view tests/test-wireproto-serverreactor.py @ 37288:9bfcbe4f4745

wireproto: add streams to frame-based protocol

Previously, the frame-based protocol was just a series of frames,
with each frame associated with a request ID.

In order to scale the protocol, we'll want to enable the use of
compression. While it is possible to enable compression at the
socket/pipe level, this has its disadvantages. The big one is it
undermines the point of frames being standalone, atomic units that
can be read and written: if you add compression above the framing
protocol, you are back to having a stream-based protocol as opposed
to something frame-based.

So in order to preserve frames, compression needs to occur at
the frame payload level.

Compressing each frame's payload individually will limit compression
ratios because the window size of the compressor will be limited
by the max frame size, which is 32-64kb as currently defined. It
will also add CPU overhead, as it is more efficient for compressors
to operate on fewer, larger blocks of data than more, smaller blocks.

So compressing each frame independently is out.

This means we need to compress each frame's payload as if it is part
of a larger stream.

The simplest approach is to have 1 stream per connection. This
could certainly work. However, it has disadvantages (documented below).

We could also have 1 stream per RPC/command invocation. (This is the
model HTTP/2 goes with.) This also has disadvantages.

The main disadvantage to one global stream is that it has the very
real potential to create CPU bottlenecks doing compression. Networks
are only getting faster and the performance of single CPU cores has
been relatively flat. Newer compression formats like zstandard offer
better CPU cycle efficiency than predecessors like zlib. But it still
all too common to saturate your CPU with compression overhead long
before you saturate the network pipe.

The main disadvantage with streams per request is that you can't
reap the benefits of the compression context for multiple requests.
For example, if you send 1000 RPC requests (or HTTP/2 requests for
that matter), the response to each would have its own compression
context. The overall size of the raw responses would be larger because
compression contexts wouldn't be able to reference data from another
request or response.

The approach for streams as implemented in this commit is to support
N streams per connection and for streams to potentially span requests
and responses. As explained by the added internals docs, this
facilitates servers and clients delegating independent streams and
compression to independent threads / CPU cores. This helps alleviate
the CPU bottleneck of compression. This design also allows compression
contexts to be reused across requests/responses. This can result in
improved compression ratios and less overhead for compressors and
decompressors having to build new contexts.

Another feature that was defined was the ability for individual frames
within a stream to declare whether that individual frame's payload
uses the content encoding (read: compression) defined by the stream.
The idea here is that some servers may serve data from a combination
of caches and dynamic resolution. Data coming from caches may be
pre-compressed. We want to facilitate servers being able to essentially
stream bytes from caches to the wire with minimal overhead. Being
able to mix and match with frames are compressed within a stream
enables these types of advanced server functionality.

This commit defines the new streams mechanism. Basic code for
supporting streams in frames has been added. But that code is
seriously lacking and doesn't fully conform to the defined protocol.
For example, we don't close any streams. And support for content
encoding within streams is not yet implemented. The change was
rather invasive and I didn't think it would be reasonable to implement
the entire feature in a single commit.

For the record, I would have loved to reuse an existing multiplexing
protocol to build the new wire protocol on top of. However, I couldn't
find a protocol that offers the performance and scaling characteristics
that I desired. Namely, it should support multiple compression
contexts to facilitate scaling out to multiple CPU cores and
compression contexts should be able to live longer than single RPC
requests. HTTP/2 *almost* fits the bill. But the semantics of HTTP
message exchange state that streams can only live for a single
request-response. We /could/ tunnel on top of HTTP/2 streams and
frames with HEADER and DATA frames. But there's no guarantee that
HTTP/2 libraries and proxies would allow us to use HTTP/2 streams
and frames without the HTTP message exchange semantics defined in
RFC 7540 Section 8. Other RPC protocols like gRPC tunnel are built
on top of HTTP/2 and thus preserve its semantics of stream per
RPC invocation. Even QUIC does this. We could attempt to invent a
higher-level stream that spans HTTP/2 streams. But this would be
violating HTTP/2 because there is no guarantee that HTTP/2 streams
are routed to the same server. The best we can do - which is what
this protocol does - is shoehorn all request and response data into
a single HTTP message and create streams within. At that point, we've
defined a Content-Type in HTTP parlance. It just so happens our
media type can also work as a standalone, stream-based protocol,
without leaning on HTTP or similar protocol.

