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
from __future__ import absolute_import, print_function
import unittest
from mercurial import (
util,
wireprotoframing as framing,
)
ffs = framing.makeframefromhumanstring
def makereactor():
return framing.serverreactor()
def sendframes(reactor, gen):
"""Send a generator of frame bytearray to a reactor.
Emits a generator of results from ``onframerecv()`` calls.
"""
for frame in gen:
frametype, frameflags, framelength = framing.parseheader(frame)
payload = frame[framing.FRAME_HEADER_SIZE:]
assert len(payload) == framelength
yield reactor.onframerecv(frametype, frameflags, payload)
def sendcommandframes(reactor, cmd, args, datafh=None):
"""Generate frames to run a command and send them to a reactor."""
return sendframes(reactor, framing.createcommandframes(cmd, args, datafh))
class FrameTests(unittest.TestCase):
def testdataexactframesize(self):
data = util.bytesio(b'x' * framing.DEFAULT_MAX_FRAME_SIZE)
frames = list(framing.createcommandframes(b'command', {}, data))
self.assertEqual(frames, [
ffs(b'command-name have-data command'),
ffs(b'command-data continuation %s' % data.getvalue()),
ffs(b'command-data eos ')
])
def testdatamultipleframes(self):
data = util.bytesio(b'x' * (framing.DEFAULT_MAX_FRAME_SIZE + 1))
frames = list(framing.createcommandframes(b'command', {}, data))
self.assertEqual(frames, [
ffs(b'command-name have-data command'),
ffs(b'command-data continuation %s' % (
b'x' * framing.DEFAULT_MAX_FRAME_SIZE)),
ffs(b'command-data eos x'),
])
def testargsanddata(self):
data = util.bytesio(b'x' * 100)
frames = list(framing.createcommandframes(b'command', {
b'key1': b'key1value',
b'key2': b'key2value',
b'key3': b'key3value',
}, data))
self.assertEqual(frames, [
ffs(b'command-name have-args|have-data command'),
ffs(br'command-argument 0 \x04\x00\x09\x00key1key1value'),
ffs(br'command-argument 0 \x04\x00\x09\x00key2key2value'),
ffs(br'command-argument eoa \x04\x00\x09\x00key3key3value'),
ffs(b'command-data eos %s' % data.getvalue()),
])
class ServerReactorTests(unittest.TestCase):
def _sendsingleframe(self, reactor, s):
results = list(sendframes(reactor, [ffs(s)]))
self.assertEqual(len(results), 1)
return results[0]
def assertaction(self, res, expected):
self.assertIsInstance(res, tuple)
self.assertEqual(len(res), 2)
self.assertIsInstance(res[1], dict)
self.assertEqual(res[0], expected)
def test1framecommand(self):
"""Receiving a command in a single frame yields request to run it."""
reactor = makereactor()
results = list(sendcommandframes(reactor, b'mycommand', {}))
self.assertEqual(len(results), 1)
self.assertaction(results[0], 'runcommand')
self.assertEqual(results[0][1], {
'command': b'mycommand',
'args': {},
'data': None,
})
def test1argument(self):
reactor = makereactor()
results = list(sendcommandframes(reactor, b'mycommand',
{b'foo': b'bar'}))
self.assertEqual(len(results), 2)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'runcommand')
self.assertEqual(results[1][1], {
'command': b'mycommand',
'args': {b'foo': b'bar'},
'data': None,
})
def testmultiarguments(self):
reactor = makereactor()
results = list(sendcommandframes(reactor, b'mycommand',
{b'foo': b'bar', b'biz': b'baz'}))
self.assertEqual(len(results), 3)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'wantframe')
self.assertaction(results[2], 'runcommand')
self.assertEqual(results[2][1], {
'command': b'mycommand',
'args': {b'foo': b'bar', b'biz': b'baz'},
'data': None,
})
def testsimplecommanddata(self):
reactor = makereactor()
results = list(sendcommandframes(reactor, b'mycommand', {},
util.bytesio(b'data!')))
