view tests/test-http-protocol.t @ 31793:69d8fcf20014

help: document bundle specifications

I softly formalized the concept of a "bundle specification" a while
ago when I was working on clone bundles and stream clone bundles and
wanted a more robust way to define what exactly is in a bundle file.

The concept has existed for a while. Since it is part of the clone
bundles feature and exposed to the user via the "-t" argument to
`hg bundle`, it is something we need to support for the long haul.

After the 4.1 release, I heard a few people comment that they didn't
realize you could generate zstd bundles with `hg bundle`. I'm
partially to blame for not documenting it in bundle's docstring.

Additionally, I added a hacky, experimental feature for controlling
the compression level of bundles in 76104a4899ad. As the commit
message says, I went with a quick and dirty solution out of time
constraints. Furthermore, I wanted to eventually store this
configuration in the "bundlespec" so it could be made more flexible.

Given:

a) bundlespecs are here to stay
b) we don't have great documentation over what they are, despite being
   a user-facing feature
c) the list of available compression engines and their behavior isn't
   exposed
d) we need an extensible place to modify behavior of compression
   engines

I want to move forward with formalizing bundlespecs as a user-facing
feature. This commit does that by introducing a "bundlespec" help
page. Leaning on the just-added compression engine documentation
and API, the topic also conveniently lists available compression
engines and details about them. This makes features like zstd
bundle compression more discoverable. e.g. you can now
`hg help -k zstd` and it lists the "bundlespec" topic.

  $ 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|