Differential Revision: https://phab.mercurial-scm.org/D2907

from __future__ import absolute_import, print_function

import unittest

from mercurial import (
    util,
    wireprotoframing as framing,
)

ffs = framing.makeframefromhumanstring

def makereactor(deferoutput=False):
    return framing.serverreactor(deferoutput=deferoutput)

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:
        header = framing.parseheader(frame)
        payload = frame[framing.FRAME_HEADER_SIZE:]
        assert len(payload) == header.length

        yield reactor.onframerecv(framing.frame(header.requestid,
                                                header.streamid,
                                                header.streamflags,
                                                header.typeid,
                                                header.flags,
                                                payload))

def sendcommandframes(reactor, stream, rid, cmd, args, datafh=None):
    """Generate frames to run a command and send them to a reactor."""
    return sendframes(reactor,
                      framing.createcommandframes(stream, rid, cmd, args,
                                                  datafh))

class FrameTests(unittest.TestCase):
    def testdataexactframesize(self):
        data = util.bytesio(b'x' * framing.DEFAULT_MAX_FRAME_SIZE)

        stream = framing.stream(1)
        frames = list(framing.createcommandframes(stream, 1, b'command',
                                                  {}, data))
        self.assertEqual(frames, [
            ffs(b'1 1 stream-begin command-name have-data command'),
            ffs(b'1 1 0 command-data continuation %s' % data.getvalue()),
            ffs(b'1 1 0 command-data eos ')
        ])

    def testdatamultipleframes(self):
        data = util.bytesio(b'x' * (framing.DEFAULT_MAX_FRAME_SIZE + 1))

        stream = framing.stream(1)
        frames = list(framing.createcommandframes(stream, 1, b'command', {},
                                                  data))
        self.assertEqual(frames, [
            ffs(b'1 1 stream-begin command-name have-data command'),
            ffs(b'1 1 0 command-data continuation %s' % (
                b'x' * framing.DEFAULT_MAX_FRAME_SIZE)),
            ffs(b'1 1 0 command-data eos x'),
        ])

    def testargsanddata(self):
        data = util.bytesio(b'x' * 100)

        stream = framing.stream(1)
        frames = list(framing.createcommandframes(stream, 1, b'command', {
            b'key1': b'key1value',
            b'key2': b'key2value',
            b'key3': b'key3value',
        }, data))

        self.assertEqual(frames, [
            ffs(b'1 1 stream-begin command-name have-args|have-data command'),
            ffs(br'1 1 0 command-argument 0 \x04\x00\x09\x00key1key1value'),
            ffs(br'1 1 0 command-argument 0 \x04\x00\x09\x00key2key2value'),
            ffs(br'1 1 0 command-argument eoa \x04\x00\x09\x00key3key3value'),
            ffs(b'1 1 0 command-data eos %s' % data.getvalue()),
        ])

    def testtextoutputexcessiveargs(self):
        """At most 255 formatting arguments are allowed."""
        with self.assertRaisesRegexp(ValueError,
                                     'cannot use more than 255 formatting'):
            args = [b'x' for i in range(256)]
            list(framing.createtextoutputframe(None, 1,
                                               [(b'bleh', args, [])]))

    def testtextoutputexcessivelabels(self):
        """At most 255 labels are allowed."""
        with self.assertRaisesRegexp(ValueError,
                                     'cannot use more than 255 labels'):
            labels = [b'l' for i in range(256)]
            list(framing.createtextoutputframe(None, 1,
                                               [(b'bleh', [], labels)]))

