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Before executing the gnuplot executable the environment variable `GDFONTPATH`
is populated with a list of font directories, which is obtained from `fc-list`.
In that process we iterated over each line and called `dirname` on it, which
introduces a performance hit for loading and executing the external executable
`dirname` every time.
The new version avoids the loop.
The author of this patch measured a 42 fold performance improvement:
old version:
$ time ./gnuplot_old/bin/gnuplot -e ''
real 0m3.828s
user 0m0.392s
sys 0m0.465s
new version:
$ time ./gnuplot_new2/bin/gnuplot -e ''
real 0m0.091s
user 0m0.112s
sys 0m0.014s
The correctness of the value of `GDFONTPATH` was confirmed with the following
command and comparing its output between versions:
$ gnuplot -e 'print system("echo $GDFONTPATH")'
4 lines
130 B
Bash
4 lines
130 B
Bash
p=( $(fc-list : file | sed "s@/[^/]*: @@" | sort -u) )
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IFS=:
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export GDFONTPATH="${GDFONTPATH}${GDFONTPATH:+:}${p[*]}"
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unset IFS p
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