xdiff: add a preprocessing step that trims files
xdiff has a `xdl_trim_ends` step that removes common lines, unmatchable
lines. That is in theory good, but happens too late - after splitting,
hashing, and adjusting the hash values so they are unique. Those splitting,
hashing and adjusting hash values steps could have noticeable overhead.
Diffing two large files with minor (one-line-ish) changes are not uncommon.
In that case, the raw performance of those preparation steps seriously
matter. Even allocating an O(N) array and storing line offsets to it is
expensive. Therefore my previous attempts [1] [2] cannot be good enough
since they do not remove the O(N) array assignment.
This patch adds a preprocessing step - `xdl_trim_files` that runs before
other preprocessing steps. It counts common prefix and suffix and lines in
them (needed for displaying line number), without doing anything else.
Testing with a crafted large (169MB) file, with minor change:
```
open('a','w').write(''.join('%s\n' % (i % 100000) for i in xrange(
30000000) if i != 6000000))
open('b','w').write(''.join('%s\n' % (i % 100000) for i in xrange(
30000000) if i != 6003000))
```
Running xdiff by a simple binary [3], this patch improves the xdiff perf by
more than 10x for the above case:
```
# xdiff before this patch
2.41s user 1.13s system 98% cpu 3.592 total
# xdiff after this patch
0.14s user 0.16s system 98% cpu 0.309 total
# gnu diffutils
0.12s user 0.15s system 98% cpu 0.272 total
# (best of 20 runs)
```
It's still slightly slower than GNU diffutils. But it's pretty close now.
Testing with real repo data:
For the whole repo, this patch makes xdiff 25% faster:
```
# hg perfbdiff --count 100 --alldata -c
d334afc585e2 --blocks [--xdiff]
# xdiff, after
! wall 0.058861 comb 0.050000 user 0.050000 sys 0.000000 (best of 100)
# xdiff, before
! wall 0.077816 comb 0.080000 user 0.080000 sys 0.000000 (best of 91)
# bdiff
! wall 0.117473 comb 0.120000 user 0.120000 sys 0.000000 (best of 67)
```
For files that are long (ex. commands.py), the speedup is more than 3x, very
significant:
```
# hg perfbdiff --count 3000 --blocks commands.py.i 1 [--xdiff]
# xdiff, after
! wall 0.690583 comb 0.690000 user 0.690000 sys 0.000000 (best of 12)
# xdiff, before
! wall 2.240361 comb 2.210000 user 2.210000 sys 0.000000 (best of 4)
# bdiff
! wall 2.469852 comb 2.440000 user 2.440000 sys 0.000000 (best of 4)
```
[1]: https://phab.mercurial-scm.org/D2631
[2]: https://phab.mercurial-scm.org/D2634
[3]:
```
// Code to run xdiff from command line. No proper error handling.
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "mercurial/thirdparty/xdiff/xdiff.h"
#define ensure(x) if (!(x)) exit(255);
mmfile_t readfile(const char *path) {
struct stat st; int fd = open(path, O_RDONLY);
fstat(fd, &st); mmfile_t file = { malloc(st.st_size), st.st_size };
ensure(read(fd, file.ptr, st.st_size) == st.st_size); close(fd);
return file;
}
int main(int argc, char const *argv[]) {
mmfile_t a = readfile(argv[1]), b = readfile(argv[2]);
xpparam_t xpp = {0}; xdemitconf_t xecfg = {0}; xdemitcb_t ecb = {0};
xdl_diff(&a, &b, &xpp, &xecfg, &ecb);
return 0;
}
```
Differential Revision: https://phab.mercurial-scm.org/D2686
# If you want to change PREFIX, do not just edit it below. The changed
# value wont get passed on to recursive make calls. You should instead
# override the variable on the command like:
#
# % make PREFIX=/opt/ install
export PREFIX=/usr/local
PYTHON=python
$(eval HGROOT := $(shell pwd))
HGPYTHONS ?= $(HGROOT)/build/pythons
PURE=
PYFILES:=$(shell find mercurial hgext doc -name '*.py')
DOCFILES=mercurial/help/*.txt
export LANGUAGE=C
export LC_ALL=C
TESTFLAGS ?= $(shell echo $$HGTESTFLAGS)
OSXVERSIONFLAGS ?= $(shell echo $$OSXVERSIONFLAGS)