    def testtextoutputformattingstringtype(self):
        """Formatting string must be bytes."""
        with self.assertRaisesRegexp(ValueError, 'must use bytes formatting '):
            list(framing.createtextoutputframe(None, 1, [
                (b'foo'.decode('ascii'), [], [])]))

    def testtextoutputargumentbytes(self):
        with self.assertRaisesRegexp(ValueError, 'must use bytes for argument'):
            list(framing.createtextoutputframe(None, 1, [
                (b'foo', [b'foo'.decode('ascii')], [])]))

    def testtextoutputlabelbytes(self):
        with self.assertRaisesRegexp(ValueError, 'must use bytes for labels'):
            list(framing.createtextoutputframe(None, 1, [
                (b'foo', [], [b'foo'.decode('ascii')])]))

    def testtextoutputtoolongformatstring(self):
        with self.assertRaisesRegexp(ValueError,
                                     'formatting string cannot be longer than'):
            list(framing.createtextoutputframe(None, 1, [
                (b'x' * 65536, [], [])]))

    def testtextoutputtoolongargumentstring(self):
        with self.assertRaisesRegexp(ValueError,
                                     'argument string cannot be longer than'):
            list(framing.createtextoutputframe(None, 1, [
                (b'bleh', [b'x' * 65536], [])]))

    def testtextoutputtoolonglabelstring(self):
        with self.assertRaisesRegexp(ValueError,
                                     'label string cannot be longer than'):
            list(framing.createtextoutputframe(None, 1, [
                (b'bleh', [], [b'x' * 65536])]))

    def testtextoutput1simpleatom(self):
        stream = framing.stream(1)
        val = list(framing.createtextoutputframe(stream, 1, [
            (b'foo', [], [])]))

        self.assertEqual(val, [
            ffs(br'1 1 stream-begin text-output 0 \x03\x00\x00\x00foo'),
        ])

    def testtextoutput2simpleatoms(self):
        stream = framing.stream(1)
        val = list(framing.createtextoutputframe(stream, 1, [
            (b'foo', [], []),
            (b'bar', [], []),
        ]))

        self.assertEqual(val, [
            ffs(br'1 1 stream-begin text-output 0 '
                br'\x03\x00\x00\x00foo\x03\x00\x00\x00bar'),
        ])

    def testtextoutput1arg(self):
        stream = framing.stream(1)
        val = list(framing.createtextoutputframe(stream, 1, [
            (b'foo %s', [b'val1'], []),
        ]))

        self.assertEqual(val, [
            ffs(br'1 1 stream-begin text-output 0 '
                br'\x06\x00\x00\x01\x04\x00foo %sval1'),
        ])

    def testtextoutput2arg(self):
        stream = framing.stream(1)
        val = list(framing.createtextoutputframe(stream, 1, [
            (b'foo %s %s', [b'val', b'value'], []),
        ]))

        self.assertEqual(val, [
            ffs(br'1 1 stream-begin text-output 0 '
                br'\x09\x00\x00\x02\x03\x00\x05\x00foo %s %svalvalue'),
        ])

    def testtextoutput1label(self):
        stream = framing.stream(1)
        val = list(framing.createtextoutputframe(stream, 1, [
            (b'foo', [], [b'label']),
        ]))

        self.assertEqual(val, [
            ffs(br'1 1 stream-begin text-output 0 '
                br'\x03\x00\x01\x00\x05foolabel'),
        ])

    def testargandlabel(self):
        stream = framing.stream(1)
        val = list(framing.createtextoutputframe(stream, 1, [
            (b'foo %s', [b'arg'], [b'label']),
        ]))

        self.assertEqual(val, [
            ffs(br'1 1 stream-begin text-output 0 '
                br'\x06\x00\x01\x01\x05\x03\x00foo %slabelarg'),
        ])

class ServerReactorTests(unittest.TestCase):
    def _sendsingleframe(self, reactor, f):
        results = list(sendframes(reactor, [f]))
        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 assertframesequal(self, frames, framestrings):
        expected = [ffs(s) for s in framestrings]
        self.assertEqual(list(frames), expected)

    def test1framecommand(self):
        """Receiving a command in a single frame yields request to run it."""
        reactor = makereactor()
        stream = framing.stream(1)
        results = list(sendcommandframes(reactor, stream, 1, b'mycommand', {}))
        self.assertEqual(len(results), 1)
        self.assertaction(results[0], 'runcommand')
        self.assertEqual(results[0][1], {
            'requestid': 1,
            'command': b'mycommand',
            'args': {},
            'data': None,
        })

        result = reactor.oninputeof()
        self.assertaction(result, 'noop')

    def test1argument(self):
        reactor = makereactor()
        stream = framing.stream(1)
        results = list(sendcommandframes(reactor, stream, 41, 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], {
            'requestid': 41,
            'command': b'mycommand',
            'args': {b'foo': b'bar'},
            'data': None,
        })

    def testmultiarguments(self):
        reactor = makereactor()
        stream = framing.stream(1)
        results = list(sendcommandframes(reactor, stream, 1, 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], {
            'requestid': 1,
            'command': b'mycommand',
            'args': {b'foo': b'bar', b'biz': b'baz'},
            'data': None,
        })

    def testsimplecommanddata(self):
        reactor = makereactor()
        stream = framing.stream(1)
        results = list(sendcommandframes(reactor, stream, 1, 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], {
            'requestid': 1,
            'command': b'mycommand',
            'args': {},
            'data': b'data!',
        })

    def testmultipledataframes(self):
        frames = [
            ffs(b'1 1 stream-begin command-name have-data mycommand'),
            ffs(b'1 1 0 command-data continuation data1'),
            ffs(b'1 1 0 command-data continuation data2'),
            ffs(b'1 1 0 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], {
            'requestid': 1,
            'command': b'mycommand',
            'args': {},
            'data': b'data1data2data3',
        })

    def testargumentanddata(self):
        frames = [
            ffs(b'1 1 stream-begin command-name have-args|have-data command'),
            ffs(br'1 1 0 command-argument 0 \x03\x00\x03\x00keyval'),
            ffs(br'1 1 0 command-argument eoa \x03\x00\x03\x00foobar'),
            ffs(b'1 1 0 command-data continuation value1'),
            ffs(b'1 1 0 command-data eos value2'),
        ]

        reactor = makereactor()
        results = list(sendframes(reactor, frames))

        self.assertaction(results[-1], 'runcommand')
        self.assertEqual(results[-1][1], {
            'requestid': 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(), ffs(b'1 1 stream-begin command-argument 0 ignored'))
        self.assertaction(result, 'error')
        self.assertEqual(result[1], {
            'message': b'expected command frame; got 2',
        })

    def testunexpectedcommandargumentreceiving(self):
        """Same as above but the command is receiving."""
        results = list(sendframes(makereactor(), [
            ffs(b'1 1 stream-begin command-name have-data command'),
            ffs(b'1 1 0 command-argument eoa ignored'),
        ]))

        self.assertaction(results[1], 'error')
        self.assertEqual(results[1][1], {
            'message': b'received command argument frame for request that is '
                       b'not expecting arguments: 1',
        })

    def testunexpectedcommanddata(self):
        """Command argument frame when not running a command is an error."""
        result = self._sendsingleframe(
            makereactor(), ffs(b'1 1 stream-begin command-data 0 ignored'))
        self.assertaction(result, 'error')
        self.assertEqual(result[1], {
            'message': b'expected command frame; got 3',
        })

