view tests/test-lfs-serve.t @ 40326:fed697fa1734

sqlitestore: file storage backend using SQLite

This commit provides an extension which uses SQLite to store file
data (as opposed to revlogs).

As the inline documentation describes, there are still several
aspects to the extension that are incomplete. But it's a start.
The extension does support basic clone, checkout, and commit
workflows, which makes it suitable for simple use cases.

One notable missing feature is support for "bundlerepos." This is
probably responsible for the most test failures when the extension
is activated as part of the test suite.

All revision data is stored in SQLite. Data is stored as zstd
compressed chunks (default if zstd is available), zlib compressed
chunks (default if zstd is not available), or raw chunks (if
configured or if a compressed delta is not smaller than the raw
delta). This makes things very similar to revlogs.

Unlike revlogs, the extension doesn't yet enforce a limit on delta
chain length. This is an obvious limitation and should be addressed.
This is somewhat mitigated by the use of zstd, which is much faster
than zlib to decompress.

There is a dedicated table for storing deltas. Deltas are stored
by the SHA-1 hash of their uncompressed content. The "fileindex" table
has columns that reference the delta for each revision and the base
delta that delta should be applied against. A recursive SQL query
is used to resolve the delta chain along with the delta data.

By storing deltas by hash, we are able to de-duplicate delta storage!
With revlogs, the same deltas in different revlogs would result in
duplicate storage of that delta. In this scheme, inserting the
duplicate delta is a no-op and delta chains simply reference the
existing delta.

When initially implementing this extension, I did not have
content-indexed deltas and deltas could be duplicated across files
(just like revlogs). When I implemented content-indexed deltas, the
size of the SQLite database for a full clone of mozilla-unified
dropped:

before: 2,554,261,504 bytes
after:  2,488,754,176 bytes

Surprisingly, this is still larger than the bytes size of revlog
files:

revlog files: 2,104,861,230 bytes
du -b:        2,254,381,614

I would have expected storage to be smaller since we're not limiting
delta chain length and since we're using zstd instead of zlib. I
suspect the SQLite indexes and per-column overhead account for the
bulk of the differences. (Keep in mind that revlog uses a 64-byte
packed struct for revision index data and deltas are stored without
padding. Aside from the 12 unused bytes in the 32 byte node field,
revlogs are pretty efficient.) Another source of overhead is file
name storage. With revlogs, file names are stored in the filesystem.
But with SQLite, we need to store file names in the database. This is
roughly equivalent to the size of the fncache file, which for the
mozilla-unified repository is ~34MB.

Since the SQLite database isn't append-only and since delta chains
can reference any delta, this opens some interesting possibilities.
For example, we could store deltas in reverse, such that fulltexts
are stored for newer revisions and deltas are applied to reconstruct
older revisions. This is likely a more optimal storage strategy for
version control, as new data tends to be more frequently accessed
than old data. We would obviously need wire protocol support for
transferring revision data from newest to oldest. And we would
probably need some kind of mechanism for "re-encoding" stores. But
it should be doable.

This extension is very much experimental quality. There are a handful
of features that don't work. It probably isn't suitable for day-to-day
use. But it could be used in limited cases (e.g. read-only checkouts
like in CI). And it is also a good proving ground for alternate
storage backends. As we continue to define interfaces for all things
storage, it will be useful to have a viable alternate storage backend
to see how things shake out in practice.

test-storage.py passes on Python 2 and introduces no new test failures on
Python 3. Having the storage-level unit tests has proved to be insanely
useful when developing this extension. Those tests caught numerous bugs
during development and I'm convinced this style of testing is the way
forward for ensuring alternate storage backends work as intended. Of
course, test coverage isn't close to what it needs to be. But it is
a start. And what coverage we have gives me confidence that basic store
functionality is implemented properly.

Differential Revision: https://phab.mercurial-scm.org/D4928

#testcases lfsremote-on lfsremote-off
#require serve no-reposimplestore no-chg

This test splits `hg serve` with and without using the extension into separate
tests cases.  The tests are broken down as follows, where "LFS"/"No-LFS"
indicates whether or not there are commits that use an LFS file, and "D"/"E"
indicates whether or not the extension is loaded.  The "X" cases are not tested
individually, because the lfs requirement causes the process to bail early if
the extension is disabled.

