view tests/test-clone-uncompressed.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 no-reposimplestore no-chg

#testcases stream-legacy stream-bundle2

#if stream-legacy
  $ cat << EOF >> $HGRCPATH
  > [server]
  > bundle2.stream = no
  > EOF
#endif

Initialize repository
the status call is to check for issue5130

  $ hg init server
  $ cd server
  $ touch foo
  $ hg -q commit -A -m initial
  >>> for i in range(1024):
  ...     with open(str(i), 'wb') as fh:
  ...         fh.write(b"%d" % i) and None
  $ hg -q commit -A -m 'add a lot of files'
  $ hg st
  $ hg --config server.uncompressed=false serve -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid > $DAEMON_PIDS
  $ cd ..

Cannot stream clone when server.uncompressed is set

  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=stream_out'
  200 Script output follows
  
  1

#if stream-legacy
  $ hg debugcapabilities http://localhost:$HGPORT
  Main capabilities:
    batch
    branchmap
    $USUAL_BUNDLE2_CAPS_SERVER$
    changegroupsubset
    compression=$BUNDLE2_COMPRESSIONS$
    getbundle
    httpheader=1024
    httpmediatype=0.1rx,0.1tx,0.2tx
    known
    lookup
    pushkey
    unbundle=HG10GZ,HG10BZ,HG10UN
    unbundlehash
  Bundle2 capabilities:
    HG20
    bookmarks
    changegroup
      01
      02
    digests
      md5
      sha1
      sha512
    error
      abort
      unsupportedcontent
      pushraced
      pushkey
    hgtagsfnodes
    listkeys
    phases
      heads
    pushkey
    remote-changegroup
      http
      https
    rev-branch-cache

  $ hg clone --stream -U http://localhost:$HGPORT server-disabled
  warning: stream clone requested but server has them disabled
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1025 changes to 1025 files
  new changesets 96ee1d7354c4:c17445101a72

  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=getbundle' content-type --bodyfile body --hgproto 0.2 --requestheader "x-hgarg-1=bundlecaps=HG20%2Cbundle2%3DHG20%250Abookmarks%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Aphases%253Dheads%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=0&common=0000000000000000000000000000000000000000&heads=c17445101a72edac06facd130d14808dfbd5c7c2&stream=1"
  200 Script output follows
  content-type: application/mercurial-0.2
  

  $ f --size body --hexdump --bytes 100
  body: size=232
  0000: 04 6e 6f 6e 65 48 47 32 30 00 00 00 00 00 00 00 |.noneHG20.......|
  0010: cf 0b 45 52 52 4f 52 3a 41 42 4f 52 54 00 00 00 |..ERROR:ABORT...|
  0020: 00 01 01 07 3c 04 72 6d 65 73 73 61 67 65 73 74 |....<.rmessagest|
  0030: 72 65 61 6d 20 64 61 74 61 20 72 65 71 75 65 73 |ream data reques|
  0040: 74 65 64 20 62 75 74 20 73 65 72 76 65 72 20 64 |ted but server d|
  0050: 6f 65 73 20 6e 6f 74 20 61 6c 6c 6f 77 20 74 68 |oes not allow th|
  0060: 69 73 20 66                                     |is f|

#endif
#if stream-bundle2
  $ hg debugcapabilities http://localhost:$HGPORT
  Main capabilities:
    batch
    branchmap
    $USUAL_BUNDLE2_CAPS_SERVER$
    changegroupsubset
    compression=$BUNDLE2_COMPRESSIONS$
    getbundle
    httpheader=1024
    httpmediatype=0.1rx,0.1tx,0.2tx
    known
    lookup
    pushkey
    unbundle=HG10GZ,HG10BZ,HG10UN
    unbundlehash
  Bundle2 capabilities:
    HG20
    bookmarks
    changegroup
      01
      02
    digests
      md5
      sha1
      sha512
    error
      abort
      unsupportedcontent
      pushraced
      pushkey
    hgtagsfnodes
    listkeys
    phases
      heads
    pushkey
    remote-changegroup
      http
      https
    rev-branch-cache

  $ hg clone --stream -U http://localhost:$HGPORT server-disabled
  warning: stream clone requested but server has them disabled
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1025 changes to 1025 files
  new changesets 96ee1d7354c4:c17445101a72

  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=getbundle' content-type --bodyfile body --hgproto 0.2 --requestheader "x-hgarg-1=bundlecaps=HG20%2Cbundle2%3DHG20%250Abookmarks%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Aphases%253Dheads%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=0&common=0000000000000000000000000000000000000000&heads=c17445101a72edac06facd130d14808dfbd5c7c2&stream=1"
  200 Script output follows
  content-type: application/mercurial-0.2
  

  $ f --size body --hexdump --bytes 100
  body: size=232
  0000: 04 6e 6f 6e 65 48 47 32 30 00 00 00 00 00 00 00 |.noneHG20.......|
  0010: cf 0b 45 52 52 4f 52 3a 41 42 4f 52 54 00 00 00 |..ERROR:ABORT...|
  0020: 00 01 01 07 3c 04 72 6d 65 73 73 61 67 65 73 74 |....<.rmessagest|
  0030: 72 65 61 6d 20 64 61 74 61 20 72 65 71 75 65 73 |ream data reques|
  0040: 74 65 64 20 62 75 74 20 73 65 72 76 65 72 20 64 |ted but server d|
  0050: 6f 65 73 20 6e 6f 74 20 61 6c 6c 6f 77 20 74 68 |oes not allow th|
  0060: 69 73 20 66                                     |is f|

#endif

  $ killdaemons.py
  $ cd server
  $ hg serve -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid > $DAEMON_PIDS
  $ cd ..

Basic clone

#if stream-legacy
  $ hg clone --stream -U http://localhost:$HGPORT clone1
  streaming all changes
  1027 files to transfer, 96.3 KB of data
  transferred 96.3 KB in * seconds (*/sec) (glob)
  searching for changes
  no changes found
#endif
#if stream-bundle2
  $ hg clone --stream -U http://localhost:$HGPORT clone1
  streaming all changes
  1030 files to transfer, 96.4 KB of data
  transferred 96.4 KB in * seconds (* */sec) (glob)

  $ ls -1 clone1/.hg/cache
  branch2-served
  rbc-names-v1
  rbc-revs-v1
#endif

getbundle requests with stream=1 are uncompressed

  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=getbundle' content-type --bodyfile body --hgproto '0.1 0.2 comp=zlib,none' --requestheader "x-hgarg-1=bundlecaps=HG20%2Cbundle2%3DHG20%250Abookmarks%250Achangegroup%253D01%252C02%250Adigests%253Dmd5%252Csha1%252Csha512%250Aerror%253Dabort%252Cunsupportedcontent%252Cpushraced%252Cpushkey%250Ahgtagsfnodes%250Alistkeys%250Aphases%253Dheads%250Apushkey%250Aremote-changegroup%253Dhttp%252Chttps&cg=0&common=0000000000000000000000000000000000000000&heads=c17445101a72edac06facd130d14808dfbd5c7c2&stream=1"
  200 Script output follows
  content-type: application/mercurial-0.2
  

  $ f --size --hex --bytes 256 body
  body: size=112230
  0000: 04 6e 6f 6e 65 48 47 32 30 00 00 00 00 00 00 00 |.noneHG20.......|
  0010: 70 07 53 54 52 45 41 4d 32 00 00 00 00 03 00 09 |p.STREAM2.......|
  0020: 05 09 04 0c 35 62 79 74 65 63 6f 75 6e 74 39 38 |....5bytecount98|
  0030: 37 35 38 66 69 6c 65 63 6f 75 6e 74 31 30 33 30 |758filecount1030|
  0040: 72 65 71 75 69 72 65 6d 65 6e 74 73 64 6f 74 65 |requirementsdote|
  0050: 6e 63 6f 64 65 25 32 43 66 6e 63 61 63 68 65 25 |ncode%2Cfncache%|
  0060: 32 43 67 65 6e 65 72 61 6c 64 65 6c 74 61 25 32 |2Cgeneraldelta%2|
  0070: 43 72 65 76 6c 6f 67 76 31 25 32 43 73 74 6f 72 |Crevlogv1%2Cstor|
  0080: 65 00 00 80 00 73 08 42 64 61 74 61 2f 30 2e 69 |e....s.Bdata/0.i|
  0090: 00 03 00 01 00 00 00 00 00 00 00 02 00 00 00 01 |................|
  00a0: 00 00 00 00 00 00 00 01 ff ff ff ff ff ff ff ff |................|
  00b0: 80 29 63 a0 49 d3 23 87 bf ce fe 56 67 92 67 2c |.)c.I.#....Vg.g,|
  00c0: 69 d1 ec 39 00 00 00 00 00 00 00 00 00 00 00 00 |i..9............|
  00d0: 75 30 73 08 42 64 61 74 61 2f 31 2e 69 00 03 00 |u0s.Bdata/1.i...|
  00e0: 01 00 00 00 00 00 00 00 02 00 00 00 01 00 00 00 |................|
  00f0: 00 00 00 00 01 ff ff ff ff ff ff ff ff f9 76 da |..............v.|

