view tests/test-show-stack.t @ 33289:abd7dedbaa36

sparse: vendor Facebook-developed extension

Facebook has developed an extension to enable "sparse" checkouts -
a working directory with a subset of files. This feature is a critical
component in enabling repositories to scale to infinite number of
files while retaining reasonable performance. It's worth noting
that sparse checkout is only one possible solution to this problem:
another is virtual filesystems that realize files on first access.
But given that virtual filesystems may not be accessible to all
users, sparse checkout is necessary as a fallback.

Per mailing list discussion at
https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/095868.html
we want to add sparse checkout to the Mercurial distribution via
roughly the following mechanism:

1. Vendor extension as-is with minimal modifications (this patch)
2. Refactor extension so it is more clearly experimental and inline
   with Mercurial practices
3. Move code from extension into core where possible
4. Drop experimental labeling and/or move feature into core
   after sign-off from narrow clone feature owners

This commit essentially copies the sparse extension and tests
from revision 71e0a2aeca92a4078fe1b8c76e32c88ff1929737 of the
https://bitbucket.org/facebook/hg-experimental repository.

A list of modifications made as part of vendoring is as follows:

* "EXPERIMENTAL" added to module docstring
* Imports were changed to match Mercurial style conventions
* "testedwith" value was updated to core Mercurial special value and
  comment boilerplate was inserted
* A "clone_sparse" function was renamed to "clonesparse" to appease
  the style checker
* Paths to the sparse extension in tests reflect built-in location
* test-sparse-extensions.t was renamed to test-sparse-fsmonitor.t
  and references to "simplecache" were removed. The test always skips
  because it isn't trivial to run it given the way we currently run
  fsmonitor tests
* A double empty line was removed from test-sparse-profiles.t

There are aspects of the added code that are obviously not ideal.
The goal is to make a minimal number of modifications as part of
the vendoring to make it easier to track changes from the original
implementation. Refactoring will occur in subsequent patches.

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > show =
  > EOF

  $ hg init repo0
  $ cd repo0

Empty repo / no checkout results in error

  $ hg show stack
  abort: stack view only available when there is a working directory
  [255]

Stack displays single draft changeset as root revision

  $ echo 0 > foo
  $ hg -q commit -A -m 'commit 0'
  $ hg show stack
    @  9f171 commit 0

Stack displays multiple draft changesets

  $ echo 1 > foo
  $ hg commit -m 'commit 1'
  $ echo 2 > foo
  $ hg commit -m 'commit 2'
  $ echo 3 > foo
  $ hg commit -m 'commit 3'
  $ echo 4 > foo
  $ hg commit -m 'commit 4'
  $ hg show stack
    @  2737b commit 4
    o  d1a69 commit 3
    o  128c8 commit 2
    o  181cc commit 1
    o  9f171 commit 0

Public parent of draft base is displayed, separated from stack

  $ hg phase --public -r 0
  $ hg show stack
    @  2737b commit 4
    o  d1a69 commit 3
    o  128c8 commit 2
    o  181cc commit 1
   /   (stack base)
  o  9f171 commit 0

  $ hg phase --public -r 1
  $ hg show stack
    @  2737b commit 4
    o  d1a69 commit 3
    o  128c8 commit 2
   /   (stack base)
  o  181cc commit 1

Draft descendants are shown

  $ hg -q up 2
  $ hg show stack
    o  2737b commit 4
    o  d1a69 commit 3
    @  128c8 commit 2
   /   (stack base)
  o  181cc commit 1

  $ hg -q up 3
  $ hg show stack
    o  2737b commit 4
    @  d1a69 commit 3
    o  128c8 commit 2
   /   (stack base)
  o  181cc commit 1

working dir on public changeset should display special message

  $ hg -q up 1
  $ hg show stack
  (empty stack; working directory parent is a published changeset)

Branch point in descendants displayed at top of graph

  $ hg -q up 3
  $ echo b > foo
  $ hg commit -m 'commit 5 (new dag branch)'
  created new head
  $ hg -q up 2
  $ hg show stack
   \ /  (multiple children)
    |
    o  d1a69 commit 3
    @  128c8 commit 2
   /   (stack base)
  o  181cc commit 1

  $ cd ..

Base is stopped at merges

  $ hg init merge-base
  $ cd merge-base
  $ echo 0 > foo
  $ hg -q commit -A -m initial
  $ echo h1 > foo
  $ hg commit -m 'head 1'
  $ hg -q up 0
  $ echo h2 > foo
  $ hg -q commit -m 'head 2'
  $ hg phase --public -r 0:tip
  $ hg -q up 1
  $ hg merge -t :local 2
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg commit -m 'merge heads'

TODO doesn't yet handle case where wdir is a draft merge

  $ hg show stack
    @  8ee90 merge heads
   /   (stack base)
  o  59478 head 1

  $ echo d1 > foo
  $ hg commit -m 'draft 1'
  $ echo d2 > foo
  $ hg commit -m 'draft 2'

  $ hg show stack
    @  430d5 draft 2
    o  787b1 draft 1
   /   (stack base)
  o  8ee90 merge heads

  $ cd ..

Now move on to stacks when there are more commits after the base branchpoint

  $ hg init public-rebase
  $ cd public-rebase
  $ echo 0 > foo
  $ hg -q commit -A -m 'base'
  $ hg phase --public -r .
  $ echo d1 > foo
  $ hg commit -m 'draft 1'
  $ echo d2 > foo
  $ hg commit -m 'draft 2'
  $ hg -q up 0
  $ echo 1 > foo
  $ hg commit -m 'new 1'
  created new head
  $ echo 2 > foo
  $ hg commit -m 'new 2'
  $ hg -q up 2

Newer draft heads don't impact output

  $ hg show stack
    @  eaffc draft 2
    o  2b218 draft 1
   /   (stack base)
  o  b66bb base

Newer public heads are rendered

  $ hg phase --public -r '::tip'

  $ hg show stack
    o  baa4b new 2
   /    (2 commits ahead)
  :
  :    (stack head)
  : @  eaffc draft 2
  : o  2b218 draft 1
  :/   (stack base)
  o  b66bb base

If rebase is available, we show a hint how to rebase to that head

  $ hg --config extensions.rebase= show stack
    o  baa4b new 2
   /    (2 commits ahead; hg rebase --source 2b218 --dest baa4b)
  :
  :    (stack head)
  : @  eaffc draft 2
  : o  2b218 draft 1
  :/   (stack base)
  o  b66bb base

Similar tests but for multiple heads

  $ hg -q up 0
  $ echo h2 > foo
  $ hg -q commit -m 'new head 2'
  $ hg phase --public -r .
  $ hg -q up 2

  $ hg show stack
    o  baa4b new 2
   /    (2 commits ahead)
  : o  9a848 new head 2
  :/    (1 commits ahead)
  :
  :    (stack head)
  : @  eaffc draft 2
  : o  2b218 draft 1
  :/   (stack base)
  o  b66bb base

  $ hg --config extensions.rebase= show stack
    o  baa4b new 2
   /    (2 commits ahead; hg rebase --source 2b218 --dest baa4b)
  : o  9a848 new head 2
  :/    (1 commits ahead; hg rebase --source 2b218 --dest 9a848)
  :
  :    (stack head)
  : @  eaffc draft 2
  : o  2b218 draft 1
  :/   (stack base)
  o  b66bb base