.                        Server
.
.                    No-LFS        LFS
.            +----------------------------+
.            |   ||  D  |  E  |  D  |  E  |
.            |---++=======================|
.  C         | D || N/A | #1  |  X  | #4  |
.  l    No   +---++-----------------------|
.  i    LFS  | E || #2  | #2  |  X  | #5  |
.  e         +---++-----------------------|
.  n         | D ||  X  |  X  |  X  |  X  |
.  t    LFS  |---++-----------------------|
.            | E || #3  | #3  |  X  | #6  |
.            |---++-----------------------+

make command server magic visible

#if windows
  $ PYTHONPATH="$TESTDIR/../contrib;$PYTHONPATH"
#else
  $ PYTHONPATH="$TESTDIR/../contrib:$PYTHONPATH"
#endif
  $ export PYTHONPATH

  $ hg init server
  $ SERVER_REQUIRES="$TESTTMP/server/.hg/requires"

  $ cat > $TESTTMP/debugprocessors.py <<EOF
  > from mercurial import (
  >     cmdutil,
  >     commands,
  >     pycompat,
  >     registrar,
  > )
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > @command(b'debugprocessors', [], b'FILE')
  > def debugprocessors(ui, repo, file_=None, **opts):
  >     opts = pycompat.byteskwargs(opts)
  >     opts[b'changelog'] = False
  >     opts[b'manifest'] = False
  >     opts[b'dir'] = False
  >     rl = cmdutil.openrevlog(repo, b'debugprocessors', file_, opts)
  >     for flag, proc in rl._flagprocessors.iteritems():
  >         ui.status(b"registered processor '%#x'\n" % (flag))
  > EOF

Skip the experimental.changegroup3=True config.  Failure to agree on this comes
first, and causes a "ValueError: no common changegroup version" or "abort:
HTTP Error 500: Internal Server Error", if the extension is only loaded on one
side.  If that *is* enabled, the subsequent failure is "abort: missing processor
for flag '0x2000'!" if the extension is only loaded on one side (possibly also
masked by the Internal Server Error message).
  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > debugprocessors = $TESTTMP/debugprocessors.py
  > [experimental]
  > lfs.disableusercache = True
  > [lfs]
  > threshold=10
  > [web]
  > allow_push=*
  > push_ssl=False
  > EOF

  $ cp $HGRCPATH $HGRCPATH.orig

#if lfsremote-on
  $ hg --config extensions.lfs= -R server \
  >    serve -p $HGPORT -d --pid-file=hg.pid --errorlog=$TESTTMP/errors.log
#else
  $ hg --config extensions.lfs=! -R server \
  >    serve -p $HGPORT -d --pid-file=hg.pid --errorlog=$TESTTMP/errors.log
#endif

  $ cat hg.pid >> $DAEMON_PIDS
  $ hg clone -q http://localhost:$HGPORT client
  $ grep 'lfs' client/.hg/requires $SERVER_REQUIRES
  [1]

This trivial repo will force commandserver to load the extension, but not call
reposetup() on another repo actually being operated on.  This gives coverage
that wrapper functions are not assuming reposetup() was called.

  $ hg init $TESTTMP/cmdservelfs
  $ cat >> $TESTTMP/cmdservelfs/.hg/hgrc << EOF
  > [extensions]
  > lfs =
  > EOF

--------------------------------------------------------------------------------
Case #1: client with non-lfs content and the extension disabled; server with
non-lfs content, and the extension enabled.

  $ cd client
  $ echo 'non-lfs' > nonlfs.txt
  >>> from __future__ import absolute_import
  >>> from hgclient import check, readchannel, runcommand
  >>> @check
  ... def diff(server):
  ...     readchannel(server)
  ...     # run an arbitrary command in the repo with the extension loaded
  ...     runcommand(server, ['id', '-R', '../cmdservelfs'])
  ...     # now run a command in a repo without the extension to ensure that
  ...     # files are added safely..
  ...     runcommand(server, ['ci', '-Aqm', 'non-lfs'])
  ...     # .. and that scmutil.prefetchfiles() safely no-ops..
  ...     runcommand(server, ['diff', '-r', '.~1'])
  ...     # .. and that debugupgraderepo safely no-ops.
  ...     runcommand(server, ['debugupgraderepo', '-q', '--run'])
  *** runcommand id -R ../cmdservelfs
  000000000000 tip
  *** runcommand ci -Aqm non-lfs
  *** runcommand diff -r .~1
  diff -r 000000000000 nonlfs.txt
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/nonlfs.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +non-lfs
  *** runcommand debugupgraderepo -q --run
  upgrade will perform the following actions:
  
