wireprotov2: implement commands as a generator of objects
Previously, wire protocol version 2 inherited version 1's model of
having separate types to represent the results of different wire
protocol commands.
As I implemented more powerful commands in future commits, I found
I was using a common pattern of returning a special type to hold a
generator. This meant the command function required a closure to
do most of the work. That made logic flow more difficult to follow.
I also noticed that many commands were effectively a sequence of
objects to be CBOR encoded.
I think it makes sense to define version 2 commands as generators.
This way, commands can simply emit the data structures they wish to
send to the client. This eliminates the need for a closure in
command functions and removes encoding from the bodies of commands.
As part of this commit, the handling of response objects has been
moved into the serverreactor class. This puts the reactor in the
driver's seat with regards to CBOR encoding and error handling.
Having error handling in the function that emits frames is
particularly important because exceptions in that function can lead
to things getting in a bad state: I'm fairly certain that uncaught
exceptions in the frame generator were causing deadlocks.
I also introduced a dedicated error type for explicit error reporting
in command handlers. This will be used in subsequent commits.
There's still a bit of work to be done here, especially around
formalizing the error handling "protocol." I've added yet another
TODO to track this so we don't forget.
Test output changed because we're using generators and no longer know
we are at the end of the data until we hit the end of the generator.
This means we can't emit the end-of-stream flag until we've exhausted
the generator. Hence the introduction of 0-sized end-of-stream frames.
Differential Revision: https://phab.mercurial-scm.org/D4472
#require no-chg
$ . $TESTDIR/wireprotohelpers.sh
$ hg init server
zstd isn't present in plain builds. Make tests easier by removing
zstd from the equation.
$ cat >> server/.hg/hgrc << EOF
> [server]
> compressionengines = zlib
> EOF
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid -E error.log
$ cat hg.pid > $DAEMON_PIDS
A normal capabilities request is serviced for version 1
$ sendhttpraw << EOF
> httprequest GET ?cmd=capabilities
> user-agent: test
> EOF
using raw connection to peer
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\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: *\r\n (glob)
s> \r\n
s> batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
A proper request without the API server enabled returns the legacy response
$ sendhttpraw << EOF
> httprequest GET ?cmd=capabilities
> user-agent: test
> x-hgupgrade-1: foo
> x-hgproto-1: cbor
> EOF
using raw connection to peer
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> x-hgproto-1: cbor\r\n
s> x-hgupgrade-1: foo\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: *\r\n (glob)
s> \r\n
s> batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
Restart with just API server enabled. This enables serving the new format.
$ killdaemons.py
$ cat error.log
$ cat >> server/.hg/hgrc << EOF
> [experimental]
> web.apiserver = true
> EOF
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid -E error.log
$ cat hg.pid > $DAEMON_PIDS
X-HgUpgrade-<N> without CBOR advertisement uses legacy response
$ sendhttpraw << EOF
> httprequest GET ?cmd=capabilities
> user-agent: test
> x-hgupgrade-1: foo bar
> EOF
using raw connection to peer
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> x-hgupgrade-1: foo bar\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: *\r\n (glob)
s> \r\n
s> batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
X-HgUpgrade-<N> without known serialization in X-HgProto-<N> uses legacy response
$ sendhttpraw << EOF
