Python selectors.EVENT_WRITE Examples

def _process_event(self, key, mask):
        """Selector has delivered us an event."""
        self._logger.debug('Processing event with key {} and mask {}'.format(key, mask))
        fileobj, (reader, writer) = key.fileobj, key.data
        if mask & selectors.EVENT_READ and reader is not None:
            if reader._cancelled:
                self.remove_reader(fileobj)
            else:
                self._logger.debug('Invoking reader callback: {}'.format(reader))
                reader._run()
        if mask & selectors.EVENT_WRITE and writer is not None:
            if writer._cancelled:
                self.remove_writer(fileobj)
            else:
                self._logger.debug('Invoking writer callback: {}'.format(writer))
                writer._run() 

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_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_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) 

def test_add_writer_existing(self):
        reader = mock.Mock()
        writer = mock.Mock()
        self.loop._selector.get_key.return_value = selectors.SelectorKey(
            1, 1, selectors.EVENT_READ, (reader, writer))
        cb = lambda: True
        self.loop.add_writer(1, cb)

        self.assertTrue(writer.cancel.called)
        self.assertFalse(self.loop._selector.register.called)
        self.assertTrue(self.loop._selector.modify.called)
        fd, mask, (r, w) = self.loop._selector.modify.call_args[0]
        self.assertEqual(1, fd)
        self.assertEqual(selectors.EVENT_WRITE | selectors.EVENT_READ, mask)
        self.assertEqual(reader, r)
        self.assertEqual(cb, w._callback) 

def test_add_reader_existing(self):
        reader = mock.Mock()
        writer = mock.Mock()
        self.loop._selector.get_key.return_value = selectors.SelectorKey(
            1, 1, selectors.EVENT_WRITE, (reader, writer))
        cb = lambda: True
        self.loop.add_reader(1, cb)

        self.assertTrue(reader.cancel.called)
        self.assertFalse(self.loop._selector.register.called)
        self.assertTrue(self.loop._selector.modify.called)
        fd, mask, (r, w) = self.loop._selector.modify.call_args[0]
        self.assertEqual(1, fd)
        self.assertEqual(selectors.EVENT_WRITE | selectors.EVENT_READ, mask)
        self.assertEqual(cb, r._callback)
        self.assertEqual(writer, w) 

def __repr__(self):
        info = [self.__class__.__name__]
        if self._pipe is None:
            info.append('closed')
        elif self._closing:
            info.append('closing')
        info.append(f'fd={self._fileno}')
        selector = getattr(self._loop, '_selector', None)
        if self._pipe is not None and selector is not None:
            polling = selector_events._test_selector_event(
                selector, self._fileno, selectors.EVENT_WRITE)
            if polling:
                info.append('polling')
            else:
                info.append('idle')

            bufsize = self.get_write_buffer_size()
            info.append(f'bufsize={bufsize}')
        elif self._pipe is not None:
            info.append('open')
        else:
            info.append('closed')
        return '<{}>'.format(' '.join(info)) 

def _remove_writer(self, fd):
        """Remove a writer callback."""
        if self.is_closed():
            return False
        try:
            key = self._selector.get_key(fd)
        except KeyError:
            return False
        else:
            mask, (reader, writer) = key.events, key.data
            # Remove both writer and connector.
            mask &= ~selectors.EVENT_WRITE
            if not mask:
                self._selector.unregister(fd)
            else:
                self._selector.modify(fd, mask, (reader, None))

            if writer is not None:
                writer.cancel()
                return True
            else:
                return False 

def _remove_writer(self, fd):
        """Remove a writer callback."""
        if self.is_closed():
            return False
        try:
            key = self._selector.get_key(fd)
        except KeyError:
            return False
        else:
            mask, (reader, writer) = key.events, key.data
            # Remove both writer and connector.
            mask &= ~selectors.EVENT_WRITE
            if not mask:
                self._selector.unregister(fd)
            else:
                self._selector.modify(fd, mask, (reader, None))

