view tests/test-wireproto-serverreactor.py @ 40326:fed697fa1734

sqlitestore: file storage backend using SQLite

This commit provides an extension which uses SQLite to store file
data (as opposed to revlogs).

As the inline documentation describes, there are still several
aspects to the extension that are incomplete. But it's a start.
The extension does support basic clone, checkout, and commit
workflows, which makes it suitable for simple use cases.

One notable missing feature is support for "bundlerepos." This is
probably responsible for the most test failures when the extension
is activated as part of the test suite.

All revision data is stored in SQLite. Data is stored as zstd
compressed chunks (default if zstd is available), zlib compressed
chunks (default if zstd is not available), or raw chunks (if
configured or if a compressed delta is not smaller than the raw
delta). This makes things very similar to revlogs.

Unlike revlogs, the extension doesn't yet enforce a limit on delta
chain length. This is an obvious limitation and should be addressed.
This is somewhat mitigated by the use of zstd, which is much faster
than zlib to decompress.

There is a dedicated table for storing deltas. Deltas are stored
by the SHA-1 hash of their uncompressed content. The "fileindex" table
has columns that reference the delta for each revision and the base
delta that delta should be applied against. A recursive SQL query
is used to resolve the delta chain along with the delta data.

By storing deltas by hash, we are able to de-duplicate delta storage!
With revlogs, the same deltas in different revlogs would result in
duplicate storage of that delta. In this scheme, inserting the
duplicate delta is a no-op and delta chains simply reference the
existing delta.

When initially implementing this extension, I did not have
content-indexed deltas and deltas could be duplicated across files
(just like revlogs). When I implemented content-indexed deltas, the
size of the SQLite database for a full clone of mozilla-unified
dropped:

before: 2,554,261,504 bytes
after:  2,488,754,176 bytes

Surprisingly, this is still larger than the bytes size of revlog
files:

revlog files: 2,104,861,230 bytes
du -b:        2,254,381,614

I would have expected storage to be smaller since we're not limiting
delta chain length and since we're using zstd instead of zlib. I
suspect the SQLite indexes and per-column overhead account for the
bulk of the differences. (Keep in mind that revlog uses a 64-byte
packed struct for revision index data and deltas are stored without
padding. Aside from the 12 unused bytes in the 32 byte node field,
revlogs are pretty efficient.) Another source of overhead is file
name storage. With revlogs, file names are stored in the filesystem.
But with SQLite, we need to store file names in the database. This is
roughly equivalent to the size of the fncache file, which for the
mozilla-unified repository is ~34MB.

Since the SQLite database isn't append-only and since delta chains
can reference any delta, this opens some interesting possibilities.
For example, we could store deltas in reverse, such that fulltexts
are stored for newer revisions and deltas are applied to reconstruct
older revisions. This is likely a more optimal storage strategy for
version control, as new data tends to be more frequently accessed
than old data. We would obviously need wire protocol support for
transferring revision data from newest to oldest. And we would
probably need some kind of mechanism for "re-encoding" stores. But
it should be doable.

This extension is very much experimental quality. There are a handful
of features that don't work. It probably isn't suitable for day-to-day
use. But it could be used in limited cases (e.g. read-only checkouts
like in CI). And it is also a good proving ground for alternate
storage backends. As we continue to define interfaces for all things
storage, it will be useful to have a viable alternate storage backend
to see how things shake out in practice.

test-storage.py passes on Python 2 and introduces no new test failures on
Python 3. Having the storage-level unit tests has proved to be insanely
useful when developing this extension. Those tests caught numerous bugs
during development and I'm convinced this style of testing is the way
forward for ensuring alternate storage backends work as intended. Of
course, test coverage isn't close to what it needs to be. But it is
a start. And what coverage we have gives me confidence that basic store
functionality is implemented properly.

