view tests/test-log-linerange.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
  > [diff]
  > git = true
  > EOF

  $ hg init
  $ cat > foo << EOF
  > 0
  > 1
  > 2
  > 3
  > 4
  > EOF
  $ hg ci -Am init
  adding foo
  $ cat > foo << EOF
  > 0
  > 0
  > 0
  > 0
  > 1
  > 2
  > 3
  > 4
  > EOF
  $ hg ci -m 'more 0'
  $ sed 's/2/2+/' foo > foo.new
  $ mv foo.new foo
  $ cat > bar << EOF
  > a
  > b
  > c
  > d
  > e
  > EOF
  $ hg add bar
  $ hg ci -Am "2 -> 2+; added bar"
  $ cat >> foo << EOF
  > 5
  > 6
  > 7
  > 8
  > 9
  > 10
  > 11
  > EOF
  $ hg ci -m "to 11"

Add some changes with two diff hunks

  $ sed 's/^1$/ 1/' foo > foo.new
  $ mv foo.new foo
  $ sed 's/^11$/11+/' foo > foo.new
  $ mv foo.new foo
  $ hg ci -m '11 -> 11+; leading space before "1"'
(make sure there are two hunks in "foo")
  $ hg diff -c .
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -2,7 +2,7 @@
   0
   0
   0
  -1
  + 1
   2+
   3
   4
  @@ -12,4 +12,4 @@
   8
   9
   10
  -11
  +11+
  $ sed 's/3/3+/' foo > foo.new
  $ mv foo.new foo
  $ sed 's/^11+$/11-/' foo > foo.new
  $ mv foo.new foo
  $ sed 's/a/a+/' bar > bar.new
  $ mv bar.new bar
  $ hg ci -m 'foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+'
(make sure there are two hunks in "foo")
  $ hg diff -c . foo
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -4,7 +4,7 @@
   0
    1
   2+
  -3
  +3+
   4
   5
   6
  @@ -12,4 +12,4 @@
   8
   9
   10
  -11+
  +11-

  $ hg log -f -L foo,5:7 -p
  changeset:   5:cfdf972b3971
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -4,7 +4,7 @@
   0
    1
   2+
  -3
  +3+
   4
   5
   6
  
  changeset:   4:eaec41c1a0c9
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11 -> 11+; leading space before "1"
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -2,7 +2,7 @@
   0
   0
   0
  -1
  + 1
   2+
   3
   4
  
  changeset:   2:63a884426fd0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2+; added bar
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -3,6 +3,6 @@
   0
   0
   1
  -2
  +2+
   3
   4
  
  changeset:   0:5ae1f82b9a00
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,5 @@
  +0
  +1
  +2
  +3
  +4
  
  $ hg log -f --graph -L foo,5:7 -p
  @  changeset:   5:cfdf972b3971
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  |
  |  diff --git a/foo b/foo
  |  --- a/foo
  |  +++ b/foo
  |  @@ -4,7 +4,7 @@
  |   0
  |    1
  |   2+
  |  -3
  |  +3+
  |   4
  |   5
  |   6
  |
  o  changeset:   4:eaec41c1a0c9
  :  user:        test
  :  date:        Thu Jan 01 00:00:00 1970 +0000
  :  summary:     11 -> 11+; leading space before "1"
  :
  :  diff --git a/foo b/foo
  :  --- a/foo
  :  +++ b/foo
  :  @@ -2,7 +2,7 @@
  :   0
  :   0
  :   0
  :  -1
  :  + 1
  :   2+
  :   3
  :   4
  :
  o  changeset:   2:63a884426fd0
  :  user:        test
  :  date:        Thu Jan 01 00:00:00 1970 +0000
  :  summary:     2 -> 2+; added bar
  :
  :  diff --git a/foo b/foo
  :  --- a/foo
  :  +++ b/foo
  :  @@ -3,6 +3,6 @@
  :   0
  :   0
  :   1
  :  -2
  :  +2+
  :   3
  :   4
  :
  o  changeset:   0:5ae1f82b9a00
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     init
  
     diff --git a/foo b/foo
     new file mode 100644
     --- /dev/null
     +++ b/foo
     @@ -0,0 +1,5 @@
     +0
     +1
     +2
     +3
     +4
  

With --template.

