Mercurial > hg
view hgeditor @ 29014:f1ca249696ed stable
bdiff: balance recursion to avoid quadratic behavior (issue4704)
For highly structured files like JSON or XML dumps with large numbers
of duplicate lines (eg braces) and isolated matching lines, bdiff
could find large numbers of equally good spans. Because it prefers
earlier matches, this would result in pathologically unbalance
recursion that resulted in quadratic performance.
This patch makes it prefer matches closer to the middle that tend to
balance recursion. This change improves the speed of a pathological
test case from 1100s to 9s.
Included is a smaller test that has a roughly 50x safety margin on the
performance it accepts. It's likely to fail on pure builds because
difflib also has a recursion-balancing problem.
author | Matt Mackall <mpm@selenic.com> |
---|---|
date | Thu, 21 Apr 2016 22:04:11 -0500 |
parents | 1aee2ab0f902 |
children |
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#!/bin/sh # # This is an example of using HGEDITOR to create of diff to review the # changes while committing. # If you want to pass your favourite editor some other parameters # only for Mercurial, modify this: case "${EDITOR}" in "") EDITOR="vi" ;; emacs) EDITOR="$EDITOR -nw" ;; gvim|vim) EDITOR="$EDITOR -f -o" ;; esac HGTMP="" cleanup_exit() { rm -rf "$HGTMP" } # Remove temporary files even if we get interrupted trap "cleanup_exit" 0 # normal exit trap "exit 255" HUP INT QUIT ABRT TERM HGTMP=$(mktemp -d ${TMPDIR-/tmp}/hgeditor.XXXXXX) [ x$HGTMP != x -a -d $HGTMP ] || { echo "Could not create temporary directory! Exiting." 1>&2 exit 1 } ( grep '^HG: changed' "$1" | cut -b 13- | while read changed; do "$HG" diff "$changed" >> "$HGTMP/diff" done ) cat "$1" > "$HGTMP/msg" MD5=$(which md5sum 2>/dev/null) || \ MD5=$(which md5 2>/dev/null) [ -x "${MD5}" ] && CHECKSUM=`${MD5} "$HGTMP/msg"` if [ -s "$HGTMP/diff" ]; then $EDITOR "$HGTMP/msg" "$HGTMP/diff" || exit $? else $EDITOR "$HGTMP/msg" || exit $? fi [ -x "${MD5}" ] && (echo "$CHECKSUM" | ${MD5} -c >/dev/null 2>&1 && exit 13) mv "$HGTMP/msg" "$1" exit $?