Docs: improve online manual lookup time time

Matching the RNA id's to the search pattern is slow because
of the function `fnmatchcase`. This patch first checks the string
prefix without any special characters used by fnmatch,
if the `startswith` check fails, there is no need to check `fnmatchcase`.
Before the optimization, an online manual lookup took about 400ms
which is quite noticeable, with this patch applied it's under 10ms.

Ref !104581.
This commit is contained in:
Erik Abrahamsson 2023-02-14 10:29:40 +11:00 committed by Campbell Barton
parent bb9eb262d4
commit 526f2273c6
1 changed files with 24 additions and 0 deletions

View File

@ -1249,7 +1249,31 @@ class WM_OT_doc_view_manual(Operator):
# XXX, for some reason all RNA ID's are stored lowercase
# Adding case into all ID's isn't worth the hassle so force lowercase.
rna_id = rna_id.lower()
# NOTE: `fnmatch` in Python is slow as it translate the string to a regular-expression
# which needs to be compiled (as of Python 3.11), this is slow enough to cause a noticeable
# delay when opening manual links (approaching half a second).
#
# Resolve by matching characters that have a special meaning to `fnmatch`.
# The characters that can occur as the first special character are `*?[`.
# If any of these are used we must let `fnmatch` run its own matching logic.
# However, in most cases a literal prefix is used making it considerably faster
# to do a simple `startswith` check before performing a full match.
# An alternative solution could be to use `fnmatch` from C which is significantly
# faster than Python's, see !104581 for details.
import re
re_match_non_special = re.compile(r"^[^?\*\[]+").match
for pattern, url_suffix in url_mapping:
# Simple optimization, makes a big difference (over 50x speedup).
# Even when `non_special.end()` is zero (resulting in an empty-string),
# the `startswith` check succeeds so there is no need to check for an empty match.
non_special = re_match_non_special(pattern)
if non_special is None or not rna_id.startswith(pattern[:non_special.end()]):
continue
# End simple optimization.
if fnmatchcase(rna_id, pattern):
if verbose:
print(" match found: '%s' --> '%s'" % (pattern, url_suffix))