            if writer is not None:
                writer.cancel()
                return True
            else:
                return False 

def service_connection(key, mask):
    sock = key.fileobj
    data = key.data
    if mask & selectors.EVENT_READ:
        recv_data = sock.recv(BUFFER_SIZE)
        if recv_data:
            data.outb += recv_data
        else:
            print('Closing connection in {}'.format(data.addr))
            selector.unregister(sock)
            sock.close()
    if mask & selectors.EVENT_WRITE:
        if data.outb:
            print('Echo from {} to {}'.format(repr(data.outb), data.addr))
            sent = sock.send(data.outb)
            data.outb = data.outb[sent:] 

def start_connections(host, port, num_conns):
    server_address = (host, port)
    for i in range(0, num_conns):
        connid = i + 1
        print('Starting connection {} towards {}'.format(connid, server_address))
        socket_tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        # We connect using connect_ex () instead of connect ()
        socket_tcp.connect_ex(server_address)
        events = selectors.EVENT_READ | selectors.EVENT_WRITE
        data = types.SimpleNamespace(connid=connid,
                                     msg_total=sum(len(m) for m in messages),
                                     recv_total=0,
                                     messages=list(messages),
                                     outb=b'')
        selector.register(socket_tcp, events, data=data)
    events = selector.select()
    for key, mask in events:
        service_connection(key, mask) 

def service_connection(key, mask):
    sock = key.fileobj
    data = key.data
    if mask & selectors.EVENT_READ:
        recv_data = sock.recv(BUFFER_SIZE)
        if recv_data:
            print('Received {} from connection {}'.format(repr(recv_data), data.connid))
            data.recv_total += len(recv_data)
        if not recv_data or data.recv_total == data.msg_total:
            print('Closing connection', data.connid)
            selector.unregister(sock)
            sock.close()
    if mask & selectors.EVENT_WRITE:
        if not data.outb and data.messages:
            data.outb = data.messages.pop(0).encode()
        if data.outb:
            print('Sending {} to connection {}'.format(repr(data.outb), data.connid))
            sent = sock.send(data.outb)
            sock.shutdown(socket.SHUT_WR)
            data.outb = data.outb[sent:] 

def _remove_writer(self, fd):
        """Remove a writer callback."""
        if self.is_closed():
            return False
        try:
            key = self._selector.get_key(fd)
        except KeyError:
            return False
        else:
            mask, (reader, writer) = key.events, key.data
            # Remove both writer and connector.
            mask &= ~selectors.EVENT_WRITE
            if not mask:
                self._selector.unregister(fd)
            else:
                self._selector.modify(fd, mask, (reader, None))

            if writer is not None:
                writer.cancel()
                return True
            else:
                return False 

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_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_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) 

def _wr_shutdown(self, conn, once=False):
        """action when connection should be write-shutdown
        :type conn: socket.socket
        """
        try:
            conn.shutdown(socket.SHUT_WR)
        except:
            pass

        if conn in self.conn_wr:
            self.conn_wr.remove(conn)
            if self.sel:
                self._sel_disable_event(conn, EVENT_WRITE)

        if not once and conn in self.map:  # use the `once` param to avoid infinite loop
            #   pair should be rd_shutdown.
            # if a socket is wr_shutdowned, then it's
            self._rd_shutdown(self.map[conn], True) 

def __repr__(self):
        info = [self.__class__.__name__]
        if self._pipe is None:
            info.append('closed')
        elif self._closing:
            info.append('closing')
        info.append(f'fd={self._fileno}')
        selector = getattr(self._loop, '_selector', None)
        if self._pipe is not None and selector is not None:
            polling = selector_events._test_selector_event(
                selector, self._fileno, selectors.EVENT_WRITE)
            if polling:
                info.append('polling')
            else:
                info.append('idle')

            bufsize = self.get_write_buffer_size()
            info.append(f'bufsize={bufsize}')
        elif self._pipe is not None:
            info.append('open')
        else:
            info.append('closed')
        return '<{}>'.format(' '.join(info)) 

