wireproto: implement basic frame reading and processing
We just implemented support for writing frames. Now let's implement
support for reading them.
The bulk of the new code is for a class that maintains the state of
a server. Essentially, you construct an instance, feed frames to it,
and it tells you what you should do next. The design is inspired by
the "sans I/O" movement and the reactor pattern. We don't want to
perform I/O or any major blocking event during frame ingestion because
this arbitrarily limits ways that server pieces can be implemented.
For example, it makes it much harder to swap in an alternate
implementation based on asyncio or do crazy things like have requests
dispatch to other processes.
We do still implement readframe() which does I/O. But it is decoupled
from the server reactor. And important parsing of frame headers is
a standalone function. So I/O is only needed to obtain frame data.
Because testing server-side ingest is useful and difficult on running
servers, we create a new "debugreflect" endpoint that will echo back
to the client what was received and how it was interpreted. This could
be useful for a server admin, someone implementing a client. But
immediately, it is useful for testing: we're able to demonstrate that
frames are parsed correctly and turned into requests to run commands
without having to implement command dispatch on the server!
In addition, we implement Python level unit tests for the reactor.
This is vastly more efficient than sending requests to the
"debugreflect" endpoint and vastly more powerful for advanced
testing.
Differential Revision: https://phab.mercurial-scm.org/D2852
$ 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 serve -R server -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 serve --config server.compressionengines=none -R server -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 serve --config server.compressionengines=none,zlib -R server -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 serve -R server -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: $HTTP_DATE$
server: testing stub value
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: $HTTP_DATE$
server: testing stub value
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: $HTTP_DATE$
server: testing stub value
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: $HTTP_DATE$
server: testing stub value
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: $HTTP_DATE$
server: testing stub value
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: $HTTP_DATE$
server: testing stub value
e93700bd72895c5addab234c56d4024b487a362f
Now test protocol preference usage
$ killdaemons.py
$ hg serve --config server.compressionengines=none,zlib -R server -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|
$ killdaemons.py
$ cd ..
Test listkeys for listing namespaces
$ hg init empty
$ hg -R empty serve -p $HGPORT -d --pid-file hg.pid
$ cat hg.pid > $DAEMON_PIDS
$ hg --verbose debugwireproto http://$LOCALIP:$HGPORT << EOF
> command listkeys
> namespace namespaces
> EOF
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> accept: application/mercurial-0.1\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> user-agent: mercurial/proto-1.0 (Mercurial *)\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 Script output follows\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-0.1\r\n
s> Content-Length: *\r\n (glob)
s> \r\n
s> lookup branchmap pushkey known getbundle unbundlehash batch changegroupsubset streamreqs=generaldelta,revlogv1 $USUAL_BUNDLE2_CAPS_SERVER$ unbundle=HG10GZ,HG10BZ,HG10UN httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx compression=$BUNDLE2_COMPRESSIONS$
sending listkeys command
s> GET /?cmd=listkeys HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> vary: X-HgArg-1,X-HgProto-1\r\n
s> x-hgarg-1: namespace=namespaces\r\n
s> x-hgproto-1: 0.1 0.2 comp=$USUAL_COMPRESSIONS$\r\n
s> accept: application/mercurial-0.1\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> user-agent: mercurial/proto-1.0 (Mercurial *)\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 Script output follows\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-0.1\r\n
s> Content-Length: 30\r\n
s> \r\n
s> bookmarks \n
s> namespaces \n
s> phases
response: bookmarks \nnamespaces \nphases
Same thing, but with "httprequest" command
$ hg --verbose debugwireproto --peer raw http://$LOCALIP:$HGPORT << EOF
> httprequest GET ?cmd=listkeys
> user-agent: test
> x-hgarg-1: namespace=namespaces
> EOF
using raw connection to peer
s> GET /?cmd=listkeys HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> x-hgarg-1: namespace=namespaces\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 Script output follows\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-0.1\r\n
s> Content-Length: 30\r\n
s> \r\n
s> bookmarks \n
s> namespaces \n
s> phases
$ killdaemons.py