This is more or less a temporary fix to restore the former behaviour. In
the long term objects will define a max value, which will be of use for
all kinds of meters.
-d was broken because fork-to-background was done after the update thread creation, so the
threads ended up in the wrong process. This delays the thread creation until after the fork.
Create each thread upon registration of the callback function, then use
semaphores to signal when it's time to update and when updating is
finished.
Many thanks to pavelo who originally came up with the idea for this.
There are no INFO_* variables any more, so the argument passed to OBJ()
is always a function pointer or zero. By checking the argument passed in
add_update_callback(), the branch in the OBJ() macro can be dropped,
too.
* Remove leftover INFO_* values from object definitions which didn't
trigger anything.
* Drop the whole INFO_* enum as it's values are not used anymore.
* Drop all need_mask alterations (no idea why there were here at all,
but surely not sane since they are missing in the non-linux
functions).
* Drop the update delay for update_meminfo(), as parsing /proc should
not lead to abnormal overhead.
* Check for x_initialised from inside update_x11info(), so we can call
it unconditionally.
Besides improving performance when updating stuff, we ideally have no
text object specific code in update_stuff() anymore (aside some
leftovers).
The macros in construct_text_object() have gotten a bit crazier than
they were before:
* using CALLBACK(&func) instead of an INFO_* parameter to OBJ() will
make it add the given callback to the list of callbacks to be iterated
over at each update interval.
* BEWARE: the above assumes function pointer values to be > 0!
* This implicitly fixes a bug in the code: passing 0 as INFO_* value
led to selecting INFO_MAIL (1 << 0 == 1).
* Now it would select INFO_CPU (== 0), which got unused and therefore is
not a problem at all (the 0 value should be unused in enums anyway).
This needs some more work, then we should be able to drop the whole
INFO_* enum. Then CALLBACK() can die again and with it goes the ugly
casting stuff done to distinguish callbacks from INFO_* values.
