view tests/test-mq-qpush-fail.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

Test that qpush cleans things up if it doesn't complete

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH
  $ hg init repo
  $ cd repo
  $ echo foo > foo
  $ hg ci -Am 'add foo'
  adding foo
  $ touch untracked-file
  $ echo 'syntax: glob' > .hgignore
  $ echo '.hgignore' >> .hgignore
  $ hg qinit

test qpush on empty series

  $ hg qpush
  no patches in series
  $ hg qnew patch1
  $ echo >> foo
  $ hg qrefresh -m 'patch 1'
  $ hg qnew patch2
  $ echo bar > bar
  $ hg add bar
  $ hg qrefresh -m 'patch 2'
  $ hg qnew --config 'mq.plain=true' -U bad-patch
  $ echo >> foo
  $ hg qrefresh
  $ hg qpop -a
  popping bad-patch
  popping patch2
  popping patch1
  patch queue now empty
  $ "$PYTHON" -c 'import sys; getattr(sys.stdout, "buffer", sys.stdout).write(b"\xe9\n")' > message
  $ cat .hg/patches/bad-patch >> message
  $ mv message .hg/patches/bad-patch
  $ cat > $TESTTMP/wrapplayback.py <<EOF
  > import os
  > from mercurial import extensions, transaction
  > def wrapplayback(orig,
  >                  journal, report, opener, vfsmap, entries, backupentries,
  >                  unlink=True, checkambigfiles=None):
  >     orig(journal, report, opener, vfsmap, entries, backupentries, unlink,
  >          checkambigfiles)
  >     # Touching files truncated at "transaction.abort" causes
  >     # forcible re-loading invalidated filecache properties
  >     # (including repo.changelog)
  >     for f, o, _ignore in entries:
  >         if o or not unlink:
  >             os.utime(opener.join(f), (0.0, 0.0))
  > def extsetup(ui):
  >     extensions.wrapfunction(transaction, '_playback', wrapplayback)
  > EOF
  $ hg qpush -a --config extensions.wrapplayback=$TESTTMP/wrapplayback.py  && echo 'qpush succeeded?!'
  applying patch1
  applying patch2
  applying bad-patch
  transaction abort!
  rollback completed
  cleaning up working directory...
  reverting foo
  done
  abort: decoding near '\xe9': 'ascii' codec can't decode byte 0xe9 in position 0: ordinal not in range(128)! (esc)
  [255]
  $ hg parents
  changeset:   0:bbd179dfa0a7
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add foo
  

test corrupt status file
  $ hg qpush
  applying patch1
  now at: patch1
  $ cp .hg/patches/status .hg/patches/status.orig
  $ hg qpop
  popping patch1
  patch queue now empty
  $ cp .hg/patches/status.orig .hg/patches/status
  $ hg qpush
  abort: working directory revision is not qtip
  [255]
  $ rm .hg/patches/status .hg/patches/status.orig


bar should be gone; other unknown/ignored files should still be around

  $ hg status -A
  ? untracked-file
  I .hgignore
  C foo

preparing qpush of a missing patch

  $ hg qpop -a
  no patches applied
  $ hg qpush
  applying patch1
  now at: patch1
  $ rm .hg/patches/patch2

now we expect the push to fail, but it should NOT complain about patch1

  $ hg qpush
  applying patch2
  unable to read patch2
  now at: patch1
  [1]

preparing qpush of missing patch with no patch applied

  $ hg qpop -a
  popping patch1
  patch queue now empty
  $ rm .hg/patches/patch1

qpush should fail the same way as below

  $ hg qpush
  applying patch1
  unable to read patch1
  [1]

Test qpush to a patch below the currently applied patch.

