view tests/test-rebase-abort.t @ 40326:fed697fa1734

sqlitestore: file storage backend using SQLite

This commit provides an extension which uses SQLite to store file
data (as opposed to revlogs).

As the inline documentation describes, there are still several
aspects to the extension that are incomplete. But it's a start.
The extension does support basic clone, checkout, and commit
workflows, which makes it suitable for simple use cases.

One notable missing feature is support for "bundlerepos." This is
probably responsible for the most test failures when the extension
is activated as part of the test suite.

All revision data is stored in SQLite. Data is stored as zstd
compressed chunks (default if zstd is available), zlib compressed
chunks (default if zstd is not available), or raw chunks (if
configured or if a compressed delta is not smaller than the raw
delta). This makes things very similar to revlogs.

Unlike revlogs, the extension doesn't yet enforce a limit on delta
chain length. This is an obvious limitation and should be addressed.
This is somewhat mitigated by the use of zstd, which is much faster
than zlib to decompress.

There is a dedicated table for storing deltas. Deltas are stored
by the SHA-1 hash of their uncompressed content. The "fileindex" table
has columns that reference the delta for each revision and the base
delta that delta should be applied against. A recursive SQL query
is used to resolve the delta chain along with the delta data.

By storing deltas by hash, we are able to de-duplicate delta storage!
With revlogs, the same deltas in different revlogs would result in
duplicate storage of that delta. In this scheme, inserting the
duplicate delta is a no-op and delta chains simply reference the
existing delta.

When initially implementing this extension, I did not have
content-indexed deltas and deltas could be duplicated across files
(just like revlogs). When I implemented content-indexed deltas, the
size of the SQLite database for a full clone of mozilla-unified
dropped:

before: 2,554,261,504 bytes
after:  2,488,754,176 bytes

Surprisingly, this is still larger than the bytes size of revlog
files:

revlog files: 2,104,861,230 bytes
du -b:        2,254,381,614

I would have expected storage to be smaller since we're not limiting
delta chain length and since we're using zstd instead of zlib. I
suspect the SQLite indexes and per-column overhead account for the
bulk of the differences. (Keep in mind that revlog uses a 64-byte
packed struct for revision index data and deltas are stored without
padding. Aside from the 12 unused bytes in the 32 byte node field,
revlogs are pretty efficient.) Another source of overhead is file
name storage. With revlogs, file names are stored in the filesystem.
But with SQLite, we need to store file names in the database. This is
roughly equivalent to the size of the fncache file, which for the
mozilla-unified repository is ~34MB.

Since the SQLite database isn't append-only and since delta chains
can reference any delta, this opens some interesting possibilities.
For example, we could store deltas in reverse, such that fulltexts
are stored for newer revisions and deltas are applied to reconstruct
older revisions. This is likely a more optimal storage strategy for
version control, as new data tends to be more frequently accessed
than old data. We would obviously need wire protocol support for
transferring revision data from newest to oldest. And we would
probably need some kind of mechanism for "re-encoding" stores. But
it should be doable.

This extension is very much experimental quality. There are a handful
of features that don't work. It probably isn't suitable for day-to-day
use. But it could be used in limited cases (e.g. read-only checkouts
like in CI). And it is also a good proving ground for alternate
storage backends. As we continue to define interfaces for all things
storage, it will be useful to have a viable alternate storage backend
to see how things shake out in practice.

test-storage.py passes on Python 2 and introduces no new test failures on
Python 3. Having the storage-level unit tests has proved to be insanely
useful when developing this extension. Those tests caught numerous bugs
during development and I'm convinced this style of testing is the way
forward for ensuring alternate storage backends work as intended. Of
course, test coverage isn't close to what it needs to be. But it is
a start. And what coverage we have gives me confidence that basic store
functionality is implemented properly.

