view tests/test-bundle-vs-outgoing.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.

this structure seems to tickle a bug in bundle's search for
changesets, so first we have to recreate it

o  8
|
| o  7
| |
| o  6
|/|
o |  5
| |
o |  4
| |
| o  3
| |
| o  2
|/
o  1
|
o  0

  $ mkrev()
  > {
  >     revno=$1
  >     echo "rev $revno"
  >     echo "rev $revno" > foo.txt
  >     hg -q ci -m"rev $revno"
  > }

setup test repo1

  $ hg init repo1
  $ cd repo1
  $ echo "rev 0" > foo.txt
  $ hg ci -Am"rev 0"
  adding foo.txt
  $ mkrev 1
  rev 1

first branch

  $ mkrev 2
  rev 2
  $ mkrev 3
  rev 3

back to rev 1 to create second branch

  $ hg up -r1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ mkrev 4
  rev 4
  $ mkrev 5
  rev 5

merge first branch to second branch

  $ hg up -C -r5
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ HGMERGE=internal:local hg merge
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ echo "merge rev 5, rev 3" > foo.txt
  $ hg ci -m"merge first branch to second branch"

one more commit following the merge

  $ mkrev 7
  rev 7

back to "second branch" to make another head

  $ hg up -r5
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ mkrev 8
  rev 8

the story so far

  $ hg log -G --template "{rev}\n"
  @  8
  |
  | o  7
  | |
  | o  6
  |/|
  o |  5
  | |
  o |  4
  | |
  | o  3
  | |
  | o  2
  |/
  o  1
  |
  o  0
  

check that "hg outgoing" really does the right thing

sanity check of outgoing: expect revs 4 5 6 7 8

  $ hg clone -r3 . ../repo2
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 4 changes to 1 files
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

this should (and does) report 5 outgoing revisions: 4 5 6 7 8

  $ hg outgoing --template "{rev}\n" ../repo2
  comparing with ../repo2
  searching for changes
  4
  5
  6
  7
  8

test bundle (destination repo): expect 5 revisions

this should bundle the same 5 revisions that outgoing reported, but it

actually bundles 7

  $ hg bundle foo.bundle ../repo2
  searching for changes
  5 changesets found

test bundle (base revision): expect 5 revisions

this should (and does) give exactly the same result as bundle

with a destination repo... i.e. it's wrong too

  $ hg bundle --base 3 foo.bundle
  5 changesets found

  $ cd ..