self.assertEqual(len(results), 2)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'runcommand')
self.assertEqual(results[1][1], {
'command': b'mycommand',
'args': {},
'data': b'data!',
})
def testmultipledataframes(self):
frames = [
ffs(b'command-name have-data mycommand'),
ffs(b'command-data continuation data1'),
ffs(b'command-data continuation data2'),
ffs(b'command-data eos data3'),
]
reactor = makereactor()
results = list(sendframes(reactor, frames))
self.assertEqual(len(results), 4)
for i in range(3):
self.assertaction(results[i], 'wantframe')
self.assertaction(results[3], 'runcommand')
self.assertEqual(results[3][1], {
'command': b'mycommand',
'args': {},
'data': b'data1data2data3',
})
def testargumentanddata(self):
frames = [
ffs(b'command-name have-args|have-data command'),
ffs(br'command-argument 0 \x03\x00\x03\x00keyval'),
ffs(br'command-argument eoa \x03\x00\x03\x00foobar'),
ffs(b'command-data continuation value1'),
ffs(b'command-data eos value2'),
]
reactor = makereactor()
results = list(sendframes(reactor, frames))
self.assertaction(results[-1], 'runcommand')
self.assertEqual(results[-1][1], {
'command': b'command',
'args': {
b'key': b'val',
b'foo': b'bar',
},
'data': b'value1value2',
})
def testunexpectedcommandargument(self):
"""Command argument frame when not running a command is an error."""
result = self._sendsingleframe(makereactor(),
b'command-argument 0 ignored')
self.assertaction(result, 'error')
self.assertEqual(result[1], {
'message': b'expected command frame; got 2',
})
def testunexpectedcommanddata(self):
"""Command argument frame when not running a command is an error."""
result = self._sendsingleframe(makereactor(),
b'command-data 0 ignored')
self.assertaction(result, 'error')
self.assertEqual(result[1], {
'message': b'expected command frame; got 3',
})
def testmissingcommandframeflags(self):
"""Command name frame must have flags set."""
result = self._sendsingleframe(makereactor(),
b'command-name 0 command')
self.assertaction(result, 'error')
self.assertEqual(result[1], {
'message': b'missing frame flags on command frame',
})
def testmissingargumentframe(self):
frames = [
ffs(b'command-name have-args command'),
ffs(b'command-name 0 ignored'),
]
results = list(sendframes(makereactor(), frames))
self.assertEqual(len(results), 2)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'error')
self.assertEqual(results[1][1], {
'message': b'expected command argument frame; got 1',
})
def testincompleteargumentname(self):
"""Argument frame with incomplete name."""
frames = [
ffs(b'command-name have-args command1'),
ffs(br'command-argument eoa \x04\x00\xde\xadfoo'),
]
results = list(sendframes(makereactor(), frames))
self.assertEqual(len(results), 2)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'error')
self.assertEqual(results[1][1], {
'message': b'malformed argument frame: partial argument name',
})
def testincompleteargumentvalue(self):
"""Argument frame with incomplete value."""
frames = [
ffs(b'command-name have-args command'),
ffs(br'command-argument eoa \x03\x00\xaa\xaafoopartialvalue'),
]
results = list(sendframes(makereactor(), frames))
self.assertEqual(len(results), 2)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'error')
self.assertEqual(results[1][1], {
'message': b'malformed argument frame: partial argument value',
})
def testmissingcommanddataframe(self):
frames = [
ffs(b'command-name have-data command1'),
ffs(b'command-name eos command2'),
]
results = list(sendframes(makereactor(), frames))
self.assertEqual(len(results), 2)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'error')
self.assertEqual(results[1][1], {
'message': b'expected command data frame; got 1',
})
def testmissingcommanddataframeflags(self):
frames = [
ffs(b'command-name have-data command1'),
ffs(b'command-data 0 data'),
]
results = list(sendframes(makereactor(), frames))
self.assertEqual(len(results), 2)
self.assertaction(results[0], 'wantframe')
self.assertaction(results[1], 'error')
self.assertEqual(results[1][1], {
'message': b'command data frame without flags',
})
if __name__ == '__main__':
import silenttestrunner
silenttestrunner.main(__name__)