view tests/test-censor.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

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > censor=
  > EOF
  $ cp $HGRCPATH $HGRCPATH.orig

Create repo with unimpeachable content

  $ hg init r
  $ cd r
  $ echo 'Initially untainted file' > target
  $ echo 'Normal file here' > bystander
  $ hg add target bystander
  $ hg ci -m init

Clone repo so we can test pull later

  $ cd ..
  $ hg clone r rpull
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd r

Introduce content which will ultimately require censorship. Name the first
censored node C1, second C2, and so on

  $ echo 'Tainted file' > target
  $ echo 'Passwords: hunter2' >> target
  $ hg ci -m taint target
  $ C1=`hg id --debug -i`

  $ echo 'hunter3' >> target
  $ echo 'Normal file v2' > bystander
  $ hg ci -m moretaint target bystander
  $ C2=`hg id --debug -i`

Add a new sanitized versions to correct our mistake. Name the first head H1,
the second head H2, and so on

  $ echo 'Tainted file is now sanitized' > target
  $ hg ci -m sanitized target
  $ H1=`hg id --debug -i`

  $ hg update -r $C2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo 'Tainted file now super sanitized' > target
  $ hg ci -m 'super sanitized' target
  created new head
  $ H2=`hg id --debug -i`

Verify target contents before censorship at each revision

  $ hg cat -r $H1 target
  Tainted file is now sanitized
  $ hg cat -r $H2 target
  Tainted file now super sanitized
  $ hg cat -r $C2 target
  Tainted file
  Passwords: hunter2
  hunter3
  $ hg cat -r $C1 target
  Tainted file
  Passwords: hunter2
  $ hg cat -r 0 target
  Initially untainted file

Try to censor revision with too large of a tombstone message

  $ hg censor -r $C1 -t 'blah blah blah blah blah blah blah blah bla' target
  abort: censor tombstone must be no longer than censored data
  [255]

Censor revision with 2 offenses

(this also tests file pattern matching: path relative to cwd case)

  $ mkdir -p foo/bar/baz
  $ hg --cwd foo/bar/baz censor -r $C2 -t "remove password" ../../../target
  $ hg cat -r $H1 target
  Tainted file is now sanitized
  $ hg cat -r $H2 target
  Tainted file now super sanitized
  $ hg cat -r $C2 target
  abort: censored node: 1e0247a9a4b7
  (set censor.policy to ignore errors)
  [255]
  $ hg cat -r $C1 target
  Tainted file
  Passwords: hunter2
  $ hg cat -r 0 target
  Initially untainted file

Censor revision with 1 offense

(this also tests file pattern matching: with 'path:' scheme)

  $ hg --cwd foo/bar/baz censor -r $C1 path:target
  $ hg cat -r $H1 target
  Tainted file is now sanitized
  $ hg cat -r $H2 target
  Tainted file now super sanitized
  $ hg cat -r $C2 target
  abort: censored node: 1e0247a9a4b7
  (set censor.policy to ignore errors)
  [255]
  $ hg cat -r $C1 target
  abort: censored node: 613bc869fceb
  (set censor.policy to ignore errors)
  [255]
  $ hg cat -r 0 target
  Initially untainted file

Can only checkout target at uncensored revisions, -X is workaround for --all

  $ hg revert -r $C2 target
  abort: censored node: 1e0247a9a4b7
  (set censor.policy to ignore errors)
  [255]
  $ hg revert -r $C1 target
  abort: censored node: 613bc869fceb
  (set censor.policy to ignore errors)
  [255]
  $ hg revert -r $C1 --all
  reverting bystander
  reverting target
  abort: censored node: 613bc869fceb
  (set censor.policy to ignore errors)
  [255]
  $ hg revert -r $C1 --all -X target
  $ cat target
  Tainted file now super sanitized
  $ hg revert -r 0 --all
  reverting target
  $ cat target
  Initially untainted file
  $ hg revert -r $H2 --all
  reverting bystander
  reverting target
  $ cat target
  Tainted file now super sanitized

Uncensored file can be viewed at any revision

  $ hg cat -r $H1 bystander
  Normal file v2
  $ hg cat -r $C2 bystander
  Normal file v2
  $ hg cat -r $C1 bystander
  Normal file here
  $ hg cat -r 0 bystander
  Normal file here

