view tests/test-wireproto-clientreactor.py @ 44118:f81c17ec303c

hgdemandimport: apply lazy module loading to sys.meta_path finders

Python's `sys.meta_path` finders are the primary objects whose job it
is to find a module at import time. When `import` is called, Python
iterates objects in this list and calls `o.find_spec(...)` to find
a `ModuleSpec` (or None if the module couldn't be found by that
finder). If no meta path finder can find a module, import fails.

One of the default meta path finders is `PathFinder`. Its job is to
import modules from the filesystem and is probably the most important
importer. This finder looks at `sys.path` and `sys.path_hooks` to do
its job.

The `ModuleSpec` returned by `MetaPathImporter.find_spec()` has a
`loader` attribute, which defines the concrete module loader to use.
`sys.path_hooks` is a hook point for teaching `PathFinder` to
instantiate custom loader types.

Previously, we injected a custom `sys.path_hook` that told `PathFinder`
to wrap the default loaders with a loader that creates a module object
that is lazy.

This approach worked. But its main limitation was that it only applied
to the `PathFinder` meta path importer. There are other meta path
importers that are registered. And in the case of PyOxidizer loading
modules from memory, `PathFinder` doesn't come into play since
PyOxidizer's own meta path importer was handling all imports.

This commit changes our approach to lazy module loading by proxying
all meta path importers. Specifically, we overload the `find_spec()`
method to swap in a wrapped loader on the `ModuleSpec` before it
is returned. The end result of this is all meta path importers should
be lazy.

As much as I would have loved to utilize .__class__ manipulation to
achieve this, some meta path importers are implemented in C/Rust
in such a way that they cannot be monkeypatched. This is why we
use __getattribute__ to define a proxy.

Also, this change could theoretically open us up to regressions in
meta path importers whose loader is creating module objects which
can't be monkeypatched. But I'm not aware of any of these in the
wild. So I think we'll be safe.

According to hyperfine, this change yields a decent startup time win of
5-6ms:

```
Benchmark #1: ~/.pyenv/versions/3.6.10/bin/python ./hg version
  Time (mean ± σ):      86.8 ms ±   0.5 ms    [User: 78.0 ms, System: 8.7 ms]
  Range (min … max):    86.0 ms …  89.1 ms    50 runs

  Time (mean ± σ):      81.1 ms ±   2.7 ms    [User: 74.5 ms, System: 6.5 ms]
  Range (min … max):    77.8 ms …  90.5 ms    50 runs

Benchmark #2: ~/.pyenv/versions/3.7.6/bin/python ./hg version
  Time (mean ± σ):      78.9 ms ±   0.6 ms    [User: 70.2 ms, System: 8.7 ms]
  Range (min … max):    78.1 ms …  81.2 ms    50 runs

  Time (mean ± σ):      73.4 ms ±   0.6 ms    [User: 65.3 ms, System: 8.0 ms]
  Range (min … max):    72.4 ms …  75.7 ms    50 runs

Benchmark #3: ~/.pyenv/versions/3.8.1/bin/python ./hg version
  Time (mean ± σ):      78.1 ms ±   0.6 ms    [User: 70.2 ms, System: 7.9 ms]
  Range (min … max):    77.4 ms …  80.9 ms    50 runs

  Time (mean ± σ):      72.1 ms ±   0.4 ms    [User: 64.4 ms, System: 7.6 ms]
  Range (min … max):    71.4 ms …  74.1 ms    50 runs
```

Differential Revision: https://phab.mercurial-scm.org/D7954

from __future__ import absolute_import

import sys
import unittest
import zlib

from mercurial import (
    error,
    ui as uimod,
    wireprotoframing as framing,
)
from mercurial.utils import cborutil

try:
    from mercurial import zstd

    zstd.__version__
except ImportError:
    zstd = None

ffs = framing.makeframefromhumanstring

globalui = uimod.ui()


def sendframe(reactor, frame):
    """Send a frame bytearray to a reactor."""
    header = framing.parseheader(frame)
    payload = frame[framing.FRAME_HEADER_SIZE :]
    assert len(payload) == header.length

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


class SingleSendTests(unittest.TestCase):
    """A reactor that can only send once rejects subsequent sends."""