> httprequest GET ?cmd=capabilities
> user-agent: test
> x-hgupgrade-1: foo bar
> x-hgproto-1: some value
> EOF
using raw connection to peer
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> x-hgproto-1: some value\r\n
s> x-hgupgrade-1: foo bar\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: *\r\n (glob)
s> \r\n
s> batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
X-HgUpgrade-<N> + X-HgProto-<N> headers trigger new response format
$ sendhttpraw << EOF
> httprequest GET ?cmd=capabilities
> user-agent: test
> x-hgupgrade-1: foo bar
> x-hgproto-1: cbor
> EOF
using raw connection to peer
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> x-hgproto-1: cbor\r\n
s> x-hgupgrade-1: foo bar\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-cbor\r\n
s> Content-Length: *\r\n (glob)
s> \r\n
s> \xa3GapibaseDapi/Dapis\xa0Nv1capabilitiesY\x01\xc5batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
cbor> {
b'apibase': b'api/',
b'apis': {},
b'v1capabilities': b'batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash'
}
Restart server to enable HTTPv2
$ killdaemons.py
$ enablehttpv2 server
$ hg -R server serve -p $HGPORT -d --pid-file hg.pid -E error.log
$ cat hg.pid > $DAEMON_PIDS
Only requested API services are returned
$ sendhttpraw << EOF
> httprequest GET ?cmd=capabilities
> user-agent: test
> x-hgupgrade-1: foo bar
> x-hgproto-1: cbor
> EOF
using raw connection to peer
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> x-hgproto-1: cbor\r\n
s> x-hgupgrade-1: foo bar\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-cbor\r\n
s> Content-Length: *\r\n (glob)
s> \r\n
s> \xa3GapibaseDapi/Dapis\xa0Nv1capabilitiesY\x01\xc5batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
cbor> {
b'apibase': b'api/',
b'apis': {},
b'v1capabilities': b'batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash'
}
Request for HTTPv2 service returns information about it
$ sendhttpraw << EOF
> httprequest GET ?cmd=capabilities
> user-agent: test
> x-hgupgrade-1: exp-http-v2-0001 foo bar
> x-hgproto-1: cbor
> EOF
using raw connection to peer
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> user-agent: test\r\n
s> x-hgproto-1: cbor\r\n
s> x-hgupgrade-1: exp-http-v2-0001 foo bar\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-cbor\r\n
s> Content-Length: *\r\n (glob)
s> \r\n
s> \xa3GapibaseDapi/Dapis\xa1Pexp-http-v2-0001\xa4Hcommands\xa7Ibranchmap\xa2Dargs\xa0Kpermissions\x81DpullLcapabilities\xa2Dargs\xa0Kpermissions\x81DpullEheads\xa2Dargs\xa1Jpubliconly\xf4Kpermissions\x81DpullEknown\xa2Dargs\xa1Enodes\x81HdeadbeefKpermissions\x81DpullHlistkeys\xa2Dargs\xa1InamespaceBnsKpermissions\x81DpullFlookup\xa2Dargs\xa1CkeyCfooKpermissions\x81DpullGpushkey\xa2Dargs\xa4CkeyCkeyInamespaceBnsCnewCnewColdColdKpermissions\x81DpushKcompression\x81\xa1DnameDzlibQframingmediatypes\x81X&application/mercurial-exp-framing-0005Nrawrepoformats\x82LgeneraldeltaHrevlogv1Nv1capabilitiesY\x01\xc5batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
cbor> {
b'apibase': b'api/',
b'apis': {
b'exp-http-v2-0001': {
b'commands': {
b'branchmap': {
b'args': {},
b'permissions': [
b'pull'
]
},
b'capabilities': {
b'args': {},
b'permissions': [
b'pull'
]
},
b'heads': {
b'args': {
b'publiconly': False
},
b'permissions': [
b'pull'
]
},
b'known': {
b'args': {
b'nodes': [
b'deadbeef'
]
},
b'permissions': [
b'pull'
]
},
b'listkeys': {
b'args': {
b'namespace': b'ns'
},
b'permissions': [
b'pull'
]
},
b'lookup': {
b'args': {
b'key': b'foo'
},
b'permissions': [
b'pull'
]
},
b'pushkey': {
b'args': {
b'key': b'key',
b'namespace': b'ns',
b'new': b'new',
b'old': b'old'
},
b'permissions': [
b'push'
]
}
},
b'compression': [
{
b'name': b'zlib'
}
],
b'framingmediatypes': [
b'application/mercurial-exp-framing-0005'
],
b'rawrepoformats': [
b'generaldelta',
b'revlogv1'
]
}
},
b'v1capabilities': b'batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash'
