view tests/test-convert-cvs-synthetic.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.

#require cvs112

This feature requires use of builtin cvsps!

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert = " >> $HGRCPATH

create cvs repository with one project

  $ mkdir cvsrepo
  $ cd cvsrepo
  $ CVSROOT=`pwd`
  $ export CVSROOT
  $ CVS_OPTIONS=-f
  $ export CVS_OPTIONS
  $ cd ..
  $ rmdir cvsrepo
  $ cvscall()
  > {
  >     cvs -f "$@"
  > }

output of 'cvs ci' varies unpredictably, so just discard it

  $ cvsci()
  > {
  >     sleep 1
  >     cvs -f ci "$@" >/dev/null
  > }
  $ cvscall -d "$CVSROOT" init
  $ mkdir cvsrepo/proj
  $ cvscall -q co proj

create file1 on the trunk

  $ cd proj
  $ touch file1
  $ cvscall -Q add file1
  $ cvsci -m"add file1 on trunk" file1

create two branches

  $ cvscall -q tag -b v1_0
  T file1
  $ cvscall -q tag -b v1_1
  T file1

create file2 on branch v1_0

  $ cvscall -Q up -rv1_0
  $ touch file2
  $ cvscall -Q add file2
  $ cvsci -m"add file2" file2

create file3, file4 on branch v1_1

  $ cvscall -Q up -rv1_1
  $ touch file3
  $ touch file4
  $ cvscall -Q add file3 file4
  $ cvsci -m"add file3, file4 on branch v1_1" file3 file4

merge file2 from v1_0 to v1_1

  $ cvscall -Q up -jv1_0
  $ cvsci -m"MERGE from v1_0: add file2"
  cvs commit: Examining .

Step things up a notch: now we make the history really hairy, with
changes bouncing back and forth between trunk and v1_2 and merges
going both ways.  (I.e., try to model the real world.)
create branch v1_2

  $ cvscall -Q up -A
  $ cvscall -q tag -b v1_2
  T file1

create file5 on branch v1_2

  $ cvscall -Q up -rv1_2
  $ touch file5
  $ cvs -Q add file5
  $ cvsci -m"add file5 on v1_2"
  cvs commit: Examining .

create file6 on trunk post-v1_2

  $ cvscall -Q up -A
  $ touch file6
  $ cvscall -Q add file6
  $ cvsci -m"add file6 on trunk post-v1_2"
  cvs commit: Examining .

merge file5 from v1_2 to trunk

  $ cvscall -Q up -A
  $ cvscall -Q up -jv1_2 file5
  $ cvsci -m"MERGE from v1_2: add file5"
  cvs commit: Examining .

merge file6 from trunk to v1_2

  $ cvscall -Q up -rv1_2
  $ cvscall up -jHEAD file6
  U file6
  $ cvsci -m"MERGE from HEAD: add file6"
  cvs commit: Examining .

cvs rlog output

  $ cvscall -q rlog proj | egrep '^(RCS file|revision)'
  RCS file: $TESTTMP/cvsrepo/proj/file1,v
  revision 1.1
  RCS file: $TESTTMP/cvsrepo/proj/Attic/file2,v
  revision 1.1
  revision 1.1.4.2
  revision 1.1.4.1
  revision 1.1.2.1
  RCS file: $TESTTMP/cvsrepo/proj/Attic/file3,v
  revision 1.1
  revision 1.1.2.1
  RCS file: $TESTTMP/cvsrepo/proj/Attic/file4,v
  revision 1.1
  revision 1.1.2.1
  RCS file: $TESTTMP/cvsrepo/proj/file5,v
  revision 1.2
  revision 1.1
  revision 1.1.2.1
  RCS file: $TESTTMP/cvsrepo/proj/file6,v
  revision 1.1
  revision 1.1.2.2
  revision 1.1.2.1

convert to hg (#1)

  $ cd ..
  $ hg convert --datesort proj proj.hg
  initializing destination proj.hg repository
  connecting to $TESTTMP/cvsrepo
  scanning source...
  collecting CVS rlog
  15 log entries
  creating changesets
  9 changeset entries
  sorting...
  converting...
  8 add file1 on trunk
  7 add file2
  6 MERGE from v1_0: add file2
  5 file file3 was initially added on branch v1_1.
  4 add file3, file4 on branch v1_1
  3 add file5 on v1_2
  2 add file6 on trunk post-v1_2
  1 MERGE from HEAD: add file6
  0 MERGE from v1_2: add file5

hg log -G output (#1)

  $ hg -R proj.hg log -G --template "{rev} {desc}\n"
  o  8 MERGE from v1_2: add file5
  |
  | o  7 MERGE from HEAD: add file6
  | |
  o |  6 add file6 on trunk post-v1_2
  | |
  | o  5 add file5 on v1_2
  | |
  | | o  4 add file3, file4 on branch v1_1
  | | |
  o | |  3 file file3 was initially added on branch v1_1.
  |/ /
  | o  2 MERGE from v1_0: add file2
  |/
  | o  1 add file2
  |/
  o  0 add file1 on trunk
  

convert to hg (#2: with merge detection)

  $ hg convert \
  >   --config convert.cvsps.mergefrom='"^MERGE from (\S+):"' \
  >   --datesort \
  >   proj proj.hg2
  initializing destination proj.hg2 repository
  connecting to $TESTTMP/cvsrepo
  scanning source...
  collecting CVS rlog
  15 log entries
  creating changesets
  9 changeset entries
  sorting...
  converting...
  8 add file1 on trunk
  7 add file2
  6 MERGE from v1_0: add file2
  5 file file3 was initially added on branch v1_1.
  4 add file3, file4 on branch v1_1
  3 add file5 on v1_2
  2 add file6 on trunk post-v1_2
  1 MERGE from HEAD: add file6
  0 MERGE from v1_2: add file5

hg log -G output (#2)

  $ hg -R proj.hg2 log -G --template "{rev} {desc}\n"
  o  8 MERGE from v1_2: add file5
  |
  | o  7 MERGE from HEAD: add file6
  | |
  o |  6 add file6 on trunk post-v1_2
  | |
  | o  5 add file5 on v1_2
  | |
  | | o  4 add file3, file4 on branch v1_1
  | | |
  o | |  3 file file3 was initially added on branch v1_1.
  |/ /
  | o  2 MERGE from v1_0: add file2
  |/
  | o  1 add file2
  |/
  o  0 add file1 on trunk