# Set this to e.g. "mingw32" to use a non-default compiler.
COMPILER=
COMPILERFLAG_tmp_ =
COMPILERFLAG_tmp_${COMPILER} ?= -c $(COMPILER)
COMPILERFLAG=${COMPILERFLAG_tmp_${COMPILER}}
help:
@echo 'Commonly used make targets:'
@echo ' all - build program and documentation'
@echo ' install - install program and man pages to $$PREFIX ($(PREFIX))'
@echo ' install-home - install with setup.py install --home=$$HOME ($(HOME))'
@echo ' local - build for inplace usage'
@echo ' tests - run all tests in the automatic test suite'
@echo ' test-foo - run only specified tests (e.g. test-merge1.t)'
@echo ' dist - run all tests and create a source tarball in dist/'
@echo ' clean - remove files created by other targets'
@echo ' (except installed files or dist source tarball)'
@echo ' update-pot - update i18n/hg.pot'
@echo
@echo 'Example for a system-wide installation under /usr/local:'
@echo ' make all && su -c "make install" && hg version'
@echo
@echo 'Example for a local installation (usable in this directory):'
@echo ' make local && ./hg version'
all: build doc
local:
$(PYTHON) setup.py $(PURE) \
build_py -c -d . \
build_ext $(COMPILERFLAG) -i \
build_hgexe $(COMPILERFLAG) -i \
build_mo
env HGRCPATH= $(PYTHON) hg version
build:
$(PYTHON) setup.py $(PURE) build $(COMPILERFLAG)
wheel:
FORCE_SETUPTOOLS=1 $(PYTHON) setup.py $(PURE) bdist_wheel $(COMPILERFLAG)
doc:
$(MAKE) -C doc
cleanbutpackages:
-$(PYTHON) setup.py clean --all # ignore errors from this command
find contrib doc hgext hgext3rd i18n mercurial tests hgdemandimport \
\( -name '*.py[cdo]' -o -name '*.so' \) -exec rm -f '{}' ';'
rm -f MANIFEST MANIFEST.in hgext/__index__.py tests/*.err
rm -f mercurial/__modulepolicy__.py
if test -d .hg; then rm -f mercurial/__version__.py; fi
rm -rf build mercurial/locale
$(MAKE) -C doc clean
$(MAKE) -C contrib/chg distclean
clean: cleanbutpackages
rm -rf packages
install: install-bin install-doc
install-bin: build
$(PYTHON) setup.py $(PURE) install --root="$(DESTDIR)/" --prefix="$(PREFIX)" --force
install-doc: doc
cd doc && $(MAKE) $(MFLAGS) install
install-home: install-home-bin install-home-doc
install-home-bin: build
$(PYTHON) setup.py $(PURE) install --home="$(HOME)" --prefix="" --force
install-home-doc: doc
cd doc && $(MAKE) $(MFLAGS) PREFIX="$(HOME)" install
MANIFEST-doc:
$(MAKE) -C doc MANIFEST
MANIFEST.in: MANIFEST-doc
hg manifest | sed -e 's/^/include /' > MANIFEST.in
echo include mercurial/__version__.py >> MANIFEST.in
sed -e 's/^/include /' < doc/MANIFEST >> MANIFEST.in
dist: tests dist-notests
dist-notests: doc MANIFEST.in
TAR_OPTIONS="--owner=root --group=root --mode=u+w,go-w,a+rX-s" $(PYTHON) setup.py -q sdist
check: tests
tests:
cd tests && $(PYTHON) run-tests.py $(TESTFLAGS)
test-%:
cd tests && $(PYTHON) run-tests.py $(TESTFLAGS) $@
testpy-%:
@echo Looking for Python $* in $(HGPYTHONS)
[ -e $(HGPYTHONS)/$*/bin/python ] || ( \
cd $$(mktemp --directory --tmpdir) && \
$(MAKE) -f $(HGROOT)/contrib/Makefile.python PYTHONVER=$* PREFIX=$(HGPYTHONS)/$* python )
cd tests && $(HGPYTHONS)/$*/bin/python run-tests.py $(TESTFLAGS)
check-code:
hg manifest | xargs python contrib/check-code.py
format-c:
clang-format --style file -i \
`hg files 'set:(**.c or **.cc or **.h) and not "listfile:contrib/clang-format-blacklist"'`
