view tests/test-http-protocol.t @ 33289:abd7dedbaa36

sparse: vendor Facebook-developed extension

Facebook has developed an extension to enable "sparse" checkouts -
a working directory with a subset of files. This feature is a critical
component in enabling repositories to scale to infinite number of
files while retaining reasonable performance. It's worth noting
that sparse checkout is only one possible solution to this problem:
another is virtual filesystems that realize files on first access.
But given that virtual filesystems may not be accessible to all
users, sparse checkout is necessary as a fallback.

Per mailing list discussion at
https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/095868.html
we want to add sparse checkout to the Mercurial distribution via
roughly the following mechanism:

1. Vendor extension as-is with minimal modifications (this patch)
2. Refactor extension so it is more clearly experimental and inline
   with Mercurial practices
3. Move code from extension into core where possible
4. Drop experimental labeling and/or move feature into core
   after sign-off from narrow clone feature owners

This commit essentially copies the sparse extension and tests
from revision 71e0a2aeca92a4078fe1b8c76e32c88ff1929737 of the
https://bitbucket.org/facebook/hg-experimental repository.

A list of modifications made as part of vendoring is as follows:

* "EXPERIMENTAL" added to module docstring
* Imports were changed to match Mercurial style conventions
* "testedwith" value was updated to core Mercurial special value and
  comment boilerplate was inserted
* A "clone_sparse" function was renamed to "clonesparse" to appease
  the style checker
* Paths to the sparse extension in tests reflect built-in location
* test-sparse-extensions.t was renamed to test-sparse-fsmonitor.t
  and references to "simplecache" were removed. The test always skips
  because it isn't trivial to run it given the way we currently run
  fsmonitor tests
* A double empty line was removed from test-sparse-profiles.t

There are aspects of the added code that are obviously not ideal.
The goal is to make a minimal number of modifications as part of
the vendoring to make it easier to track changes from the original
implementation. Refactoring will occur in subsequent patches.

  $ cat >> $HGRCPATH << EOF
  > [web]
  > push_ssl = false
  > allow_push = *
  > EOF

  $ hg init server
  $ cd server
  $ touch a
  $ hg -q commit -A -m initial
  $ cd ..

  $ hg -R server serve -p $HGPORT -d --pid-file hg.pid
  $ cat hg.pid >> $DAEMON_PIDS

compression formats are advertised in compression capability

#if zstd
  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=zstd,zlib$' > /dev/null
#else
  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=zlib$' > /dev/null
#endif

  $ killdaemons.py

server.compressionengines can replace engines list wholesale

  $ hg --config server.compressionengines=none -R server serve -p $HGPORT -d --pid-file hg.pid
  $ cat hg.pid > $DAEMON_PIDS
  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=none$' > /dev/null

  $ killdaemons.py

Order of engines can also change

  $ hg --config server.compressionengines=none,zlib -R server serve -p $HGPORT -d --pid-file hg.pid
  $ cat hg.pid > $DAEMON_PIDS
  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=capabilities' | tr ' ' '\n' | grep '^compression=none,zlib$' > /dev/null

  $ killdaemons.py

Start a default server again

  $ hg -R server serve -p $HGPORT -d --pid-file hg.pid
  $ cat hg.pid > $DAEMON_PIDS

Server should send application/mercurial-0.1 to clients if no Accept is used

  $ get-with-headers.py --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
  200 Script output follows
  content-type: application/mercurial-0.1
  date: * (glob)
  server: * (glob)
  transfer-encoding: chunked

Server should send application/mercurial-0.1 when client says it wants it

  $ get-with-headers.py --hgproto '0.1' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
  200 Script output follows
  content-type: application/mercurial-0.1
  date: * (glob)
  server: * (glob)
  transfer-encoding: chunked

Server should send application/mercurial-0.2 when client says it wants it

  $ get-with-headers.py --hgproto '0.2' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
  200 Script output follows
  content-type: application/mercurial-0.2
  date: * (glob)
  server: * (glob)
  transfer-encoding: chunked