    if not getattr(unittest.TestCase, 'assertRaisesRegex', False):
        # Python 3.7 deprecates the regex*p* version, but 2.7 lacks
        # the regex version.
        assertRaisesRegex = (  # camelcase-required
            unittest.TestCase.assertRaisesRegexp
        )

    def testbasic(self):
        reactor = framing.clientreactor(
            globalui, hasmultiplesend=False, buffersends=True
        )

        request, action, meta = reactor.callcommand(b'foo', {})
        self.assertEqual(request.state, b'pending')
        self.assertEqual(action, b'noop')

        action, meta = reactor.flushcommands()
        self.assertEqual(action, b'sendframes')

        for frame in meta[b'framegen']:
            self.assertEqual(request.state, b'sending')

        self.assertEqual(request.state, b'sent')

        with self.assertRaisesRegex(
            error.ProgrammingError, 'cannot issue new commands'
        ):
            reactor.callcommand(b'foo', {})

        with self.assertRaisesRegex(
            error.ProgrammingError, 'cannot issue new commands'
        ):
            reactor.callcommand(b'foo', {})


class NoBufferTests(unittest.TestCase):
    """A reactor without send buffering sends requests immediately."""

    def testbasic(self):
        reactor = framing.clientreactor(
            globalui, hasmultiplesend=True, buffersends=False
        )

        request, action, meta = reactor.callcommand(b'command1', {})
        self.assertEqual(request.requestid, 1)
        self.assertEqual(action, b'sendframes')

        self.assertEqual(request.state, b'pending')

        for frame in meta[b'framegen']:
            self.assertEqual(request.state, b'sending')

        self.assertEqual(request.state, b'sent')

        action, meta = reactor.flushcommands()
        self.assertEqual(action, b'noop')

        # And we can send another command.
        request, action, meta = reactor.callcommand(b'command2', {})
        self.assertEqual(request.requestid, 3)
        self.assertEqual(action, b'sendframes')

        for frame in meta[b'framegen']:
            self.assertEqual(request.state, b'sending')

        self.assertEqual(request.state, b'sent')


class BadFrameRecvTests(unittest.TestCase):
    if not getattr(unittest.TestCase, 'assertRaisesRegex', False):
        # Python 3.7 deprecates the regex*p* version, but 2.7 lacks
        # the regex version.
        assertRaisesRegex = (  # camelcase-required
            unittest.TestCase.assertRaisesRegexp
        )

    def testoddstream(self):
        reactor = framing.clientreactor(globalui)

        action, meta = sendframe(reactor, ffs(b'1 1 0 1 0 foo'))
        self.assertEqual(action, b'error')
        self.assertEqual(
            meta[b'message'], b'received frame with odd numbered stream ID: 1'
        )

    def testunknownstream(self):
        reactor = framing.clientreactor(globalui)

        action, meta = sendframe(reactor, ffs(b'1 0 0 1 0 foo'))
        self.assertEqual(action, b'error')
        self.assertEqual(
            meta[b'message'],
            b'received frame on unknown stream without beginning '
            b'of stream flag set',
        )

    def testunhandledframetype(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for frame in meta[b'framegen']:
            pass

        with self.assertRaisesRegex(
            error.ProgrammingError, 'unhandled frame type'
        ):
            sendframe(reactor, ffs(b'1 0 stream-begin text-output 0 foo'))


class StreamTests(unittest.TestCase):
    def testmultipleresponseframes(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})

        self.assertEqual(action, b'sendframes')
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 0 stream-begin command-response 0 foo' % request.requestid
            ),
        )
        self.assertEqual(action, b'responsedata')

        action, meta = sendframe(
            reactor, ffs(b'%d 0 0 command-response eos bar' % request.requestid)
        )
        self.assertEqual(action, b'responsedata')


class RedirectTests(unittest.TestCase):
    def testredirect(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        redirect = {
            b'targets': [b'a', b'b'],
            b'hashes': [b'sha256'],
        }

        request, action, meta = reactor.callcommand(
            b'foo', {}, redirect=redirect
        )

        self.assertEqual(action, b'sendframes')

        frames = list(meta[b'framegen'])
        self.assertEqual(len(frames), 1)

        self.assertEqual(
            frames[0],
            ffs(
                b'1 1 stream-begin command-request new '
                b"cbor:{b'name': b'foo', "
                b"b'redirect': {b'targets': [b'a', b'b'], "
                b"b'hashes': [b'sha256']}}"
            ),
        )


class StreamSettingsTests(unittest.TestCase):
    def testnoflags(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor, ffs(b'1 2 stream-begin stream-settings 0 ')
        )

        self.assertEqual(action, b'error')
        self.assertEqual(
            meta,
            {
                b'message': b'stream encoding settings frame must have '
                b'continuation or end of stream flag set',
            },
        )

    def testconflictflags(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor, ffs(b'1 2 stream-begin stream-settings continuation|eos ')
        )

