Revision d699676dda5fdf0996601006c3bac2a9c077a862 authored by Linus Torvalds on 10 August 2007, 19:31:20 UTC, committed by Junio C Hamano on 10 August 2007, 21:00:25 UTC
This trivially optimizes the two-way merge case of git-read-tree too,
which affects switching branches.

When you have tons and tons of files in your repository, but there are
only small differences in the branches (maybe just a couple of files
changed), the biggest cost of the branch switching was actually just the
index calculations.

This fixes it (timings for switching between the "testing" and "master"
branches in the 100,000 file testing-repo-from-hell, where the branches
only differ in one small file).

Before:
	[torvalds@woody bummer]$ time git checkout master
	real    0m9.919s
	user    0m8.461s
	sys     0m0.264s

After:
	[torvalds@woody bummer]$ time git checkout testing
	real    0m0.576s
	user    0m0.348s
	sys     0m0.228s

so it's easily an order of magnitude different.

This concludes the series. I think we could/should do the three-way merge
too (to speed up merges), but I'm lazy. Somebody else can do it.

The rule is very simple: you need to remove the old entry if:
 - you want to remove the file entirely
 - you replace it with a "merge conflict" entry (ie a non-stage-0 entry)

and you can avoid removing it if you either

 - keep the old one
 - or resolve it to a new one.

and these rules should all be valid for the three-way case too.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 288f072
Raw File
git-sh-setup.sh
#!/bin/sh
#
# This is included in commands that either have to be run from the toplevel
# of the repository, or with GIT_DIR environment variable properly.
# If the GIT_DIR does not look like the right correct git-repository,
# it dies.

# Having this variable in your environment would break scripts because
# you would cause "cd" to be be taken to unexpected places.  If you
# like CDPATH, define it for your interactive shell sessions without
# exporting it.
unset CDPATH

die() {
	echo >&2 "$@"
	exit 1
}

usage() {
	die "Usage: $0 $USAGE"
}

set_reflog_action() {
	if [ -z "${GIT_REFLOG_ACTION:+set}" ]
	then
		GIT_REFLOG_ACTION="$*"
		export GIT_REFLOG_ACTION
	fi
}

git_editor() {
	: "${GIT_EDITOR:=$(git config core.editor)}"
	: "${GIT_EDITOR:=${VISUAL:-${EDITOR}}}"
	case "$GIT_EDITOR,$TERM" in
	,dumb)
		echo >&2 "No editor specified in GIT_EDITOR, core.editor, VISUAL,"
		echo >&2 "or EDITOR. Tried to fall back to vi but terminal is dumb."
		echo >&2 "Please set one of these variables to an appropriate"
		echo >&2 "editor or run $0 with options that will not cause an"
		echo >&2 "editor to be invoked (e.g., -m or -F for git-commit)."
		exit 1
		;;
	esac
	eval "${GIT_EDITOR:=vi}" '"$@"'
}

is_bare_repository () {
	git rev-parse --is-bare-repository
}

cd_to_toplevel () {
	cdup=$(git rev-parse --show-cdup)
	if test ! -z "$cdup"
	then
		cd "$cdup" || {
			echo >&2 "Cannot chdir to $cdup, the toplevel of the working tree"
			exit 1
		}
	fi
}

require_work_tree () {
	test $(git rev-parse --is-inside-work-tree) = true ||
	die "fatal: $0 cannot be used without a working tree."
}

get_author_ident_from_commit () {
	pick_author_script='
	/^author /{
		s/'\''/'\''\\'\'\''/g
		h
		s/^author \([^<]*\) <[^>]*> .*$/\1/
		s/'\''/'\''\'\'\''/g
		s/.*/GIT_AUTHOR_NAME='\''&'\''/p

		g
		s/^author [^<]* <\([^>]*\)> .*$/\1/
		s/'\''/'\''\'\'\''/g
		s/.*/GIT_AUTHOR_EMAIL='\''&'\''/p

		g
		s/^author [^<]* <[^>]*> \(.*\)$/\1/
		s/'\''/'\''\'\'\''/g
		s/.*/GIT_AUTHOR_DATE='\''&'\''/p

		q
	}
	'
	encoding=$(git config i18n.commitencoding || echo UTF-8)
	git show -s --pretty=raw --encoding="$encoding" "$1" |
	LANG=C LC_ALL=C sed -ne "$pick_author_script"
}

if [ -z "$LONG_USAGE" ]
then
	LONG_USAGE="Usage: $0 $USAGE"
else
	LONG_USAGE="Usage: $0 $USAGE

$LONG_USAGE"
fi

case "$1" in
	-h|--h|--he|--hel|--help)
	echo "$LONG_USAGE"
	exit
esac

# Make sure we are in a valid repository of a vintage we understand.
if [ -z "$SUBDIRECTORY_OK" ]
then
	: ${GIT_DIR=.git}
	GIT_DIR=$(GIT_DIR="$GIT_DIR" git rev-parse --git-dir) || {
		exit=$?
		echo >&2 "You need to run this command from the toplevel of the working tree."
		exit $exit
	}
else
	GIT_DIR=$(git rev-parse --git-dir) || exit
fi
: ${GIT_OBJECT_DIRECTORY="$GIT_DIR/objects"}
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