Python tornado.gen.Return() Examples

def connect(self, host, port, af=socket.AF_UNSPEC, ssl_options=None,
                max_buffer_size=None):
        """Connect to the given host and port.

        Asynchronously returns an `.IOStream` (or `.SSLIOStream` if
        ``ssl_options`` is not None).
        """
        addrinfo = yield self.resolver.resolve(host, port, af)
        connector = _Connector(
            addrinfo, self.io_loop,
            functools.partial(self._create_stream, max_buffer_size))
        af, addr, stream = yield connector.start()
        # TODO: For better performance we could cache the (af, addr)
        # information here and re-use it on subsequent connections to
        # the same host. (http://tools.ietf.org/html/rfc6555#section-4.2)
        if ssl_options is not None:
            stream = yield stream.start_tls(False, ssl_options=ssl_options,
                                            server_hostname=host)
        raise gen.Return(stream) 

def test_async_await_mixed_multi_native_yieldpoint(self):
        namespace = exec_test(globals(), locals(), """
        async def f1():
            await gen.Task(self.io_loop.add_callback)
            return 42
        """)

        @gen.coroutine
        def f2():
            yield gen.Task(self.io_loop.add_callback)
            raise gen.Return(43)

        f2(callback=(yield gen.Callback('cb')))
        results = yield [namespace['f1'](), gen.Wait('cb')]
        self.assertEqual(results, [42, 43])
        self.finished = True 

def test_swallow_context_exception(self):
        # Test exception handling: exceptions thrown into the stack context
        # can be caught and ignored.
        @gen.coroutine
        def f2():
            (yield gen.Callback(1))()
            yield gen.Wait(1)
            self.io_loop.add_callback(lambda: 1 / 0)
            try:
                yield gen.Task(self.io_loop.add_timeout,
                               self.io_loop.time() + 10)
            except ZeroDivisionError:
                raise gen.Return(42)

        result = yield f2()
        self.assertEqual(result, 42)
        self.finished = True 

def _do_all_execute_forasync(self, handler, clear, method_name, **kwargs):

        for c_module in self.common_modules:
            result = self._execute_module(handler, clear, c_module, getattr(c_module, method_name), **kwargs)
            if is_future(result):
                result = yield result
            if result:
                raise gen.Return(1)

        for name, r_module in self.route_modules.items():
            for md in r_module:
                result = self._execute_module(handler, clear, md, getattr(md, method_name), name, **kwargs)
                if is_future(result):
                    result = yield result
                if result:
                    raise gen.Return(1) 

def _call_subprocess(self, function_to_evaluate, arguments):
        restricted_tabpy = RestrictedTabPy(
            self.protocol, self.port, self.logger, self.eval_timeout
        )
        # Exec does not run the function, so it does not block.
        exec(function_to_evaluate, globals())

        # 'noqa' comments below tell flake8 to ignore undefined _user_script
        # name - the name is actually defined with user script being wrapped
        # in _user_script function (constructed as a striong) and then executed
        # with exec() call above.
        if arguments is None:
            future = self.executor.submit(_user_script,  # noqa: F821
                                          restricted_tabpy)
        else:
            future = self.executor.submit(_user_script,  # noqa: F821
                                          restricted_tabpy, **arguments)

        ret = yield gen.with_timeout(timedelta(seconds=self.eval_timeout), future)
        raise gen.Return(ret) 

def test_swallow_yieldpoint_exception(self):
        # Test exception handling: a coroutine can catch an exception
        # raised by a yield point and not raise a different one.
        @gen.coroutine
        def f1():
            1 / 0

        @gen.coroutine
        def f2():
            try:
                yield f1()
            except ZeroDivisionError:
                raise gen.Return(42)

        result = yield f2()
        self.assertEqual(result, 42)
        self.finished = True 

def test_async_await_mixed_multi_native_future(self):
        @gen.coroutine
        def f1():
            yield gen.moment

        async def f2():
            await f1()
            return 42

        @gen.coroutine
        def f3():
            yield gen.moment
            raise gen.Return(43)

        results = yield [f2(), f3()]
        self.assertEqual(results, [42, 43])
        self.finished = True 

def connect(self, host, port, af=socket.AF_UNSPEC, ssl_options=None,
                max_buffer_size=None):
        """Connect to the given host and port.

        Asynchronously returns an `.IOStream` (or `.SSLIOStream` if
        ``ssl_options`` is not None).
        """
        addrinfo = yield self.resolver.resolve(host, port, af)
        connector = _Connector(
            addrinfo, self.io_loop,
            functools.partial(self._create_stream, max_buffer_size))
        af, addr, stream = yield connector.start()
        # TODO: For better performance we could cache the (af, addr)
        # information here and re-use it on subsequent connections to
        # the same host. (http://tools.ietf.org/html/rfc6555#section-4.2)
        if ssl_options is not None:
            stream = yield stream.start_tls(False, ssl_options=ssl_options,
                                            server_hostname=host)
        raise gen.Return(stream) 

def test_swallow_yieldpoint_exception(self):
        # Test exception handling: a coroutine can catch an exception
        # raised by a yield point and not raise a different one.
        @gen.coroutine
        def f1():
            1 / 0

        @gen.coroutine
        def f2():
            try:
                yield f1()
            except ZeroDivisionError:
                raise gen.Return(42)

        result = yield f2()
        self.assertEqual(result, 42)
        self.finished = True 

def test_swallow_context_exception(self):
        # Test exception handling: exceptions thrown into the stack context
        # can be caught and ignored.
        @gen.coroutine
        def f2():
            (yield gen.Callback(1))()
            yield gen.Wait(1)
            self.io_loop.add_callback(lambda: 1 / 0)
            try:
                yield gen.Task(self.io_loop.add_timeout,
                               self.io_loop.time() + 10)
            except ZeroDivisionError:
                raise gen.Return(42)

        result = yield f2()
        self.assertEqual(result, 42)
        self.finished = True 

def resolve(self, host, port, family=0):
        # getHostByName doesn't accept IP addresses, so if the input
        # looks like an IP address just return it immediately.
        if twisted.internet.abstract.isIPAddress(host):
            resolved = host
            resolved_family = socket.AF_INET
        elif twisted.internet.abstract.isIPv6Address(host):
            resolved = host
            resolved_family = socket.AF_INET6
        else:
            deferred = self.resolver.getHostByName(utf8(host))
            resolved = yield gen.Task(deferred.addCallback)
            if twisted.internet.abstract.isIPAddress(resolved):
                resolved_family = socket.AF_INET
            elif twisted.internet.abstract.isIPv6Address(resolved):
                resolved_family = socket.AF_INET6
            else:
                resolved_family = socket.AF_UNSPEC
        if family != socket.AF_UNSPEC and family != resolved_family:
            raise Exception('Requested socket family %d but got %d' %
                            (family, resolved_family))
        result = [
            (resolved_family, (resolved, port)),
        ]
        raise gen.Return(result) 

def get_links_from_url(url):
    """Download the page at `url` and parse it for links.

    Returned links have had the fragment after `#` removed, and have been made
    absolute so, e.g. the URL 'gen.html#tornado.gen.coroutine' becomes
    'http://www.tornadoweb.org/en/stable/gen.html'.
    """
    try:
        response = yield httpclient.AsyncHTTPClient().fetch(url)
        print('fetched %s' % url)

        html = response.body if isinstance(response.body, str) \
            else response.body.decode()
        urls = [urljoin(url, remove_fragment(new_url))
                for new_url in get_links(html)]
    except Exception as e:
        print('Exception: %s %s' % (e, url))
        raise gen.Return([])

    raise gen.Return(urls) 

def open(self, timeout=None):
        logger.debug('socket connecting')
        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0)
        self.stream = iostream.IOStream(sock)

        try:
            connect = self.stream.connect((self.host, self.port))
            if timeout is not None:
                yield self.with_timeout(timeout, connect)
            else:
                yield connect
        except (socket.error, IOError, ioloop.TimeoutError) as e:
            message = 'could not connect to {}:{} ({})'.format(self.host, self.port, e)
            raise TTransportException(
                type=TTransportException.NOT_OPEN,
                message=message)

        raise gen.Return(self) 

def get_links_from_url(url):
    """Download the page at `url` and parse it for links.