Differential Revision: https://phab.mercurial-scm.org/D4928

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > rebase=
  > 
  > [phases]
  > publish=False
  > 
  > [alias]
  > tglog = log -G --template "{rev}:{phase} '{desc}' {branches}\n"
  > EOF


  $ hg init a
  $ cd a

  $ touch .hg/rebasestate
  $ hg sum
  parent: -1:000000000000 tip (empty repository)
  branch: default
  commit: (clean)
  update: (current)
  abort: .hg/rebasestate is incomplete
  [255]
  $ rm .hg/rebasestate

  $ echo c1 > common
  $ hg add common
  $ hg ci -m C1

  $ echo c2 >> common
  $ hg ci -m C2

  $ echo c3 >> common
  $ hg ci -m C3

  $ hg up -q -C 1

  $ echo l1 >> extra
  $ hg add extra
  $ hg ci -m L1
  created new head

  $ sed -e 's/c2/l2/' common > common.new
  $ mv common.new common
  $ hg ci -m L2

  $ hg phase --force --secret 2

  $ hg tglog
  @  4:draft 'L2'
  |
  o  3:draft 'L1'
  |
  | o  2:secret 'C3'
  |/
  o  1:draft 'C2'
  |
  o  0:draft 'C1'
  

Conflicting rebase:

  $ hg rebase -s 3 -d 2
  rebasing 3:3163e20567cc "L1"
  rebasing 4:46f0b057b5c0 "L2" (tip)
  merging common
  warning: conflicts while merging common! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

Insert unsupported advisory merge record:

  $ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -x
  $ hg debugmergestate
  * version 2 records
  local: 3e046f2ecedb793b97ed32108086edd1a162f8bc
  other: 46f0b057b5c061d276b91491c22151f78698abd2
  labels:
    local: dest
    other: source
  unrecognized entry: x	advisory record
  file extras: common (ancestorlinknode = 3163e20567cc93074fbb7a53c8b93312e59dbf2c)
  file: common (record type "F", state "u", hash 94c8c21d08740f5da9eaa38d1f175c592692f0d1)
    local path: common (flags "")
    ancestor path: common (node de0a666fdd9c1a0b0698b90d85064d8bd34f74b6)
    other path: common (node 2f6411de53677f6f1048fef5bf888d67a342e0a5)
  $ hg resolve -l
  U common

Insert unsupported mandatory merge record:

  $ hg --config extensions.fakemergerecord=$TESTDIR/fakemergerecord.py fakemergerecord -X
  $ hg debugmergestate
  * version 2 records
  local: 3e046f2ecedb793b97ed32108086edd1a162f8bc
  other: 46f0b057b5c061d276b91491c22151f78698abd2
  labels:
    local: dest
    other: source
  file extras: common (ancestorlinknode = 3163e20567cc93074fbb7a53c8b93312e59dbf2c)
  file: common (record type "F", state "u", hash 94c8c21d08740f5da9eaa38d1f175c592692f0d1)
    local path: common (flags "")
    ancestor path: common (node de0a666fdd9c1a0b0698b90d85064d8bd34f74b6)
    other path: common (node 2f6411de53677f6f1048fef5bf888d67a342e0a5)
  unrecognized entry: X	mandatory record
  $ hg resolve -l
  abort: unsupported merge state records: X
  (see https://mercurial-scm.org/wiki/MergeStateRecords for more information)
  [255]
  $ hg resolve -ma
  abort: unsupported merge state records: X
  (see https://mercurial-scm.org/wiki/MergeStateRecords for more information)
  [255]

Abort (should clear out unsupported merge state):

  $ hg rebase --abort
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/3e046f2ecedb-6beef7d5-backup.hg
  rebase aborted
  $ hg debugmergestate
  no merge state found

  $ hg tglog
  @  4:draft 'L2'
  |
  o  3:draft 'L1'
  |
  | o  2:secret 'C3'
  |/
  o  1:draft 'C2'
  |
  o  0:draft 'C1'
  
Test safety for inconsistent rebase state, which may be created (and
forgotten) by Mercurial earlier than 2.7. This emulates Mercurial
earlier than 2.7 by renaming ".hg/rebasestate" temporarily.

  $ hg rebase -s 3 -d 2
  rebasing 3:3163e20567cc "L1"
  rebasing 4:46f0b057b5c0 "L2" (tip)
  merging common
  warning: conflicts while merging common! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ mv .hg/rebasestate .hg/rebasestate.back
  $ hg update --quiet --clean 2
  $ hg --config extensions.mq= strip --quiet "destination()"
  $ mv .hg/rebasestate.back .hg/rebasestate

  $ hg rebase --continue
  abort: cannot continue inconsistent rebase
  (use "hg rebase --abort" to clear broken state)
  [255]
  $ hg summary | grep '^rebase: '
  rebase: (use "hg rebase --abort" to clear broken state)
  $ hg rebase --abort
  rebase aborted (no revision is removed, only broken state is cleared)

  $ cd ..