  requirements
     preserved: dotencode, fncache, generaldelta, revlogv1, store
  
  beginning upgrade...
  repository locked and read-only
  creating temporary repository to stage migrated data: * (glob)
  (it is safe to interrupt this process any time before data migration completes)
  migrating 3 total revisions (1 in filelogs, 1 in manifests, 1 in changelog)
  migrating 324 bytes in store; 129 bytes tracked data
  migrating 1 filelogs containing 1 revisions (73 bytes in store; 8 bytes tracked data)
  finished migrating 1 filelog revisions across 1 filelogs; change in size: 0 bytes
  migrating 1 manifests containing 1 revisions (117 bytes in store; 52 bytes tracked data)
  finished migrating 1 manifest revisions across 1 manifests; change in size: 0 bytes
  migrating changelog containing 1 revisions (134 bytes in store; 69 bytes tracked data)
  finished migrating 1 changelog revisions; change in size: 0 bytes
  finished migrating 3 total revisions; total change in store size: 0 bytes
  copying phaseroots
  data fully migrated to temporary repository
  marking source repository as being upgraded; clients will be unable to read from repository
  starting in-place swap of repository data
  replaced files will be backed up at * (glob)
  replacing store...
  store replacement complete; repository was inconsistent for *s (glob)
  finalizing requirements file and making repository readable again
  removing temporary repository * (glob)
  copy of old repository backed up at * (glob)
  the old repository will not be deleted; remove it to free up disk space once the upgraded repository is verified

  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  [1]

#if lfsremote-on

  $ hg push -q
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  [1]

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client1_clone
  $ grep 'lfs' $TESTTMP/client1_clone/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg init $TESTTMP/client1_pull
  $ hg -R $TESTTMP/client1_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client1_pull/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg identify http://localhost:$HGPORT
  d437e1d24fbd

#endif

--------------------------------------------------------------------------------
Case #2: client with non-lfs content and the extension enabled; server with
non-lfs content, and the extension state controlled by #testcases.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > lfs =
  > EOF
  $ echo 'non-lfs' > nonlfs2.txt
  $ hg ci -Aqm 'non-lfs file with lfs client'

Since no lfs content has been added yet, the push is allowed, even when the
extension is not enabled remotely.

  $ hg push -q
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  [1]

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client2_clone
  $ grep 'lfs' $TESTTMP/client2_clone/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg init $TESTTMP/client2_pull
  $ hg -R $TESTTMP/client2_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client2_pull/.hg/requires $SERVER_REQUIRES
  [1]

  $ hg identify http://localhost:$HGPORT
  1477875038c6

--------------------------------------------------------------------------------
Case #3: client with lfs content and the extension enabled; server with
non-lfs content, and the extension state controlled by #testcases.  The server
should have an 'lfs' requirement after it picks up its first commit with a blob.

  $ echo 'this is a big lfs file' > lfs.bin
  $ hg ci -Aqm 'lfs'
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  .hg/requires:lfs

#if lfsremote-off
  $ hg push -q
  abort: required features are not supported in the destination: lfs
  (enable the lfs extension on the server)
  [255]
#else
  $ hg push -q
#endif
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  .hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs (lfsremote-on !)

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client3_clone
  $ grep 'lfs' $TESTTMP/client3_clone/.hg/requires $SERVER_REQUIRES || true
  $TESTTMP/client3_clone/.hg/requires:lfs (lfsremote-on !)
  $TESTTMP/server/.hg/requires:lfs (lfsremote-on !)

  $ hg init $TESTTMP/client3_pull
  $ hg -R $TESTTMP/client3_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client3_pull/.hg/requires $SERVER_REQUIRES || true
  $TESTTMP/client3_pull/.hg/requires:lfs (lfsremote-on !)
  $TESTTMP/server/.hg/requires:lfs (lfsremote-on !)

