Session._enqueue_request() - Code Metrics - Inspection of "Fix 'SyntaxError: invalid syntax' on Python 3.7 al..." - neovim/python-client - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Pull Request — master (#274)

by Lambda

created 2018-04-17 15:33 UTC

Session._enqueue_request() A

↳ Parent: Session

Complexity

Conditions

Size

Total Lines

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	1
CRAP Score	1.125

Importance

Changes

Metric	Value
cc	1
dl	0
loc	2
ccs	1
cts	2
cp	0.5
crap	1.125
rs	10
c	0
b	0
f	0

"""Synchronous msgpack-rpc session layer."""
import logging
import warnings
from collections import deque
from traceback import format_exc

import greenlet
# .scrutinizer.yml
before_commands:
    - sudo pip install abc # Python2
    - sudo pip3 install abc # Python3

logger = logging.getLogger(__name__)
error, debug, info, warn = (logger.error, logger.debug, logger.info,
                            logger.warning,)


class Session(object):

    """Msgpack-rpc session layer that uses coroutines for a synchronous API.

    This class provides the public msgpack-rpc API required by this library.
    It uses the greenlet module to handle requests and notifications coming
    from Nvim with a synchronous API.
    """

    def __init__(self, async_session):
        """Wrap `async_session` on a synchronous msgpack-rpc interface."""
        self._async_session = async_session
        self._request_cb = self._notification_cb = None
        self._pending_messages = deque()
        self._is_running = False
        self._setup_exception = None
        self.loop = async_session.loop

    def threadsafe_call(self, fn, *args, **kwargs):
        """Wrapper around `AsyncSession.threadsafe_call`."""
        def handler():
            try:
                fn(*args, **kwargs)
            except Exception:

                warn("error caught while excecuting async callback\n%s\n",
                     format_exc())

        def greenlet_wrapper():
            gr = greenlet.greenlet(handler)
            gr.switch()

        self._async_session.threadsafe_call(greenlet_wrapper)

    def next_message(self):
        """Block until a message(request or notification) is available.

        If any messages were previously enqueued, return the first in queue.
        If not, run the event loop until one is received.
        """
        if self._is_running:
            raise Exception('Event loop already running')
        if self._pending_messages:
            return self._pending_messages.popleft()
        self._async_session.run(self._enqueue_request_and_stop,
                                self._enqueue_notification_and_stop)
        if self._pending_messages:
            return self._pending_messages.popleft()

    def request(self, method, *args, **kwargs):
        """Send a msgpack-rpc request and block until as response is received.

        If the event loop is running, this method must have been called by a
        request or notification handler running on a greenlet. In that case,
        send the quest and yield to the parent greenlet until a response is
        available.

        When the event loop is not running, it will perform a blocking request
        like this:
        - Send the request
        - Run the loop until the response is available
        - Put requests/notifications received while waiting into a queue

        If the `async_` flag is present and True, a asynchronous notification
        is sent instead. This will never block, and the return value or error
        is ignored.
        """
        if 'async_' not in kwargs and 'async' in kwargs:
            warnings.warn(
                '"async" attribute is deprecated. Use "async_" instead.',
                DeprecationWarning,
            )
            async_ = kwargs.pop('async')
        else:
            async_ = kwargs.pop('async_', False)
        if async_:
            self._async_session.notify(method, args)
            return

        if kwargs:
            raise ValueError("request got unsupported keyword argument(s): {}"
                             .format(', '.join(kwargs.keys())))

        if self._is_running:
            v = self._yielding_request(method, args)
        else:
            v = self._blocking_request(method, args)
        if not v:
            # EOF
            raise IOError('EOF')
        err, rv = v
a, b = ("a", "b", "c")  # only 2 labels for 3 values
        if err:
            info("'Received error: %s", err)
            raise self.error_wrapper(err)

        return rv

    def run(self, request_cb, notification_cb, setup_cb=None):
        """Run the event loop to receive requests and notifications from Nvim.