Construct new repo:

  $ hg init b
  $ cd b

  $ echo a > a
  $ hg ci -Am A
  adding a

  $ echo b > b
  $ hg ci -Am B
  adding b

  $ echo c > c
  $ hg ci -Am C
  adding c

  $ hg up -q 0

  $ echo b > b
  $ hg ci -Am 'B bis'
  adding b
  created new head

  $ echo c1 > c
  $ hg ci -Am C1
  adding c

  $ hg phase --force --secret 1
  $ hg phase --public 1

Rebase and abort without generating new changesets:

  $ hg tglog
  @  4:draft 'C1'
  |
  o  3:draft 'B bis'
  |
  | o  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  
  $ hg rebase -b 4 -d 2
  rebasing 3:a6484957d6b9 "B bis"
  note: rebase of 3:a6484957d6b9 created no changes to commit
  rebasing 4:145842775fec "C1" (tip)
  merging c
  warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ hg tglog
  @  4:draft 'C1'
  |
  o  3:draft 'B bis'
  |
  | @  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  
  $ hg rebase -a
  rebase aborted

  $ hg tglog
  @  4:draft 'C1'
  |
  o  3:draft 'B bis'
  |
  | o  2:secret 'C'
  | |
  | o  1:public 'B'
  |/
  o  0:public 'A'
  

  $ cd ..

rebase abort should not leave working copy in a merge state if tip-1 is public
(issue4082)

  $ hg init abortpublic
  $ cd abortpublic
  $ echo a > a && hg ci -Aqm a
  $ hg book master
  $ hg book foo
  $ echo b > b && hg ci -Aqm b
  $ hg up -q master
  $ echo c > c && hg ci -Aqm c
  $ hg phase -p -r .
  $ hg up -q foo
  $ echo C > c && hg ci -Aqm C
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  @  3 C foo
  |
  | o  2 c master
  | |
  o |  1 b
  |/
  o  0 a
  

  $ hg rebase -d master -r foo
  rebasing 3:6c0f977a22d8 "C" (foo tip)
  merging c
  warning: conflicts while merging c! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg rebase --abort
  rebase aborted
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  @  3 C foo
  |
  | o  2 c master
  | |
  o |  1 b
  |/
  o  0 a
  
  $ cd ..

Make sure we don't clobber changes in the working directory when the
user has somehow managed to update to a different revision (issue4009)

  $ hg init noupdate
  $ cd noupdate
  $ hg book @
  $ echo original > a
  $ hg add a
  $ hg commit -m a
  $ echo x > b
  $ hg add b
  $ hg commit -m b1
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (leaving bookmark @)
  $ hg book foo
  $ echo y > b
  $ hg add b
  $ hg commit -m b2
  created new head

  $ hg rebase -d @ -b foo --tool=internal:fail
  rebasing 2:070cf4580bb5 "b2" (foo tip)
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]

  $ mv .hg/rebasestate ./ # so we're allowed to hg up like in mercurial <2.6.3
  $ hg up -C 0            # user does other stuff in the repo
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ mv rebasestate .hg/   # user upgrades to 2.7

  $ echo new > a
  $ hg up 1               # user gets an error saying to run hg rebase --abort
  abort: rebase in progress
  (use 'hg rebase --continue' or 'hg rebase --abort')
  [255]

  $ cat a
  new
  $ hg rebase --abort
  rebase aborted
  $ cat a
  new

  $ cd ..