Test that the commit/changegroup requirement check hook can be run multiple
times.

  $ hg clone -qr 0 http://localhost:$HGPORT $TESTTMP/cmdserve_client3

  $ cd ../cmdserve_client3

  >>> from __future__ import absolute_import
  >>> from hgclient import check, readchannel, runcommand
  >>> @check
  ... def addrequirement(server):
  ...     readchannel(server)
  ...     # change the repo in a way that adds the lfs requirement
  ...     runcommand(server, ['pull', '-qu'])
  ...     # Now cause the requirement adding hook to fire again, without going
  ...     # through reposetup() again.
  ...     with open('file.txt', 'wb') as fp:
  ...         fp.write('data')
  ...     runcommand(server, ['ci', '-Aqm', 'non-lfs'])
  *** runcommand pull -qu
  *** runcommand ci -Aqm non-lfs

  $ cd ../client

The difference here is the push failed above when the extension isn't
enabled on the server.
  $ hg identify http://localhost:$HGPORT
  8374dc4052cb (lfsremote-on !)
  1477875038c6 (lfsremote-off !)

Don't bother testing the lfsremote-off cases- the server won't be able
to launch if there's lfs content and the extension is disabled.

#if lfsremote-on

--------------------------------------------------------------------------------
Case #4: client with non-lfs content and the extension disabled; server with
lfs content, and the extension enabled.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > lfs = !
  > EOF

  $ hg init $TESTTMP/client4
  $ cd $TESTTMP/client4
  $ cat >> .hg/hgrc <<EOF
  > [paths]
  > default = http://localhost:$HGPORT
  > EOF
  $ echo 'non-lfs' > nonlfs2.txt
  $ hg ci -Aqm 'non-lfs'
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

  $ hg push -q --force
  warning: repository is unrelated
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

  $ hg clone http://localhost:$HGPORT $TESTTMP/client4_clone
  (remote is using large file support (lfs), but it is explicitly disabled in the local configuration)
  abort: repository requires features unknown to this Mercurial: lfs!
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]
  $ grep 'lfs' $TESTTMP/client4_clone/.hg/requires $SERVER_REQUIRES
  grep: $TESTTMP/client4_clone/.hg/requires: $ENOENT$
  $TESTTMP/server/.hg/requires:lfs
  [2]

TODO: fail more gracefully.

  $ hg init $TESTTMP/client4_pull
  $ hg -R $TESTTMP/client4_pull pull -q http://localhost:$HGPORT
  abort: HTTP Error 500: Internal Server Error
  [255]
  $ grep 'lfs' $TESTTMP/client4_pull/.hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

  $ hg identify http://localhost:$HGPORT
  03b080fa9d93

--------------------------------------------------------------------------------
Case #5: client with non-lfs content and the extension enabled; server with
lfs content, and the extension enabled.

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > lfs =
  > EOF
  $ echo 'non-lfs' > nonlfs3.txt
  $ hg ci -Aqm 'non-lfs file with lfs client'

  $ hg push -q
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  $TESTTMP/server/.hg/requires:lfs

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client5_clone
  $ grep 'lfs' $TESTTMP/client5_clone/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client5_clone/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg init $TESTTMP/client5_pull
  $ hg -R $TESTTMP/client5_pull pull -q http://localhost:$HGPORT
  $ grep 'lfs' $TESTTMP/client5_pull/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client5_pull/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg identify http://localhost:$HGPORT
  c729025cc5e3

  $ mv $HGRCPATH $HGRCPATH.tmp
  $ cp $HGRCPATH.orig $HGRCPATH

  >>> from __future__ import absolute_import
  >>> from hgclient import check, readchannel, runcommand
  >>> @check
  ... def checkflags(server):
  ...     readchannel(server)
  ...     print('')
  ...     print('# LFS required- both lfs and non-lfs revlogs have 0x2000 flag')
  ...     runcommand(server, ['debugprocessors', 'lfs.bin', '-R',
  ...                '../server'])
  ...     runcommand(server, ['debugprocessors', 'nonlfs2.txt', '-R',
  ...                '../server'])
  ...     runcommand(server, ['config', 'extensions', '--cwd',
  ...                '../server'])
  ... 
  ...     print("\n# LFS not enabled- revlogs don't have 0x2000 flag")
  ...     runcommand(server, ['debugprocessors', 'nonlfs3.txt'])
  ...     runcommand(server, ['config', 'extensions'])
  
