view tests/test-fetch.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

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

test fetch with default branches only

  $ hg init a
  $ echo a > a/a
  $ hg --cwd a commit -Ama
  adding a
  $ hg clone a b
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone a c
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b > a/b
  $ hg --cwd a commit -Amb
  adding b
  $ hg --cwd a parents -q
  1:d2ae7f538514

should pull one change

  $ hg --cwd b fetch ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets d2ae7f538514
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg --cwd b parents -q
  1:d2ae7f538514
  $ echo c > c/c
  $ hg --cwd c commit -Amc
  adding c
  $ hg clone c d
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone c e
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

We cannot use the default commit message if fetching from a local
repo, because the path of the repo will be included in the commit
message, making every commit appear different.
should merge c into a

  $ hg --cwd c fetch -d '0 0' -m 'automated merge' ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets d2ae7f538514
  updating to 2:d2ae7f538514
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  merging with 1:d36c0562f908
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  new changeset 3:a323a0c43ec4 merges remote changes with local
  $ ls c
  a
  b
  c
  $ hg serve --cwd a -a localhost -p $HGPORT -d --pid-file=hg.pid
  $ cat a/hg.pid >> "$DAEMON_PIDS"

fetch over http, no auth
(this also tests that editor is invoked if '--edit' is specified)

  $ HGEDITOR=cat hg --cwd d fetch --edit http://localhost:$HGPORT/
  pulling from http://localhost:$HGPORT/
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets d2ae7f538514
  updating to 2:d2ae7f538514
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  merging with 1:d36c0562f908
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  Automated merge with http://localhost:$HGPORT/
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch merge
  HG: branch 'default'
  HG: changed c
  new changeset 3:* merges remote changes with local (glob)
  $ hg --cwd d tip --template '{desc}\n'
  Automated merge with http://localhost:$HGPORT/
  $ hg --cwd d status --rev 'tip^1' --rev tip
  A c
  $ hg --cwd d status --rev 'tip^2' --rev tip
  A b

fetch over http with auth (should be hidden in desc)
(this also tests that editor is not invoked if '--edit' is not
specified, even though commit message is not specified explicitly)

  $ HGEDITOR=cat hg --cwd e fetch http://user:password@localhost:$HGPORT/
  pulling from http://user:***@localhost:$HGPORT/
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets d2ae7f538514
  updating to 2:d2ae7f538514
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  merging with 1:d36c0562f908
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  new changeset 3:* merges remote changes with local (glob)
  $ hg --cwd e tip --template '{desc}\n'
  Automated merge with http://localhost:$HGPORT/
  $ hg clone a f
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone a g
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo f > f/f
  $ hg --cwd f ci -Amf
  adding f
  $ echo g > g/g
  $ hg --cwd g ci -Amg
  adding g
  $ hg clone -q f h
  $ hg clone -q g i

should merge f into g

  $ hg --cwd g fetch -d '0 0' --switch -m 'automated merge' ../f
  pulling from ../f
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 6343ca3eff20
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  merging with 3:6343ca3eff20
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  new changeset 4:f7faa0b7d3c6 merges remote changes with local
  $ rm i/g

should abort, because i is modified

  $ hg --cwd i fetch ../h
  abort: uncommitted changes
  [255]

test fetch with named branches

  $ hg init nbase
  $ echo base > nbase/a
  $ hg -R nbase ci -Am base
  adding a
  $ hg -R nbase branch a
  marked working directory as branch a
  (branches are permanent and global, did you want a bookmark?)
  $ echo a > nbase/a
  $ hg -R nbase ci -m a
  $ hg -R nbase up -C 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R nbase branch b
  marked working directory as branch b
  $ echo b > nbase/b
  $ hg -R nbase ci -Am b
  adding b

pull in change on foreign branch

  $ hg clone nbase n1
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone nbase n2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R n1 up -C a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo aa > n1/a
  $ hg -R n1 ci -m a1
  $ hg -R n2 up -C b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R n2 fetch -m 'merge' n1
  pulling from n1
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 8fdc9284bbc5

parent should be 2 (no automatic update)

  $ hg -R n2 parents --template '{rev}\n'
  2
  $ rm -fr n1 n2

pull in changes on both foreign and local branches

  $ hg clone nbase n1
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone nbase n2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R n1 up -C a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo aa > n1/a
  $ hg -R n1 ci -m a1
  $ hg -R n1 up -C b
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo bb > n1/b
  $ hg -R n1 ci -m b1
  $ hg -R n2 up -C b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R n2 fetch -m 'merge' n1
  pulling from n1
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets 8fdc9284bbc5:3c4a837a864f
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

parent should be 4 (fast forward)