        Like `AsyncSession.run()`, but `request_cb` and `notification_cb` are
        inside greenlets.
        """
        self._request_cb = request_cb
        self._notification_cb = notification_cb
        self._is_running = True
        self._setup_exception = None

        def on_setup():
            try:
                setup_cb()
            except Exception as e:

                self._setup_exception = e
                self.stop()

        if setup_cb:
            # Create a new greenlet to handle the setup function
            gr = greenlet.greenlet(on_setup)
            gr.switch()

        if self._setup_exception:
            error('Setup error: {}'.format(self._setup_exception))
            raise self._setup_exception


        # Process all pending requests and notifications
        while self._pending_messages:
            msg = self._pending_messages.popleft()
            getattr(self, '_on_{}'.format(msg[0]))(*msg[1:])
        self._async_session.run(self._on_request, self._on_notification)
        self._is_running = False
        self._request_cb = None
        self._notification_cb = None

        if self._setup_exception:
            raise self._setup_exception


    def stop(self):
        """Stop the event loop."""
        self._async_session.stop()

    def close(self):
        """Close the event loop."""
        self._async_session.close()

    def _yielding_request(self, method, args):
        gr = greenlet.getcurrent()
        parent = gr.parent

        def response_cb(err, rv):
            debug('response is available for greenlet %s, switching back', gr)
            gr.switch(err, rv)

        self._async_session.request(method, args, response_cb)
        debug('yielding from greenlet %s to wait for response', gr)
        return parent.switch()

    def _blocking_request(self, method, args):
        result = []

        def response_cb(err, rv):
            result.extend([err, rv])
            self.stop()

        self._async_session.request(method, args, response_cb)
        self._async_session.run(self._enqueue_request,
                                self._enqueue_notification)
        return result

    def _enqueue_request_and_stop(self, name, args, response):
        self._enqueue_request(name, args, response)
        self.stop()

    def _enqueue_notification_and_stop(self, name, args):
        self._enqueue_notification(name, args)
        self.stop()

    def _enqueue_request(self, name, args, response):
        self._pending_messages.append(('request', name, args, response,))

    def _enqueue_notification(self, name, args):
        self._pending_messages.append(('notification', name, args,))

    def _on_request(self, name, args, response):
        def handler():
            try:
                rv = self._request_cb(name, args)
                debug('greenlet %s finished executing, ' +
                      'sending %s as response', gr, rv)
                response.send(rv)
            except ErrorResponse as err:
                warn("error response from request '%s %s': %s", name,
                     args, format_exc())
                response.send(err.args[0], error=True)
            except Exception as err:

                warn("error caught while processing request '%s %s': %s", name,
                     args, format_exc())
                response.send(repr(err) + "\n" + format_exc(5), error=True)
            debug('greenlet %s is now dying...', gr)

        # Create a new greenlet to handle the request
        gr = greenlet.greenlet(handler)
        debug('received rpc request, greenlet %s will handle it', gr)
        gr.switch()

    def _on_notification(self, name, args):
        def handler():
            try:
                self._notification_cb(name, args)
                debug('greenlet %s finished executing', gr)
            except Exception:

                warn("error caught while processing notification '%s %s': %s",
                     name, args, format_exc())

            debug('greenlet %s is now dying...', gr)

        gr = greenlet.greenlet(handler)
        debug('received rpc notification, greenlet %s will handle it', gr)
        gr.switch()


class ErrorResponse(BaseException):

    """Raise this in a request handler to respond with a given error message.

    Unlike when other exceptions are caught, this gives full control off the
    error response sent. When "ErrorResponse(msg)" is caught "msg" will be
    sent verbatim as the error response.No traceback will be appended.
    """

    pass


Pull Request — master (#274)

