tests/test-relink.t

exchange: make clone bundles non-experimental and enabled by default

The clone bundles feature was introduced in Mercurial 3.6 behind an
experimental and disabled by default flag. The feature has been enabled
on hg.mozilla.org for a few months and has served many terabytes of
clones. Users have been encouraged to use the feature and reception
has been very positive (mainly due to faster clones as a result of
connecting to a CDN). I have heard no feedback about changing the
feature other than inquiries about when it will be enabled by default.
So, I think the feature is ready to be enabled by default.

This patch renames experimental.clonebundles to ui.clonebundles,
documents the option, and enables it by default. References to the
experimental state of clone bundles have been removed. The remaining
config option docs in clonebundles.py have been removed because they
are redudant with `hg help config`.

There are some oddities with behavior of clone bundles. Because clones
with clone bundles are effectively 2 `hg pull` operations, there may be
2 transactions. This could result in hooks running twice. If the
subsequent pull is aborted, it could result in partial rollback and an
incomplete clone. This behavior is a bit wonky and should probably
be documented. If this patch is accepted, I'll send a follow-up to
document it. I don't think this behavior should prevent the feature
being enabled by default. Reworking the clone mechanism to support
interrupted or multi-part clones feels like a major new feature and
something that when implemented can change the hook and rollback
semantics of clone bundles. Besides, partial clone is better than
full rollback and hooks running on initial clone are likely rare, so I
think the impact is minimal.

#require hardlink

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

  $ fix_path() {
  >     tr '\\' /
  > }

  $ cat > arelinked.py <<EOF
  > import sys, os
  > from mercurial import util
  > path1, path2 = sys.argv[1:3]
  > if util.samefile(path1, path2):
  >     print '%s == %s' % (path1, path2)
  > else:
  >     print '%s != %s' % (path1, path2)
  > EOF


create source repository

  $ hg init repo
  $ cd repo
  $ echo a > a
  $ echo b > b
  $ hg ci -Am addfile
  adding a
  adding b
  $ cat "$TESTDIR/binfile.bin" >> a
  $ cat "$TESTDIR/binfile.bin" >> b
  $ hg ci -Am changefiles

make another commit to create files larger than 1 KB to test
formatting of final byte count

  $ cat "$TESTDIR/binfile.bin" >> a
  $ cat "$TESTDIR/binfile.bin" >> b
  $ hg ci -m anotherchange

don't sit forever trying to double-lock the source repo

  $ hg relink .
  relinking $TESTTMP/repo/.hg/store to $TESTTMP/repo/.hg/store (glob)
  there is nothing to relink


Test files are read in binary mode

  $ $PYTHON -c "file('.hg/store/data/dummy.i', 'wb').write('a\r\nb\n')"
  $ cd ..


clone and pull to break links

  $ hg clone --pull -r0 repo clone
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 2 changes to 2 files
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd clone
  $ hg pull -q
  $ echo b >> b
  $ hg ci -m changeb
  created new head
  $ $PYTHON -c "file('.hg/store/data/dummy.i', 'wb').write('a\nb\r\n')"


relink

  $ hg relink --debug --config progress.debug=true | fix_path
  relinking $TESTTMP/repo/.hg/store to $TESTTMP/clone/.hg/store
  tip has 2 files, estimated total number of files: 3
  collecting: 00changelog.i 1/3 files (33.33%)
  collecting: 00manifest.i 2/3 files (66.67%)
  collecting: a.i 3/3 files (100.00%)
  collecting: b.i 4/3 files (133.33%)
  collecting: dummy.i 5/3 files (166.67%)
  collected 5 candidate storage files
  not linkable: 00changelog.i
  not linkable: 00manifest.i
  pruning: data/a.i 3/5 files (60.00%)
  not linkable: data/b.i
  pruning: data/dummy.i 5/5 files (100.00%)
  pruned down to 2 probably relinkable files
  relinking: data/a.i 1/2 files (50.00%)
  not linkable: data/dummy.i
  relinked 1 files (1.36 KB reclaimed)
  $ cd ..


check hardlinks

  $ python arelinked.py repo/.hg/store/data/a.i clone/.hg/store/data/a.i
  repo/.hg/store/data/a.i == clone/.hg/store/data/a.i
  $ python arelinked.py repo/.hg/store/data/b.i clone/.hg/store/data/b.i
  repo/.hg/store/data/b.i != clone/.hg/store/data/b.i