is a list index; self.timer_folders is a list of Timer objects. i in self.timer_folders is a membership test, not a bounds check — it asks whether the integer i equals one of the timers. Timer doesn't implement __eq__, so it is always False:

>>> from glances.timer import Timer
>>> 0 in [Timer(600), Timer(600)]
False

So the skip branch is unreachable, and the self.timer_folders[i].reset() below it never runs either.

What it costs

folder_N_refresh has no effect. Every monitored folder is re-walked on every refresh cycle (2s by default) instead of on its own schedule — and folder_size() is a full recursive walk, which is the whole reason the setting exists.

Measured with folder_1_refresh=600 and folder_size counted:

	walks after 4 update cycles
before	4
after	1

The fix

Use the bound the code meant: i < len(self.timer_folders).

The guard is worth keeping rather than dropping — __folder_list is a class attribute while timer_folders is per-instance, so the folder list can outgrow the timer list and the index has to be checked.

Tests

tests/test_folder_list_refresh.py, 4 cases: refresh delay honoured, folder walked again once the timer is over, timer restarted after a walk, and a folder with no timer still updated.

Mutation-checked — putting i in self.timer_folders back turns 2 of the 4 red:

FAILED test_folder_is_not_walked_again_before_its_refresh_delay
FAILED test_the_timer_is_restarted_after_a_walk
2 failed, 2 passed

ruff check and ruff format --check clean on both files.

[nicolargo]

Thanks for the PR @ntdatt812

This one is tricky !

Merged into develop.