martinvonz created this revision. Herald added a reviewer: hg-reviewers. Herald added a subscriber: mercurial-patches.
REVISION SUMMARY `encoding.trim()` iterated over the possible lengths smaller than the input and created a slice for each. It then calculated the column width of the result, which is of course O(n), so the overall algorithm was O(n). This patch rewrites it to iterate over the unicode characters, keeping track of the length so far. Also, the old algorithm started from the end of the string, which made it much worse when the input is large and the limit is small (such as the typical 72 we pass to it). You can time it by running something like this: time python3 -c 'from mercurial.utils import stringutil; print(stringutil.ellipsis(b"0123456789" * 1000, 5))' That drops from 4.05 s to 83 ms with this patch (and most of that is of course startup time). REPOSITORY rHG Mercurial BRANCH default REVISION DETAIL https://phab.mercurial-scm.org/D12089 AFFECTED FILES mercurial/encoding.py CHANGE DETAILS diff --git a/mercurial/encoding.py b/mercurial/encoding.py --- a/mercurial/encoding.py +++ b/mercurial/encoding.py @@ -511,17 +511,21 @@ if width <= 0: # no enough room even for ellipsis return ellipsis[: width + len(ellipsis)] + chars = list(u) if leftside: - uslice = lambda i: u[i:] - concat = lambda s: ellipsis + s - else: - uslice = lambda i: u[:-i] - concat = lambda s: s + ellipsis - for i in pycompat.xrange(1, len(u)): - usub = uslice(i) - if ucolwidth(usub) <= width: - return concat(usub.encode(_sysstr(encoding))) - return ellipsis # no enough room for multi-column characters + chars.reverse() + width_so_far = 0 + for i, c in enumerate(chars): + width_so_far += ucolwidth(c) + if width_so_far > width: + break + chars = chars[:i] + if leftside: + chars.reverse() + u = u''.join(chars).encode(_sysstr(encoding)) + if leftside: + return ellipsis + u + return u + ellipsis class normcasespecs(object): To: martinvonz, #hg-reviewers Cc: mercurial-patches, mercurial-devel _______________________________________________ Mercurial-devel mailing list Mercurial-devel@mercurial-scm.org https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel