view tests/test-incoming-outgoing.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 serve

  $ hg init test
  $ cd test
  $ for i in 0 1 2 3 4 5 6 7 8; do
  >     echo $i >> foo
  >     hg commit -A -m $i
  > done
  adding foo
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 9 changesets with 9 changes to 1 files
  $ hg serve -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid >> $DAEMON_PIDS
  $ cd ..

  $ hg init new

http incoming

  $ hg -R new incoming http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R new incoming -r 4 http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  

local incoming

  $ hg -R new incoming test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R new incoming -r 4 test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  

limit to 2 changesets

  $ hg -R new incoming -l 2 test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  

limit to 2 changesets, test with -p --git

  $ hg -R new incoming -l 2 -p --git test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  diff --git a/foo b/foo
  new file mode 100644
  --- /dev/null
  +++ b/foo
  @@ -0,0 +1,1 @@
  +0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  diff --git a/foo b/foo
  --- a/foo
  +++ b/foo
  @@ -1,1 +1,2 @@
   0
  +1
  

test with --bundle

  $ hg -R new incoming --bundle test.hg http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R new incoming --bundle test2.hg test
  comparing with test
  changeset:   0:00a43fa82f62
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     0
  
  changeset:   1:5460a410df01
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  
  changeset:   2:d9f42cd1a1ec
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  
  changeset:   3:376476025137
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     3
  
  changeset:   4:70d7eb252d49
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     4
  
  changeset:   5:ad284ee3b5ee
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     5
  
  changeset:   6:e9229f2de384
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     6
  
  changeset:   7:d152815bb8db
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     7
  
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  


test the resulting bundles

  $ hg init temp
  $ hg init temp2
  $ hg -R temp unbundle test.hg
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 9 changes to 1 files
  new changesets 00a43fa82f62:e4feb4ac9035 (9 drafts)
  (run 'hg update' to get a working copy)
  $ hg -R temp2 unbundle test2.hg
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 9 changes to 1 files
  new changesets 00a43fa82f62:e4feb4ac9035 (9 drafts)
  (run 'hg update' to get a working copy)
  $ hg -R temp tip
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  
  $ hg -R temp2 tip
  changeset:   8:e4feb4ac9035
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     8
  

  $ rm -r temp temp2 new

test outgoing

  $ hg clone test test-dev
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd test-dev
  $ for i in 9 10 11 12 13; do
  >     echo $i >> foo
  >     hg commit -A -m $i
  > done
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 14 changesets with 14 changes to 1 files
  $ cd ..
  $ hg -R test-dev outgoing test
  comparing with test
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  
  changeset:   12:e576b1bed305
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     12
  
  changeset:   13:96bbff09a7cc
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     13
  
test outgoing with secret changesets

  $ hg -R test-dev phase --force --secret 9
  $ hg -R test-dev outgoing test
  comparing with test
  searching for changes
  no changes found (ignored 5 secret changesets)
  [1]
  $ hg -R test-dev phase --draft -r 'head()'

limit to 3 changesets

  $ hg -R test-dev outgoing -l 3 test
  comparing with test
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  
  $ hg -R test-dev outgoing http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  
  changeset:   12:e576b1bed305
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     12
  
  changeset:   13:96bbff09a7cc
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     13
  
  $ hg -R test-dev outgoing -r 11 http://localhost:$HGPORT/
  comparing with http://localhost:$HGPORT/
  searching for changes
  changeset:   9:d89d4abea5bc
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     9
  
  changeset:   10:820095aa7158
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     10
  
  changeset:   11:09ede2f3a638
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     11
  

incoming from empty remote repository

  $ hg init r1
  $ hg init r2
  $ echo a > r1/foo
  $ hg -R r1 ci -Ama
  adding foo
  $ hg -R r1 incoming r2 --bundle x.hg
  comparing with r2
  searching for changes
  no changes found
  [1]

Create a "split" repo that pulls from r1 and pushes to r2, using default-push

  $ hg clone r1 split
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat > split/.hg/hgrc << EOF
  > [paths]
  > default = $TESTTMP/r3
  > default-push = $TESTTMP/r2
  > EOF
  $ hg -R split outgoing
  comparing with $TESTTMP/r2
  searching for changes
  changeset:   0:3e92d79f743a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  

Use default:pushurl instead of default-push

Windows needs a leading slash to make a URL that passes all of the checks
  $ WD=`pwd`
#if windows
  $ WD="/$WD"
#endif
  $ cat > split/.hg/hgrc << EOF
  > [paths]
  > default = $WD/r3
  > default:pushurl = file://$WD/r2
  > EOF
  $ hg -R split outgoing
  comparing with file:/*/$TESTTMP/r2 (glob)
  searching for changes
  changeset:   0:3e92d79f743a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  

Push and then double-check outgoing

  $ echo a >> split/foo
  $ hg -R split commit -Ama
  $ hg -R split push
  pushing to file:/*/$TESTTMP/r2 (glob)
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  $ hg -R split outgoing
  comparing with file:/*/$TESTTMP/r2 (glob)
  searching for changes
  no changes found
  [1]