hg: obtain lock when creating share from pooled repo (
issue5104)
There are race conditions between clients performing a shared clone
to pooled storage:
1) Clients race to create the new shared repo in the pool directory
2) 1 client is seeding the repo in the pool directory and another goes
to share it before it is fully cloned
We prevent these race conditions by obtaining a lock in the pool
directory that is derived from the name of the repo we will be
accessing.
To test this, a simple generic "lockdelay" extension has been added.
The extension inserts an optional, configurable delay before or after
lock acquisition. In the test, we delay 2 seconds after lock acquisition
in the first process and 1 second before lock acquisition in the 2nd
process. This means the first process has 1s to obtain the lock. There
is a race condition here. If we encounter it in the wild, we could
change the dummy extension to wait on the lock file to appear instead
of relying on timing. But that's more complicated. Let's see what
happens first.
PYTHONVER=2.7.10
PYTHONNAME=python-
PREFIX=$(HOME)/bin/prefix-$(PYTHONNAME)$(PYTHONVER)
SYMLINKDIR=$(HOME)/bin
help:
@echo
@echo 'Make a custom installation of a Python version'
@echo
@echo 'Common make parameters:'
@echo ' PYTHONVER=... [$(PYTHONVER)]'
@echo ' PREFIX=... [$(PREFIX)]'
@echo ' SYMLINKDIR=... [$(SYMLINKDIR) creating $(PYTHONNAME)$(PYTHONVER)]'
@echo
@echo 'Common make targets:'
@echo ' python - install Python $$PYTHONVER in $$PREFIX'
@echo ' symlink - create a $$SYMLINKDIR/$(PYTHONNAME)$$PYTHONVER symlink'
@echo
@echo 'Example: create a temporary Python installation:'
@echo ' $$ make -f Makefile.python python PYTHONVER=${PYTHONVER} PREFIX=/tmp/p27'
@echo ' $$ /tmp/p27/bin/python -V'
@echo ' Python 2.7'
@echo
@echo 'Some external libraries are required for building Python: zlib bzip2 openssl.'
@echo 'Make sure their development packages are installed systemwide.'
# fedora: yum install zlib-devel bzip2-devel openssl-devel
# debian: apt-get install zlib1g-dev libbz2-dev libssl-dev
@echo
@echo 'To build a nice collection of interesting Python versions:'
@echo ' $$ for v in 2.{6{,.1,.2,.9},7{,.8,.10}}; do'
@echo ' make -f Makefile.python symlink PYTHONVER=$$v || break; done'
@echo 'To run a Mercurial test on all these Python versions:'
@echo ' $$ for py in `cd ~/bin && ls $(PYTHONNAME)2.*`; do'
@echo ' echo $$py; $$py run-tests.py test-http.t; echo; done'
@echo
export LANGUAGE=C
export LC_ALL=C
python: $(PREFIX)/bin/python docutils
printf 'import sys, zlib, bz2, docutils, ssl' | $(PREFIX)/bin/python
PYTHON_SRCDIR=Python-$(PYTHONVER)
PYTHON_SRCFILE=$(PYTHON_SRCDIR).tgz
$(PREFIX)/bin/python:
[ -f $(PYTHON_SRCFILE) ] || wget http://www.python.org/ftp/python/$(PYTHONVER)/$(PYTHON_SRCFILE) || curl -OL http://www.python.org/ftp/python/$(PYTHONVER)/$(PYTHON_SRCFILE) || [ -f $(PYTHON_SRCFILE) ]
rm -rf $(PYTHON_SRCDIR)
tar xf $(PYTHON_SRCFILE)
# Debian/Ubuntu disables SSLv2,3 the hard way, disable it on old Pythons too
-sed -i 's,self.*SSLv[23]_method(),0;//\0,g' $(PYTHON_SRCDIR)/Modules/_ssl.c
# Find multiarch system libraries on Ubuntu and disable fortify error when setting argv
LDFLAGS="-L/usr/lib/`dpkg-architecture -qDEB_HOST_MULTIARCH`"; \
BASECFLAGS=-U_FORTIFY_SOURCE; \
export LDFLAGS BASECFLAGS; \
cd $(PYTHON_SRCDIR) && ./configure --prefix=$(PREFIX) && make all SVNVERSION=pwd && make install
printf 'import sys, zlib, bz2, ssl' | $(PREFIX)/bin/python
rm -rf $(PYTHON_SRCDIR)
DOCUTILSVER=0.12
DOCUTILS_SRCDIR=docutils-$(DOCUTILSVER)
DOCUTILS_SRCFILE=$(DOCUTILS_SRCDIR).tar.gz
docutils: $(PREFIX)/bin/python
@$(PREFIX)/bin/python -c 'import docutils' || ( set -ex; \
[ -f $(DOCUTILS_SRCFILE) ] || wget http://downloads.sourceforge.net/project/docutils/docutils/$(DOCUTILSVER)/$(DOCUTILS_SRCFILE) || [ -f $(DOCUTILS_SRCFILE) ]; \
rm -rf $(DOCUTILS_SRCDIR); \
tar xf $(DOCUTILS_SRCFILE); \
cd $(DOCUTILS_SRCDIR) && $(PREFIX)/bin/python setup.py install --prefix=$(PREFIX); \
$(PREFIX)/bin/python -c 'import docutils'; \
rm -rf $(DOCUTILS_SRCDIR); )
symlink: python $(SYMLINKDIR)
ln -sf $(PREFIX)/bin/python $(SYMLINKDIR)/$(PYTHONNAME)$(PYTHONVER)
.PHONY: help python docutils symlink