view tests/test-import-bypass.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

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

  $ shortlog() {
  >     hg log -G --template '{rev}:{node|short} {author} {date|hgdate} - {branch} - {desc|firstline}\n'
  > }

Test --bypass with other options

  $ hg init repo-options
  $ cd repo-options
  $ echo a > a
  $ hg ci -Am adda
  adding a
  $ echo a >> a
  $ hg branch foo
  marked working directory as branch foo
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -Am changea
  $ hg export . > ../test.diff
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

Test importing an existing revision
(this also tests that "hg import" disallows combination of '--exact'
and '--edit')

  $ hg import --bypass --exact --edit ../test.diff
  abort: cannot use --exact with --edit
  [255]
  $ hg import --bypass --exact ../test.diff
  applying ../test.diff
  $ shortlog
  o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |
  o  0:07f494440405 test 0 0 - default - adda
  

Test failure without --exact

  $ hg import --bypass ../test.diff
  applying ../test.diff
  unable to find 'a' for patching
  (use '--prefix' to apply patch relative to the current directory)
  abort: patch failed to apply
  [255]
  $ hg st
  $ shortlog
  o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |
  o  0:07f494440405 test 0 0 - default - adda
  

Test --user, --date and --message

  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg import --bypass --u test2 -d '1 0' -m patch2 ../test.diff
  applying ../test.diff
  $ cat .hg/last-message.txt
  patch2 (no-eol)
  $ shortlog
  o  2:2e127d1da504 test2 1 0 - default - patch2
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  @  0:07f494440405 test 0 0 - default - adda
  
  $ hg rollback
  repository tip rolled back to revision 1 (undo import)

Test --import-branch
(this also tests that editor is not invoked for '--bypass', if the
patch contains the commit message, regardless of '--edit')

  $ HGEDITOR=cat hg import --bypass --import-branch --edit ../test.diff
  applying ../test.diff
  $ shortlog
  o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |
  @  0:07f494440405 test 0 0 - default - adda
  
  $ hg rollback
  repository tip rolled back to revision 1 (undo import)

Test --strip

  $ hg import --bypass --strip 0 - <<EOF
  > # HG changeset patch
  > # User test
  > # Date 0 0
  > # Branch foo
  > # Node ID 4e322f7ce8e3e4203950eac9ece27bf7e45ffa6c
  > # Parent  07f4944404050f47db2e5c5071e0e84e7a27bba9
  > changea
  > 
  > diff -r 07f494440405 -r 4e322f7ce8e3 a
  > --- a	Thu Jan 01 00:00:00 1970 +0000
  > +++ a	Thu Jan 01 00:00:00 1970 +0000
  > @@ -1,1 +1,2 @@
  >  a
  > +a
  > EOF
  applying patch from stdin
  $ hg rollback
  repository tip rolled back to revision 1 (undo import)

Test --strip with --bypass

  $ mkdir -p dir/dir2
  $ echo bb > dir/dir2/b
  $ echo cc > dir/dir2/c
  $ echo d > dir/d
  $ hg ci -Am 'addabcd'
  adding dir/d
  adding dir/dir2/b
  adding dir/dir2/c
  $ shortlog
  @  2:d805bc8236b6 test 0 0 - default - addabcd
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  
  $ hg import --bypass --strip 2 --prefix dir/ - <<EOF
  > # HG changeset patch
  > # User test
  > # Date 0 0
  > # Branch foo
  > changeabcd
  > 
  > diff --git a/foo/a b/foo/a
  > new file mode 100644
  > --- /dev/null
  > +++ b/foo/a
  > @@ -0,0 +1 @@
  > +a
  > diff --git a/foo/dir2/b b/foo/dir2/b2
  > rename from foo/dir2/b
  > rename to foo/dir2/b2
  > diff --git a/foo/dir2/c b/foo/dir2/c
  > --- a/foo/dir2/c
  > +++ b/foo/dir2/c
  > @@ -0,0 +1 @@
  > +cc
  > diff --git a/foo/d b/foo/d
  > deleted file mode 100644
  > --- a/foo/d
  > +++ /dev/null
  > @@ -1,1 +0,0 @@
  > -d
  > EOF
  applying patch from stdin

  $ shortlog
  o  3:5bd46886ca3e test 0 0 - default - changeabcd
  |
  @  2:d805bc8236b6 test 0 0 - default - addabcd
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  
  $ hg diff --change 3 --git
  diff --git a/dir/a b/dir/a
  new file mode 100644
  --- /dev/null
  +++ b/dir/a
  @@ -0,0 +1,1 @@
  +a
  diff --git a/dir/d b/dir/d
  deleted file mode 100644
  --- a/dir/d
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -d
  diff --git a/dir/dir2/b b/dir/dir2/b2
  rename from dir/dir2/b
  rename to dir/dir2/b2
  diff --git a/dir/dir2/c b/dir/dir2/c
  --- a/dir/dir2/c
  +++ b/dir/dir2/c
  @@ -1,1 +1,2 @@
   cc
  +cc
  $ hg -q --config extensions.strip= strip .

