view tests/test-merge-subrepos.t @ 35121:66c5a8cf2868

lfs: import the Facebook git-lfs client extension

The purpose of this is the same as the built-in largefiles extension- to handle
huge files outside of the normal storage system, generally to keep the amount of
data cloned to a lower amount.  There are several benefits of implementing the
git-lfs protocol, instead of using the largefiles extension:

  - Bitbucket and Github support (and probably wider support in 3rd party
    hosting sites in general). [1][2]

  - The number of hg internals monkey patched are several orders of magnitude
    lower, so it will be easier to reason about and maintain.  Future commands
    will likely just work, without requiring various wrappers.

  - The "standin" files are only written to the filelog, not the disk.  That
    should avoid weird edge cases where the largefile and standin files get out
    of sync. [3]  It also avoids the occasional printing of the "hidden" standin
    file in various messages.

  - Filesets like size() will work, even if the file isn't present.  (It always
    says 41 bytes for largefiles, whether present or not.)

The only place that I see where largefiles comes out on top is that it works
with `hg serve` for simple sharing, without external infrastructure.  Getting
lfs-test-server working was a hassle, and took awhile to figure out.  Maybe we
can do something to make it work in the future.

Long term, I expect that this will be highly preferred over largefiles.  But if
we are to recommend this to largefile users, there are some UI issues to
bikeshed.  Until they are resolved, I've marked this experimental, and am not
putting a pointer to this in the largefiles help.  The (non exhaustive) list of
issues I've seen so far are:

  - It isn't sufficient to just enable the largefiles extension- you have to
    explicitly add a file with --large before it will pay attention to the
    configured sizes and patterns on future adds.  The justification being that
    once you use it, you're stuck with it.  I've seen people confused by this,
    and haven't liked it myself.  But it's also saved me a few times.  Should we
    do something like have a specific enabling config setting that must be set
    in the local repo config, so that enabling this extension in the user or
    system hgrc doesn't silently start storing lfs files?

  - The largefiles extension adds a repo requirement when the first largefile is
    committed, so that the extension must always be enabled in the future.  This
    extension is not doing that, and since I only enabled it locally to avoid
    infecting other repos, I got a cryptic error about missing flag processors
    when I cloned.  Is there no repo requirement due to shallow/narrow clone
    considerations (or other future advanced things)?

  - In the (small amount of) reading I've done about the git implementation, it
    seems that the files and sizes are stored in a tracked .gitattributes file.
    I think a tracked file for this would be extremely useful for consistency
    across developers, but this kind of touches on the tracked hgrc file
    proposal a few months back.

  - The git client can specify file patterns, not just sizes.

  - The largefiles extension has a cache directory in the local repo, but also a
    system wide one.  We should probably implement a system wide cache too, so
    that multiple clones don't have to refetch the files from the server.

  - Jun mentioned other missing features, like SSH authentication, gc, etc.

The code corresponds to c0492b73c7ef in hg-experimental. [4]  The only tweaks
are to load the extension in the tests with 'lfs=' instead of
'lfs=$TESTDIR/../hgext3rd/lfs', change the import in the *.py test to hgext
(from hgext3rd), add the 'testedwith' declaration, and mark it experimental for
now.  The infinite-push, p4fastimport, and remotefilelog tests were left behind.

The devel-warnings for unregistered config options are not corrected yet, nor
are the import check warnings.

[1] https://www.mercurial-scm.org/pipermail/mercurial/2017-November/050699.html
[2] https://bitbucket.org/site/master/issues/3843/largefiles-support-bb-3903
[3] https://bz.mercurial-scm.org/show_bug.cgi?id=5738
[4] https://bitbucket.org/facebook/hg-experimental

  $ hg init

  $ echo a > a
  $ hg ci -qAm 'add a'

  $ hg init subrepo
  $ echo 'subrepo = http://example.net/libfoo' > .hgsub
  $ hg ci -qAm 'added subrepo'

  $ hg up -qC 0
  $ echo ax > a
  $ hg ci -m 'changed a'
  created new head

  $ hg up -qC 1
  $ cd subrepo
  $ echo b > b
  $ hg add b
  $ cd ..

Should fail, since there are added files to subrepo:

  $ hg merge
  abort: uncommitted changes in subrepository "subrepo"
  [255]

Deleted files trigger a '+' marker in top level repos.  Deleted files are also
noticed by `update --check` in the top level repo.

  $ hg ci -Sqm 'add b'
  $ echo change > subrepo/b

  $ hg ci -Sm 'change b'
  committing subrepository subrepo

  $ rm a
  $ hg id
  9bfe45a197d7+ tip
  $ hg sum
  parent: 4:9bfe45a197d7 tip
   change b
  branch: default
  commit: 1 deleted (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 5 draft

  $ hg up --check -r '.^'
  abort: uncommitted changes
  [255]
  $ hg st -S
  ! a
  $ hg up -Cq .

Test that dirty is consistent through subrepos

  $ rm subrepo/b

A deleted subrepo file is flagged as dirty, like the top level repo

  $ hg id --config extensions.blackbox= --config blackbox.dirty=True
  9bfe45a197d7+ tip
  $ cat .hg/blackbox.log
  * @9bfe45a197d7b0ab09bf287729dd57e9619c9da5+ (*)> serve --cmdserver chgunix * (glob) (chg !)
  * @9bfe45a197d7b0ab09bf287729dd57e9619c9da5+ (*)> id (glob)
  * @9bfe45a197d7b0ab09bf287729dd57e9619c9da5+ (*)> id --config *extensions.blackbox=* --config *blackbox.dirty=True* exited 0 * (glob)

TODO: a deleted file should be listed as such, like the top level repo

  $ hg sum
  parent: 4:9bfe45a197d7 tip
   change b
  branch: default
  commit: (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 5 draft

Modified subrepo files are noticed by `update --check` and `summary`

  $ echo mod > subrepo/b
  $ hg st -S
  M subrepo/b

  $ hg up -r '.^' --check
  abort: uncommitted changes in subrepository "subrepo"
  [255]

  $ hg sum
  parent: 4:9bfe45a197d7 tip
   change b
  branch: default
  commit: 1 subrepos
  update: 1 new changesets, 2 branch heads (merge)
  phases: 5 draft

TODO: why is -R needed here?  If it's because the subrepo is treated as a
discrete unit, then this should probably warn or something.
  $ hg revert -R subrepo --no-backup subrepo/b -r .

  $ rm subrepo/b
  $ hg st -S
  ! subrepo/b

`hg update --check` notices a subrepo with a missing file, like it notices a
missing file in the top level repo.

  $ hg up -r '.^' --check
  abort: uncommitted changes in subrepository "subrepo"
  [255]

  $ hg up -r '.^' --config ui.interactive=True << EOF
  > d
  > EOF
  other [destination] changed b which local [working copy] deleted
  use (c)hanged version, leave (d)eleted, or leave (u)nresolved? d
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

XXX: There's a difference between wdir() and '.', so there should be a status.
`hg files -S` from the top is also missing 'subrepo/b'.

  $ hg st -S
  $ hg st -R subrepo
  $ hg files -R subrepo
  [1]
  $ hg files -R subrepo -r '.'
  subrepo/b (glob)

  $ hg bookmark -r tip @other
  $ echo xyz > subrepo/c
  $ hg ci -SAm 'add c'
  adding subrepo/c
  committing subrepository subrepo
  created new head
  $ rm subrepo/c

Merge sees deleted subrepo files as an uncommitted change

  $ hg merge @other
  abort: uncommitted changes in subrepository "subrepo"
  [255]