view tests/test-revert-interactive.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

Revert interactive tests
1 add and commit file f
2 add commit file folder1/g
3 add and commit file folder2/h
4 add and commit file folder1/i
5 commit change to file f
6 commit changes to files folder1/g folder2/h
7 commit changes to files folder1/g folder2/h
8 revert interactive to commit id 2 (line 3 above), check that folder1/i is removed and
9 make workdir match 7
10 run the same test than 8 from within folder1 and check same expectations

  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interactive = true
  > [extensions]
  > record =
  > purge = 
  > EOF


  $ mkdir -p a/folder1 a/folder2
  $ cd a
  $ hg init
  >>> open('f', 'wb').write(b"1\n2\n3\n4\n5\n") and None
  $ hg add f ; hg commit -m "adding f"
  $ cat f > folder1/g ; hg add folder1/g ; hg commit -m "adding folder1/g"
  $ cat f > folder2/h ; hg add folder2/h ; hg commit -m "adding folder2/h"
  $ cat f > folder1/i ; hg add folder1/i ; hg commit -m "adding folder1/i"
  >>> open('f', 'wb').write(b"a\n1\n2\n3\n4\n5\nb\n") and None
  $ hg commit -m "modifying f"
  >>> open('folder1/g', 'wb').write(b"c\n1\n2\n3\n4\n5\nd\n") and None
  $ hg commit -m "modifying folder1/g"
  >>> open('folder2/h', 'wb').write(b"e\n1\n2\n3\n4\n5\nf\n") and None
  $ hg commit -m "modifying folder2/h"
  $ hg tip
  changeset:   6:59dd6e4ab63a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modifying folder2/h
  
  $ hg revert -i -r 2 --all -- << EOF
  > y
  > y
  > y
  > y
  > y
  > ?
  > y
  > n
  > n
  > EOF
  remove added file folder1/i (Yn)? y
  removing folder1/i
  diff --git a/f b/f
  2 hunks, 2 lines changed
  examine changes to 'f'? [Ynesfdaq?] y
  
  @@ -1,6 +1,5 @@
  -a
   1
   2
   3
   4
   5
  apply change 1/6 to 'f'? [Ynesfdaq?] y
  
  @@ -2,6 +1,5 @@
   1
   2
   3
   4
   5
  -b
  apply change 2/6 to 'f'? [Ynesfdaq?] y
  
  diff --git a/folder1/g b/folder1/g
  2 hunks, 2 lines changed
  examine changes to 'folder1/g'? [Ynesfdaq?] y
  
  @@ -1,6 +1,5 @@
  -c
   1
   2
   3
   4
   5
  apply change 3/6 to 'folder1/g'? [Ynesfdaq?] ?
  
  y - yes, apply this change
  n - no, skip this change
  e - edit this change manually
  s - skip remaining changes to this file
  f - apply remaining changes to this file
  d - done, skip remaining changes and files
  a - apply all changes to all remaining files
  q - quit, applying no changes
  ? - ? (display help)
  apply change 3/6 to 'folder1/g'? [Ynesfdaq?] y
  
  @@ -2,6 +1,5 @@
   1
   2
   3
   4
   5
  -d
  apply change 4/6 to 'folder1/g'? [Ynesfdaq?] n
  
  diff --git a/folder2/h b/folder2/h
  2 hunks, 2 lines changed
  examine changes to 'folder2/h'? [Ynesfdaq?] n
  
  reverting f
  reverting folder1/g
  $ cat f
  1
  2
  3
  4
  5
  $ cat folder1/g
  1
  2
  3
  4
  5
  d
  $ cat folder2/h
  e
  1
  2
  3
  4
  5
  f

Test that --interactive lift the need for --all

  $ echo q | hg revert -i -r 2
  diff --git a/folder1/g b/folder1/g
  1 hunks, 1 lines changed
  examine changes to 'folder1/g'? [Ynesfdaq?] q
  
  abort: user quit
  [255]
  $ ls folder1/
  g

Test that a noop revert doesn't do an unnecessary backup
  $ (echo y; echo n) | hg revert -i -r 2 folder1/g
  diff --git a/folder1/g b/folder1/g
  1 hunks, 1 lines changed
  examine changes to 'folder1/g'? [Ynesfdaq?] y
  
  @@ -3,4 +3,3 @@
   3
   4
   5
  -d
  apply this change to 'folder1/g'? [Ynesfdaq?] n
  
  $ ls folder1/
  g

Test --no-backup
  $ (echo y; echo y) | hg revert -i -C -r 2 folder1/g
  diff --git a/folder1/g b/folder1/g
  1 hunks, 1 lines changed
  examine changes to 'folder1/g'? [Ynesfdaq?] y
  
  @@ -3,4 +3,3 @@
   3
   4
   5
  -d
  apply this change to 'folder1/g'? [Ynesfdaq?] y
  
  $ ls folder1/
  g
  >>> open('folder1/g', 'wb').write(b"1\n2\n3\n4\n5\nd\n") and None


