Fixes #338 - Also cache fonts registered through fontconfig

[claudep]

Fixes a performance regression in 83d2ec043e094562f.

[karlb]

This does not resolve the performance regression for me. Here's a profile of my (admittedly far from minimal) case using this branch:

Sat May 14 08:28:24 2022    pdfgen.prof

         68571541 function calls (60673417 primitive calls) in 417.654 seconds

   Ordered by: internal time
   List reduced from 9286 to 20 due to restriction <20>

   ncalls  tottime  percall  cumtime  percall filename:lineno(function)
    60067  254.892    0.004  254.892    0.004 {method 'poll' of 'select.poll' objects}
    90093   50.078    0.001   50.078    0.001 {built-in method posix.read}
    15016   41.077    0.003   41.077    0.003 {built-in method _posixsubprocess.fork_exec}
791892/261374    2.729    0.000    3.625    0.000 svglib.py:173(findAttr)
   849194    2.345    0.000    2.345    0.000 {built-in method posix.stat}
    15016    2.032    0.000   98.412    0.007 subprocess.py:1663(_execute_child)
    21532    1.838    0.000  197.603    0.009 svglib.py:1342(applyStyleOnShape)
   626738    1.786    0.000    3.845    0.000 attrmap.py:99(validateSetattr)
  1008191    1.524    0.000    2.459    0.000 posixpath.py:71(join)
    30044    1.521    0.000    9.022    0.000 ttfonts.py:145(TTFOpenFile)
    15016    1.356    0.000  260.523    0.017 subprocess.py:1928(_communicate)
8244450/8244430    1.351    0.000    1.456    0.000 {built-in method builtins.isinstance}
6250695/520643    1.261    0.000    1.434    0.000 basic.py:2028(_preorder_traversal)
3406254/3406189    1.165    0.000    1.253    0.000 {built-in method builtins.getattr}
     7504    1.014    0.000  385.925    0.051 svglib.py:1038(convertText)
   219409    1.013    0.000    1.013    0.000 {method 'split' of 'str' objects}
    15016    0.987    0.000    2.823    0.000 subprocess.py:1207(_close_pipe_fds)
    60729    0.921    0.000    0.923    0.000 {built-in method io.open}
    15016    0.878    0.000  365.387    0.024 fonts.py:77(use_fontconfig)
   362903    0.826    0.000    0.826    0.000 {built-in method reportlab.lib._rl_accel.fp_str}

pdfgen.prof.zip

Do I have to use svglib in a specific way to take advantage of the caching?

[claudep]

Ah yes, sorry. I see my patch does improve things for unknown fonts, but in this case, there is another branching scenario where registering the font fails with a TTFError. I'll work on improving this.

[claudep]

Could you please test the result now?

[karlb]

Works for me now. This makes a 20x speed difference in my case. Thanks for fixing it so quickly!

[Holger-Bartel]

Thanks a lot @claudep for fixing that one and to @salistha-shakya and @karlb for reporting it!