Differential Revision: https://phab.mercurial-scm.org/D4928

from __future__ import absolute_import, print_function

import unittest

from mercurial.thirdparty import (
    cbor,
)
from mercurial import (
    ui as uimod,
    util,
    wireprotoframing as framing,
)
from mercurial.utils import (
    cborutil,
)

ffs = framing.makeframefromhumanstring

OK = cbor.dumps({b'status': b'ok'})

def makereactor(deferoutput=False):
    ui = uimod.ui()
    return framing.serverreactor(ui, 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 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], b'runcommand')
        self.assertEqual(results[0][1], {
            b'requestid': 1,
            b'command': b'mycommand',
            b'args': {},
            b'redirect': None,
            b'data': None,
        })

        result = reactor.oninputeof()
        self.assertaction(result, b'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), 1)
        self.assertaction(results[0], b'runcommand')
        self.assertEqual(results[0][1], {
            b'requestid': 41,
            b'command': b'mycommand',
            b'args': {b'foo': b'bar'},
            b'redirect': None,
            b'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), 1)
        self.assertaction(results[0], b'runcommand')
        self.assertEqual(results[0][1], {
            b'requestid': 1,
            b'command': b'mycommand',
            b'args': {b'foo': b'bar', b'biz': b'baz'},
            b'redirect': None,
            b'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], b'wantframe')
        self.assertaction(results[1], b'runcommand')
        self.assertEqual(results[1][1], {
            b'requestid': 1,
            b'command': b'mycommand',
            b'args': {},
            b'redirect': None,
            b'data': b'data!',
        })

    def testmultipledataframes(self):
        frames = [
            ffs(b'1 1 stream-begin command-request new|have-data '
                b"cbor:{b'name': b'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], b'wantframe')
        self.assertaction(results[3], b'runcommand')
        self.assertEqual(results[3][1], {
            b'requestid': 1,
            b'command': b'mycommand',
            b'args': {},
            b'redirect': None,
            b'data': b'data1data2data3',
        })

    def testargumentanddata(self):
        frames = [
            ffs(b'1 1 stream-begin command-request new|have-data '
                b"cbor:{b'name': b'command', b'args': {b'key': b'val',"
                b"b'foo': b'bar'}}"),
            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], b'runcommand')
        self.assertEqual(results[-1][1], {
            b'requestid': 1,
            b'command': b'command',
            b'args': {
                b'key': b'val',
                b'foo': b'bar',
            },
            b'redirect': None,
            b'data': b'value1value2',
        })

    def testnewandcontinuation(self):
        result = self._sendsingleframe(makereactor(),
            ffs(b'1 1 stream-begin command-request new|continuation '))
        self.assertaction(result, b'error')
        self.assertEqual(result[1], {
            b'message': b'received command request frame with both new and '
                        b'continuation flags set',
        })

    def testneithernewnorcontinuation(self):
        result = self._sendsingleframe(makereactor(),
            ffs(b'1 1 stream-begin command-request 0 '))
        self.assertaction(result, b'error')
        self.assertEqual(result[1], {
            b'message': b'received command request frame with neither new nor '
                        b'continuation flags set',
        })

    def testunexpectedcommanddata(self):
        """Command data 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, b'error')
        self.assertEqual(result[1], {
            b'message': b'expected sender protocol settings or command request '
                        b'frame; got 2',
        })

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

        self.assertaction(results[0], b'wantframe')
        self.assertaction(results[1], b'error')
        self.assertEqual(results[1][1], {
            b'message': b'received command data frame for request that is not '
                        b'expecting data: 1',
        })

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

        for i in range(3):
            self.assertaction(results[i], b'runcommand')
            self.assertEqual(results[i][1], {
                b'requestid': 1,
                b'command': b'command',
                b'args': {},
                b'redirect': None,
                b'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-request new|more '
                b"cbor:{b'name': b'command'}"),
            ffs(b'1 1 0 command-request new '
                b"cbor:{b'name': b'command1'}"),
        ]))

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

    def testinterleavedcommands(self):
        cbor1 = cbor.dumps({
            b'name': b'command1',
            b'args': {
                b'foo': b'bar',
                b'key1': b'val',
            }
        }, canonical=True)
        cbor3 = cbor.dumps({
            b'name': b'command3',
            b'args': {
                b'biz': b'baz',
                b'key': b'val',
            },
        }, canonical=True)

        results = list(sendframes(makereactor(), [
            ffs(b'1 1 stream-begin command-request new|more %s' % cbor1[0:6]),
            ffs(b'3 1 0 command-request new|more %s' % cbor3[0:10]),
            ffs(b'1 1 0 command-request continuation|more %s' % cbor1[6:9]),
            ffs(b'3 1 0 command-request continuation|more %s' % cbor3[10:13]),
            ffs(b'3 1 0 command-request continuation %s' % cbor3[13:]),
            ffs(b'1 1 0 command-request continuation %s' % cbor1[9:]),
        ]))

