view Makefile @ 40022:c537144fdbef

wireprotov2: support response caching

One of the things I've learned from managing VCS servers over the
years is that they are hard to scale. It is well known that some
companies have very beefy (read: very expensive) servers to power
their VCS needs. It is also known that specialized servers for
various VCS exist in order to facilitate scaling servers. (Mercurial
is in this boat.)

One of the aspects that make a VCS server hard to scale is the
high CPU load incurred by constant client clone/pull operations.

To alleviate the scaling pain associated with data retrieval
operations, I want to integrate caching into the Mercurial wire
protocol server as robustly as possible such that servers can
aggressively cache responses and defer as much server load as
possible.

This commit represents the initial implementation of a general
caching layer in wire protocol version 2.

We define a new interface and behavior for a wire protocol cacher
in repository.py. (This is probably where a reviewer should look
first to understand what is going on.)

The bulk of the added code is in wireprotov2server.py, where we
define how a command can opt in to being cached and integrate
caching into command dispatching.

From a very high-level:

* A command can declare itself as cacheable by providing a callable
  that can be used to derive a cache key.
* At dispatch time, if a command is cacheable, we attempt to
  construct a cacher and use it for serving the request and/or
  caching the request.
* The dispatch layer handles the bulk of the business logic for
  caching, making cachers mostly "dumb content stores."
* The mechanism for invalidating cached entries (one of the harder
  parts about caching in general) is by varying the cache key when
  state changes. As such, cachers don't need to be concerned with
  cache invalidation.

Initially, we've hooked up support for caching "manifestdata" and
"filedata" commands. These are the simplest to cache, as they should
be immutable over time. Caching of commands related to changeset
data is a bit harder (because cache validation is impacted by
changes to bookmarks, phases, etc). This will be implemented later.
(Strictly speaking, censoring a file should invalidate caches. I've
added an inline TODO to track this edge case.)

To prove it works, this commit implements a test-only extension
providing in-memory caching backed by an lrucachedict. A new test
showing this extension behaving properly is added. FWIW, the
cacher is ~50 lines of code, demonstrating the relative ease with
which a cache can be added to a server.

While the test cacher is not suitable for production workloads, just
for kicks I performed a clone of just the changeset and manifest data
for the mozilla-unified repository. With a fully warmed cache (of just
the manifest data since changeset data is not cached), server-side
CPU usage dropped from ~73s to ~28s. That's pretty significant and
demonstrates the potential that response caching has on server
scalability!

Differential Revision: https://phab.mercurial-scm.org/D4773

# 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 ?= $(HGROOT)/build/pythons
PURE=
PYFILESCMD=find mercurial hgext doc -name '*.py'
PYFILES:=$(shell $(PYFILESCMD))
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.
	$(PYFILESCMD) | xargs \
	  xgettext --package-name "Mercurial" \
	  --msgid-bugs-address "<[e-mail]>" \
	  --copyright-holder "Matt Mackall <[e-mail]> 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