test aborting an interrupted series (issue5084)
  $ hg init interrupted
  $ cd interrupted
  $ touch base
  $ hg add base
  $ hg commit -m base
  $ touch a
  $ hg add a
  $ hg commit -m a
  $ echo 1 > a
  $ hg commit -m 1
  $ touch b
  $ hg add b
  $ hg commit -m b
  $ echo 2 >> a
  $ hg commit -m c
  $ touch d
  $ hg add d
  $ hg commit -m d
  $ hg co -q 1
  $ hg rm a
  $ hg commit -m no-a
  created new head
  $ hg co 0
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  o  6 no-a
  |
  | o  5 d
  | |
  | o  4 c
  | |
  | o  3 b
  | |
  | o  2 1
  |/
  o  1 a
  |
  @  0 base
  
  $ hg --config extensions.n=$TESTDIR/failfilemerge.py rebase -s 3 -d tip
  rebasing 3:3a71550954f1 "b"
  rebasing 4:e80b69427d80 "c"
  abort: ^C
  [255]

New operations are blocked with the correct state message

  $ find .hg -name '*state' -prune | sort
  .hg/dirstate
  .hg/merge/state
  .hg/rebasestate
  .hg/undo.backup.dirstate
  .hg/undo.dirstate
  .hg/updatestate

  $ hg rebase -s 3 -d tip
  abort: rebase in progress
  (use 'hg rebase --continue' or 'hg rebase --abort')
  [255]
  $ hg up .
  abort: rebase in progress
  (use 'hg rebase --continue' or 'hg rebase --abort')
  [255]
  $ hg up -C .
  abort: rebase in progress
  (use 'hg rebase --continue' or 'hg rebase --abort')
  [255]

  $ hg graft 3
  abort: rebase in progress
  (use 'hg rebase --continue' or 'hg rebase --abort')
  [255]

  $ hg rebase --abort
  saved backup bundle to $TESTTMP/interrupted/.hg/strip-backup/3d8812cf300d-93041a90-backup.hg
  rebase aborted
  $ hg log -G --template "{rev} {desc} {bookmarks}"
  o  6 no-a
  |
  | o  5 d
  | |
  | o  4 c
  | |
  | o  3 b
  | |
  | o  2 1
  |/
  o  1 a
  |
  @  0 base
  
  $ hg summary
  parent: 0:df4f53cec30a 
   base
  branch: default
  commit: (clean)
  update: 6 new changesets (update)
  phases: 7 draft

  $ cd ..
On the other hand, make sure we *do* clobber changes whenever we
haven't somehow managed to update the repo to a different revision
during a rebase (issue4661)

  $ hg ini yesupdate
  $ cd yesupdate
  $ echo "initial data" > foo.txt
  $ hg add
  adding foo.txt
  $ hg ci -m "initial checkin"
  $ echo "change 1" > foo.txt
  $ hg ci -m "change 1"
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "conflicting change 1" > foo.txt
  $ hg ci -m "conflicting 1"
  created new head
  $ echo "conflicting change 2" > foo.txt
  $ hg ci -m "conflicting 2"

  $ hg rebase -d 1 --tool 'internal:fail'
  rebasing 2:e4ea5cdc9789 "conflicting 1"
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg rebase --abort
  rebase aborted
  $ hg summary
  parent: 3:b16646383533 tip
   conflicting 2
  branch: default
  commit: (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 4 draft
  $ cd ..

test aborting a rebase succeeds after rebasing with skipped commits onto a
public changeset (issue4896)

  $ hg init succeedonpublic
  $ cd succeedonpublic
  $ echo 'content' > root
  $ hg commit -A -m 'root' -q

set up public branch
  $ echo 'content' > disappear
  $ hg commit -A -m 'disappear public' -q
commit will cause merge conflict on rebase
  $ echo '' > root
  $ hg commit -m 'remove content public' -q
  $ hg phase --public

setup the draft branch that will be rebased onto public commit
  $ hg up -r 0 -q
  $ echo 'content' > disappear
commit will disappear
  $ hg commit -A -m 'disappear draft' -q
  $ echo 'addedcontADDEDentadded' > root
commit will cause merge conflict on rebase
  $ hg commit -m 'add content draft' -q

  $ hg rebase -d 'public()' --tool :merge -q
  note: rebase of 3:0682fd3dabf5 created no changes to commit
  warning: conflicts while merging root! (edit, then use 'hg resolve --mark')
  unresolved conflicts (see hg resolve, then hg rebase --continue)
  [1]
  $ hg rebase --abort
  rebase aborted
  $ cd ..