Test unsupported combinations

  $ hg import --bypass --no-commit ../test.diff
  abort: cannot use --no-commit with --bypass
  [255]
  $ hg import --bypass --similarity 50 ../test.diff
  abort: cannot use --similarity with --bypass
  [255]
  $ hg import --exact --prefix dir/ ../test.diff
  abort: cannot use --exact with --prefix
  [255]

Test commit editor
(this also tests that editor is invoked, if the patch doesn't contain
the commit message, regardless of '--edit')

  $ cat > ../test.diff <<EOF
  > diff -r 07f494440405 -r 4e322f7ce8e3 a
  > --- a/a	Thu Jan 01 00:00:00 1970 +0000
  > +++ b/a	Thu Jan 01 00:00:00 1970 +0000
  > @@ -1,1 +1,2 @@
  > -a
  > +b
  > +c
  > EOF
  $ HGEDITOR=cat hg import --bypass ../test.diff
  applying ../test.diff
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: changed a
  abort: empty commit message
  [255]

Test patch.eol is handled
(this also tests that editor is not invoked for '--bypass', if the
commit message is explicitly specified, regardless of '--edit')

  $ "$PYTHON" -c 'open("a", "wb").write(b"a\r\n")'
  $ hg ci -m makeacrlf
  $ HGEDITOR=cat hg import -m 'should fail because of eol' --edit --bypass ../test.diff
  applying ../test.diff
  patching file a
  Hunk #1 FAILED at 0
  abort: patch failed to apply
  [255]
  $ hg --config patch.eol=auto import -d '0 0' -m 'test patch.eol' --bypass ../test.diff
  applying ../test.diff
  $ shortlog
  o  3:c606edafba99 test 0 0 - default - test patch.eol
  |
  @  2:872023de769d test 0 0 - default - makeacrlf
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  

Test applying multiple patches

  $ hg up -qC 0
  $ echo e > e
  $ hg ci -Am adde
  adding e
  created new head
  $ hg export . > ../patch1.diff
  $ hg up -qC 1
  $ echo f > f
  $ hg ci -Am addf
  adding f
  $ hg export . > ../patch2.diff
  $ cd ..
  $ hg clone -r1 repo-options repo-multi1
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 07f494440405:4e322f7ce8e3
  updating to branch foo
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd repo-multi1
  $ hg up 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg import --bypass ../patch1.diff ../patch2.diff
  applying ../patch1.diff
  applying ../patch2.diff
  $ shortlog
  o  3:bc8ca3f8a7c4 test 0 0 - default - addf
  |
  o  2:16581080145e test 0 0 - default - adde
  |
  | o  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  @  0:07f494440405 test 0 0 - default - adda
  

Test applying multiple patches with --exact

  $ cd ..
  $ hg clone -r1 repo-options repo-multi2
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  new changesets 07f494440405:4e322f7ce8e3
  updating to branch foo
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd repo-multi2
  $ hg import --bypass --exact ../patch1.diff ../patch2.diff
  applying ../patch1.diff
  applying ../patch2.diff
  $ shortlog
  o  3:d60cb8989666 test 0 0 - foo - addf
  |
  | o  2:16581080145e test 0 0 - default - adde
  | |
  @ |  1:4e322f7ce8e3 test 0 0 - foo - changea
  |/
  o  0:07f494440405 test 0 0 - default - adda
  

  $ cd ..

Test avoiding editor invocation at applying the patch with --exact
even if commit message is empty

  $ cd repo-options

  $ echo a >> a
  $ hg commit -m ' '
  $ hg tip -T "{node}\n"
  1b77bc7d1db9f0e7f1716d515b630516ab386c89
  $ hg export -o ../empty-log.diff .
  $ hg update -q -C ".^1"
  $ hg --config extensions.strip= strip -q tip
  $ HGEDITOR=cat hg import --exact --bypass ../empty-log.diff
  applying ../empty-log.diff
  $ hg tip -T "{node}\n"
  1b77bc7d1db9f0e7f1716d515b630516ab386c89

  $ cd ..

#if symlink execbit

Test complicated patch with --exact

  $ hg init repo-exact
  $ cd repo-exact
  $ echo a > a
  $ echo c > c
  $ echo d > d
  $ echo e > e
  $ echo f > f
  $ chmod +x f
  $ ln -s c linkc
  $ hg ci -Am t
  adding a
  adding c
  adding d
  adding e
  adding f
  adding linkc
  $ hg cp a aa1
  $ echo b >> a
  $ echo b > b
  $ hg add b
  $ hg cp a aa2
  $ echo aa >> aa2
  $ chmod +x e
  $ chmod -x f
  $ ln -s a linka
  $ hg rm d
  $ hg rm linkc
  $ hg mv c cc
  $ hg ci -m patch
  $ hg export --git . > ../test.diff
  $ hg up -C null
  0 files updated, 0 files merged, 7 files removed, 0 files unresolved
  $ hg purge
  $ hg st
  $ hg import --bypass --exact ../test.diff
  applying ../test.diff

The patch should have matched the exported revision and generated no additional
data. If not, diff both heads to debug it.

  $ shortlog
  o  1:2978fd5c8aa4 test 0 0 - default - patch
  |
  o  0:a0e19e636a43 test 0 0 - default - t
  
#endif

  $ cd ..