view tests/test-commit-interactive-curses.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

#require tic

Set up a repo

  $ cp $HGRCPATH $HGRCPATH.pretest
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interactive = true
  > interface = curses
  > [experimental]
  > crecordtest = testModeCommands
  > EOF

Record with noeol at eof (issue5268)
  $ hg init noeol
  $ cd noeol
  $ printf '0' > a
  $ printf '0\n' > b
  $ hg ci -Aqm initial
  $ printf '1\n0' > a
  $ printf '1\n0\n' > b
  $ cat <<EOF >testModeCommands
  > c
  > EOF
  $ HGEDITOR="\"sh\" \"`pwd`/editor.sh\"" hg commit  -i -m "add hunks" -d "0 0"
  $ cd ..

Normal repo
  $ hg init a
  $ cd a

Committing some changes but stopping on the way

  $ echo "a" > a
  $ hg add a
  $ cat <<EOF >testModeCommands
  > TOGGLE
  > X
  > EOF
  $ hg commit -i  -m "a" -d "0 0"
  no changes to record
  [1]
  $ hg tip
  changeset:   -1:000000000000
  tag:         tip
  user:        
  date:        Thu Jan 01 00:00:00 1970 +0000
  

Committing some changes

  $ cat <<EOF >testModeCommands
  > X
  > EOF
  $ hg commit -i  -m "a" -d "0 0"
  $ hg tip
  changeset:   0:cb9a9f314b8b
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
Check that commit -i works with no changes
  $ hg commit -i
  no changes to record
  [1]

Committing only one file

  $ echo "a" >> a
  >>> open('b', 'wb').write(b"1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n") and None
  $ hg add b
  $ cat <<EOF >testModeCommands
  > TOGGLE
  > KEY_DOWN
  > X
  > EOF
  $ hg commit -i  -m "one file" -d "0 0"
  $ hg tip
  changeset:   1:fb2705a663ea
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     one file
  
  $ hg cat -r tip a
  a
  $ cat a
  a
  a

Committing only one hunk while aborting edition of hunk

- Untoggle all the hunks, go down to the second file
- unfold it
- go down to second hunk (1 for the first hunk, 1 for the first hunkline, 1 for the second hunk, 1 for the second hunklike)
- toggle the second hunk
- toggle on and off the amend mode (to check that it toggles off)
- edit the hunk and quit the editor immediately with non-zero status
- commit

  $ printf "printf 'editor ran\n'; exit 1" > editor.sh
  $ echo "x" > c
  $ cat b >> c
  $ echo "y" >> c
  $ mv c b
  $ cat <<EOF >testModeCommands
  > A
  > KEY_DOWN
  > f
  > KEY_DOWN
  > KEY_DOWN
  > KEY_DOWN
  > KEY_DOWN
  > TOGGLE
  > a
  > a
  > e
  > X
  > EOF
  $ HGEDITOR="\"sh\" \"`pwd`/editor.sh\"" hg commit -i  -m "one hunk" -d "0 0"
  editor ran
  $ rm editor.sh
  $ hg tip
  changeset:   2:7d10dfe755a8
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     one hunk
  
  $ hg cat -r tip b
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  y
  $ cat b
  x
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  y
  $ hg commit -m "other hunks"
  $ hg tip
  changeset:   3:a6735021574d
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     other hunks
  
  $ hg cat -r tip b
  x
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  y

Newly added files can be selected with the curses interface

  $ hg update -C .
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "hello" > x
  $ hg add x
  $ cat <<EOF >testModeCommands
  > TOGGLE
  > TOGGLE
  > X
  > EOF
  $ hg st
  A x
  ? testModeCommands
  $ hg commit -i  -m "newly added file" -d "0 0"
  $ hg st
  ? testModeCommands

Amend option works
  $ echo "hello world" > x
  $ hg diff -c .
  diff -r a6735021574d -r 2b0e9be4d336 x
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/x	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +hello
  $ cat <<EOF >testModeCommands
  > a
  > X
  > EOF
  $ hg commit -i  -m "newly added file" -d "0 0"
  saved backup bundle to $TESTTMP/a/.hg/strip-backup/2b0e9be4d336-3cf0bc8c-amend.hg
  $ hg diff -c .
  diff -r a6735021574d -r c1d239d165ae x
  --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
  +++ b/x	Thu Jan 01 00:00:00 1970 +0000
  @@ -0,0 +1,1 @@
  +hello world

Make file empty
  $ printf "" > x
  $ cat <<EOF >testModeCommands
  > X
  > EOF
  $ hg ci -i -m emptify -d "0 0"
  $ hg update -C '.^' -q

Editing a hunk puts you back on that hunk when done editing (issue5041)
To do that, we change two lines in a file, pretend to edit the second line,
exit, toggle the line selected at the end of the edit and commit.
The first line should be recorded if we were put on the second line at the end
of the edit.