  $ hg qq -c guardedseriesorder
  $ hg qnew a
  $ hg qguard +block
  $ hg qnew b
  $ hg qnew c

  $ hg qpop -a
  popping c
  popping b
  popping a
  patch queue now empty

try to push and pop while a is guarded

  $ hg qpush a
  cannot push 'a' - guarded by '+block'
  [1]
  $ hg qpush -a
  applying b
  patch b is empty
  applying c
  patch c is empty
  now at: c

now try it when a is unguarded, and we're at the top of the queue

  $ hg qapplied -v
  0 G a
  1 A b
  2 A c
  $ hg qsel block
  $ hg qpush b
  abort: cannot push to a previous patch: b
  [255]
  $ hg qpush a
  abort: cannot push to a previous patch: a
  [255]

and now we try it one more time with a unguarded, while we're not at the top of the queue

  $ hg qpop b
  popping c
  now at: b
  $ hg qpush a
  abort: cannot push to a previous patch: a
  [255]

test qpop --force and backup files

  $ hg qpop -a
  popping b
  patch queue now empty
  $ hg qq --create force
  $ echo a > a
  $ echo b > b
  $ echo c > c
  $ hg ci -Am add a b c
  $ echo a >> a
  $ hg rm b
  $ hg rm c
  $ hg qnew p1
  $ echo a >> a
  $ echo bb > b
  $ hg add b
  $ echo cc > c
  $ hg add c
  $ hg qpop --force --verbose
  saving current version of a as a.orig
  saving current version of b as b.orig
  saving current version of c as c.orig
  popping p1
  patch queue now empty
  $ hg st
  ? a.orig
  ? b.orig
  ? c.orig
  ? untracked-file
  $ cat a.orig
  a
  a
  a
  $ cat b.orig
  bb
  $ cat c.orig
  cc

test qpop --force --no-backup

  $ hg qpush
  applying p1
  now at: p1
  $ rm a.orig
  $ echo a >> a
  $ hg qpop --force --no-backup --verbose
  popping p1
  patch queue now empty
  $ test -f a.orig && echo 'error: backup with --no-backup'
  [1]

test qpop --keep-changes

  $ hg qpush
  applying p1
  now at: p1
  $ hg qpop --keep-changes --force
  abort: cannot use both --force and --keep-changes
  [255]
  $ echo a >> a
  $ hg qpop --keep-changes
  abort: local changes found, qrefresh first
  [255]
  $ hg revert -qa a
  $ rm a
  $ hg qpop --keep-changes
  abort: local changes found, qrefresh first
  [255]
  $ hg rm -A a
  $ hg qpop --keep-changes
  abort: local changes found, qrefresh first
  [255]
  $ hg revert -qa a
  $ echo b > b
  $ hg add b
  $ hg qpop --keep-changes
  abort: local changes found, qrefresh first
  [255]
  $ hg forget b
  $ echo d > d
  $ hg add d
  $ hg qpop --keep-changes
  popping p1
  patch queue now empty
  $ hg forget d
  $ rm d

test qpush --force and backup files

  $ echo a >> a
  $ hg qnew p2
  $ echo b >> b
  $ echo d > d
  $ echo e > e
  $ hg add d e
  $ hg rm c
  $ hg qnew p3
  $ hg qpop -a
  popping p3
  popping p2
  patch queue now empty
  $ echo a >> a
  $ echo b1 >> b
  $ echo d1 > d
  $ hg add d
  $ echo e1 > e
  $ hg qpush -a --force --verbose
  applying p2
  saving current version of a as a.orig
  patching file a
  committing files:
  a
  committing manifest
  committing changelog
  applying p3
  saving current version of b as b.orig
  saving current version of d as d.orig
  patching file b
  patching file c
  patching file d
  file d already exists
  1 out of 1 hunks FAILED -- saving rejects to file d.rej
  patching file e
  file e already exists
  1 out of 1 hunks FAILED -- saving rejects to file e.rej
  patch failed to apply
  committing files:
  b
  committing manifest
  committing changelog
  patch failed, rejects left in working directory
  errors during apply, please fix and qrefresh p3
  [2]
  $ cat a.orig
  a
  a
  $ cat b.orig
  b
  b1
  $ cat d.orig
  d1

