This commit is based on exploratory work by Sohaib Mohamed.
The end goal is two-fold - to support addition of Meters we
build via configuration files for both the PCP platform and
for scripts ( https://github.com/htop-dev/htop/issues/526 )
Here, we focus on generic code and the PCP support. A new
class DynamicMeter is introduced - it uses the special case
'param' field handling that previously was used only by the
CPUMeter, such that every runtime-configured Meter is given
a unique identifier. Unlike with the CPUMeter this is used
internally only. When reading/writing to htoprc instead of
CPU(N) - where N is an integer param (CPU number) - we use
the string name for each meter. For example, if we have a
configuration for a DynamicMeter for some Redis metrics, we
might read and write "Dynamic(redis)". This identifier is
subsequently matched (back) up to the configuration file so
we're able to re-create arbitrary user configurations.
The PCP platform configuration file format is fairly simple.
We expand configs from several directories, including the
users homedir alongside htoprc (below htop/meters/) and also
/etc/pcp/htop/meters. The format will be described via a
new pcp-htop(5) man page, but its basically ini-style and
each Meter has one or more metric expressions associated, as
well as specifications for labels, color and so on via a dot
separated notation for individual metrics within the Meter.
A few initial sample configuration files are provided below
./pcp/meters that give the general idea. The PCP "derived"
metric specification - see pmRegisterDerived(3) - is used
as the syntax for specifying metrics in PCP DynamicMeters.
When manipulating CPUMeters in the AvailableMeterPanel we
use the bottom 16 bits to hold the CPU number. However,
the bitmask used to extract the CPU number only masks the
lower 8 bits (0xff).
Draw the FunctionBar within Panel_draw instead of manually throughout
the code.
Add an optional PanelClass function drawFunctionBar, to allow specific
panels to override the default FunctionBar_draw call.
Rework the code on color change, to really change all colors (selection
markers and panel headers).
Closes: #402
Reasoning:
- implementation was unsound -- broke down when I added a fairly
basic macro definition expanding to a struct initializer in a *.c
file.
- made it way too easy (e.g. via otherwise totally innocuous git
commands) to end up with timestamps such that it always ran
MakeHeader.py but never used its output, leading to overbuild noise
when running what should be a null 'make'.
- but mostly: it's just an awkward way of dealing with C code.
In the listing of Available Meters for CPUs, the list of CPUs is always
presented by counting them from one. However, if the user prefers to
count CPUs from zero, this is sometimes confusing when fine-tuning the
meters.
Just assume Platform_meterTypes[0] is always &CPUMeter_class for every
platform. This removes a conditional in AvailableMetersPanel_new().
Also adds some comments about the logic here. Without assuming
Platform_meterTypes[0], the (int i=1) clause in this for loop will not
make sense. (I.e. Why not (int i=0)? )
Also replaced a sprintf() call with safer snprintf() in code further
below.