  # LFS required- both lfs and non-lfs revlogs have 0x2000 flag
  *** runcommand debugprocessors lfs.bin -R ../server
  registered processor '0x8000'
  registered processor '0x2000'
  *** runcommand debugprocessors nonlfs2.txt -R ../server
  registered processor '0x8000'
  registered processor '0x2000'
  *** runcommand config extensions --cwd ../server
  extensions.debugprocessors=$TESTTMP/debugprocessors.py
  extensions.lfs=
  
  # LFS not enabled- revlogs don't have 0x2000 flag
  *** runcommand debugprocessors nonlfs3.txt
  registered processor '0x8000'
  *** runcommand config extensions
  extensions.debugprocessors=$TESTTMP/debugprocessors.py

  $ rm $HGRCPATH
  $ mv $HGRCPATH.tmp $HGRCPATH

  $ hg clone $TESTTMP/client $TESTTMP/nonlfs -qr 0 --config extensions.lfs=
  $ cat >> $TESTTMP/nonlfs/.hg/hgrc <<EOF
  > [extensions]
  > lfs = !
  > EOF

  >>> from __future__ import absolute_import, print_function
  >>> from hgclient import check, readchannel, runcommand
  >>> @check
  ... def checkflags2(server):
  ...     readchannel(server)
  ...     print('')
  ...     print('# LFS enabled- both lfs and non-lfs revlogs have 0x2000 flag')
  ...     runcommand(server, ['debugprocessors', 'lfs.bin', '-R',
  ...                '../server'])
  ...     runcommand(server, ['debugprocessors', 'nonlfs2.txt', '-R',
  ...                '../server'])
  ...     runcommand(server, ['config', 'extensions', '--cwd',
  ...                '../server'])
  ... 
  ...     print('\n# LFS enabled without requirement- revlogs have 0x2000 flag')
  ...     runcommand(server, ['debugprocessors', 'nonlfs3.txt'])
  ...     runcommand(server, ['config', 'extensions'])
  ... 
  ...     print("\n# LFS disabled locally- revlogs don't have 0x2000 flag")
  ...     runcommand(server, ['debugprocessors', 'nonlfs.txt', '-R',
  ...                '../nonlfs'])
  ...     runcommand(server, ['config', 'extensions', '--cwd',
  ...                '../nonlfs'])
  
  # LFS enabled- both lfs and non-lfs revlogs have 0x2000 flag
  *** runcommand debugprocessors lfs.bin -R ../server
  registered processor '0x8000'
  registered processor '0x2000'
  *** runcommand debugprocessors nonlfs2.txt -R ../server
  registered processor '0x8000'
  registered processor '0x2000'
  *** runcommand config extensions --cwd ../server
  extensions.debugprocessors=$TESTTMP/debugprocessors.py
  extensions.lfs=
  
  # LFS enabled without requirement- revlogs have 0x2000 flag
  *** runcommand debugprocessors nonlfs3.txt
  registered processor '0x8000'
  registered processor '0x2000'
  *** runcommand config extensions
  extensions.debugprocessors=$TESTTMP/debugprocessors.py
  extensions.lfs=
  
  # LFS disabled locally- revlogs don't have 0x2000 flag
  *** runcommand debugprocessors nonlfs.txt -R ../nonlfs
  registered processor '0x8000'
  *** runcommand config extensions --cwd ../nonlfs
  extensions.debugprocessors=$TESTTMP/debugprocessors.py
  extensions.lfs=!

--------------------------------------------------------------------------------
Case #6: client with lfs content and the extension enabled; server with
lfs content, and the extension enabled.

