view tests/test-infinitepush-ci.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 no-reposimplestore

Testing the case when there is no infinitepush extension present on the client
side and the server routes each push to bundlestore. This case is very much
similar to CI use case.

Setup
-----

  $ . "$TESTDIR/library-infinitepush.sh"
  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > ssh = python "$TESTDIR/dummyssh"
  > [alias]
  > glog = log -GT "{rev}:{node|short} {desc}\n{phase}"
  > EOF
  $ cp $HGRCPATH $TESTTMP/defaulthgrc
  $ hg init repo
  $ cd repo
  $ setupserver
  $ echo "pushtobundlestore = True" >> .hg/hgrc
  $ echo "[extensions]" >> .hg/hgrc
  $ echo "infinitepush=" >> .hg/hgrc
  $ echo initialcommit > initialcommit
  $ hg ci -Aqm "initialcommit"
  $ hg phase --public .

  $ cd ..
  $ hg clone repo client -q
  $ hg clone repo client2 -q
  $ hg clone ssh://user@dummy/repo client3 -q
  $ cd client

Pushing a new commit from the client to the server
-----------------------------------------------------

  $ echo foobar > a
  $ hg ci -Aqm "added a"
  $ hg glog
  @  1:6cb0989601f1 added a
  |  draft
  o  0:67145f466344 initialcommit
     public

  $ hg push
  pushing to $TESTTMP/repo
  searching for changes
  storing changesets on the bundlestore
  pushing 1 commit:
      6cb0989601f1  added a

  $ scratchnodes
  6cb0989601f1fb5805238edfb16f3606713d9a0b a4c202c147a9c4bb91bbadb56321fc5f3950f7f2

Understanding how data is stored on the bundlestore in server
-------------------------------------------------------------

There are two things, filebundlestore and index
  $ ls ../repo/.hg/scratchbranches
  filebundlestore
  index

filebundlestore stores the bundles
  $ ls ../repo/.hg/scratchbranches/filebundlestore/a4/c2/
  a4c202c147a9c4bb91bbadb56321fc5f3950f7f2

index/nodemap stores a map of node id and file in which bundle is stored in filebundlestore
  $ ls ../repo/.hg/scratchbranches/index/
  nodemap
  $ ls ../repo/.hg/scratchbranches/index/nodemap/
  6cb0989601f1fb5805238edfb16f3606713d9a0b

  $ cd ../repo

Checking that the commit was not applied to revlog on the server
------------------------------------------------------------------

  $ hg glog
  @  0:67145f466344 initialcommit
     public

Applying the changeset from the bundlestore
--------------------------------------------

  $ hg unbundle .hg/scratchbranches/filebundlestore/a4/c2/a4c202c147a9c4bb91bbadb56321fc5f3950f7f2
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 6cb0989601f1
  (run 'hg update' to get a working copy)

  $ hg glog
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

Pushing more changesets from the local repo
--------------------------------------------

  $ cd ../client
  $ echo b > b
  $ hg ci -Aqm "added b"
  $ echo c > c
  $ hg ci -Aqm "added c"
  $ hg glog
  @  3:bf8a6e3011b3 added c
  |  draft
  o  2:eaba929e866c added b
  |  draft
  o  1:6cb0989601f1 added a
  |  public
  o  0:67145f466344 initialcommit
     public

  $ hg push
  pushing to $TESTTMP/repo
  searching for changes
  storing changesets on the bundlestore
  pushing 2 commits:
      eaba929e866c  added b
      bf8a6e3011b3  added c

Checking that changesets are not applied on the server
------------------------------------------------------

  $ hg glog -R ../repo
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

Both of the new changesets are stored in a single bundle-file
  $ scratchnodes
  6cb0989601f1fb5805238edfb16f3606713d9a0b a4c202c147a9c4bb91bbadb56321fc5f3950f7f2
  bf8a6e3011b345146bbbedbcb1ebd4837571492a ee41a41cefb7817cbfb235b4f6e9f27dbad6ca1f
  eaba929e866c59bc9a6aada5a9dd2f6990db83c0 ee41a41cefb7817cbfb235b4f6e9f27dbad6ca1f

Pushing more changesets to the server
-------------------------------------

  $ echo d > d
  $ hg ci -Aqm "added d"
  $ echo e > e
  $ hg ci -Aqm "added e"