--uncompressed is an alias to --stream

#if stream-legacy
  $ hg clone --uncompressed -U http://localhost:$HGPORT clone1-uncompressed
  streaming all changes
  1027 files to transfer, 96.3 KB of data
  transferred 96.3 KB in * seconds (*/sec) (glob)
  searching for changes
  no changes found
#endif
#if stream-bundle2
  $ hg clone --uncompressed -U http://localhost:$HGPORT clone1-uncompressed
  streaming all changes
  1030 files to transfer, 96.4 KB of data
  transferred 96.4 KB in * seconds (* */sec) (glob)
#endif

Clone with background file closing enabled

#if stream-legacy
  $ hg --debug --config worker.backgroundclose=true --config worker.backgroundcloseminfilecount=1 clone --stream -U http://localhost:$HGPORT clone-background | grep -v adding
  using http://localhost:$HGPORT/
  sending capabilities command
  sending branchmap command
  streaming all changes
  sending stream_out command
  1027 files to transfer, 96.3 KB of data
  starting 4 threads for background file closing
  updating the branch cache
  transferred 96.3 KB in * seconds (*/sec) (glob)
  query 1; heads
  sending batch command
  searching for changes
  all remote heads known locally
  no changes found
  sending getbundle command
  bundle2-input-bundle: with-transaction
  bundle2-input-part: "listkeys" (params: 1 mandatory) supported
  bundle2-input-part: "phase-heads" supported
  bundle2-input-part: total payload size 24
  bundle2-input-bundle: 1 parts total
  checking for updated bookmarks
  (sent 5 HTTP requests and * bytes; received * bytes in responses) (glob)
#endif
#if stream-bundle2
  $ hg --debug --config worker.backgroundclose=true --config worker.backgroundcloseminfilecount=1 clone --stream -U http://localhost:$HGPORT clone-background | grep -v adding
  using http://localhost:$HGPORT/
  sending capabilities command
  query 1; heads
  sending batch command
  streaming all changes
  sending getbundle command
  bundle2-input-bundle: with-transaction
  bundle2-input-part: "stream2" (params: 3 mandatory) supported
  applying stream bundle
  1030 files to transfer, 96.4 KB of data
  starting 4 threads for background file closing
  starting 4 threads for background file closing
  updating the branch cache
  transferred 96.4 KB in * seconds (* */sec) (glob)
  bundle2-input-part: total payload size 112077
  bundle2-input-part: "listkeys" (params: 1 mandatory) supported
  bundle2-input-bundle: 1 parts total
  checking for updated bookmarks
  (sent 3 HTTP requests and * bytes; received * bytes in responses) (glob)
#endif

Cannot stream clone when there are secret changesets

  $ hg -R server phase --force --secret -r tip
  $ hg clone --stream -U http://localhost:$HGPORT secret-denied
  warning: stream clone requested but server has them disabled
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 96ee1d7354c4

  $ killdaemons.py

Streaming of secrets can be overridden by server config

  $ cd server
  $ hg serve --config server.uncompressedallowsecret=true -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid > $DAEMON_PIDS
  $ cd ..

#if stream-legacy
  $ hg clone --stream -U http://localhost:$HGPORT secret-allowed
  streaming all changes
  1027 files to transfer, 96.3 KB of data
  transferred 96.3 KB in * seconds (*/sec) (glob)
  searching for changes
  no changes found
#endif
#if stream-bundle2
  $ hg clone --stream -U http://localhost:$HGPORT secret-allowed
  streaming all changes
  1030 files to transfer, 96.4 KB of data
  transferred 96.4 KB in * seconds (* */sec) (glob)
#endif

  $ killdaemons.py

Verify interaction between preferuncompressed and secret presence

  $ cd server
  $ hg serve --config server.preferuncompressed=true -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid > $DAEMON_PIDS
  $ cd ..

  $ hg clone -U http://localhost:$HGPORT preferuncompressed-secret
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 96ee1d7354c4

  $ killdaemons.py

Clone not allowed when full bundles disabled and can't serve secrets

  $ cd server
  $ hg serve --config server.disablefullbundle=true -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid > $DAEMON_PIDS
  $ cd ..

  $ hg clone --stream http://localhost:$HGPORT secret-full-disabled
  warning: stream clone requested but server has them disabled
  requesting all changes
  remote: abort: server has pull-based clones disabled
  abort: pull failed on remote
  (remove --pull if specified or upgrade Mercurial)
  [255]

Local stream clone with secrets involved
(This is just a test over behavior: if you have access to the repo's files,
there is no security so it isn't important to prevent a clone here.)