update-pot: i18n/hg.pot
i18n/hg.pot: $(PYFILES) $(DOCFILES) i18n/posplit i18n/hggettext
$(PYTHON) i18n/hggettext mercurial/commands.py \
hgext/*.py hgext/*/__init__.py \
mercurial/fileset.py mercurial/revset.py \
mercurial/templatefilters.py mercurial/templatekw.py \
mercurial/templater.py \
mercurial/filemerge.py \
mercurial/hgweb/webcommands.py \
mercurial/util.py \
$(DOCFILES) > i18n/hg.pot.tmp
# All strings marked for translation in Mercurial contain
# ASCII characters only. But some files contain string
# literals like this '\037\213'. xgettext thinks it has to
# parse them even though they are not marked for translation.
# Extracting with an explicit encoding of ISO-8859-1 will make
# xgettext "parse" and ignore them.
echo $(PYFILES) | xargs \
xgettext --package-name "Mercurial" \
--msgid-bugs-address "<mercurial-devel@mercurial-scm.org>" \
--copyright-holder "Matt Mackall <mpm@selenic.com> and others" \
--from-code ISO-8859-1 --join --sort-by-file --add-comments=i18n: \
-d hg -p i18n -o hg.pot.tmp
$(PYTHON) i18n/posplit i18n/hg.pot.tmp
# The target file is not created before the last step. So it never is in
# an intermediate state.
mv -f i18n/hg.pot.tmp i18n/hg.pot
%.po: i18n/hg.pot
# work on a temporary copy for never having a half completed target
cp $@ $@.tmp
msgmerge --no-location --update $@.tmp $^
mv -f $@.tmp $@
# Packaging targets
osx:
rm -rf build/mercurial
/usr/bin/python2.7 setup.py install --optimize=1 \
--root=build/mercurial/ --prefix=/usr/local/ \
--install-lib=/Library/Python/2.7/site-packages/
make -C doc all install DESTDIR="$(PWD)/build/mercurial/"
# Place a bogon .DS_Store file in the target dir so we can be
# sure it doesn't get included in the final package.
touch build/mercurial/.DS_Store
# install zsh completions - this location appears to be
# searched by default as of macOS Sierra.
install -d build/mercurial/usr/local/share/zsh/site-functions/
install -m 0644 contrib/zsh_completion build/mercurial/usr/local/share/zsh/site-functions/_hg