Session._enqueue_request() A

Complexity

Size

Duplication

Code Coverage

Importance

1. Missing Dependencies

2. Missing init.py files

1		"""Synchronous msgpack-rpc session layer."""
2	5	import logging
3	5	import warnings
4		from collections import deque
5	5	from traceback import format_exc
6
7	5	import greenlet
		0 ignored issues – show Configuration introduced 2015-12-02 06:47 UTC by Report Bug Copy Issue Report The import `greenlet` could not be resolved. This can be caused by one of the following: 1. Missing Dependencies This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands. # .scrutinizer.yml before_commands: - sudo pip install abc # Python2 - sudo pip3 install abc # Python3 Tip: We are currently not using virtualenv to run pylint, when installing your modules make sure to use the command for the correct version. 2. Missing __init__.py files This error could also result from missing `__init__.py` files in your module folders. Make sure that you place one file in each sub-folder. Loading history...
8
9	5	logger = logging.getLogger(__name__)
10	5	error, debug, info, warn = (logger.error, logger.debug, logger.info,
11		logger.warning,)
12
13
14	5	class Session(object):
15
16		"""Msgpack-rpc session layer that uses coroutines for a synchronous API.
17
18		This class provides the public msgpack-rpc API required by this library.
19		It uses the greenlet module to handle requests and notifications coming
20		from Nvim with a synchronous API.
21		"""
22
23	5	def __init__(self, async_session):
24		"""Wrap `async_session` on a synchronous msgpack-rpc interface."""
25	5	self._async_session = async_session
26	5	self._request_cb = self._notification_cb = None
27	5	self._pending_messages = deque()
28	5	self._is_running = False
29	5	self._setup_exception = None
30		self.loop = async_session.loop
31	5
32		def threadsafe_call(self, fn, args, *kwargs):
33	5	"""Wrapper around `AsyncSession.threadsafe_call`."""
34	5	def handler():
35	5	try:
36		fn(args, *kwargs)
37		except Exception:
		0 ignored issues – show Best Practice introduced 2016-02-28 12:45 UTC by Report Bug Copy Issue Report Catching very general exceptions such as `Exception` is usually not recommended. Generally, you would want to handle very specific errors in the exception handler. This ensure that you do not hide other types of errors which should be fixed. So, unless you specifically plan to handle any error, consider adding a more specific exception. Loading history...
38		warn("error caught while excecuting async callback\n%s\n",
39		format_exc())
40	5
41	5	def greenlet_wrapper():
42	5	gr = greenlet.greenlet(handler)
43		gr.switch()
44	5
45		self._async_session.threadsafe_call(greenlet_wrapper)
46	5
47		def next_message(self):
48		"""Block until a message(request or notification) is available.
49
50		If any messages were previously enqueued, return the first in queue.
51		If not, run the event loop until one is received.
52	5	"""
53	5	if self._is_running:
54	5	raise Exception('Event loop already running')
55	5	if self._pending_messages:
56	5	return self._pending_messages.popleft()
57		self._async_session.run(self._enqueue_request_and_stop,
58	5	self._enqueue_notification_and_stop)
59	5	if self._pending_messages:
60		return self._pending_messages.popleft()
61	5
62		def request(self, method, args, *kwargs):
63		"""Send a msgpack-rpc request and block until as response is received.
64
65		If the event loop is running, this method must have been called by a
66		request or notification handler running on a greenlet. In that case,
67		send the quest and yield to the parent greenlet until a response is
68		available.
69
70		When the event loop is not running, it will perform a blocking request
71		like this:
72		- Send the request
73		- Run the loop until the response is available
74		- Put requests/notifications received while waiting into a queue
75
76		If the `async_` flag is present and True, a asynchronous notification
77		is sent instead. This will never block, and the return value or error
78		is ignored.
79	5	"""
80	5	if 'async_' not in kwargs and 'async' in kwargs:
81	5	warnings.warn(
82	5	'"async" attribute is deprecated. Use "async_" instead.',
83		DeprecationWarning,
84	5	)
85		async_ = kwargs.pop('async')
86		else:
87		async_ = kwargs.pop('async_', False)
88	5	if async_:
89	5	self._async_session.notify(method, args)
90		return
91	5
92	5	if kwargs:
93		raise ValueError("request got unsupported keyword argument(s): {}"
94		.format(', '.join(kwargs.keys())))
95	5
96	5	if self._is_running:
97	5	v = self._yielding_request(method, args)
98	5	else:
99	5	v = self._blocking_request(method, args)
100		if not v:
101	5	# EOF
102		raise IOError('EOF')
103		err, rv = v
		0 ignored issues – show Bug introduced 2018-04-12 22:26 UTC by Report Bug Copy Issue Report The tuple unpacking with sequence defined at line 169 seems to be unbalanced; 2 value(s) for 0 label(s) This happens when the amount of values does not equal the amount of labels: a, b = ("a", "b", "c") # only 2 labels for 3 values Loading history...
104		if err:
105		info("'Received error: %s", err)
106		raise self.error_wrapper(err)
		0 ignored issues – show Bug introduced 2015-12-02 06:47 UTC by Report Bug Copy Issue Report The Instance of `Session` does not seem to have a member named `error_wrapper`. This check looks for calls to members that are non-existent. These calls will fail. The member could have been renamed or removed. Loading history...