XXX: we should have pushed only the parts which are not in bundlestore
  $ hg push
  pushing to $TESTTMP/repo
  searching for changes
  storing changesets on the bundlestore
  pushing 4 commits:
      eaba929e866c  added b
      bf8a6e3011b3  added c
      1bb96358eda2  added d
      b4e4bce66051  added e

Sneak peek into the bundlestore at the server
  $ scratchnodes
  1bb96358eda285b536c6d1c66846a7cdb2336cea 57e00c0d4f26e2a2a72b751b63d9abc4f3eb28e7
  6cb0989601f1fb5805238edfb16f3606713d9a0b a4c202c147a9c4bb91bbadb56321fc5f3950f7f2
  b4e4bce660512ad3e71189e14588a70ac8e31fef 57e00c0d4f26e2a2a72b751b63d9abc4f3eb28e7
  bf8a6e3011b345146bbbedbcb1ebd4837571492a 57e00c0d4f26e2a2a72b751b63d9abc4f3eb28e7
  eaba929e866c59bc9a6aada5a9dd2f6990db83c0 57e00c0d4f26e2a2a72b751b63d9abc4f3eb28e7

Checking if `hg pull` pulls something or `hg incoming` shows something
-----------------------------------------------------------------------

  $ hg incoming
  comparing with $TESTTMP/repo
  searching for changes
  no changes found
  [1]

  $ hg pull
  pulling from $TESTTMP/repo
  searching for changes
  no changes found

Pulling from second client which is a localpeer to test `hg pull -r <rev>`
--------------------------------------------------------------------------

Pulling the revision which is applied

  $ cd ../client2
  $ hg pull -r 6cb0989601f1
  pulling from $TESTTMP/repo
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 6cb0989601f1
  (run 'hg update' to get a working copy)
  $ hg glog
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

Pulling the revision which is in bundlestore
XXX: we should support pulling revisions from a local peers bundlestore without
client side wrapping

  $ hg pull -r b4e4bce660512ad3e71189e14588a70ac8e31fef
  pulling from $TESTTMP/repo
  abort: unknown revision 'b4e4bce660512ad3e71189e14588a70ac8e31fef'!
  [255]
  $ hg glog
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

  $ cd ../client

Pulling from third client which is not a localpeer
---------------------------------------------------

Pulling the revision which is applied

  $ cd ../client3
  $ hg pull -r 6cb0989601f1
  pulling from ssh://user@dummy/repo
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 6cb0989601f1
  (run 'hg update' to get a working copy)
  $ hg glog
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

Pulling the revision which is in bundlestore

Trying to specify short hash
XXX: we should support this
  $ hg pull -r b4e4bce660512
  pulling from ssh://user@dummy/repo
  abort: unknown revision 'b4e4bce660512'!
  [255]

XXX: we should show better message when the pull is happening from bundlestore
  $ hg pull -r b4e4bce660512ad3e71189e14588a70ac8e31fef
  pulling from ssh://user@dummy/repo
  searching for changes
  no changes found
  adding changesets
  adding manifests
  adding file changes
  added 4 changesets with 4 changes to 4 files
  new changesets eaba929e866c:b4e4bce66051
  $ hg glog
  o  5:b4e4bce66051 added e
  |  public
  o  4:1bb96358eda2 added d
  |  public
  o  3:bf8a6e3011b3 added c
  |  public
  o  2:eaba929e866c added b
  |  public
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

  $ cd ../client

Checking storage of phase information with the bundle on bundlestore
---------------------------------------------------------------------

creating a draft commit
  $ cat >> $HGRCPATH <<EOF
  > [phases]
  > publish = False
  > EOF
  $ echo f > f
  $ hg ci -Aqm "added f"
  $ hg glog -r '.^::'
  @  6:9b42578d4447 added f
  |  draft
  o  5:b4e4bce66051 added e
  |  public
  ~

  $ hg push
  pushing to $TESTTMP/repo
  searching for changes
  storing changesets on the bundlestore
  pushing 5 commits:
      eaba929e866c  added b
      bf8a6e3011b3  added c
      1bb96358eda2  added d
      b4e4bce66051  added e
      9b42578d4447  added f

