Hi,
I run a profiler on hachoir-urwid [1] and top 10 is:
ncalls tottime percall cumtime percall filename:lineno(function)
10989 9.742 0.001 18.329 0.002 util.py:563(calc_width)
1406531 8.568 0.000 8.568 0.000 utable.py:78(get_width)
69 7.676 0.111 7.676 0.111 curses_display.py:247(_getch)
61 0.450 0.007 0.827 0.014 curses_display.py:484(draw_screen)
2553 0.328 0.000 18.757 0.007 canvas.py:37(__init__)
300 0.267 0.001 1.532 0.005 listbox.py:110(calculate_visible)
2309 0.203 0.000 2.080 0.001 canvas.py:354(apply_text_layout)
11454 0.190 0.000 0.666 0.000 urwid_ui.py:252(_get)
24025 0.182 0.000 0.182 0.000 util.py:871(rle_len)
10996 0.174 0.000 0.379 0.000 widget.py:237(rows)
I'm using a UTF-8 terminal and calc_width() takes 10% of the time!
I read calc_width() and get_width() functions and they aren't optimized.
For get_width(), it's hard to optimized the algorithm. So I propose to use a
cache:
====================== 8< ========================================
def _get_width( o ):
global widths
if o == 0xe or o == 0xf:
return 0
for num, wid in widths:
if o <= num:
return wid
return 1
def get_width( o ):
"""Return the screen column width for unicode ordinal o."""
global _get_width_cache
if o not in _get_width_cache:
_get_width_cache[o] = _get_width(o)
return _get_width_cache[o]
====================== 8< ========================================
In my program, the cache has 71 entries. That's small ;-)
For calc_width():
* avoid it? (use it only when it's needed)
* use cache? (sound complex)
* only accept unicode
Manipulate UTF-8 is complex. In general, it would be a better idea to only
store Unicode string, and convert to UTF-8 when text is written in the
terminal.
-------
But I just proposed "micro-optimization". To really improve urwid, we have to
implement:
http://excess.org/urwid/ticket/1
Partial screen updates
And also:
http://excess.org/urwid/ticket/2
C code for performance critical sections
-------
References:
[1] hachoir-urwid: http://hachoir.org/wiki/hachoir-urwid
Victor Stinner aka haypo
http://hachoir.org/
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