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

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

    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-request new|have-data '
                b"cbor:{b'name': b'command1'}"),
            ffs(b'3 1 0 command-request new '
                b"cbor:{b'name': b'command2'}"),
        ]
        results = list(sendframes(makereactor(), frames))
        self.assertEqual(len(results), 2)
        self.assertaction(results[0], b'wantframe')
        self.assertaction(results[1], b'runcommand')

    def testmissingcommanddataframeflags(self):
        frames = [
            ffs(b'1 1 stream-begin command-request new|have-data '
                b"cbor:{b'name': b'command1'}"),
            ffs(b'1 1 0 command-data 0 data'),
        ]
        results = list(sendframes(makereactor(), frames))
        self.assertEqual(len(results), 2)
        self.assertaction(results[0], b'wantframe')
        self.assertaction(results[1], b'error')
        self.assertEqual(results[1][1], {
            b'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-request new '
                b"cbor:{b'name': b'command1'}"),
            ffs(b'3 1 0 command-request new|have-data '
                b"cbor:{b'name': b'command3'}"),
            ffs(b'5 1 0 command-data eos ignored'),
        ]))
        self.assertaction(results[2], b'error')
        self.assertEqual(results[2][1], {
            b'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 = reactor.makeoutputstream()
        result = reactor.oncommandresponsereadyobjects(
            outstream, 1, [b'response'])
        self.assertaction(result, b'sendframes')
        self.assertframesequal(result[1][b'framegen'], [
            b'1 2 stream-begin stream-settings eos cbor:b"identity"',
            b'1 2 encoded command-response continuation %s' % OK,
            b'1 2 encoded command-response continuation cbor:b"response"',
            b'1 2 0 command-response eos ',
        ])

    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 = reactor.makeoutputstream()
        result = reactor.oncommandresponsereadyobjects(
            outstream, 1, [first + second])
        self.assertaction(result, b'sendframes')
        self.assertframesequal(result[1][b'framegen'], [
            b'1 2 stream-begin stream-settings eos cbor:b"identity"',
            b'1 2 encoded command-response continuation %s' % OK,
            b'1 2 encoded command-response continuation Y\x80d',
            b'1 2 encoded command-response continuation %s' % first,
            b'1 2 encoded command-response continuation %s' % second,
            b'1 2 0 command-response eos '
        ])

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

        outstream = reactor.makeoutputstream()
        result = reactor.onservererror(outstream, 1, b'some message')
        self.assertaction(result, b'sendframes')
        self.assertframesequal(result[1][b'framegen'], [
            b"1 2 stream-begin error-response 0 "
            b"cbor:{b'type': b'server', "
            b"b'message': [{b'msg': b'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], b'runcommand')

        outstream = reactor.makeoutputstream()
        result = reactor.oncommandresponsereadyobjects(
            outstream, 1, [b'response'])
        self.assertaction(result, b'noop')
        result = reactor.oninputeof()
        self.assertaction(result, b'sendframes')
        self.assertframesequal(result[1][b'framegen'], [
            b'1 2 stream-begin stream-settings eos cbor:b"identity"',
            b'1 2 encoded command-response continuation %s' % OK,
            b'1 2 encoded command-response continuation cbor:b"response"',
            b'1 2 0 command-response eos ',
        ])

    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 = reactor.makeoutputstream()
        result = reactor.oncommandresponsereadyobjects(
            outstream, 1, [b'response1'])
        self.assertaction(result, b'noop')
        result = reactor.oncommandresponsereadyobjects(
            outstream, 3, [b'response2'])
        self.assertaction(result, b'noop')
        result = reactor.oninputeof()
        self.assertaction(result, b'sendframes')
        self.assertframesequal(result[1][b'framegen'], [
            b'1 2 stream-begin stream-settings eos cbor:b"identity"',
            b'1 2 encoded command-response continuation %s' % OK,
            b'1 2 encoded command-response continuation cbor:b"response1"',
            b'1 2 0 command-response eos ',
            b'3 2 encoded command-response continuation %s' % OK,
            b'3 2 encoded command-response continuation cbor:b"response2"',
            b'3 2 0 command-response eos ',
        ])