Can update to children of censored revision

  $ hg update -r $H1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Tainted file is now sanitized
  $ hg update -r $H2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Tainted file now super sanitized

Set censor policy to abort in trusted $HGRC so hg verify fails

  $ cp $HGRCPATH.orig $HGRCPATH
  $ cat >> $HGRCPATH <<EOF
  > [censor]
  > policy = abort
  > EOF

Repo fails verification due to censorship

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
   target@1: censored file data
   target@2: censored file data
  checked 5 changesets with 7 changes to 2 files
  2 integrity errors encountered!
  (first damaged changeset appears to be 1)
  [1]

Cannot update to revision with censored data

  $ hg update -r $C2
  abort: censored node: 1e0247a9a4b7
  (set censor.policy to ignore errors)
  [255]
  $ hg update -r $C1
  abort: censored node: 613bc869fceb
  (set censor.policy to ignore errors)
  [255]
  $ hg update -r 0
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg update -r $H2
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

Set censor policy to ignore in trusted $HGRC so hg verify passes

  $ cp $HGRCPATH.orig $HGRCPATH
  $ cat >> $HGRCPATH <<EOF
  > [censor]
  > policy = ignore
  > EOF

Repo passes verification with warnings with explicit config

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 5 changesets with 7 changes to 2 files

May update to revision with censored data with explicit config

  $ hg update -r $C2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  $ hg update -r $C1
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  $ hg update -r 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Initially untainted file
  $ hg update -r $H2
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Tainted file now super sanitized

Can merge in revision with censored data. Test requires one branch of history
with the file censored, but we can't censor at a head, so advance H1.

  $ hg update -r $H1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ C3=$H1
  $ echo 'advanced head H1' > target
  $ hg ci -m 'advance head H1' target
  $ H1=`hg id --debug -i`
  $ hg censor -r $C3 target
  $ hg update -r $H2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg merge -r $C3
  merging target
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

Revisions present in repository heads may not be censored

  $ hg update -C -r $H2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg censor -r $H2 target
  abort: cannot censor file in heads (78a8fc215e79)
  (clean/delete and commit first)
  [255]
  $ echo 'twiddling thumbs' > bystander
  $ hg ci -m 'bystander commit'
  $ H2=`hg id --debug -i`
  $ hg censor -r "$H2^" target
  abort: cannot censor file in heads (efbe78065929)
  (clean/delete and commit first)
  [255]

Cannot censor working directory

  $ echo 'seriously no passwords' > target
  $ hg ci -m 'extend second head arbitrarily' target
  $ H2=`hg id --debug -i`
  $ hg update -r "$H2^"
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg censor -r . target
  abort: cannot censor working directory
  (clean/delete/update first)
  [255]
  $ hg update -r $H2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Can re-add file after being deleted + censored

  $ C4=$H2
  $ hg rm target
  $ hg ci -m 'delete target so it may be censored'
  $ H2=`hg id --debug -i`
  $ hg censor -r $C4 target
  $ hg cat -r $C4 target
  $ hg cat -r "$H2^^" target
  Tainted file now super sanitized
  $ echo 'fresh start' > target
  $ hg add target
  $ hg ci -m reincarnated target
  $ H2=`hg id --debug -i`
  $ hg cat -r $H2 target
  fresh start
  $ hg cat -r "$H2^" target
  target: no such file in rev 452ec1762369
  [1]
  $ hg cat -r $C4 target
  $ hg cat -r "$H2^^^" target
  Tainted file now super sanitized

Can censor after revlog has expanded to no longer permit inline storage

  $ for x in `"$PYTHON" $TESTDIR/seq.py 0 50000`
  > do
  >   echo "Password: hunter$x" >> target
  > done
  $ hg ci -m 'add 100k passwords'
  $ H2=`hg id --debug -i`
  $ C5=$H2
  $ hg revert -r "$H2^" target
  $ hg ci -m 'cleaned 100k passwords'
  $ H2=`hg id --debug -i`
  $ hg censor -r $C5 target
  $ hg cat -r $C5 target
  $ hg cat -r $H2 target
  fresh start