        self.assertEqual(action, b'error')
        self.assertEqual(
            meta,
            {
                b'message': b'stream encoding settings frame cannot have both '
                b'continuation and end of stream flags set',
            },
        )

    def testemptypayload(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor, ffs(b'1 2 stream-begin stream-settings eos ')
        )

        self.assertEqual(action, b'error')
        self.assertEqual(
            meta,
            {
                b'message': b'stream encoding settings frame did not contain '
                b'CBOR data'
            },
        )

    def testbadcbor(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor, ffs(b'1 2 stream-begin stream-settings eos badvalue')
        )

        self.assertEqual(action, b'error')

    def testsingleobject(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor,
            ffs(b'1 2 stream-begin stream-settings eos cbor:b"identity"'),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

    def testmultipleobjects(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        data = b''.join(
            [
                b''.join(cborutil.streamencode(b'identity')),
                b''.join(cborutil.streamencode({b'foo', b'bar'})),
            ]
        )

        action, meta = sendframe(
            reactor, ffs(b'1 2 stream-begin stream-settings eos %s' % data)
        )

        self.assertEqual(action, b'error')
        self.assertEqual(
            meta,
            {
                b'message': b'error setting stream decoder: identity decoder '
                b'received unexpected additional values',
            },
        )

    def testmultipleframes(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        data = b''.join(cborutil.streamencode(b'identity'))

        action, meta = sendframe(
            reactor,
            ffs(
                b'1 2 stream-begin stream-settings continuation %s' % data[0:3]
            ),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

        action, meta = sendframe(
            reactor, ffs(b'1 2 0 stream-settings eos %s' % data[3:])
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

    def testinvalidencoder(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor,
            ffs(b'1 2 stream-begin stream-settings eos cbor:b"badvalue"'),
        )

        self.assertEqual(action, b'error')
        self.assertEqual(
            meta,
            {
                b'message': b'error setting stream decoder: unknown stream '
                b'decoder: badvalue',
            },
        )

    def testzlibencoding(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 stream-begin stream-settings eos cbor:b"zlib"'
                % request.requestid
            ),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

        result = {
            b'status': b'ok',
        }
        encoded = b''.join(cborutil.streamencode(result))

        compressed = zlib.compress(encoded)
        self.assertEqual(zlib.decompress(compressed), encoded)

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response eos %s'
                % (request.requestid, compressed)
            ),
        )

        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], encoded)

    def testzlibencodingsinglebyteframes(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 stream-begin stream-settings eos cbor:b"zlib"'
                % request.requestid
            ),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

        result = {
            b'status': b'ok',
        }
        encoded = b''.join(cborutil.streamencode(result))

        compressed = zlib.compress(encoded)
        self.assertEqual(zlib.decompress(compressed), encoded)

        chunks = []

        for i in range(len(compressed)):
            char = compressed[i : i + 1]
            if char == b'\\':
                char = b'\\\\'
            action, meta = sendframe(
                reactor,
                ffs(
                    b'%d 2 encoded command-response continuation %s'
                    % (request.requestid, char)
                ),
            )

            self.assertEqual(action, b'responsedata')
            chunks.append(meta[b'data'])
            self.assertTrue(meta[b'expectmore'])
            self.assertFalse(meta[b'eos'])

        # zlib will have the full data decoded at this point, even though
        # we haven't flushed.
        self.assertEqual(b''.join(chunks), encoded)

        # End the stream for good measure.
        action, meta = sendframe(
            reactor,
            ffs(b'%d 2 stream-end command-response eos ' % request.requestid),
        )

        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], b'')
        self.assertFalse(meta[b'expectmore'])
        self.assertTrue(meta[b'eos'])

    def testzlibmultipleresponses(self):
        # We feed in zlib compressed data on the same stream but belonging to
        # 2 different requests. This tests our flushing behavior.
        reactor = framing.clientreactor(
            globalui, buffersends=False, hasmultiplesend=True
        )

        request1, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        request2, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        outstream = framing.outputstream(2)
        outstream.setencoder(globalui, b'zlib')

        response1 = b''.join(
            cborutil.streamencode(
                {b'status': b'ok', b'extra': b'response1' * 10,}
            )
        )

        response2 = b''.join(
            cborutil.streamencode(
                {b'status': b'error', b'extra': b'response2' * 10,}
            )
        )

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 stream-begin stream-settings eos cbor:b"zlib"'
                % request1.requestid
            ),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

        # Feeding partial data in won't get anything useful out.
        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response continuation %s'
                % (request1.requestid, outstream.encode(response1))
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], b'')

