view hgeditor @ 2079:ee96ca273f32

New lazy index code for revlogs.

This tunes for large repositories.   It does not read the whole
index file in one big chunk, but tries to buffer reads in more
reasonable chunks instead.

Search speeds are improved in two ways.  When trying to find a
specific sha hash, it searches from the end of the file backward.
More recent entries are more likely to be relevant, especially the
tip.

Also, this can load only the mapping of nodes to revlog index number.
Loading the map uses less cpu (no struct.unpack) and much less
memory than loading both the map and the index.

This cuts down the time for hg tip on the 80,000 changeset
kernel repo from 1.8s to 3.69s.  Most commands the pull a single
rev out of a big index get roughly the same benefit.  Commands
that read the whole index are not slower.

#!/bin/sh
#
# This is an example of using HGEDITOR to create of diff to review the
# changes while commiting.

# 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" 1 2 3 6 15 # HUP INT QUIT ABRT TERM

HGTMP="${TMPDIR-/tmp}/hgeditor.$RANDOM.$RANDOM.$RANDOM.$$"
(umask 077 && mkdir "$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"

CHECKSUM=`md5sum "$HGTMP/msg"`
if [ -s "$HGTMP/diff" ]; then
    $EDITOR "$HGTMP/msg" "$HGTMP/diff" || exit $?
else
    $EDITOR "$HGTMP/msg" || exit $?
fi
echo "$CHECKSUM" | md5sum -c >/dev/null 2>&1 && exit 13

mv "$HGTMP/msg" "$1"

exit $?