annotate hgext/largefiles/__init__.py @ 18704:d69585a5c5c0

largefiles: don't cache largefiles for pulled heads by default

After discussion, we've agreed that largefiles for newly pulled heads should
not be cached by default.  The use case for this is using largefiles repos
with multiple remote servers (and therefore multiple remote largefiles caches),
where users will be pulling from non-default locations on a regular basis.  We
think this use case will be significantly less common than the use case where
all largefiles are stored on the same central server, so the default should be
no caching.

The old behavior can be obtained by passing the --cache-largefiles flag to
pull.

# Copyright 2009-2010 Gregory P. Ward
# Copyright 2009-2010 Intelerad Medical Systems Incorporated
# Copyright 2010-2011 Fog Creek Software
# Copyright 2010-2011 Unity Technologies
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''track large binary files

Large binary files tend to be not very compressible, not very
diffable, and not at all mergeable. Such files are not handled
efficiently by Mercurial's storage format (revlog), which is based on
compressed binary deltas; storing large binary files as regular
Mercurial files wastes bandwidth and disk space and increases
Mercurial's memory usage. The largefiles extension addresses these
problems by adding a centralized client-server layer on top of
Mercurial: largefiles live in a *central store* out on the network
somewhere, and you only fetch the revisions that you need when you
need them.

largefiles works by maintaining a "standin file" in .hglf/ for each
largefile. The standins are small (41 bytes: an SHA-1 hash plus
newline) and are tracked by Mercurial. Largefile revisions are
identified by the SHA-1 hash of their contents, which is written to
the standin. largefiles uses that revision ID to get/put largefile
revisions from/to the central store. This saves both disk space and
bandwidth, since you don't need to retrieve all historical revisions
of large files when you clone or pull.

To start a new repository or add new large binary files, just add
--large to your :hg:`add` command. For example::

  $ dd if=/dev/urandom of=randomdata count=2000
  $ hg add --large randomdata
  $ hg commit -m 'add randomdata as a largefile'

When you push a changeset that adds/modifies largefiles to a remote
repository, its largefile revisions will be uploaded along with it.
Note that the remote Mercurial must also have the largefiles extension
enabled for this to work.

When you pull a changeset that affects largefiles from a remote
repository, the largefiles for the changeset won't be pulled down.
Instead, when you later update to such a revision, any largefiles
needed by that revision are downloaded and cached (if they have
never been downloaded before).  This means that network access may
be required to update to changesets you have previously updated to.

If you know you are pulling from a non-default location and want to
ensure that you will have the largefiles needed to merge or rebase
with new heads that you are pulling, then you can pull with the
--cache-largefiles flag to pre-emptively download any largefiles
that are new in the heads you are pulling.

The one exception to the "largefiles won't be pulled until you update
to a revision that changes them" rule is when you pull new heads.
Because you could be pulling new heads (that you may later want to
merge with) from a non-default location (that Mercurial won't know
about later), when you pull new heads, largefiles revisions for those
heads are downloaded and cached locally.

If you already have large files tracked by Mercurial without the
largefiles extension, you will need to convert your repository in
order to benefit from largefiles. This is done with the
:hg:`lfconvert` command::

  $ hg lfconvert --size 10 oldrepo newrepo

In repositories that already have largefiles in them, any new file
over 10MB will automatically be added as a largefile. To change this
threshold, set ``largefiles.minsize`` in your Mercurial config file
to the minimum size in megabytes to track as a largefile, or use the
--lfsize option to the add command (also in megabytes)::

  [largefiles]
  minsize = 2

  $ hg add --lfsize 2

The ``largefiles.patterns`` config option allows you to specify a list
of filename patterns (see :hg:`help patterns`) that should always be
tracked as largefiles::

  [largefiles]
  patterns =
    *.jpg
    re:.*\.(png|bmp)$
    library.zip
    content/audio/*

Files that match one of these patterns will be added as largefiles
regardless of their size.

The ``largefiles.minsize`` and ``largefiles.patterns`` config options
will be ignored for any repositories not already containing a
largefile. To add the first largefile to a repository, you must
explicitly do so with the --large flag passed to the :hg:`add`
command.
'''

from mercurial import commands

import lfcommands
import reposetup
import uisetup

testedwith = 'internal'

reposetup = reposetup.reposetup
uisetup = uisetup.uisetup

commands.norepo += " lfconvert"

cmdtable = lfcommands.cmdtable