        # But flushing data at both ends will get our original data.
        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response eos %s'
                % (request1.requestid, outstream.flush())
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], response1)

        # We should be able to reuse the compressor/decompressor for the
        # 2nd response.
        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response continuation %s'
                % (request2.requestid, outstream.encode(response2))
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], b'')

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response eos %s'
                % (request2.requestid, outstream.flush())
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], response2)

    @unittest.skipUnless(zstd, 'zstd not available')
    def testzstd8mbencoding(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 stream-begin stream-settings eos cbor:b"zstd-8mb"'
                % request.requestid
            ),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

        result = {
            b'status': b'ok',
        }
        encoded = b''.join(cborutil.streamencode(result))

        encoder = framing.zstd8mbencoder(globalui)
        compressed = encoder.encode(encoded) + encoder.finish()
        self.assertEqual(
            zstd.ZstdDecompressor().decompress(
                compressed, max_output_size=len(encoded)
            ),
            encoded,
        )

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response eos %s'
                % (request.requestid, compressed)
            ),
        )

        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], encoded)

    @unittest.skipUnless(zstd, 'zstd not available')
    def testzstd8mbencodingsinglebyteframes(self):
        reactor = framing.clientreactor(globalui, buffersends=False)

        request, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 stream-begin stream-settings eos cbor:b"zstd-8mb"'
                % request.requestid
            ),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

        result = {
            b'status': b'ok',
        }
        encoded = b''.join(cborutil.streamencode(result))

        compressed = zstd.ZstdCompressor().compress(encoded)
        self.assertEqual(
            zstd.ZstdDecompressor().decompress(compressed), encoded
        )

        chunks = []

        for i in range(len(compressed)):
            char = compressed[i : i + 1]
            if char == b'\\':
                char = b'\\\\'
            action, meta = sendframe(
                reactor,
                ffs(
                    b'%d 2 encoded command-response continuation %s'
                    % (request.requestid, char)
                ),
            )

            self.assertEqual(action, b'responsedata')
            chunks.append(meta[b'data'])
            self.assertTrue(meta[b'expectmore'])
            self.assertFalse(meta[b'eos'])

        # zstd decompressor will flush at frame boundaries.
        self.assertEqual(b''.join(chunks), encoded)

        # End the stream for good measure.
        action, meta = sendframe(
            reactor,
            ffs(b'%d 2 stream-end command-response eos ' % request.requestid),
        )

        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], b'')
        self.assertFalse(meta[b'expectmore'])
        self.assertTrue(meta[b'eos'])

    @unittest.skipUnless(zstd, 'zstd not available')
    def testzstd8mbmultipleresponses(self):
        # We feed in zstd compressed data on the same stream but belonging to
        # 2 different requests. This tests our flushing behavior.
        reactor = framing.clientreactor(
            globalui, buffersends=False, hasmultiplesend=True
        )

        request1, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        request2, action, meta = reactor.callcommand(b'foo', {})
        for f in meta[b'framegen']:
            pass

        outstream = framing.outputstream(2)
        outstream.setencoder(globalui, b'zstd-8mb')

        response1 = b''.join(
            cborutil.streamencode(
                {b'status': b'ok', b'extra': b'response1' * 10,}
            )
        )

        response2 = b''.join(
            cborutil.streamencode(
                {b'status': b'error', b'extra': b'response2' * 10,}
            )
        )

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 stream-begin stream-settings eos cbor:b"zstd-8mb"'
                % request1.requestid
            ),
        )

        self.assertEqual(action, b'noop')
        self.assertEqual(meta, {})

        # Feeding partial data in won't get anything useful out.
        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response continuation %s'
                % (request1.requestid, outstream.encode(response1))
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], b'')

        # But flushing data at both ends will get our original data.
        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response eos %s'
                % (request1.requestid, outstream.flush())
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], response1)

        # We should be able to reuse the compressor/decompressor for the
        # 2nd response.
        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response continuation %s'
                % (request2.requestid, outstream.encode(response2))
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], b'')

        action, meta = sendframe(
            reactor,
            ffs(
                b'%d 2 encoded command-response eos %s'
                % (request2.requestid, outstream.flush())
            ),
        )
        self.assertEqual(action, b'responsedata')
        self.assertEqual(meta[b'data'], response2)


if __name__ == '__main__':
    if (3, 6, 0) <= sys.version_info < (3, 6, 4):
        # Python 3.6.0 through 3.6.3 inclusive shipped with
        # https://bugs.python.org/issue31825 and we can't run these
        # tests on those specific versions of Python. Sigh.
        sys.exit(80)
    import silenttestrunner

    silenttestrunner.main(__name__)