cpython/Lib/test/test_selectors.py

import errno
import os
import random
import selectors
import signal
import socket
import sys
from test import support
from time import sleep
import unittest
import unittest.mock
import tempfile
from time import monotonic as time
try:
    import resource
except ImportError:
    resource = None


if hasattr(socket, 'socketpair'):
    socketpair = socket.socketpair
else:
    def socketpair(family=socket.AF_INET, type=socket.SOCK_STREAM, proto=0):
        with socket.socket(family, type, proto) as l:
            l.bind((support.HOST, 0))
            l.listen()
            c = socket.socket(family, type, proto)
            try:
                c.connect(l.getsockname())
                caddr = c.getsockname()
                while True:
                    a, addr = l.accept()
                    # check that we've got the correct client
                    if addr == caddr:
                        return c, a
                    a.close()
            except OSError:
                c.close()
                raise


def find_ready_matching(ready, flag):
    match = []
    for key, events in ready:
        if events & flag:
            match.append(key.fileobj)
    return match


class BaseSelectorTestCase(unittest.TestCase):

    def make_socketpair(self):
        rd, wr = socketpair()
        self.addCleanup(rd.close)
        self.addCleanup(wr.close)
        return rd, wr

    def test_register(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        key = s.register(rd, selectors.EVENT_READ, "data")
        self.assertIsInstance(key, selectors.SelectorKey)
        self.assertEqual(key.fileobj, rd)
        self.assertEqual(key.fd, rd.fileno())
        self.assertEqual(key.events, selectors.EVENT_READ)
        self.assertEqual(key.data, "data")

        # register an unknown event
        self.assertRaises(ValueError, s.register, 0, 999999)

        # register an invalid FD
        self.assertRaises(ValueError, s.register, -10, selectors.EVENT_READ)

        # register twice
        self.assertRaises(KeyError, s.register, rd, selectors.EVENT_READ)

        # register the same FD, but with a different object
        self.assertRaises(KeyError, s.register, rd.fileno(),
                          selectors.EVENT_READ)

    def test_unregister(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        s.register(rd, selectors.EVENT_READ)
        s.unregister(rd)

        # unregister an unknown file obj
        self.assertRaises(KeyError, s.unregister, 999999)

        # unregister twice
        self.assertRaises(KeyError, s.unregister, rd)

    def test_unregister_after_fd_close(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)
        rd, wr = self.make_socketpair()
        r, w = rd.fileno(), wr.fileno()
        s.register(r, selectors.EVENT_READ)
        s.register(w, selectors.EVENT_WRITE)
        rd.close()
        wr.close()
        s.unregister(r)
        s.unregister(w)

    @unittest.skipUnless(os.name == 'posix', "requires posix")
    def test_unregister_after_fd_close_and_reuse(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)
        rd, wr = self.make_socketpair()
        r, w = rd.fileno(), wr.fileno()
        s.register(r, selectors.EVENT_READ)
        s.register(w, selectors.EVENT_WRITE)
        rd2, wr2 = self.make_socketpair()
        rd.close()
        wr.close()
        os.dup2(rd2.fileno(), r)
        os.dup2(wr2.fileno(), w)
        self.addCleanup(os.close, r)
        self.addCleanup(os.close, w)
        s.unregister(r)
        s.unregister(w)

    def test_unregister_after_socket_close(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)
        rd, wr = self.make_socketpair()
        s.register(rd, selectors.EVENT_READ)
        s.register(wr, selectors.EVENT_WRITE)
        rd.close()
        wr.close()
        s.unregister(rd)
        s.unregister(wr)

    def test_modify(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        key = s.register(rd, selectors.EVENT_READ)

        # modify events
        key2 = s.modify(rd, selectors.EVENT_WRITE)
        self.assertNotEqual(key.events, key2.events)
        self.assertEqual(key2, s.get_key(rd))

        s.unregister(rd)

        # modify data
        d1 = object()
        d2 = object()

        key = s.register(rd, selectors.EVENT_READ, d1)
        key2 = s.modify(rd, selectors.EVENT_READ, d2)
        self.assertEqual(key.events, key2.events)
        self.assertNotEqual(key.data, key2.data)
        self.assertEqual(key2, s.get_key(rd))
        self.assertEqual(key2.data, d2)