    def testunexpectedcommanddatareceiving(self):
        """Same as above except the command is receiving."""
        results = list(sendframes(makereactor(), [
            ffs(b'1 1 stream-begin command-name have-args command'),
            ffs(b'1 1 0 command-data eos ignored'),
        ]))

        self.assertaction(results[1], 'error')
        self.assertEqual(results[1][1], {
            'message': b'received command data frame for request that is not '
                       b'expecting data: 1',
        })

    def testmissingcommandframeflags(self):
        """Command name frame must have flags set."""
        result = self._sendsingleframe(
            makereactor(), ffs(b'1 1 stream-begin command-name 0 command'))
        self.assertaction(result, 'error')
        self.assertEqual(result[1], {
            'message': b'missing frame flags on command frame',
        })

    def testconflictingrequestidallowed(self):
        """Multiple fully serviced commands with same request ID is allowed."""
        reactor = makereactor()
        results = []
        outstream = framing.stream(2)
        results.append(self._sendsingleframe(
            reactor, ffs(b'1 1 stream-begin command-name eos command')))
        result = reactor.onbytesresponseready(outstream, 1, b'response1')
        self.assertaction(result, 'sendframes')
        list(result[1]['framegen'])
        results.append(self._sendsingleframe(
            reactor, ffs(b'1 1 0 command-name eos command')))
        result = reactor.onbytesresponseready(outstream, 1, b'response2')
        self.assertaction(result, 'sendframes')
        list(result[1]['framegen'])
        results.append(self._sendsingleframe(
            reactor, ffs(b'1 1 0 command-name eos command')))
        result = reactor.onbytesresponseready(outstream, 1, b'response3')
        self.assertaction(result, 'sendframes')
        list(result[1]['framegen'])

        for i in range(3):
            self.assertaction(results[i], 'runcommand')
            self.assertEqual(results[i][1], {
                'requestid': 1,
                'command': b'command',
                'args': {},
                'data': None,
            })

    def testconflictingrequestid(self):
        """Request ID for new command matching in-flight command is illegal."""
        results = list(sendframes(makereactor(), [
            ffs(b'1 1 stream-begin command-name have-args command'),
            ffs(b'1 1 0 command-name eos command'),
        ]))

        self.assertaction(results[0], 'wantframe')
        self.assertaction(results[1], 'error')
        self.assertEqual(results[1][1], {
            'message': b'request with ID 1 already received',
        })

    def testinterleavedcommands(self):
        results = list(sendframes(makereactor(), [
            ffs(b'1 1 stream-begin command-name have-args command1'),
            ffs(b'3 1 0 command-name have-args command3'),
            ffs(br'1 1 0 command-argument 0 \x03\x00\x03\x00foobar'),
            ffs(br'3 1 0 command-argument 0 \x03\x00\x03\x00bizbaz'),
            ffs(br'3 1 0 command-argument eoa \x03\x00\x03\x00keyval'),
            ffs(br'1 1 0 command-argument eoa \x04\x00\x03\x00key1val'),
        ]))

        self.assertEqual([t[0] for t in results], [
            'wantframe',
            'wantframe',
            'wantframe',
            'wantframe',
            'runcommand',
            'runcommand',
        ])

        self.assertEqual(results[4][1], {
            'requestid': 3,
            'command': 'command3',
            'args': {b'biz': b'baz', b'key': b'val'},
            'data': None,
        })
        self.assertEqual(results[5][1], {
            'requestid': 1,
            'command': 'command1',
            'args': {b'foo': b'bar', b'key1': b'val'},
            'data': None,
        })

    def testmissingargumentframe(self):
        # This test attempts to test behavior when reactor has an incomplete
        # command request waiting on argument data. But it doesn't handle that
        # scenario yet. So this test does nothing of value.
        frames = [
            ffs(b'1 1 stream-begin command-name have-args command'),
        ]

        results = list(sendframes(makereactor(), frames))
        self.assertaction(results[0], 'wantframe')