test qpush --force --no-backup

  $ hg revert -qa
  $ hg qpop -a
  popping p3
  popping p2
  patch queue now empty
  $ echo a >> a
  $ rm a.orig
  $ hg qpush --force --no-backup --verbose
  applying p2
  patching file a
  committing files:
  a
  committing manifest
  committing changelog
  now at: p2
  $ test -f a.orig && echo 'error: backup with --no-backup'
  [1]

test qgoto --force --no-backup

  $ hg qpop
  popping p2
  patch queue now empty
  $ echo a >> a
  $ hg qgoto --force --no-backup p2 --verbose
  applying p2
  patching file a
  committing files:
  a
  committing manifest
  committing changelog
  now at: p2
  $ test -f a.orig && echo 'error: backup with --no-backup'
  [1]

test qpush --keep-changes

  $ hg qpush --keep-changes --force
  abort: cannot use both --force and --keep-changes
  [255]
  $ hg qpush --keep-changes --exact
  abort: cannot use --exact and --keep-changes together
  [255]
  $ echo b >> b
  $ hg qpush --keep-changes
  applying p3
  abort: conflicting local changes found
  (did you forget to qrefresh?)
  [255]
  $ rm b
  $ hg qpush --keep-changes
  applying p3
  abort: conflicting local changes found
  (did you forget to qrefresh?)
  [255]
  $ hg rm -A b
  $ hg qpush --keep-changes
  applying p3
  abort: conflicting local changes found
  (did you forget to qrefresh?)
  [255]
  $ hg revert -aq b
  $ echo d > d
  $ hg add d
  $ hg qpush --keep-changes
  applying p3
  abort: conflicting local changes found
  (did you forget to qrefresh?)
  [255]
  $ hg forget d
  $ rm d
  $ hg qpop
  popping p2
  patch queue now empty
  $ echo b >> b
  $ hg qpush -a --keep-changes
  applying p2
  applying p3
  abort: conflicting local changes found
  (did you forget to qrefresh?)
  [255]
  $ hg qtop
  p2
  $ hg parents --template "{rev} {desc}\n"
  2 imported patch p2
  $ hg st b
  M b
  $ cat b
  b
  b

test qgoto --keep-changes

  $ hg revert -aq b
  $ rm e
  $ hg qgoto --keep-changes --force p3
  abort: cannot use both --force and --keep-changes
  [255]
  $ echo a >> a
  $ hg qgoto --keep-changes p3
  applying p3
  now at: p3
  $ hg st a
  M a
  $ hg qgoto --keep-changes p2
  popping p3
  now at: p2
  $ hg st a
  M a

test mq.keepchanges setting

  $ hg --config mq.keepchanges=1 qpush
  applying p3
  now at: p3
  $ hg st a
  M a
  $ hg --config mq.keepchanges=1 qpop
  popping p3
  now at: p2
  $ hg st a
  M a
  $ hg --config mq.keepchanges=1 qgoto p3
  applying p3
  now at: p3
  $ hg st a
  M a
  $ echo b >> b
  $ hg --config mq.keepchanges=1 qpop --force --config 'ui.origbackuppath=.hg/origbackups'
  popping p3
  now at: p2
  $ hg st b
  $ hg --config mq.keepchanges=1 qpush --exact
  abort: local changes found, qrefresh first
  [255]
  $ hg revert -qa a
  $ hg qpop
  popping p2
  patch queue now empty
  $ echo a >> a
  $ hg --config mq.keepchanges=1 qpush --force
  applying p2
  now at: p2
  $ hg st a

test previous qpop (with --force and --config) saved .orig files to where user
wants them
  $ ls .hg/origbackups
  b
  $ rm -rf .hg/origbackups

  $ cd ..