  $ echo 'this is another lfs file' > lfs2.txt
  $ hg ci -Aqm 'lfs file with lfs client'

  $ hg --config paths.default= push -v http://localhost:$HGPORT
  pushing to http://localhost:$HGPORT/
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  searching for changes
  remote has heads on branch 'default' that are not known locally: 8374dc4052cb
  lfs: uploading a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de (25 bytes)
  lfs: processed: a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de
  lfs: uploaded 1 files (25 bytes)
  1 changesets found
  uncompressed size of bundle content:
       206 (changelog)
       172 (manifests)
       275  lfs2.txt
  remote: adding changesets
  remote: adding manifests
  remote: adding file changes
  remote: added 1 changesets with 1 changes to 1 files
  $ grep 'lfs' .hg/requires $SERVER_REQUIRES
  .hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg clone -q http://localhost:$HGPORT $TESTTMP/client6_clone
  $ grep 'lfs' $TESTTMP/client6_clone/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client6_clone/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg init $TESTTMP/client6_pull
  $ hg -R $TESTTMP/client6_pull pull -u -v http://localhost:$HGPORT
  pulling from http://localhost:$HGPORT/
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 6 changesets with 5 changes to 5 files (+1 heads)
  calling hook pretxnchangegroup.lfs: hgext.lfs.checkrequireslfs
  new changesets d437e1d24fbd:d3b84d50eacb
  resolving manifests
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: downloading a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de (25 bytes)
  lfs: processed: a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de
  lfs: downloaded 1 files (25 bytes)
  getting lfs2.txt
  lfs: found a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de in the local lfs store
  getting nonlfs2.txt
  getting nonlfs3.txt
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updated to "d3b84d50eacb: lfs file with lfs client"
  1 other heads for branch "default"
  (sent 3 HTTP requests and * bytes; received * bytes in responses) (glob)
  $ grep 'lfs' $TESTTMP/client6_pull/.hg/requires $SERVER_REQUIRES
  $TESTTMP/client6_pull/.hg/requires:lfs
  $TESTTMP/server/.hg/requires:lfs

  $ hg identify http://localhost:$HGPORT
  d3b84d50eacb

--------------------------------------------------------------------------------
Misc: process dies early if a requirement exists and the extension is disabled

  $ hg --config extensions.lfs=! summary
  abort: repository requires features unknown to this Mercurial: lfs!
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]

  $ echo 'this is an lfs file' > $TESTTMP/client6_clone/lfspair1.bin
  $ echo 'this is an lfs file too' > $TESTTMP/client6_clone/lfspair2.bin
  $ hg -R $TESTTMP/client6_clone ci -Aqm 'add lfs pair'
  $ hg -R $TESTTMP/client6_clone push -q

  $ hg clone -qU http://localhost:$HGPORT $TESTTMP/bulkfetch

Export will prefetch all needed files across all needed revisions

  $ hg -R $TESTTMP/bulkfetch -v export -r 0:tip -o all.export
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  exporting patches:
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: need to transfer 4 objects (92 bytes)
  lfs: downloading a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de (25 bytes)
  lfs: processed: a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de
  lfs: downloading bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc (23 bytes)
  lfs: processed: bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc
  lfs: downloading cf1b2787b74e66547d931b6ebe28ff63303e803cb2baa14a8f57c4383d875782 (20 bytes)
  lfs: processed: cf1b2787b74e66547d931b6ebe28ff63303e803cb2baa14a8f57c4383d875782
  lfs: downloading d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e (24 bytes)
  lfs: processed: d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e
  lfs: downloaded 4 files (92 bytes)
  all.export
  lfs: found bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc in the local lfs store
  lfs: found a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de in the local lfs store
  lfs: found cf1b2787b74e66547d931b6ebe28ff63303e803cb2baa14a8f57c4383d875782 in the local lfs store
  lfs: found d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e in the local lfs store

Export with selected files is used with `extdiff --patch`

  $ rm -r $TESTTMP/bulkfetch/.hg/store/lfs
  $ hg --config extensions.extdiff= \
  >    -R $TESTTMP/bulkfetch -v extdiff -r 2:tip --patch $TESTTMP/bulkfetch/lfs.bin
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: downloading bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc (23 bytes)
  lfs: processed: bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc
  lfs: downloaded 1 files (23 bytes)
  */hg-8374dc4052cb.patch (glob)
  lfs: found bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc in the local lfs store
  */hg-9640b57e77b1.patch (glob)
  --- */hg-8374dc4052cb.patch	* (glob)
  +++ */hg-9640b57e77b1.patch	* (glob)
  @@ -2,12 +2,7 @@
   # User test
   # Date 0 0
   #      Thu Jan 01 00:00:00 1970 +0000
  -# Node ID 8374dc4052cbd388e79d9dc4ddb29784097aa354
  -# Parent  1477875038c60152e391238920a16381c627b487
  -lfs
  +# Node ID 9640b57e77b14c3a0144fb4478b6cc13e13ea0d1
  +# Parent  d3b84d50eacbd56638e11abce6b8616aaba54420
  +add lfs pair
   