    def testincompleteargumentname(self):
        """Argument frame with incomplete name."""
        frames = [
            ffs(b'1 1 stream-begin command-name have-args command1'),
            ffs(br'1 1 0 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'1 1 stream-begin command-name have-args command'),
            ffs(br'1 1 0 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):
        # The reactor doesn't currently handle partially received commands.
        # So this test is failing to do anything with request 1.
        frames = [
            ffs(b'1 1 stream-begin command-name have-data command1'),
            ffs(b'3 1 0 command-name eos command2'),
        ]
        results = list(sendframes(makereactor(), frames))
        self.assertEqual(len(results), 2)
        self.assertaction(results[0], 'wantframe')
        self.assertaction(results[1], 'runcommand')

    def testmissingcommanddataframeflags(self):
        frames = [
            ffs(b'1 1 stream-begin command-name have-data command1'),
            ffs(b'1 1 0 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',
        })

    def testframefornonreceivingrequest(self):
        """Receiving a frame for a command that is not receiving is illegal."""
        results = list(sendframes(makereactor(), [
            ffs(b'1 1 stream-begin command-name eos command1'),
            ffs(b'3 1 0 command-name have-data command3'),
            ffs(b'5 1 0 command-argument eoa ignored'),
        ]))
        self.assertaction(results[2], 'error')
        self.assertEqual(results[2][1], {
            'message': b'received frame for request that is not receiving: 5',
        })

    def testsimpleresponse(self):
        """Bytes response to command sends result frames."""
        reactor = makereactor()
        instream = framing.stream(1)
        list(sendcommandframes(reactor, instream, 1, b'mycommand', {}))

        outstream = framing.stream(2)
        result = reactor.onbytesresponseready(outstream, 1, b'response')
        self.assertaction(result, 'sendframes')
        self.assertframesequal(result[1]['framegen'], [
            b'1 2 stream-begin bytes-response eos response',
        ])

    def testmultiframeresponse(self):
        """Bytes response spanning multiple frames is handled."""
        first = b'x' * framing.DEFAULT_MAX_FRAME_SIZE
        second = b'y' * 100

        reactor = makereactor()
        instream = framing.stream(1)
        list(sendcommandframes(reactor, instream, 1, b'mycommand', {}))

        outstream = framing.stream(2)
        result = reactor.onbytesresponseready(outstream, 1, first + second)
        self.assertaction(result, 'sendframes')
        self.assertframesequal(result[1]['framegen'], [
            b'1 2 stream-begin bytes-response continuation %s' % first,
            b'1 2 0 bytes-response eos %s' % second,
        ])

    def testapplicationerror(self):
        reactor = makereactor()
        instream = framing.stream(1)
        list(sendcommandframes(reactor, instream, 1, b'mycommand', {}))

        outstream = framing.stream(2)
        result = reactor.onapplicationerror(outstream, 1, b'some message')
        self.assertaction(result, 'sendframes')
        self.assertframesequal(result[1]['framegen'], [
            b'1 2 stream-begin error-response application some message',
        ])

    def test1commanddeferresponse(self):
        """Responses when in deferred output mode are delayed until EOF."""
        reactor = makereactor(deferoutput=True)
        instream = framing.stream(1)
        results = list(sendcommandframes(reactor, instream, 1, b'mycommand',
                                         {}))
        self.assertEqual(len(results), 1)
        self.assertaction(results[0], 'runcommand')

        outstream = framing.stream(2)
        result = reactor.onbytesresponseready(outstream, 1, b'response')
        self.assertaction(result, 'noop')
        result = reactor.oninputeof()
        self.assertaction(result, 'sendframes')
        self.assertframesequal(result[1]['framegen'], [
            b'1 2 stream-begin bytes-response eos response',
        ])

    def testmultiplecommanddeferresponse(self):
        reactor = makereactor(deferoutput=True)
        instream = framing.stream(1)
        list(sendcommandframes(reactor, instream, 1, b'command1', {}))
        list(sendcommandframes(reactor, instream, 3, b'command2', {}))