  $ get-with-headers.py --hgproto '0.1 0.2' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
  200 Script output follows
  content-type: application/mercurial-0.2
  date: * (glob)
  server: * (glob)
  transfer-encoding: chunked

Requesting a compression format that server doesn't support results will fall back to 0.1

  $ get-with-headers.py --hgproto '0.2 comp=aa' --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' -
  200 Script output follows
  content-type: application/mercurial-0.1
  date: * (glob)
  server: * (glob)
  transfer-encoding: chunked

#if zstd
zstd is used if available

  $ get-with-headers.py --hgproto '0.2 comp=zstd' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' > resp
  $ f --size --hexdump --bytes 36 --sha1 resp
  resp: size=248, sha1=4d8d8f87fb82bd542ce52881fdc94f850748
  0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
  0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 7a 73 74 64 |t follows...zstd|
  0020: 28 b5 2f fd                                     |(./.|

#endif

application/mercurial-0.2 is not yet used on non-streaming responses

  $ get-with-headers.py --hgproto '0.2' $LOCALIP:$HGPORT '?cmd=heads' -
  200 Script output follows
  content-length: 41
  content-type: application/mercurial-0.1
  date: * (glob)
  server: * (glob)
  
  e93700bd72895c5addab234c56d4024b487a362f

Now test protocol preference usage

  $ killdaemons.py
  $ hg --config server.compressionengines=none,zlib -R server serve -p $HGPORT -d --pid-file hg.pid
  $ cat hg.pid > $DAEMON_PIDS

No Accept will send 0.1+zlib, even though "none" is preferred b/c "none" isn't supported on 0.1

  $ get-with-headers.py --headeronly $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000' Content-Type
  200 Script output follows
  content-type: application/mercurial-0.1

  $ get-with-headers.py $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000'  > resp
  $ f --size --hexdump --bytes 28 --sha1 resp
  resp: size=227, sha1=35a4c074da74f32f5440da3cbf04
  0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
  0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 78             |t follows..x|

Explicit 0.1 will send zlib because "none" isn't supported on 0.1

  $ get-with-headers.py --hgproto '0.1' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000'  > resp
  $ f --size --hexdump --bytes 28 --sha1 resp
  resp: size=227, sha1=35a4c074da74f32f5440da3cbf04
  0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
  0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 78             |t follows..x|

0.2 with no compression will get "none" because that is server's preference
(spec says ZL and UN are implicitly supported)

  $ get-with-headers.py --hgproto '0.2' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000'  > resp
  $ f --size --hexdump --bytes 32 --sha1 resp
  resp: size=432, sha1=ac931b412ec185a02e0e5bcff98dac83
  0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
  0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 6e 6f 6e 65 |t follows...none|

Client receives server preference even if local order doesn't match

  $ get-with-headers.py --hgproto '0.2 comp=zlib,none' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000'  > resp
  $ f --size --hexdump --bytes 32 --sha1 resp
  resp: size=432, sha1=ac931b412ec185a02e0e5bcff98dac83
  0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
  0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 6e 6f 6e 65 |t follows...none|

Client receives only supported format even if not server preferred format

  $ get-with-headers.py --hgproto '0.2 comp=zlib' $LOCALIP:$HGPORT '?cmd=getbundle&heads=e93700bd72895c5addab234c56d4024b487a362f&common=0000000000000000000000000000000000000000'  > resp
  $ f --size --hexdump --bytes 33 --sha1 resp
  resp: size=232, sha1=a1c727f0c9693ca15742a75c30419bc36
  0000: 32 30 30 20 53 63 72 69 70 74 20 6f 75 74 70 75 |200 Script outpu|
  0010: 74 20 66 6f 6c 6c 6f 77 73 0a 0a 04 7a 6c 69 62 |t follows...zlib|
  0020: 78                                              |x|