    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 = reactor.makeoutputstream()
        reactor.oncommandresponsereadyobjects(outstream, 3, [b'response3'])
        reactor.oncommandresponsereadyobjects(outstream, 1, [b'response1'])
        reactor.oncommandresponsereadyobjects(outstream, 5, [b'response5'])

        result = reactor.oninputeof()
        self.assertaction(result, b'sendframes')
        self.assertframesequal(result[1][b'framegen'], [
            b'3 2 stream-begin stream-settings eos cbor:b"identity"',
            b'3 2 encoded command-response continuation %s' % OK,
            b'3 2 encoded command-response continuation cbor:b"response3"',
            b'3 2 0 command-response eos ',
            b'1 2 encoded command-response continuation %s' % OK,
            b'1 2 encoded command-response continuation cbor:b"response1"',
            b'1 2 0 command-response eos ',
            b'5 2 encoded command-response continuation %s' % OK,
            b'5 2 encoded command-response continuation cbor:b"response5"',
            b'5 2 0 command-response eos ',
        ])

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

    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 = reactor.makeoutputstream()
        res = reactor.oncommandresponsereadyobjects(outstream, 1, [b'response'])
        list(res[1][b'framegen'])

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

    def testprotocolsettingsnoflags(self):
        result = self._sendsingleframe(
            makereactor(),
            ffs(b'0 1 stream-begin sender-protocol-settings 0 '))
        self.assertaction(result, b'error')
        self.assertEqual(result[1], {
            b'message': b'sender protocol settings frame must have '
                        b'continuation or end of stream flag set',
        })

    def testprotocolsettingsconflictflags(self):
        result = self._sendsingleframe(
            makereactor(),
            ffs(b'0 1 stream-begin sender-protocol-settings continuation|eos '))
        self.assertaction(result, b'error')
        self.assertEqual(result[1], {
            b'message': b'sender protocol settings frame cannot have both '
                        b'continuation and end of stream flags set',
        })

    def testprotocolsettingsemptypayload(self):
        result = self._sendsingleframe(
            makereactor(),
            ffs(b'0 1 stream-begin sender-protocol-settings eos '))
        self.assertaction(result, b'error')
        self.assertEqual(result[1], {
            b'message': b'sender protocol settings frame did not contain CBOR '
                        b'data',
        })

    def testprotocolsettingsmultipleobjects(self):
        result = self._sendsingleframe(
            makereactor(),
            ffs(b'0 1 stream-begin sender-protocol-settings eos '
                b'\x46foobar\x43foo'))
        self.assertaction(result, b'error')
        self.assertEqual(result[1], {
            b'message': b'sender protocol settings frame contained multiple '
                        b'CBOR values',
        })

    def testprotocolsettingscontentencodings(self):
        reactor = makereactor()

        result = self._sendsingleframe(
            reactor,
            ffs(b'0 1 stream-begin sender-protocol-settings eos '
                b'cbor:{b"contentencodings": [b"a", b"b"]}'))
        self.assertaction(result, b'wantframe')

        self.assertEqual(reactor._state, b'idle')
        self.assertEqual(reactor._sendersettings[b'contentencodings'],
                         [b'a', b'b'])

    def testprotocolsettingsmultipleframes(self):
        reactor = makereactor()

        data = b''.join(cborutil.streamencode({
            b'contentencodings': [b'value1', b'value2'],
        }))

        results = list(sendframes(reactor, [
            ffs(b'0 1 stream-begin sender-protocol-settings continuation %s' %
                data[0:5]),
            ffs(b'0 1 0 sender-protocol-settings eos %s' % data[5:]),
        ]))

        self.assertEqual(len(results), 2)

        self.assertaction(results[0], b'wantframe')
        self.assertaction(results[1], b'wantframe')

        self.assertEqual(reactor._state, b'idle')
        self.assertEqual(reactor._sendersettings[b'contentencodings'],
                         [b'value1', b'value2'])

    def testprotocolsettingsbadcbor(self):
        result = self._sendsingleframe(
            makereactor(),
            ffs(b'0 1 stream-begin sender-protocol-settings eos badvalue'))
        self.assertaction(result, b'error')

    def testprotocolsettingsnoninitial(self):
        # Cannot have protocol settings frames as non-initial frames.
        reactor = makereactor()

        stream = framing.stream(1)
        results = list(sendcommandframes(reactor, stream, 1, b'mycommand', {}))
        self.assertEqual(len(results), 1)
        self.assertaction(results[0], b'runcommand')

        result = self._sendsingleframe(
            reactor,
            ffs(b'0 1 0 sender-protocol-settings eos '))
        self.assertaction(result, b'error')
        self.assertEqual(result[1], {
            b'message': b'expected command request frame; got 8',
        })

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