def _remove_writer(self, fd):
        """Remove a writer callback."""
        if self.is_closed():
            return False
        try:
            key = self._selector.get_key(fd)
        except KeyError:
            return False
        else:
            mask, (reader, writer) = key.events, key.data
            # Remove both writer and connector.
            mask &= ~selectors.EVENT_WRITE
            if not mask:
                self._selector.unregister(fd)
            else:
                self._selector.modify(fd, mask, (reader, None))

            if writer is not None:
                writer.cancel()
                return True
            else:
                return False 

def __repr__(self):
        info = [self.__class__.__name__]
        if self._pipe is None:
            info.append('closed')
        elif self._closing:
            info.append('closing')
        info.append(f'fd={self._fileno}')
        selector = getattr(self._loop, '_selector', None)
        if self._pipe is not None and selector is not None:
            polling = selector_events._test_selector_event(
                selector, self._fileno, selectors.EVENT_WRITE)
            if polling:
                info.append('polling')
            else:
                info.append('idle')

            bufsize = self.get_write_buffer_size()
            info.append(f'bufsize={bufsize}')
        elif self._pipe is not None:
            info.append('open')
        else:
            info.append('closed')
        return '<{}>'.format(' '.join(info)) 

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) 

def __repr__(self):
        info = [self.__class__.__name__]
        if self._pipe is None:
            info.append('closed')
        elif self._closing:
            info.append('closing')
        info.append(f'fd={self._fileno}')
        selector = getattr(self._loop, '_selector', None)
        if self._pipe is not None and selector is not None:
            polling = selector_events._test_selector_event(
                selector, self._fileno, selectors.EVENT_WRITE)
            if polling:
                info.append('polling')
            else:
                info.append('idle')

            bufsize = self.get_write_buffer_size()
            info.append(f'bufsize={bufsize}')
        elif self._pipe is not None:
            info.append('open')
        else:
            info.append('closed')
        return '<{}>'.format(' '.join(info)) 

def _add_writer(self, fd, callback, *args):
        self._check_closed()
        handle = events.Handle(callback, args, self, None)
        try:
            key = self._selector.get_key(fd)
        except KeyError:
            self._selector.register(fd, selectors.EVENT_WRITE,
                                    (None, handle))
        else:
            mask, (reader, writer) = key.events, key.data
            self._selector.modify(fd, mask | selectors.EVENT_WRITE,
                                  (reader, handle))
            if writer is not None:
                writer.cancel() 

def test_add_writer(self):
        self.loop._selector.get_key.side_effect = KeyError
        cb = lambda: True
        self.loop.add_writer(1, cb)

        self.assertTrue(self.loop._selector.register.called)
        fd, mask, (r, w) = self.loop._selector.register.call_args[0]
        self.assertEqual(1, fd)
        self.assertEqual(selectors.EVENT_WRITE, mask)
        self.assertIsNone(r)
        self.assertEqual(cb, w._callback) 

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_remove_writer_read_write(self):
        reader = mock.Mock()
        writer = mock.Mock()
        self.loop._selector.get_key.return_value = selectors.SelectorKey(
            1, 1, selectors.EVENT_READ | selectors.EVENT_WRITE,
            (reader, writer))
        self.assertTrue(
            self.loop.remove_writer(1))

        self.assertFalse(self.loop._selector.unregister.called)
        self.assertEqual(
            (1, selectors.EVENT_READ, (reader, None)),
            self.loop._selector.modify.call_args[0]) 

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_process_events_write_cancelled(self):
        writer = mock.Mock()
        writer.cancelled = True
        self.loop._remove_writer = mock.Mock()

        self.loop._process_events(
            [(selectors.SelectorKey(1, 1, selectors.EVENT_WRITE,
                                    (None, writer)),
              selectors.EVENT_WRITE)])
        self.loop._remove_writer.assert_called_with(1) 

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_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

        self.assertEqual(NUM_FDS // 2, len(s.select()))