fix race in localrepo.addchangegroup.
localrepo.addchangegroup writes to changelog, then manifest, then normal
files. this breaks access ordering. if reader reads changelog while
manifest is being written, can find pointers into places in manifest
that are not yet written. same can happen for manifest and normal files.
fix is to make almost no change to localrepo.addchangegroup. it must
to write changelog and manifest data early because it has to read them
while writing other files. instead, write changelog and manifest data
to temp file that reader cannot see, then append temp data to manifest
after all normal files written, finally append temp data to changelog.
temp file code is in new appendfile module. can be used in other places
with small changes.
much smaller race still left. we write all new data in one write call,
but reader can maybe see partial update because python or os or filesystem
cannot always make write really atomic. file locking no help: slow, not
portable, not reliable over nfs. only real safe other plan is write to
temp file every time and rename, but performance bad when manifest or
changelog is big.
MERCURIAL QUICK-START
Setting up Mercurial:
Note: some distributions fails to include bits of distutils by
default, you'll need python-dev to install. You'll also need a C
compiler and a 3-way merge tool like merge, tkdiff, or kdiff3.
First, unpack the source:
$ tar xvzf mercurial-<ver>.tar.gz
$ cd mercurial-<ver>
To install system-wide:
$ python setup.py install # change python to python2.3 if 2.2 is default
To install in your home directory (~/bin and ~/lib, actually), run:
$ python2.3 setup.py install --home=~
$ export PYTHONPATH=${HOME}/lib/python # (or lib64/ on some systems)
$ export PATH=${HOME}/bin:$PATH # add these to your .bashrc
And finally:
$ hg # test installation, show help
If you get complaints about missing modules, you probably haven't set
PYTHONPATH correctly.
Setting up a Mercurial project:
$ cd project/
$ hg init # creates .hg
$ hg addremove # add all unknown files and remove all missing files
$ hg commit # commit all changes, edit changelog entry
Mercurial will look for a file named .hgignore in the root of your
repository which contains a set of regular expressions to ignore in
file paths.
Branching and merging:
$ hg clone linux linux-work # create a new branch
$ cd linux-work
$ <make changes>
$ hg commit
$ cd ../linux
$ hg pull ../linux-work # pull changesets from linux-work
$ hg update -m # merge the new tip from linux-work into
# our working directory
$ hg commit # commit the result of the merge
Importing patches:
Fast:
$ patch < ../p/foo.patch
$ hg addremove
$ hg commit
Faster:
$ patch < ../p/foo.patch
$ hg commit `lsdiff -p1 ../p/foo.patch`
Fastest:
$ cat ../p/patchlist | xargs hg import -p1 -b ../p
Exporting a patch:
(make changes)
$ hg commit
$ hg tip
28237:747a537bd090880c29eae861df4d81b245aa0190
$ hg export 28237 > foo.patch # export changeset 28237
Network support:
# pull from the primary Mercurial repo
foo$ hg clone http://selenic.com/hg/
foo$ cd hg
# export your current repo via HTTP with browsable interface
foo$ hg serve -n "My repo" -p 80
# pushing changes to a remote repo with SSH
foo$ hg push ssh://user@example.com/~/hg/
# merge changes from a remote machine
bar$ hg pull http://foo/
bar$ hg update -m # merge changes into your working directory
# Set up a CGI server on your webserver
foo$ cp hgweb.cgi ~/public_html/hg/index.cgi
foo$ emacs ~/public_html/hg/index.cgi # adjust the defaults
For more info:
Documentation in doc/
Mercurial website at http://selenic.com/mercurial
Mercurial wiki at http://selenic.com/mercurial/wiki