    Returned links have had the fragment after `#` removed, and have been made
    absolute so, e.g. the URL 'gen.html#tornado.gen.coroutine' becomes
    'http://www.tornadoweb.org/en/stable/gen.html'.
    """
    try:
        response = yield httpclient.AsyncHTTPClient().fetch(url)#获取到
        print('fetched %s' % url)


        html = response.body if isinstance(response.body, str) \
            else response.body.decode()
        urls = [urljoin(url, remove_fragment(new_url))
                for new_url in get_links(html)]
    except Exception as e:
        print('Exception: %s %s' % (e, url))
        raise gen.Return([])

    raise gen.Return(urls) 

def _oauth_get_user_future(self, access_token):
        user = yield self.twitter_request(
            "/account/verify_credentials",
            access_token=access_token)
        if user:
            user["username"] = user["screen_name"]
        raise gen.Return(user) 

def test_sync_raise_return(self):
        # gen.Return is allowed in @gen.engine, but it may not be used
        # to return a value.
        @gen.engine
        def f():
            self.stop(42)
            raise gen.Return()

        result = self.run_gen(f)
        self.assertEqual(result, 42) 

def test_sync_gen_return(self):
        @gen.coroutine
        def f():
            raise gen.Return(42)

        result = yield f()
        self.assertEqual(result, 42)
        self.finished = True 

def test_async_raise_return_value_tuple(self):
        @gen.coroutine
        def f():
            yield gen.moment
            raise gen.Return((1, 2))

        self.assertEqual((1, 2), self.io_loop.run_sync(f)) 

def test_multi_moment(self):
        # Test gen.multi with moment
        # now that it's not a real Future
        @gen.coroutine
        def wait_a_moment():
            result = yield gen.multi([gen.moment, gen.moment])
            raise gen.Return(result)

        loop = self.get_new_ioloop()
        result = loop.run_sync(wait_a_moment)
        self.assertEqual(result, [None, None]) 

def resolve(self, host, port, family=0):
        if is_valid_ip(host):
            addresses = [host]
        else:
            # gethostbyname doesn't take callback as a kwarg
            self.channel.gethostbyname(host, family, (yield gen.Callback(1)))
            callback_args = yield gen.Wait(1)
            assert isinstance(callback_args, gen.Arguments)
            assert not callback_args.kwargs
            result, error = callback_args.args
            if error:
                raise Exception('C-Ares returned error %s: %s while resolving %s' %
                                (error, pycares.errno.strerror(error), host))
            addresses = result.addresses
        addrinfo = []
        for address in addresses:
            if '.' in address:
                address_family = socket.AF_INET
            elif ':' in address:
                address_family = socket.AF_INET6
            else:
                address_family = socket.AF_UNSPEC
            if family != socket.AF_UNSPEC and family != address_family:
                raise Exception('Requested socket family %d but got %d' %
                                (family, address_family))
            addrinfo.append((address_family, (address, port)))
        raise gen.Return(addrinfo) 

def test_async_raise_return_value(self):
        @gen.coroutine
        def f():
            yield gen.moment
            raise gen.Return(42)

        self.assertEqual(42, self.io_loop.run_sync(f)) 

def test_sync_raise_return_value_tuple(self):
        @gen.coroutine
        def f():
            raise gen.Return((1, 2))

        self.assertEqual((1, 2), self.io_loop.run_sync(f)) 

def test_async_raise_return(self):
        @gen.coroutine
        def f():
            yield gen.moment
            raise gen.Return()

        self.io_loop.run_sync(f) 

def test_sync_raise_return(self):
        @gen.coroutine
        def f():
            raise gen.Return()

        self.io_loop.run_sync(f) 

def add_one_async(self, x):
        yield gen.moment
        raise gen.Return(x + 1) 

def delay(self, iterations, arg):
        """Returns arg after a number of IOLoop iterations."""
        for i in range(iterations):
            yield gen.moment
        raise gen.Return(arg) 

def ws_connect(self, path, **kwargs):
        ws = yield websocket_connect(
            "ws://127.0.0.1:%d%s" % (self.get_http_port(), path), **kwargs
        )
        raise gen.Return(ws) 

def readFrame(self):
        # IOStream processes reads one at a time
        with (yield self._read_lock.acquire()):
            with self.io_exception_context():
                frame_header = yield self.stream.read_bytes(4)
                if len(frame_header) == 0:
                    raise iostream.StreamClosedError('Read zero bytes from stream')
                frame_length, = struct.unpack('!i', frame_header)
                frame = yield self.stream.read_bytes(frame_length)
                raise gen.Return(frame) 

def acquire(self):
        blocker = self._waiters[-1] if self.acquired() else None
        future = concurrent.Future()
        self._waiters.append(future)
        if blocker:
            yield blocker

        raise gen.Return(self._lock_context()) 

def wait_read_frame(self, timeout=None):
        frame = yield self._get_frame(timeout=timeout)
        raise gen.Return(self._split_response(frame.data))