        outstream = framing.stream(2)
        result = reactor.onbytesresponseready(outstream, 1, b'response1')
        self.assertaction(result, 'noop')
        result = reactor.onbytesresponseready(outstream, 3, b'response2')
        self.assertaction(result, 'noop')
        result = reactor.oninputeof()
        self.assertaction(result, 'sendframes')
        self.assertframesequal(result[1]['framegen'], [
            b'1 2 stream-begin bytes-response eos response1',
            b'3 2 0 bytes-response eos response2'
        ])

    def testrequestidtracking(self):
        reactor = makereactor(deferoutput=True)
        instream = framing.stream(1)
        list(sendcommandframes(reactor, instream, 1, b'command1', {}))
        list(sendcommandframes(reactor, instream, 3, b'command2', {}))
        list(sendcommandframes(reactor, instream, 5, b'command3', {}))

        # Register results for commands out of order.
        outstream = framing.stream(2)
        reactor.onbytesresponseready(outstream, 3, b'response3')
        reactor.onbytesresponseready(outstream, 1, b'response1')
        reactor.onbytesresponseready(outstream, 5, b'response5')

        result = reactor.oninputeof()
        self.assertaction(result, 'sendframes')
        self.assertframesequal(result[1]['framegen'], [
            b'3 2 stream-begin bytes-response eos response3',
            b'1 2 0 bytes-response eos response1',
            b'5 2 0 bytes-response eos response5',
        ])

    def testduplicaterequestonactivecommand(self):
        """Receiving a request ID that matches a request that isn't finished."""
        reactor = makereactor()
        stream = framing.stream(1)
        list(sendcommandframes(reactor, stream, 1, b'command1', {}))
        results = list(sendcommandframes(reactor, stream, 1, b'command1', {}))

        self.assertaction(results[0], 'error')
        self.assertEqual(results[0][1], {
            'message': b'request with ID 1 is already active',
        })

    def testduplicaterequestonactivecommandnosend(self):
        """Same as above but we've registered a response but haven't sent it."""
        reactor = makereactor()
        instream = framing.stream(1)
        list(sendcommandframes(reactor, instream, 1, b'command1', {}))
        outstream = framing.stream(2)
        reactor.onbytesresponseready(outstream, 1, b'response')

        # We've registered the response but haven't sent it. From the
        # perspective of the reactor, the command is still active.

        results = list(sendcommandframes(reactor, instream, 1, b'command1', {}))
        self.assertaction(results[0], 'error')
        self.assertEqual(results[0][1], {
            'message': b'request with ID 1 is already active',
        })

    def testduplicaterequestargumentframe(self):
        """Variant on above except we sent an argument frame instead of name."""
        reactor = makereactor()
        stream = framing.stream(1)
        list(sendcommandframes(reactor, stream, 1, b'command', {}))
        results = list(sendframes(reactor, [
            ffs(b'3 1 stream-begin command-name have-args command'),
            ffs(b'1 1 0 command-argument 0 ignored'),
        ]))
        self.assertaction(results[0], 'wantframe')
        self.assertaction(results[1], 'error')
        self.assertEqual(results[1][1], {
            'message': 'received frame for request that is still active: 1',
        })

    def testduplicaterequestaftersend(self):
        """We can use a duplicate request ID after we've sent the response."""
        reactor = makereactor()
        instream = framing.stream(1)
        list(sendcommandframes(reactor, instream, 1, b'command1', {}))
        outstream = framing.stream(2)
        res = reactor.onbytesresponseready(outstream, 1, b'response')
        list(res[1]['framegen'])

        results = list(sendcommandframes(reactor, instream, 1, b'command1', {}))
        self.assertaction(results[0], 'runcommand')

if __name__ == '__main__':
    import silenttestrunner
    silenttestrunner.main(__name__)