        # modify unknown file obj
        self.assertRaises(KeyError, s.modify, 999999, selectors.EVENT_READ)

        # modify use a shortcut
        d3 = object()
        s.register = unittest.mock.Mock()
        s.unregister = unittest.mock.Mock()

        s.modify(rd, selectors.EVENT_READ, d3)
        self.assertFalse(s.register.called)
        self.assertFalse(s.unregister.called)

    def test_modify_unregister(self):
        # Make sure the fd is unregister()ed in case of error on
        # modify(): http://bugs.python.org/issue30014
        if self.SELECTOR.__name__ == 'EpollSelector':
            patch = unittest.mock.patch(
                'selectors.EpollSelector._selector_cls')
        elif self.SELECTOR.__name__ == 'PollSelector':
            patch = unittest.mock.patch(
                'selectors.PollSelector._selector_cls')
        elif self.SELECTOR.__name__ == 'DevpollSelector':
            patch = unittest.mock.patch(
                'selectors.DevpollSelector._selector_cls')
        else:
            raise self.skipTest("")

        with patch as m:
            m.return_value.modify = unittest.mock.Mock(
                side_effect=ZeroDivisionError)
            s = self.SELECTOR()
            self.addCleanup(s.close)
            rd, wr = self.make_socketpair()
            s.register(rd, selectors.EVENT_READ)
            self.assertEqual(len(s._map), 1)
            with self.assertRaises(ZeroDivisionError):
                s.modify(rd, selectors.EVENT_WRITE)
            self.assertEqual(len(s._map), 0)

    def test_close(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        mapping = s.get_map()
        rd, wr = self.make_socketpair()

        s.register(rd, selectors.EVENT_READ)
        s.register(wr, selectors.EVENT_WRITE)

        s.close()
        self.assertRaises(RuntimeError, s.get_key, rd)
        self.assertRaises(RuntimeError, s.get_key, wr)
        self.assertRaises(KeyError, mapping.__getitem__, rd)
        self.assertRaises(KeyError, mapping.__getitem__, wr)

    def test_get_key(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        key = s.register(rd, selectors.EVENT_READ, "data")
        self.assertEqual(key, s.get_key(rd))

        # unknown file obj
        self.assertRaises(KeyError, s.get_key, 999999)

    def test_get_map(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        keys = s.get_map()
        self.assertFalse(keys)
        self.assertEqual(len(keys), 0)
        self.assertEqual(list(keys), [])
        key = s.register(rd, selectors.EVENT_READ, "data")
        self.assertIn(rd, keys)
        self.assertEqual(key, keys[rd])
        self.assertEqual(len(keys), 1)
        self.assertEqual(list(keys), [rd.fileno()])
        self.assertEqual(list(keys.values()), [key])

        # unknown file obj
        with self.assertRaises(KeyError):
            keys[999999]

        # Read-only mapping
        with self.assertRaises(TypeError):
            del keys[rd]

    def test_select(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        s.register(rd, selectors.EVENT_READ)
        wr_key = s.register(wr, selectors.EVENT_WRITE)

        result = s.select()
        for key, events in result:
            self.assertTrue(isinstance(key, selectors.SelectorKey))
            self.assertTrue(events)
            self.assertFalse(events & ~(selectors.EVENT_READ |
                                        selectors.EVENT_WRITE))

        self.assertEqual([(wr_key, selectors.EVENT_WRITE)], result)

    def test_context_manager(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        with s as sel:
            sel.register(rd, selectors.EVENT_READ)
            sel.register(wr, selectors.EVENT_WRITE)

        self.assertRaises(RuntimeError, s.get_key, rd)
        self.assertRaises(RuntimeError, s.get_key, wr)

    def test_fileno(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        if hasattr(s, 'fileno'):
            fd = s.fileno()
            self.assertTrue(isinstance(fd, int))
            self.assertGreaterEqual(fd, 0)

    def test_selector(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        NUM_SOCKETS = 12
        MSG = b" This is a test."
        MSG_LEN = len(MSG)
        readers = []
        writers = []
        r2w = {}
        w2r = {}