  $ hg clone -U --stream server local-secret
  warning: stream clone requested but server has them disabled
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 96ee1d7354c4

Stream clone while repo is changing:

  $ mkdir changing
  $ cd changing

extension for delaying the server process so we reliably can modify the repo
while cloning

  $ cat > delayer.py <<EOF
  > import time
  > from mercurial import extensions, vfs
  > def __call__(orig, self, path, *args, **kwargs):
  >     if path == 'data/f1.i':
  >         time.sleep(2)
  >     return orig(self, path, *args, **kwargs)
  > extensions.wrapfunction(vfs.vfs, '__call__', __call__)
  > EOF

prepare repo with small and big file to cover both code paths in emitrevlogdata

  $ hg init repo
  $ touch repo/f1
  $ $TESTDIR/seq.py 50000 > repo/f2
  $ hg -R repo ci -Aqm "0"
  $ hg serve -R repo -p $HGPORT1 -d --pid-file=hg.pid --config extensions.delayer=delayer.py
  $ cat hg.pid >> $DAEMON_PIDS

clone while modifying the repo between stating file with write lock and
actually serving file content

  $ hg clone -q --stream -U http://localhost:$HGPORT1 clone &
  $ sleep 1
  $ echo >> repo/f1
  $ echo >> repo/f2
  $ hg -R repo ci -m "1"
  $ wait
  $ hg -R clone id
  000000000000
  $ cd ..

Stream repository with bookmarks
--------------------------------

(revert introduction of secret changeset)

  $ hg -R server phase --draft 'secret()'

add a bookmark

  $ hg -R server bookmark -r tip some-bookmark

clone it

#if stream-legacy
  $ hg clone --stream http://localhost:$HGPORT with-bookmarks
  streaming all changes
  1027 files to transfer, 96.3 KB of data
  transferred 96.3 KB in * seconds (*) (glob)
  searching for changes
  no changes found
  updating to branch default
  1025 files updated, 0 files merged, 0 files removed, 0 files unresolved
#endif
#if stream-bundle2
  $ hg clone --stream http://localhost:$HGPORT with-bookmarks
  streaming all changes
  1033 files to transfer, 96.6 KB of data
  transferred 96.6 KB in * seconds (* */sec) (glob)
  updating to branch default
  1025 files updated, 0 files merged, 0 files removed, 0 files unresolved
#endif
  $ hg -R with-bookmarks bookmarks
     some-bookmark             1:c17445101a72

Stream repository with phases
-----------------------------

Clone as publishing

  $ hg -R server phase -r 'all()'
  0: draft
  1: draft

#if stream-legacy
  $ hg clone --stream http://localhost:$HGPORT phase-publish
  streaming all changes
  1027 files to transfer, 96.3 KB of data
  transferred 96.3 KB in * seconds (*) (glob)
  searching for changes
  no changes found
  updating to branch default
  1025 files updated, 0 files merged, 0 files removed, 0 files unresolved
#endif
#if stream-bundle2
  $ hg clone --stream http://localhost:$HGPORT phase-publish
  streaming all changes
  1033 files to transfer, 96.6 KB of data
  transferred 96.6 KB in * seconds (* */sec) (glob)
  updating to branch default
  1025 files updated, 0 files merged, 0 files removed, 0 files unresolved
#endif
  $ hg -R phase-publish phase -r 'all()'
  0: public
  1: public

Clone as non publishing

  $ cat << EOF >> server/.hg/hgrc
  > [phases]
  > publish = False
  > EOF
  $ killdaemons.py
  $ hg -R server serve -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid > $DAEMON_PIDS

#if stream-legacy

With v1 of the stream protocol, changeset are always cloned as public. It make
stream v1 unsuitable for non-publishing repository.

  $ hg clone --stream http://localhost:$HGPORT phase-no-publish
  streaming all changes
  1027 files to transfer, 96.3 KB of data
  transferred 96.3 KB in * seconds (*) (glob)
  searching for changes
  no changes found
  updating to branch default
  1025 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R phase-no-publish phase -r 'all()'
  0: public
  1: public
#endif
#if stream-bundle2
  $ hg clone --stream http://localhost:$HGPORT phase-no-publish
  streaming all changes
  1034 files to transfer, 96.7 KB of data
  transferred 96.7 KB in * seconds (* */sec) (glob)
  updating to branch default
  1025 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg -R phase-no-publish phase -r 'all()'
  0: draft
  1: draft
#endif

  $ killdaemons.py