# 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 will by default not be

pulled down. However, when you update to such a revision, any

largefiles needed by that revision are downloaded and cached (if

they have never been downloaded before). One way to pull largefiles

when pulling is thus to use --update, which will update your working

copy to the latest pulled revision (and thereby downloading any new

largefiles).

If you want to pull largefiles you don't need for update yet, then

you can use pull with the `--lfrev` option or the :hg:`lfpull` command.

If you know you are pulling from a non-default location and want to

download all the largefiles that correspond to the new changesets at

the same time, then you can pull with `--lfrev "pulled()"`.

If you just 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 `--lfrev "head(pulled())"` flag to pre-emptively download any largefiles

that are new in the heads you are pulling.

Keep in mind that network access may now be required to update to

changesets that you have not previously updated to. The nature of the

largefiles extension means that updating is no longer guaranteed to

be a local-only operation.

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 __future__ import absolute_import

from mercurial import (

    hg,

    localrepo,

)

from . import (

    lfcommands,

    overrides,

    proto,

    reposetup,

    uisetup as uisetupmod,

)

# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should

# be specifying the version(s) of Mercurial they are tested with, or

# leave the attribute unspecified.

reposetup = reposetup.reposetup

def featuresetup(ui, supported):

    # don't die on seeing a repo with the largefiles requirement

    supported |= set(['largefiles'])

def uisetup(ui):

    localrepo.localrepository.featuresetupfuncs.add(featuresetup)

    hg.wirepeersetupfuncs.append(proto.wirereposetup)

    uisetupmod.uisetup(ui)

cmdtable = lfcommands.cmdtable

revsetpredicate = overrides.revsetpredicate