# install bash completions - there doesn't appear to be a
# place that's searched by default for bash, so we'll follow
# the lead of Apple's git install and just put it in a
# location of our own.
install -d build/mercurial/usr/local/hg/contrib/
install -m 0644 contrib/bash_completion build/mercurial/usr/local/hg/contrib/hg-completion.bash
make -C contrib/chg \
HGPATH=/usr/local/bin/hg \
PYTHON=/usr/bin/python2.7 \
HGEXTDIR=/Library/Python/2.7/site-packages/hgext \
DESTDIR=../../build/mercurial \
PREFIX=/usr/local \
clean install
mkdir -p $${OUTPUTDIR:-dist}
HGVER=$$(python contrib/genosxversion.py $(OSXVERSIONFLAGS) build/mercurial/Library/Python/2.7/site-packages/mercurial/__version__.py) && \
OSXVER=$$(sw_vers -productVersion | cut -d. -f1,2) && \
pkgbuild --filter \\.DS_Store --root build/mercurial/ \
--identifier org.mercurial-scm.mercurial \
--version "$${HGVER}" \
build/mercurial.pkg && \
productbuild --distribution contrib/macosx/distribution.xml \
--package-path build/ \
--version "$${HGVER}" \
--resources contrib/macosx/ \
"$${OUTPUTDIR:-dist/}"/Mercurial-"$${HGVER}"-macosx"$${OSXVER}".pkg
deb:
contrib/builddeb
ppa:
contrib/builddeb --source-only
contrib/docker/debian-%: contrib/docker/debian.template
sed "s/__CODENAME__/$*/" $< > $@
docker-debian-jessie: contrib/docker/debian-jessie
mkdir -p packages/debian-jessie
contrib/dockerdeb debian jessie
docker-debian-stretch: contrib/docker/debian-stretch
mkdir -p packages/debian-stretch
contrib/dockerdeb debian stretch
contrib/docker/ubuntu-%: contrib/docker/ubuntu.template
sed "s/__CODENAME__/$*/" $< > $@
docker-ubuntu-trusty: contrib/docker/ubuntu-trusty
contrib/dockerdeb ubuntu trusty
docker-ubuntu-trusty-ppa: contrib/docker/ubuntu-trusty
contrib/dockerdeb ubuntu trusty --source-only
docker-ubuntu-xenial: contrib/docker/ubuntu-xenial
contrib/dockerdeb ubuntu xenial
docker-ubuntu-xenial-ppa: contrib/docker/ubuntu-xenial
contrib/dockerdeb ubuntu xenial --source-only
docker-ubuntu-artful: contrib/docker/ubuntu-artful
contrib/dockerdeb ubuntu artful
docker-ubuntu-artful-ppa: contrib/docker/ubuntu-artful
contrib/dockerdeb ubuntu artful --source-only
fedora20:
mkdir -p packages/fedora20
contrib/buildrpm
cp rpmbuild/RPMS/*/* packages/fedora20
cp rpmbuild/SRPMS/* packages/fedora20
rm -rf rpmbuild
docker-fedora20:
mkdir -p packages/fedora20
contrib/dockerrpm fedora20
fedora21:
mkdir -p packages/fedora21
contrib/buildrpm
cp rpmbuild/RPMS/*/* packages/fedora21
cp rpmbuild/SRPMS/* packages/fedora21
rm -rf rpmbuild
docker-fedora21:
mkdir -p packages/fedora21
contrib/dockerrpm fedora21
centos5:
mkdir -p packages/centos5
contrib/buildrpm --withpython
cp rpmbuild/RPMS/*/* packages/centos5
cp rpmbuild/SRPMS/* packages/centos5
docker-centos5:
mkdir -p packages/centos5
contrib/dockerrpm centos5 --withpython
centos6:
mkdir -p packages/centos6
contrib/buildrpm --withpython
cp rpmbuild/RPMS/*/* packages/centos6
cp rpmbuild/SRPMS/* packages/centos6
docker-centos6:
mkdir -p packages/centos6
contrib/dockerrpm centos6 --withpython
centos7:
mkdir -p packages/centos7
contrib/buildrpm
cp rpmbuild/RPMS/*/* packages/centos7
cp rpmbuild/SRPMS/* packages/centos7
docker-centos7:
mkdir -p packages/centos7
contrib/dockerrpm centos7
linux-wheels: linux-wheels-x86_64 linux-wheels-i686
linux-wheels-x86_64:
docker run -e "HGTEST_JOBS=$(shell nproc)" --rm -ti -v `pwd`:/src quay.io/pypa/manylinux1_x86_64 /src/contrib/build-linux-wheels.sh
linux-wheels-i686:
docker run -e "HGTEST_JOBS=$(shell nproc)" --rm -ti -v `pwd`:/src quay.io/pypa/manylinux1_i686 linux32 /src/contrib/build-linux-wheels.sh
.PHONY: help all local build doc cleanbutpackages clean install install-bin \
install-doc install-home install-home-bin install-home-doc \
dist dist-notests check tests check-code format-c update-pot \
osx deb ppa docker-debian-jessie docker-debian-stretch \
docker-ubuntu-trusty docker-ubuntu-trusty-ppa \
docker-ubuntu-xenial docker-ubuntu-xenial-ppa \
docker-ubuntu-artful docker-ubuntu-artful-ppa \
fedora20 docker-fedora20 fedora21 docker-fedora21 \
centos5 docker-centos5 centos6 docker-centos6 centos7 docker-centos7 \
linux-wheels