  $ hg log -f -L foo,5:7 -T '{rev}:{node|short} {desc|firstline}\n'
  5:cfdf972b3971 foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  4:eaec41c1a0c9 11 -> 11+; leading space before "1"
  2:63a884426fd0 2 -> 2+; added bar
  0:5ae1f82b9a00 init
  $ hg log -f -L foo,5:7 -T json
  [
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+",
    "node": "cfdf972b3971a2a59638bf9583c0debbffee5404",
    "parents": ["eaec41c1a0c9ad0a5e999611d0149d171beffb8c"],
    "phase": "draft",
    "rev": 5,
    "tags": ["tip"],
    "user": "test"
   },
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "11 -> 11+; leading space before \"1\"",
    "node": "eaec41c1a0c9ad0a5e999611d0149d171beffb8c",
    "parents": ["730a61fbaecf426c17c2c66bc42d195b5d5b0ba8"],
    "phase": "draft",
    "rev": 4,
    "tags": [],
    "user": "test"
   },
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "2 -> 2+; added bar",
    "node": "63a884426fd0b277fcd55895bbb2f230434576eb",
    "parents": ["29a1e7c6b80024f63f310a2d71de979e9d2996d7"],
    "phase": "draft",
    "rev": 2,
    "tags": [],
    "user": "test"
   },
   {
    "bookmarks": [],
    "branch": "default",
    "date": [0, 0],
    "desc": "init",
    "node": "5ae1f82b9a000ff1e0967d0dac1c58b9d796e1b4",
    "parents": ["0000000000000000000000000000000000000000"],
    "phase": "draft",
    "rev": 0,
    "tags": [],
    "user": "test"
   }
  ]

With some white-space diff option, respective revisions are skipped.

  $ hg log -f -L foo,5:7 -p --config diff.ignorews=true
  changeset:   5:cfdf972b3971
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -4,7 +4,7 @@
   0
    1
   2+
  -3
  +3+
   4
   5
   6
  
  changeset:   2:63a884426fd0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2+; added bar
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -3,6 +3,6 @@
   0
   0
   1
  -2
  +2+
   3
   4
  
  changeset:   0:5ae1f82b9a00
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,5 @@
  +0
  +1
  +2
  +3
  +4
  

Regular file patterns are not allowed.

  $ hg log -f -L foo,5:7 -p bar
  abort: FILE arguments are not compatible with --line-range option
  [255]

Option --rev acts as a restriction.

  $ hg log -f -L foo,5:7 -p -r 'desc(2)'
  changeset:   2:63a884426fd0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2+; added bar
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -3,6 +3,6 @@
   0
   0
   1
  -2
  +2+
   3
   4
  
  changeset:   0:5ae1f82b9a00
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,5 @@
  +0
  +1
  +2
  +3
  +4
  

With several -L patterns, changes touching any files in their respective line
range are show.

  $ hg log -f -L foo,5:7 -L bar,1:2 -p
  changeset:   5:cfdf972b3971
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  
  diff --git a/bar b/bar
  --- a/bar
  +++ b/bar
  @@ -1,4 +1,4 @@
  -a
  +a+
   b
   c
   d
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -4,7 +4,7 @@
   0
    1
   2+
  -3
  +3+
   4
   5
   6
  
  changeset:   4:eaec41c1a0c9
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11 -> 11+; leading space before "1"
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -2,7 +2,7 @@
   0
   0
   0
  -1
  + 1
   2+
   3
   4
  
  changeset:   2:63a884426fd0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2+; added bar
  
  diff --git a/bar b/bar
  new file mode 100644
  --- /dev/null
  +++ b/bar
  @@ -0,0 +1,5 @@
  +a
  +b
  +c
  +d
  +e
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -3,6 +3,6 @@
   0
   0
   1
  -2
  +2+
   3
   4
  
  changeset:   0:5ae1f82b9a00
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,5 @@
  +0
  +1
  +2
  +3
  +4
  

Multiple -L options with the same file yields changes touching any of
specified line ranges.

  $ hg log -f -L foo,5:7 -L foo,14:15 -p
  changeset:   5:cfdf972b3971
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -4,7 +4,7 @@
   0
    1
   2+
  -3
  +3+
   4
   5
   6
  @@ -12,4 +12,4 @@
   8
   9
   10
  -11+
  +11-
  
  changeset:   4:eaec41c1a0c9
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11 -> 11+; leading space before "1"
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -2,7 +2,7 @@
   0
   0
   0
  -1
  + 1
   2+
   3
   4
  @@ -12,4 +12,4 @@
   8
   9
   10
  -11
  +11+
  
  changeset:   3:730a61fbaecf
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     to 11
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -6,3 +6,10 @@
   2+
   3
   4
  +5
  +6
  +7
  +8
  +9
  +10
  +11
  
  changeset:   2:63a884426fd0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2+; added bar
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -3,6 +3,6 @@
   0
   0
   1
  -2
  +2+
   3
   4
  
  changeset:   0:5ae1f82b9a00
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,5 @@
  +0
  +1
  +2
  +3
  +4
  

A file with a comma in its name.