  $ hg -R n2 parents --template '{rev}\n'
  4
  $ rm -fr n1 n2

pull changes on foreign (2 new heads) and local (1 new head) branches
with a local change

  $ hg clone nbase n1
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone nbase n2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R n1 up -C a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo a1 > n1/a
  $ hg -R n1 ci -m a1
  $ hg -R n1 up -C b
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo bb > n1/b
  $ hg -R n1 ci -m b1
  $ hg -R n1 up -C 1
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo a2 > n1/a
  $ hg -R n1 ci -m a2
  created new head
  $ hg -R n2 up -C b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo change >> n2/c
  $ hg -R n2 ci -A -m local
  adding c
  $ hg -R n2 fetch -d '0 0' -m 'merge' n1
  pulling from n1
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+2 heads)
  new changesets d05ce59ff88d:a7954de24e4c
  updating to 5:3c4a837a864f
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  merging with 3:1267f84a9ea5
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  new changeset 7:2cf2a1261f21 merges remote changes with local

parent should be 7 (new merge changeset)

  $ hg -R n2 parents --template '{rev}\n'
  7
  $ rm -fr n1 n2

pull in changes on foreign (merge of local branch) and local (2 new
heads) with a local change

  $ hg clone nbase n1
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg clone nbase n2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R n1 up -C a
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R n1 merge b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg -R n1 ci -m merge
  $ hg -R n1 up -C 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo c > n1/a
  $ hg -R n1 ci -m c
  $ hg -R n1 up -C 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo cc > n1/a
  $ hg -R n1 ci -m cc
  created new head
  $ hg -R n2 up -C b
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo change >> n2/b
  $ hg -R n2 ci -A -m local
  $ hg -R n2 fetch -m 'merge' n1
  pulling from n1
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 1 files (+2 heads)
  new changesets b84e8d0f020f:3d3bf54f99c0
  not merging with 1 other new branch heads (use "hg heads ." and "hg merge" to merge them)
  [1]

parent should be 3 (fetch did not merge anything)

  $ hg -R n2 parents --template '{rev}\n'
  3
  $ rm -fr n1 n2

pull in change on different branch than dirstate

  $ hg init n1
  $ echo a > n1/a
  $ hg -R n1 ci -Am initial
  adding a
  $ hg clone n1 n2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b > n1/a
  $ hg -R n1 ci -m next
  $ hg -R n2 branch topic
  marked working directory as branch topic
  (branches are permanent and global, did you want a bookmark?)
  $ hg -R n2 fetch -m merge n1
  abort: working directory not at branch tip
  (use 'hg update' to check out branch tip)
  [255]

parent should be 0 (fetch did not update or merge anything)

  $ hg -R n2 parents --template '{rev}\n'
  0
  $ rm -fr n1 n2

test fetch with inactive branches

  $ hg init ib1
  $ echo a > ib1/a
  $ hg --cwd ib1 ci -Am base
  adding a
  $ hg --cwd ib1 branch second
  marked working directory as branch second
  (branches are permanent and global, did you want a bookmark?)
  $ echo b > ib1/b
  $ hg --cwd ib1 ci -Am onsecond
  adding b
  $ hg --cwd ib1 branch -f default
  marked working directory as branch default
  $ echo c > ib1/c
  $ hg --cwd ib1 ci -Am newdefault
  adding c
  created new head
  $ hg clone ib1 ib2
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved

fetch should succeed

  $ hg --cwd ib2 fetch ../ib1
  pulling from ../ib1
  searching for changes
  no changes found
  $ rm -fr ib1 ib2

test issue1726

  $ hg init i1726r1
  $ echo a > i1726r1/a
  $ hg --cwd i1726r1 ci -Am base
  adding a
  $ hg clone i1726r1 i1726r2
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo b > i1726r1/a
  $ hg --cwd i1726r1 ci -m second
  $ echo c > i1726r2/a
  $ hg --cwd i1726r2 ci -m third
  $ HGMERGE=true hg --cwd i1726r2 fetch ../i1726r1
  pulling from ../i1726r1
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 7837755a2789
  updating to 2:7837755a2789
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  merging with 1:d1f0c6c48ebd
  merging a
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  new changeset 3:* merges remote changes with local (glob)
  $ hg --cwd i1726r2 heads default --template '{rev}\n'
  3

test issue2047

  $ hg -q init i2047a
  $ cd i2047a
  $ echo a > a
  $ hg -q ci -Am a
  $ hg -q branch stable
  $ echo b > b
  $ hg -q ci -Am b
  $ cd ..
  $ hg -q clone -r 0 i2047a i2047b
  $ cd i2047b
  $ hg fetch ../i2047a
  pulling from ../i2047a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets c8735224de5c

  $ cd ..