  -diff -r 1477875038c6 -r 8374dc4052cb lfs.bin
  ---- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  -+++ b/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
  -@@ -0,0 +1,1 @@
  -+this is a big lfs file
  cleaning up temp directory
  [1]

Diff will prefetch files

  $ rm -r $TESTTMP/bulkfetch/.hg/store/lfs
  $ hg -R $TESTTMP/bulkfetch -v diff -r 2:tip
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: need to transfer 4 objects (92 bytes)
  lfs: downloading a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de (25 bytes)
  lfs: processed: a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de
  lfs: downloading bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc (23 bytes)
  lfs: processed: bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc
  lfs: downloading cf1b2787b74e66547d931b6ebe28ff63303e803cb2baa14a8f57c4383d875782 (20 bytes)
  lfs: processed: cf1b2787b74e66547d931b6ebe28ff63303e803cb2baa14a8f57c4383d875782
  lfs: downloading d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e (24 bytes)
  lfs: processed: d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e
  lfs: downloaded 4 files (92 bytes)
  lfs: found bed80f00180ac404b843628ab56a1c1984d6145c391cd1628a7dd7d2598d71fc in the local lfs store
  lfs: found a82f1c5cea0d40e3bb3a849686bb4e6ae47ca27e614de55c1ed0325698ef68de in the local lfs store
  lfs: found cf1b2787b74e66547d931b6ebe28ff63303e803cb2baa14a8f57c4383d875782 in the local lfs store
  lfs: found d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e in the local lfs store
  diff -r 8374dc4052cb -r 9640b57e77b1 lfs.bin
  --- a/lfs.bin	Thu Jan 01 00:00:00 1970 +0000
  +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +0,0 @@
  -this is a big lfs file
  diff -r 8374dc4052cb -r 9640b57e77b1 lfs2.txt
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/lfs2.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +this is another lfs file
  diff -r 8374dc4052cb -r 9640b57e77b1 lfspair1.bin
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/lfspair1.bin	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +this is an lfs file
  diff -r 8374dc4052cb -r 9640b57e77b1 lfspair2.bin
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/lfspair2.bin	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +this is an lfs file too
  diff -r 8374dc4052cb -r 9640b57e77b1 nonlfs.txt
  --- a/nonlfs.txt	Thu Jan 01 00:00:00 1970 +0000
  +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,1 +0,0 @@
  -non-lfs
  diff -r 8374dc4052cb -r 9640b57e77b1 nonlfs3.txt
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/nonlfs3.txt	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +non-lfs

Only the files required by diff are prefetched

  $ rm -r $TESTTMP/bulkfetch/.hg/store/lfs
  $ hg -R $TESTTMP/bulkfetch -v diff -r 2:tip $TESTTMP/bulkfetch/lfspair2.bin
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: assuming remote store: http://localhost:$HGPORT/.git/info/lfs
  lfs: downloading d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e (24 bytes)
  lfs: processed: d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e
  lfs: downloaded 1 files (24 bytes)
  lfs: found d96eda2c74b56e95cfb5ffb66b6503e198cc6fc4a09dc877de925feebc65786e in the local lfs store
  diff -r 8374dc4052cb -r 9640b57e77b1 lfspair2.bin
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/lfspair2.bin	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +this is an lfs file too

#endif

  $ "$PYTHON" $TESTDIR/killdaemons.py $DAEMON_PIDS

#if lfsremote-on
  $ cat $TESTTMP/errors.log | grep '^[A-Z]'
  Traceback (most recent call last):
  ValueError: no common changegroup version
#else
  $ cat $TESTTMP/errors.log
#endif