        for i in range(NUM_SOCKETS):
            rd, wr = self.make_socketpair()
            s.register(rd, selectors.EVENT_READ)
            s.register(wr, selectors.EVENT_WRITE)
            readers.append(rd)
            writers.append(wr)
            r2w[rd] = wr
            w2r[wr] = rd

        bufs = []

        while writers:
            ready = s.select()
            ready_writers = find_ready_matching(ready, selectors.EVENT_WRITE)
            if not ready_writers:
                self.fail("no sockets ready for writing")
            wr = random.choice(ready_writers)
            wr.send(MSG)

            for i in range(10):
                ready = s.select()
                ready_readers = find_ready_matching(ready,
                                                    selectors.EVENT_READ)
                if ready_readers:
                    break
                # there might be a delay between the write to the write end and
                # the read end is reported ready
                sleep(0.1)
            else:
                self.fail("no sockets ready for reading")
            self.assertEqual([w2r[wr]], ready_readers)
            rd = ready_readers[0]
            buf = rd.recv(MSG_LEN)
            self.assertEqual(len(buf), MSG_LEN)
            bufs.append(buf)
            s.unregister(r2w[rd])
            s.unregister(rd)
            writers.remove(r2w[rd])

        self.assertEqual(bufs, [MSG] * NUM_SOCKETS)

    @unittest.skipIf(sys.platform == 'win32',
                     'select.select() cannot be used with empty fd sets')
    def test_empty_select(self):
        # Issue #23009: Make sure EpollSelector.select() works when no FD is
        # registered.
        s = self.SELECTOR()
        self.addCleanup(s.close)
        self.assertEqual(s.select(timeout=0), [])

    def test_timeout(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        s.register(wr, selectors.EVENT_WRITE)
        t = time()
        self.assertEqual(1, len(s.select(0)))
        self.assertEqual(1, len(s.select(-1)))
        self.assertLess(time() - t, 0.5)

        s.unregister(wr)
        s.register(rd, selectors.EVENT_READ)
        t = time()
        self.assertFalse(s.select(0))
        self.assertFalse(s.select(-1))
        self.assertLess(time() - t, 0.5)

        t0 = time()
        self.assertFalse(s.select(1))
        t1 = time()
        dt = t1 - t0
        # Tolerate 2.0 seconds for very slow buildbots
        self.assertTrue(0.8 <= dt <= 2.0, dt)

    @unittest.skipUnless(hasattr(signal, "alarm"),
                         "signal.alarm() required for this test")
    def test_select_interrupt_exc(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        class InterruptSelect(Exception):
            pass

        def handler(*args):
            raise InterruptSelect

        orig_alrm_handler = signal.signal(signal.SIGALRM, handler)
        self.addCleanup(signal.signal, signal.SIGALRM, orig_alrm_handler)

        try:
            signal.alarm(1)

            s.register(rd, selectors.EVENT_READ)
            t = time()
            # select() is interrupted by a signal which raises an exception
            with self.assertRaises(InterruptSelect):
                s.select(30)
            # select() was interrupted before the timeout of 30 seconds
            self.assertLess(time() - t, 5.0)
        finally:
            signal.alarm(0)

    @unittest.skipUnless(hasattr(signal, "alarm"),
                         "signal.alarm() required for this test")
    def test_select_interrupt_noraise(self):
        s = self.SELECTOR()
        self.addCleanup(s.close)

        rd, wr = self.make_socketpair()

        orig_alrm_handler = signal.signal(signal.SIGALRM, lambda *args: None)
        self.addCleanup(signal.signal, signal.SIGALRM, orig_alrm_handler)

        try:
            signal.alarm(1)

            s.register(rd, selectors.EVENT_READ)
            t = time()
            # select() is interrupted by a signal, but the signal handler doesn't
            # raise an exception, so select() should by retries with a recomputed
            # timeout
            self.assertFalse(s.select(1.5))
            self.assertGreaterEqual(time() - t, 1.0)
        finally:
            signal.alarm(0)


class ScalableSelectorMixIn:

    # see issue #18963 for why it's skipped on older OS X versions
    @support.requires_mac_ver(10, 5)
    @unittest.skipUnless(resource, "Test needs resource module")
    def test_above_fd_setsize(self):
        # A scalable implementation should have no problem with more than
        # FD_SETSIZE file descriptors. Since we don't know the value, we just
        # try to set the soft RLIMIT_NOFILE to the hard RLIMIT_NOFILE ceiling.
        soft, hard = resource.getrlimit(resource.RLIMIT_NOFILE)
        try:
            resource.setrlimit(resource.RLIMIT_NOFILE, (hard, hard))
            self.addCleanup(resource.setrlimit, resource.RLIMIT_NOFILE,
                            (soft, hard))
            NUM_FDS = min(hard, 2**16)
        except (OSError, ValueError):
            NUM_FDS = soft

        # guard for already allocated FDs (stdin, stdout...)
        NUM_FDS -= 32

        s = self.SELECTOR()
        self.addCleanup(s.close)

        for i in range(NUM_FDS // 2):
            try:
                rd, wr = self.make_socketpair()
            except OSError:
                # too many FDs, skip - note that we should only catch EMFILE
                # here, but apparently *BSD and Solaris can fail upon connect()
                # or bind() with EADDRNOTAVAIL, so let's be safe
                self.skipTest("FD limit reached")

            try:
                s.register(rd, selectors.EVENT_READ)
                s.register(wr, selectors.EVENT_WRITE)
            except OSError as e:
                if e.errno == errno.ENOSPC:
                    # this can be raised by epoll if we go over
                    # fs.epoll.max_user_watches sysctl
                    self.skipTest("FD limit reached")
                raise

        try:
            fds = s.select()
        except OSError as e:
            if e.errno == errno.EINVAL and sys.platform == 'darwin':
                # unexplainable errors on macOS don't need to fail the test
                self.skipTest("Invalid argument error calling poll()")
            raise
        self.assertEqual(NUM_FDS // 2, len(fds))


class DefaultSelectorTestCase(BaseSelectorTestCase):

    SELECTOR = selectors.DefaultSelector


class SelectSelectorTestCase(BaseSelectorTestCase):

    SELECTOR = selectors.SelectSelector


@unittest.skipUnless(hasattr(selectors, 'PollSelector'),
                     "Test needs selectors.PollSelector")
class PollSelectorTestCase(BaseSelectorTestCase, ScalableSelectorMixIn):

    SELECTOR = getattr(selectors, 'PollSelector', None)


@unittest.skipUnless(hasattr(selectors, 'EpollSelector'),
                     "Test needs selectors.EpollSelector")
class EpollSelectorTestCase(BaseSelectorTestCase, ScalableSelectorMixIn):

    SELECTOR = getattr(selectors, 'EpollSelector', None)

    def test_register_file(self):
        # epoll(7) returns EPERM when given a file to watch
        s = self.SELECTOR()
        with tempfile.NamedTemporaryFile() as f:
            with self.assertRaises(IOError):
                s.register(f, selectors.EVENT_READ)
            # the SelectorKey has been removed
            with self.assertRaises(KeyError):
                s.get_key(f)


@unittest.skipUnless(hasattr(selectors, 'KqueueSelector'),
                     "Test needs selectors.KqueueSelector)")
class KqueueSelectorTestCase(BaseSelectorTestCase, ScalableSelectorMixIn):

    SELECTOR = getattr(selectors, 'KqueueSelector', None)

    def test_register_bad_fd(self):
        # a file descriptor that's been closed should raise an OSError
        # with EBADF
        s = self.SELECTOR()
        bad_f = support.make_bad_fd()
        with self.assertRaises(OSError) as cm:
            s.register(bad_f, selectors.EVENT_READ)
        self.assertEqual(cm.exception.errno, errno.EBADF)
        # the SelectorKey has been removed
        with self.assertRaises(KeyError):
            s.get_key(bad_f)


@unittest.skipUnless(hasattr(selectors, 'DevpollSelector'),
                     "Test needs selectors.DevpollSelector")
class DevpollSelectorTestCase(BaseSelectorTestCase, ScalableSelectorMixIn):

    SELECTOR = getattr(selectors, 'DevpollSelector', None)



def test_main():
    tests = [DefaultSelectorTestCase, SelectSelectorTestCase,
             PollSelectorTestCase, EpollSelectorTestCase,
             KqueueSelectorTestCase, DevpollSelectorTestCase]
    support.run_unittest(*tests)
    support.reap_children()


if __name__ == "__main__":
    test_main()