Repo with censored nodes can be cloned and cloned nodes are censored

  $ cd ..
  $ hg clone r rclone
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd rclone
  $ hg cat -r $H1 target
  advanced head H1
  $ hg cat -r $H2~5 target
  Tainted file now super sanitized
  $ hg cat -r $C2 target
  $ hg cat -r $C1 target
  $ hg cat -r 0 target
  Initially untainted file
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 12 changesets with 13 changes to 2 files

Repo cloned before tainted content introduced can pull censored nodes

  $ cd ../rpull
  $ hg cat -r tip target
  Initially untainted file
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 2 changes to 2 files
  $ hg pull -r $H1 -r $H2
  pulling from $TESTTMP/r
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 11 changesets with 11 changes to 2 files (+1 heads)
  new changesets 186fb27560c3:683e4645fded
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg update 4
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Tainted file now super sanitized
  $ hg cat -r $H1 target
  advanced head H1
  $ hg cat -r $H2~5 target
  Tainted file now super sanitized
  $ hg cat -r $C2 target
  $ hg cat -r $C1 target
  $ hg cat -r 0 target
  Initially untainted file
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 12 changesets with 13 changes to 2 files

Censored nodes can be pushed if they censor previously unexchanged nodes

  $ echo 'Passwords: hunter2hunter2' > target
  $ hg ci -m 're-add password from clone' target
  created new head
  $ H3=`hg id --debug -i`
  $ REV=$H3
  $ echo 'Re-sanitized; nothing to see here' > target
  $ hg ci -m 're-sanitized' target
  $ H2=`hg id --debug -i`
  $ CLEANREV=$H2
  $ hg cat -r $REV target
  Passwords: hunter2hunter2
  $ hg censor -r $REV target
  $ hg cat -r $REV target
  $ hg cat -r $CLEANREV target
  Re-sanitized; nothing to see here
  $ hg push -f -r $H2
  pushing to $TESTTMP/r
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files (+1 heads)

  $ cd ../r
  $ hg cat -r $REV target
  $ hg cat -r $CLEANREV target
  Re-sanitized; nothing to see here
  $ hg update $CLEANREV
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Re-sanitized; nothing to see here

Censored nodes can be bundled up and unbundled in another repo

  $ hg bundle --base 0 ../pwbundle
  13 changesets found
  $ cd ../rclone
  $ hg unbundle ../pwbundle
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)
  new changesets 075be80ac777:dcbaf17bf3a1 (2 drafts)
  (run 'hg heads .' to see heads, 'hg merge' to merge)
  $ hg cat -r $REV target
  $ hg cat -r $CLEANREV target
  Re-sanitized; nothing to see here
  $ hg update $CLEANREV
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Re-sanitized; nothing to see here
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 14 changesets with 15 changes to 2 files

Censored nodes can be imported on top of censored nodes, consecutively

  $ hg init ../rimport
  $ hg bundle --base 1 ../rimport/splitbundle
  12 changesets found
  $ cd ../rimport
  $ hg pull -r $H1 -r $H2 ../r
  pulling from ../r
  adding changesets
  adding manifests
  adding file changes
  added 8 changesets with 10 changes to 2 files (+1 heads)
  new changesets e97f55b2665a:dcbaf17bf3a1
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg unbundle splitbundle
  adding changesets
  adding manifests
  adding file changes
  added 6 changesets with 5 changes to 2 files (+1 heads)
  new changesets efbe78065929:683e4645fded (6 drafts)
  (run 'hg heads .' to see heads, 'hg merge' to merge)
  $ hg update $H2
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat target
  Re-sanitized; nothing to see here
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 14 changesets with 15 changes to 2 files
  $ cd ../r

Can import bundle where first revision of a file is censored

  $ hg init ../rinit
  $ hg censor -r 0 target
  $ hg bundle -r 0 --base null ../rinit/initbundle
  1 changesets found
  $ cd ../rinit
  $ hg unbundle initbundle
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 2 changes to 2 files
  new changesets e97f55b2665a (1 drafts)
  (run 'hg update' to get a working copy)
  $ hg cat -r 0 target