[Kde-hardware-devel] Ksysguardd and solid

[John Tapsell]

Hey all,

In ksysguard there is a daemon, ksysguardd.  This is a C/C++ program
with a different source for each OS (Linux, FreeBSD etc).  This is in
kdebase/workspace/ksysguard/ksysguardd/Linux/

ksysguard runs ksysguardd and talks to it via stdin and stdout.  It
conversation is like:

ksysguardd> ps?
Name    PID     PPID    UID     GID     Status  User%   System% Nice
 VmSize  VmRss   Login   Command
s       d       d       d       d       S       f       f       d
 D       D       s       s
ksysguardd>


Then  to get the data for ps:

ksysguardd> ps
init    1       0       0       0       sleeping        0.00    0.00
 0       2640    580     root    init [2]
migration/0     2       1       0       0       sleeping        0.00
 0.00    0       0       12      root
...

There is also an xres command, which looks like:

ksysguardd> xres?
XPid    XIdentifier     XPxmMem XNumPxm XMemOther
d       s       D       d       D

and:
4969    KDE Desktop     7919176 78      8032
5139    http://mail.google.com - Google Mail - Compose Mail - Mozilla
Firefox   23449584        1194    26056
5001    KDE Wallet Manager      20024   11      888
...


In ksysguard, I call "ps" every 2 seconds (it's very fast)  and xres
every 6 seconds or so (it can take about 2 seconds to run sometimes)

What I do next is a bit complicated.  I basically look at the new data
and compare it against what I already know.  Thus I can deduce what
are new processes, what processes disapeared, which processes have
changed, and so on.  I then emit changed information only for what has
changed.

This allows the view to update smoothly, allows selections to be kept,
and reduces the redrawing needed.

Now I mention this because I think it would be nice to keep this model
in solid, so that any app can use the model.