Mercurial > hg
changeset 44759:e58422afbc74 stable
diff: re-establish linear runtime performance
The previous method with sum() and list() creates a new list object
for every hunk. Then sum() is used to flatten out this sequence of
lists. The sum() function is not "lazy", but creates a new list object
for every "+" operation and so this code had quadratic runtime behaviour.
| author | Elmar Bartel <elb_hg@leo.org> |
|---|---|
| date | Thu, 30 Apr 2020 15:10:05 +0200 |
| parents | a467416c493c |
| children | 6a6c15cea1fa |
| files | mercurial/patch.py |
| diffstat | 1 files changed, 1 insertions(+), 1 deletions(-) [+] |
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--- a/mercurial/patch.py Thu Apr 23 09:59:38 2020 +0200 +++ b/mercurial/patch.py Thu Apr 30 15:10:05 2020 +0200 @@ -2558,7 +2558,7 @@ fctx2 is not None ), b'fctx2 unexpectly None in diff hunks filtering' hunks = hunksfilterfn(fctx2, hunks) - text = b''.join(sum((list(hlines) for hrange, hlines in hunks), [])) + text = b''.join(b''.join(hlines) for hrange, hlines in hunks) if hdr and (text or len(hdr) > 1): yield b'\n'.join(hdr) + b'\n' if text: