sparse-revlog: implement algorithm to write sparse delta chains (
issue5480)
The classic behavior of revlog._isgooddeltainfo is to consider the span size
of the whole delta chain, and limit it to 4 * textlen.
Once sparse-revlog writing is allowed (and enforced with a requirement),
revlog._isgooddeltainfo considers the span of the largest chunk as the
distance used in the verification, instead of using the span of the whole
delta chain.
In order to compute the span of the largest chunk, we need to slice into
chunks a chain with the new revision at the top of the revlog, and take the
maximal span of these chunks. The sparse read density is a parameter to the
slicing, as it will stop when the global read density reaches this threshold.
For instance, a density of 50% means that 2 of 4 read bytes are actually used
for the reconstruction of the revision (the others are part of other chains).
This allows a new revision to be potentially stored with a diff against
another revision anywhere in the history, instead of forcing it in the last 4
* textlen. The result is a much better compression on repositories that have
many concurrent branches. Here are a comparison between using deltas from
current upstream (aggressive-merge-deltas on by default) and deltas from a
sparse-revlog
Comparison of `.hg/store/` size:
mercurial (6.74% merges):
before: 46,831,873 bytes
after: 46,795,992 bytes (no relevant change)
pypy (8.30% merges):
before: 333,524,651 bytes
after: 308,417,511 bytes -8%
netbeans (34.21% merges):
before: 1,141,847,554 bytes
after: 1,131,093,161 bytes -1%
mozilla-central (4.84% merges):
before: 2,344,248,850 bytes
after: 2,328,459,258 bytes -1%
large-private-repo-A (merge 19.73%)
before: 41,510,550,163 bytes
after: 8,121,763,428 bytes -80%
large-private-repo-B (23.77%)
before: 58,702,221,709 bytes
after: 8,351,588,828 bytes -76%
Comparison of `00manifest.d` size:
mercurial (6.74% merges):
before: 6,143,044 bytes
after: 6,107,163 bytes
pypy (8.30% merges):
before: 52,941,780 bytes
after: 27,834,082 bytes -48%
netbeans (34.21% merges):
before: 130,088,982 bytes
after: 119,337,636 bytes -10%
mozilla-central (4.84% merges):
before: 215,096,339 bytes
after: 199,496,863 bytes -8%
large-private-repo-A (merge 19.73%)
before: 33,725,285,081 bytes
after: 390,302,545 bytes -99%
large-private-repo-B (23.77%)
before: 49,457,701,645 bytes
after: 1,366,752,187 bytes -97%
The better delta chains provide a performance boost in relevant repositories:
pypy, bundling 1000 revisions:
before: 1.670s
after: 1.149s -31%
Unbundling got a bit slower. probably because the sparse algorithm is still
pure
python.
pypy, unbundling 1000 revisions:
before: 4.062s
after: 4.507s +10%
Performance of bundle/unbundle in repository with few concurrent branches (eg:
mercurial) are unaffected.
No significant differences have been noticed then timing `hg push` and `hg
pull` locally. More state timings are being gathered.
Same as for aggressive-merge-delta, better delta comes with longer delta
chains. Longer chains have a performance impact. For example. The length of
the chain needed to get the manifest of pypy's tip moves from 82 item to 1929
items. This moves the restore time from 3.88ms to 11.3ms.
Delta chain length is an independent issue that affects repository without
this changes. It will be dealt with independently.
No significant differences have been observed on repositories where
`sparse-revlog` have not much effect (mercurial, unity, netbeans). On pypy,
small differences have been observed on some operation affected by delta chain
building and retrieval.
pypy, perfmanifest
before: 0.006162s
after: 0.017899s +190%
pypy, commit:
before: 0.382
after: 0.376 -1%
pypy, status:
before: 0.157
after: 0.168 +7%
More comprehensive and stable timing comparisons are in progress.
# 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-ignorelist"'`
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/templatefuncs.py \
mercurial/templatekw.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
packaging_targets := \
centos5 \
centos6 \
centos7 \
deb \
docker-centos5 \
docker-centos6 \
docker-centos7 \
docker-debian-jessie \
docker-debian-stretch \
docker-fedora20 \
docker-fedora21 \
docker-fedora28 \
docker-ubuntu-trusty \
docker-ubuntu-trusty-ppa \
docker-ubuntu-xenial \
docker-ubuntu-xenial-ppa \
docker-ubuntu-artful \
docker-ubuntu-artful-ppa \
docker-ubuntu-bionic \
docker-ubuntu-bionic-ppa \
fedora20 \
fedora21 \
fedora28 \
linux-wheels \
linux-wheels-x86_64 \
linux-wheels-i686 \
ppa
# Forward packaging targets for convenience.
$(packaging_targets):
$(MAKE) -C contrib/packaging $@
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 "$${HGVER}" \
build/mercurial.pkg && \
productbuild --distribution contrib/packaging/macosx/distribution.xml \
--package-path build/ \
--version "$${HGVER}" \
--resources contrib/packaging/macosx/ \
"$${OUTPUTDIR:-dist/}"/Mercurial-"$${HGVER}"-macosx"$${OSXVER}".pkg
.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 \
$(packaging_targets) \
osx