XXX: the phase of 9b42578d4447 should not be changed here
  $ hg glog -r .
  @  6:9b42578d4447 added f
  |  public
  ~

applying the bundle on the server to check preservation of phase-information

  $ cd ../repo
  $ scratchnodes
  1bb96358eda285b536c6d1c66846a7cdb2336cea 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  6cb0989601f1fb5805238edfb16f3606713d9a0b a4c202c147a9c4bb91bbadb56321fc5f3950f7f2
  9b42578d44473575994109161430d65dd147d16d 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  b4e4bce660512ad3e71189e14588a70ac8e31fef 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  bf8a6e3011b345146bbbedbcb1ebd4837571492a 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  eaba929e866c59bc9a6aada5a9dd2f6990db83c0 0a6e70ecd5b98d22382f69b93909f557ac6a9927

  $ hg unbundle .hg/scratchbranches/filebundlestore/0a/6e/0a6e70ecd5b98d22382f69b93909f557ac6a9927
  adding changesets
  adding manifests
  adding file changes
  added 5 changesets with 5 changes to 5 files
  new changesets eaba929e866c:9b42578d4447 (1 drafts)
  (run 'hg update' to get a working copy)

  $ hg glog
  o  6:9b42578d4447 added f
  |  draft
  o  5:b4e4bce66051 added e
  |  public
  o  4:1bb96358eda2 added d
  |  public
  o  3:bf8a6e3011b3 added c
  |  public
  o  2:eaba929e866c added b
  |  public
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

Checking storage of obsmarkers in the bundlestore
--------------------------------------------------

enabling obsmarkers and rebase extension

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > evolution = all
  > [extensions]
  > rebase =
  > EOF

  $ cd ../client

  $ hg phase -r . --draft --force
  $ hg rebase -r 6 -d 3
  rebasing 6:9b42578d4447 "added f" (tip)

  $ hg glog
  @  7:99949238d9ac added f
  |  draft
  | o  5:b4e4bce66051 added e
  | |  public
  | o  4:1bb96358eda2 added d
  |/   public
  o  3:bf8a6e3011b3 added c
  |  public
  o  2:eaba929e866c added b
  |  public
  o  1:6cb0989601f1 added a
  |  public
  o  0:67145f466344 initialcommit
     public

  $ hg push -f
  pushing to $TESTTMP/repo
  searching for changes
  storing changesets on the bundlestore
  pushing 1 commit:
      99949238d9ac  added f

XXX: the phase should not have changed here
  $ hg glog -r .
  @  7:99949238d9ac added f
  |  public
  ~

Unbundling on server to see obsmarkers being applied

  $ cd ../repo

  $ scratchnodes
  1bb96358eda285b536c6d1c66846a7cdb2336cea 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  6cb0989601f1fb5805238edfb16f3606713d9a0b a4c202c147a9c4bb91bbadb56321fc5f3950f7f2
  99949238d9ac7f2424a33a46dface6f866afd059 090a24fe63f31d3b4bee714447f835c8c362ff57
  9b42578d44473575994109161430d65dd147d16d 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  b4e4bce660512ad3e71189e14588a70ac8e31fef 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  bf8a6e3011b345146bbbedbcb1ebd4837571492a 0a6e70ecd5b98d22382f69b93909f557ac6a9927
  eaba929e866c59bc9a6aada5a9dd2f6990db83c0 0a6e70ecd5b98d22382f69b93909f557ac6a9927

  $ hg glog
  o  6:9b42578d4447 added f
  |  draft
  o  5:b4e4bce66051 added e
  |  public
  o  4:1bb96358eda2 added d
  |  public
  o  3:bf8a6e3011b3 added c
  |  public
  o  2:eaba929e866c added b
  |  public
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public

  $ hg unbundle .hg/scratchbranches/filebundlestore/09/0a/090a24fe63f31d3b4bee714447f835c8c362ff57
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 1 files (+1 heads)
  1 new obsolescence markers
  obsoleted 1 changesets
  new changesets 99949238d9ac (1 drafts)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg glog
  o  7:99949238d9ac added f
  |  draft
  | o  5:b4e4bce66051 added e
  | |  public
  | o  4:1bb96358eda2 added d
  |/   public
  o  3:bf8a6e3011b3 added c
  |  public
  o  2:eaba929e866c added b
  |  public
  o  1:6cb0989601f1 added a
  |  public
  @  0:67145f466344 initialcommit
     public