This function updates a hierarchy if the layout of some widgets changed. It does
nothing on the parts that did not change. This should be more efficient than
recomputing the whole hierarchy whenever something changes.
Once again, this has some positive results on the "benchmark test":
Before:
create wibox: 0.083016 sec/iter ( 13 iters, 1.161 sec for benchmark)
update textclock: 0.00391091 sec/iter (271 iters, 3.219 sec for benchmark)
relayout textclock: 0.00273234 sec/iter (397 iters, 1.087 sec for benchmark)
redraw textclock: 0.0010191 sec/iter (989 iters, 1.745 sec for benchmark)
After:
create wibox: 0.083146 sec/iter ( 13 iters, 1.163 sec for benchmark)
update textclock: 0.00170519 sec/iter (647 iters, 2.201 sec for benchmark)
relayout textclock: 0.000581637 sec/iter (1880 iters, 1.094 sec for benchmark)
redraw textclock: 0.0010167 sec/iter (997 iters, 1.773 sec for benchmark)
So again no difference for creating wiboxes (100.16% compared to before). This
time we also have no real difference for creating wiboxes (99.76%). Update (44%)
and relayout (21%) are improved a lot.
Closes https://github.com/awesomeWM/awesome/pull/463.
Signed-off-by: Uli Schlachter <psychon@znc.in>