  $ cat > ba,z << EOF
  > q
  > w
  > e
  > r
  > t
  > y
  > EOF
  $ hg ci -Am 'querty'
  adding ba,z
  $ cat >> ba,z << EOF
  > u
  > i
  > o
  > p
  > EOF
  $ hg ci -m 'more keys'
  $ cat > ba,z << EOF
  > a
  > z
  > e
  > r
  > t
  > y
  > u
  > i
  > o
  > p
  > EOF
  $ hg ci -m 'azerty'
  $ hg log -f -L ba,z,1:2 -p
  changeset:   8:52373265138b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     azerty
  
  diff --git a/ba,z b/ba,z
  --- a/ba,z
  +++ b/ba,z
  @@ -1,5 +1,5 @@
  -q
  -w
  +a
  +z
   e
   r
   t
  
  changeset:   6:96ba8850f316
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     querty
  
  diff --git a/ba,z b/ba,z
  new file mode 100644
  --- /dev/null
  +++ b/ba,z
  @@ -0,0 +1,6 @@
  +q
  +w
  +e
  +r
  +t
  +y
  

Exact prefix kinds work in -L options.

  $ mkdir dir
  $ cd dir
  $ hg log -f -L path:foo,5:7 -p
  changeset:   5:cfdf972b3971
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -4,7 +4,7 @@
   0
    1
   2+
  -3
  +3+
   4
   5
   6
  
  changeset:   4:eaec41c1a0c9
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11 -> 11+; leading space before "1"
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -2,7 +2,7 @@
   0
   0
   0
  -1
  + 1
   2+
   3
   4
  
  changeset:   2:63a884426fd0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2+; added bar
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -3,6 +3,6 @@
   0
   0
   1
  -2
  +2+
   3
   4
  
  changeset:   0:5ae1f82b9a00
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,5 @@
  +0
  +1
  +2
  +3
  +4
  

Renames are followed.

  $ hg mv ../foo baz
  $ sed 's/1/1+/' baz > baz.new
  $ mv baz.new baz
  $ hg ci -m 'foo -> dir/baz; 1-1+'
  $ hg diff -c .
  diff --git a/foo b/dir/baz
  rename from foo
  rename to dir/baz
  --- a/foo
  +++ b/dir/baz
  @@ -2,7 +2,7 @@
   0
   0
   0
  - 1
  + 1+
   2+
   3+
   4
  @@ -11,5 +11,5 @@
   7
   8
   9
  -10
  -11-
  +1+0
  +1+1-
  $ hg log -f -L relpath:baz,5:7 -p
  changeset:   9:6af29c3a778f
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo -> dir/baz; 1-1+
  
  diff --git a/foo b/dir/baz
  copy from foo
  copy to dir/baz
  --- a/foo
  +++ b/dir/baz
  @@ -2,7 +2,7 @@
   0
   0
   0
  - 1
  + 1+
   2+
   3+
   4
  
  changeset:   5:cfdf972b3971
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo: 3 -> 3+ and 11+ -> 11-; bar: a -> a+
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -4,7 +4,7 @@
   0
    1
   2+
  -3
  +3+
   4
   5
   6
  
  changeset:   4:eaec41c1a0c9
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11 -> 11+; leading space before "1"
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -2,7 +2,7 @@
   0
   0
   0
  -1
  + 1
   2+
   3
   4
  
  changeset:   2:63a884426fd0
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2 -> 2+; added bar
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -3,6 +3,6 @@
   0
   0
   1
  -2
  +2+
   3
   4
  
  changeset:   0:5ae1f82b9a00
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,5 @@
  +0
  +1
  +2
  +3
  +4
  

Binary files work but without diff hunks filtering.
(Checking w/ and w/o diff.git option.)

  >>> open('binary', 'wb').write(b'this\nis\na\nbinary\0') and None
  $ hg add binary
  $ hg ci -m 'add a binary file' --quiet
  $ hg log -f -L binary,1:2 -p
  changeset:   10:c96381c229df
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a binary file
  
  diff --git a/dir/binary b/dir/binary
  new file mode 100644
  index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..c2e1fbed209fe919b3f189a6a31950e9adf61e45
  GIT binary patch
  literal 17
  Wc$_QA$SmdpqC~Ew%)G>+N(KNlNClYy
  
  
  $ hg log -f -L binary,1:2 -p --config diff.git=false
  changeset:   10:c96381c229df
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a binary file
  
  diff -r 6af29c3a778f -r c96381c229df dir/binary
  Binary file dir/binary has changed
  

Option --follow is required.

  $ hg log -L foo,5:7
  abort: --line-range requires --follow
  [255]

Non-exact pattern kinds are not allowed.

  $ cd ..
  $ hg log -f -L glob:*a*,1:2
  hg: parse error: line range pattern 'glob:*a*' must match exactly one file
  [255]

We get an error for removed files.

  $ hg rm dir/baz
  $ hg ci -m 'remove baz' --quiet
  $ hg log -f -L dir/baz,5:7 -p
  abort: cannot follow file not in parent revision: "dir/baz"
  [255]