status: prefer relative paths in Rust code
… when the repository root is under the current directory,
so the kernel needs to traverse fewer directory in every call
to `read_dir` or `symlink_metadata`.
Better yet would be to use libc functions like `openat` and `fstatat`
to remove such repeated traversals entirely, but the standard library
does not provide APIs based on those.
Maybe with a crate like https://crates.io/crates/openat instead?
Benchmarks of `rhg status` show that this patch is neutral in some configurations,
and makes the command up to ~20% faster in others.
Below is semi-arbitrary subset of results. The four numeric columns are:
time (in seconds) with this changeset’s parent, time with this changeset,
time difference (negative is better), time ratio (less than 1 is better).
```
mercurial-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.0061 -> 0.0059: -0.0002 (0.97)
mercurial-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0029 -> 0.0028: -0.0001 (0.97)
mozilla-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.2110 -> 0.2102: -0.0007 (1.00)
mozilla-dirstate-v2 | default-copies-clean.ignored.pbr | 0.0489 -> 0.0401: -0.0088 (0.82)
mozilla-dirstate-v2 | default-copies-clean.no-iu.pbr | 0.0479 -> 0.0393: -0.0085 (0.82)
mozilla-dirstate-v2 | default-copies-large.all.pbr | 0.1262 -> 0.1210: -0.0051 (0.96)
mozilla-dirstate-v2 | default-copies-small.ignored-unknown.pbr | 0.1262 -> 0.1200: -0.0062 (0.95)
mozilla-dirstate-v2 | default-copies-small.ignored.pbr | 0.0536 -> 0.0417: -0.0119 (0.78)
mozilla-dirstate-v2 | default-copies-small.no-iu.pbr | 0.0482 -> 0.0393: -0.0089 (0.81)
mozilla-dirstate-v2 | default-plain-clean.ignored.pbr | 0.0518 -> 0.0402: -0.0116 (0.78)
mozilla-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0481 -> 0.0392: -0.0088 (0.82)
mozilla-dirstate-v2 | default-plain-large.all.pbr | 0.1271 -> 0.1218: -0.0052 (0.96)
mozilla-dirstate-v2 | default-plain-small.ignored-unknown.pbr | 0.1225 -> 0.1202: -0.0022 (0.98)
mozilla-dirstate-v2 | default-plain-small.ignored.pbr | 0.0510 -> 0.0418: -0.0092 (0.82)
mozilla-dirstate-v2 | default-plain-small.no-iu.pbr | 0.0480 -> 0.0394: -0.0086 (0.82)
netbeans-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.1442 -> 0.1422: -0.0020 (0.99)
netbeans-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0325 -> 0.0282: -0.0043 (0.87)
```
Differential Revision: https://phab.mercurial-scm.org/D12175
#!/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 $?