  $ hg update -C 6
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg revert -i -r 2 --all -- << EOF
  > n
  > y
  > y
  > y
  > y
  > y
  > n
  > n
  > EOF
  remove added file folder1/i (Yn)? n
  diff --git a/f b/f
  2 hunks, 2 lines changed
  examine changes to 'f'? [Ynesfdaq?] y
  
  @@ -1,6 +1,5 @@
  -a
   1
   2
   3
   4
   5
  apply change 1/6 to 'f'? [Ynesfdaq?] y
  
  @@ -2,6 +1,5 @@
   1
   2
   3
   4
   5
  -b
  apply change 2/6 to 'f'? [Ynesfdaq?] y
  
  diff --git a/folder1/g b/folder1/g
  2 hunks, 2 lines changed
  examine changes to 'folder1/g'? [Ynesfdaq?] y
  
  @@ -1,6 +1,5 @@
  -c
   1
   2
   3
   4
   5
  apply change 3/6 to 'folder1/g'? [Ynesfdaq?] y
  
  @@ -2,6 +1,5 @@
   1
   2
   3
   4
   5
  -d
  apply change 4/6 to 'folder1/g'? [Ynesfdaq?] n
  
  diff --git a/folder2/h b/folder2/h
  2 hunks, 2 lines changed
  examine changes to 'folder2/h'? [Ynesfdaq?] n
  
  reverting f
  reverting folder1/g
  $ cat f
  1
  2
  3
  4
  5
  $ cat folder1/g
  1
  2
  3
  4
  5
  d
  $ cat folder2/h
  e
  1
  2
  3
  4
  5
  f
  $ hg st
  M f
  M folder1/g
  $ hg revert --interactive f << EOF
  > y
  > ?
  > y
  > n
  > n
  > EOF
  diff --git a/f b/f
  2 hunks, 2 lines changed
  examine changes to 'f'? [Ynesfdaq?] y
  
  @@ -1,6 +1,5 @@
  -a
   1
   2
   3
   4
   5
  discard change 1/2 to 'f'? [Ynesfdaq?] ?
  
  y - yes, discard this change
  n - no, skip this change
  e - edit this change manually
  s - skip remaining changes to this file
  f - discard remaining changes to this file
  d - done, skip remaining changes and files
  a - discard all changes to all remaining files
  q - quit, discarding no changes
  ? - ? (display help)
  discard change 1/2 to 'f'? [Ynesfdaq?] y
  
  @@ -2,6 +1,5 @@
   1
   2
   3
   4
   5
  -b
  discard change 2/2 to 'f'? [Ynesfdaq?] n
  
  $ hg st
  M f
  M folder1/g
  ? f.orig
  $ cat f
  a
  1
  2
  3
  4
  5
  $ cat f.orig
  1
  2
  3
  4
  5
  $ rm f.orig
  $ hg update -C .
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

Check editing files newly added by a revert

1) Create a dummy editor changing 1 to 42
  $ cat > $TESTTMP/editor.sh << '__EOF__'
  > cat "$1"  | sed "s/1/42/g"  > tt
  > mv tt  "$1"
  > __EOF__

2) Add k
  $ printf "1\n" > k
  $ hg add k
  $ hg commit -m "add k"

3) Use interactive revert with editing (replacing +1 with +42):
  $ printf "0\n2\n" > k
  $ HGEDITOR="\"sh\" \"${TESTTMP}/editor.sh\"" hg revert -i  <<EOF
  > y
  > e
  > EOF
  diff --git a/k b/k
  1 hunks, 2 lines changed
  examine changes to 'k'? [Ynesfdaq?] y
  
  @@ -1,1 +1,2 @@
  -1
  +0
  +2
  discard this change to 'k'? [Ynesfdaq?] e
  
  reverting k
  $ cat k
  42

  $ hg update -C .
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg purge
  $ touch newfile
  $ hg add newfile
  $ hg status
  A newfile
  $ hg revert -i <<EOF
  > n
  > EOF
  forget added file newfile (Yn)? n
  $ hg status
  A newfile
  $ hg revert -i <<EOF
  > y
  > EOF
  forget added file newfile (Yn)? y
  forgetting newfile
  $ hg status
  ? newfile

When a line without EOL is selected during "revert -i" (issue5651)

  $ hg init $TESTTMP/revert-i-eol
  $ cd $TESTTMP/revert-i-eol
  $ echo 0 > a
  $ hg ci -qAm 0
  $ printf 1 >> a
  $ hg ci -qAm 1
  $ cat a
  0
  1 (no-eol)

  $ hg revert -ir'.^' <<EOF
  > y
  > y
  > EOF
  diff --git a/a b/a
  1 hunks, 1 lines changed
  examine changes to 'a'? [Ynesfdaq?] y
  
  @@ -1,2 +1,1 @@
   0
  -1
  \ No newline at end of file
  apply this change to 'a'? [Ynesfdaq?] y
  
  reverting a
  $ cat a
  0

When specified pattern does not exist, we should exit early (issue5789).

  $ hg files
  a
  $ hg rev b
  b: no such file in rev b40d1912accf
  $ hg rev -i b
  b: no such file in rev b40d1912accf

  $ cd ..