}
capabilities command returns expected info
$ sendhttpv2peerhandshake << EOF
> command capabilities
> EOF
creating http peer for wire protocol version 2
s> GET /?cmd=capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> vary: X-HgProto-1,X-HgUpgrade-1\r\n
s> x-hgproto-1: cbor\r\n
s> x-hgupgrade-1: exp-http-v2-0001\r\n
s> accept: application/mercurial-0.1\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> user-agent: Mercurial debugwireproto\r\n
s> \r\n
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-cbor\r\n
s> Content-Length: *\r\n (glob)
s> \r\n
s> \xa3GapibaseDapi/Dapis\xa1Pexp-http-v2-0001\xa4Hcommands\xa7Ibranchmap\xa2Dargs\xa0Kpermissions\x81DpullLcapabilities\xa2Dargs\xa0Kpermissions\x81DpullEheads\xa2Dargs\xa1Jpubliconly\xf4Kpermissions\x81DpullEknown\xa2Dargs\xa1Enodes\x81HdeadbeefKpermissions\x81DpullHlistkeys\xa2Dargs\xa1InamespaceBnsKpermissions\x81DpullFlookup\xa2Dargs\xa1CkeyCfooKpermissions\x81DpullGpushkey\xa2Dargs\xa4CkeyCkeyInamespaceBnsCnewCnewColdColdKpermissions\x81DpushKcompression\x81\xa1DnameDzlibQframingmediatypes\x81X&application/mercurial-exp-framing-0005Nrawrepoformats\x82LgeneraldeltaHrevlogv1Nv1capabilitiesY\x01\xc5batch branchmap $USUAL_BUNDLE2_CAPS_SERVER$ changegroupsubset compression=$BUNDLE2_COMPRESSIONS$ getbundle httpheader=1024 httpmediatype=0.1rx,0.1tx,0.2tx known lookup pushkey streamreqs=generaldelta,revlogv1 unbundle=HG10GZ,HG10BZ,HG10UN unbundlehash
sending capabilities command
s> POST /api/exp-http-v2-0001/ro/capabilities HTTP/1.1\r\n
s> Accept-Encoding: identity\r\n
s> *\r\n (glob)
s> content-type: application/mercurial-exp-framing-0005\r\n
s> content-length: 27\r\n
s> host: $LOCALIP:$HGPORT\r\n (glob)
s> user-agent: Mercurial debugwireproto\r\n
s> \r\n
s> \x13\x00\x00\x01\x00\x01\x01\x11\xa1DnameLcapabilities
s> makefile('rb', None)
s> HTTP/1.1 200 OK\r\n
s> Server: testing stub value\r\n
s> Date: $HTTP_DATE$\r\n
s> Content-Type: application/mercurial-exp-framing-0005\r\n
s> Transfer-Encoding: chunked\r\n
s> \r\n
s> 13\r\n
s> \x0b\x00\x00\x01\x00\x02\x011
s> \xa1FstatusBok
s> \r\n
received frame(size=11; request=1; stream=2; streamflags=stream-begin; type=command-response; flags=continuation)
s> 1cc\r\n
s> \xc4\x01\x00\x01\x00\x02\x001
s> \xa4Hcommands\xa7Ibranchmap\xa2Dargs\xa0Kpermissions\x81DpullLcapabilities\xa2Dargs\xa0Kpermissions\x81DpullEheads\xa2Dargs\xa1Jpubliconly\xf4Kpermissions\x81DpullEknown\xa2Dargs\xa1Enodes\x81HdeadbeefKpermissions\x81DpullHlistkeys\xa2Dargs\xa1InamespaceBnsKpermissions\x81DpullFlookup\xa2Dargs\xa1CkeyCfooKpermissions\x81DpullGpushkey\xa2Dargs\xa4CkeyCkeyInamespaceBnsCnewCnewColdColdKpermissions\x81DpushKcompression\x81\xa1DnameDzlibQframingmediatypes\x81X&application/mercurial-exp-framing-0005Nrawrepoformats\x82LgeneraldeltaHrevlogv1
s> \r\n
received frame(size=452; request=1; stream=2; streamflags=; type=command-response; flags=continuation)
s> 8\r\n
s> \x00\x00\x00\x01\x00\x02\x002
s> \r\n
s> 0\r\n
s> \r\n
received frame(size=0; request=1; stream=2; streamflags=; type=command-response; flags=eos)
response: [
{
b'status': b'ok'
},
{
b'commands': {
b'branchmap': {
b'args': {},
b'permissions': [
b'pull'
]
},
b'capabilities': {
b'args': {},
b'permissions': [
b'pull'
]
},
b'heads': {
b'args': {
b'publiconly': False
},
b'permissions': [
b'pull'
]
},
b'known': {
b'args': {
b'nodes': [
b'deadbeef'
]
},
b'permissions': [
b'pull'
]
},
b'listkeys': {
b'args': {
b'namespace': b'ns'
},
b'permissions': [
b'pull'
]
},
b'lookup': {
b'args': {
b'key': b'foo'
},
b'permissions': [
b'pull'
]
},
b'pushkey': {
b'args': {
b'key': b'key',
b'namespace': b'ns',
b'new': b'new',
b'old': b'old'
},
b'permissions': [
b'push'
]
}
},
b'compression': [
{
b'name': b'zlib'
}
],
b'framingmediatypes': [
b'application/mercurial-exp-framing-0005'
],
b'rawrepoformats': [
b'generaldelta',
b'revlogv1'
]
}
]
$ cat error.log