  $ hg update -C .
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "foo" > x
  $ echo "hello world" >> x
  $ echo "bar" >> x
  $ cat <<EOF >testModeCommands
  > f
  > KEY_DOWN
  > KEY_DOWN
  > KEY_DOWN
  > KEY_DOWN
  > e
  > TOGGLE
  > X
  > EOF
  $ printf "printf 'editor ran\n'; exit 0" > editor.sh
  $ HGEDITOR="\"sh\" \"`pwd`/editor.sh\"" hg commit  -i -m "edit hunk" -d "0 0" -q
  editor ran
  $ hg cat -r . x
  foo
  hello world

Testing the review option. The entire final filtered patch should show
up in the editor and be editable. We will unselect the second file and
the first hunk of the third file. During review, we will decide that
"lower" sounds better than "bottom", and the final commit should
reflect this edition.

  $ hg update -C .
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo "top" > c
  $ cat x >> c
  $ echo "bottom" >> c
  $ mv c x
  $ echo "third a" >> a
  $ echo "we will unselect this" >> b

  $ cat > editor.sh <<EOF
  > cat "\$1"
  > cat "\$1" | sed s/bottom/lower/ > tmp
  > mv tmp "\$1"
  > EOF
  $ cat > testModeCommands <<EOF
  > KEY_DOWN
  > TOGGLE
  > KEY_DOWN
  > f
  > KEY_DOWN
  > TOGGLE
  > R
  > EOF

  $ HGEDITOR="\"sh\" \"`pwd`/editor.sh\"" hg commit  -i -m "review hunks" -d "0 0"
  # To remove '-' lines, make them ' ' lines (context).
  # To remove '+' lines, delete them.
  # Lines starting with # will be removed from the patch.
  #
  # If the patch applies cleanly, the edited patch will immediately
  # be finalised. If it does not apply cleanly, rejects files will be
  # generated. You can use those when you try again.
  diff --git a/a b/a
  --- a/a
  +++ b/a
  @@ -1,2 +1,3 @@
   a
   a
  +third a
  diff --git a/x b/x
  --- a/x
  +++ b/x
  @@ -1,2 +1,3 @@
   foo
   hello world
  +bottom

  $ hg cat -r . a
  a
  a
  third a

  $ hg cat -r . b
  x
  1
  2
  3
  4
  5
  6
  7
  8
  9
  10
  y

  $ hg cat -r . x
  foo
  hello world
  lower

Check ui.interface logic for the chunkselector

The default interface is text
  $ cp $HGRCPATH.pretest $HGRCPATH
  $ chunkselectorinterface() {
  > "$PYTHON" <<EOF
  > from mercurial import hg, ui;\
  > repo = hg.repository(ui.ui.load(), ".");\
  > print(repo.ui.interface("chunkselector"))
  > EOF
  > }
  $ chunkselectorinterface
  text

If only the default is set, we'll use that for the feature, too
  $ cp $HGRCPATH.pretest $HGRCPATH
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interface = curses
  > EOF
  $ chunkselectorinterface
  curses

If TERM=dumb, we use text, even if the config says curses
  $ chunkselectorinterface
  curses
  $ TERM=dumb chunkselectorinterface
  text
(Something is keeping TERM=dumb in the environment unless I do this, it's not
scoped to just that previous command like in many shells)
  $ TERM=xterm chunkselectorinterface
  curses

It is possible to override the default interface with a feature specific
interface
  $ cp $HGRCPATH.pretest $HGRCPATH
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interface = text
  > interface.chunkselector = curses
  > EOF

  $ chunkselectorinterface
  curses

  $ cp $HGRCPATH.pretest $HGRCPATH
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interface = curses
  > interface.chunkselector = text
  > EOF

  $ chunkselectorinterface
  text

If a bad interface name is given, we use the default value (with a nice
error message to suggest that the configuration needs to be fixed)

  $ cp $HGRCPATH.pretest $HGRCPATH
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interface = blah
  > EOF
  $ chunkselectorinterface
  invalid value for ui.interface: blah (using text)
  text

  $ cp $HGRCPATH.pretest $HGRCPATH
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interface = curses
  > interface.chunkselector = blah
  > EOF
  $ chunkselectorinterface
  invalid value for ui.interface.chunkselector: blah (using curses)
  curses

  $ cp $HGRCPATH.pretest $HGRCPATH
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interface = blah
  > interface.chunkselector = curses
  > EOF
  $ chunkselectorinterface
  invalid value for ui.interface: blah
  curses

  $ cp $HGRCPATH.pretest $HGRCPATH
  $ cat <<EOF >> $HGRCPATH
  > [ui]
  > interface = blah
  > interface.chunkselector = blah
  > EOF
  $ chunkselectorinterface
  invalid value for ui.interface: blah
  invalid value for ui.interface.chunkselector: blah (using text)
  text