107	5	return rv
108	5
109	5	def run(self, request_cb, notification_cb, setup_cb=None):
110	5	"""Run the event loop to receive requests and notifications from Nvim.
111
112	5	Like `AsyncSession.run()`, but `request_cb` and `notification_cb` are
113	5	inside greenlets.
114	5	"""
115		self._request_cb = request_cb
116		self._notification_cb = notification_cb
117		self._is_running = True
118		self._setup_exception = None
119	5
120		def on_setup():
121	5	try:
122	5	setup_cb()
123		except Exception as e:
		0 ignored issues – show Best Practice introduced 2015-12-02 06:47 UTC by Report Bug Copy Issue Report Catching very general exceptions such as `Exception` is usually not recommended. Generally, you would want to handle very specific errors in the exception handler. This ensure that you do not hide other types of errors which should be fixed. So, unless you specifically plan to handle any error, consider adding a more specific exception. Loading history...
124	5	self._setup_exception = e
125		self.stop()
126
127		if setup_cb:
128		# Create a new greenlet to handle the setup function
129	5	gr = greenlet.greenlet(on_setup)
130		gr.switch()
131	1
132	5	if self._setup_exception:
133	5	error('Setup error: {}'.format(self._setup_exception))
134	5	raise self._setup_exception
		0 ignored issues – show Bug introduced 2017-04-14 11:18 UTC by Report Bug Copy Issue Report Raising NoneType while only classes or instances are allowed Loading history...
135	5
136		# Process all pending requests and notifications
137	5	while self._pending_messages:
138		msg = self._pending_messages.popleft()
139		getattr(self, '_on_{}'.format(msg[0]))(*msg[1:])
140	5	self._async_session.run(self._on_request, self._on_notification)
141		self._is_running = False
142	5	self._request_cb = None
143		self._notification_cb = None
144	5
145	5	if self._setup_exception:
146	5	raise self._setup_exception
		0 ignored issues – show Bug introduced 2016-08-28 19:44 UTC by Report Bug Copy Issue Report Raising NoneType while only classes or instances are allowed Loading history...
147
148	5	def stop(self):
149	5	"""Stop the event loop."""
150	5	self._async_session.stop()
151
152	5	def close(self):
153	5	"""Close the event loop."""
154	5	self._async_session.close()
155
156	5	def _yielding_request(self, method, args):
157	5	gr = greenlet.getcurrent()
158		parent = gr.parent
159	5
160	5	def response_cb(err, rv):
161	5	debug('response is available for greenlet %s, switching back', gr)
162		gr.switch(err, rv)
163	5
164	5	self._async_session.request(method, args, response_cb)
165		debug('yielding from greenlet %s to wait for response', gr)
166	5	return parent.switch()
167
168	5	def _blocking_request(self, method, args):
169		result = []
170
171		def response_cb(err, rv):
172	5	result.extend([err, rv])
173	5	self.stop()
174	5
175		self._async_session.request(method, args, response_cb)
176	5	self._async_session.run(self._enqueue_request,
177		self._enqueue_notification)
178		return result
179	5
180	5	def _enqueue_request_and_stop(self, name, args, response):
181		self._enqueue_request(name, args, response)
182	5	self.stop()
183	5
184	5	def _enqueue_notification_and_stop(self, name, args):
185	5	self._enqueue_notification(name, args)
186	5	self.stop()
187
188	5	def _enqueue_request(self, name, args, response):
189		self._pending_messages.append(('request', name, args, response,))
190
191		def _enqueue_notification(self, name, args):
192		self._pending_messages.append(('notification', name, args,))
193
194		def _on_request(self, name, args, response):
195		def handler():
196		try:
197	5	rv = self._request_cb(name, args)
198		debug('greenlet %s finished executing, ' +
199		'sending %s as response', gr, rv)
200	5	response.send(rv)
201	5	except ErrorResponse as err:
202	5	warn("error response from request '%s %s': %s", name,
203		args, format_exc())
204	5	response.send(err.args[0], error=True)
205		except Exception as err:
		0 ignored issues – show Best Practice introduced 2015-12-02 06:47 UTC by Report Bug Copy Issue Report Catching very general exceptions such as `Exception` is usually not recommended. Generally, you would want to handle very specific errors in the exception handler. This ensure that you do not hide other types of errors which should be fixed. So, unless you specifically plan to handle any error, consider adding a more specific exception. Loading history...
206		warn("error caught while processing request '%s %s': %s", name,
207		args, format_exc())
208		response.send(repr(err) + "\n" + format_exc(5), error=True)
209		debug('greenlet %s is now dying...', gr)
210
211		# Create a new greenlet to handle the request
212		gr = greenlet.greenlet(handler)
213		debug('received rpc request, greenlet %s will handle it', gr)
214		gr.switch()
215
216		def _on_notification(self, name, args):
217		def handler():
218		try:
219		self._notification_cb(name, args)
220	5	debug('greenlet %s finished executing', gr)
221		except Exception:
		0 ignored issues – show Best Practice introduced 2016-08-28 19:44 UTC by Report Bug Copy Issue Report Catching very general exceptions such as `Exception` is usually not recommended. Generally, you would want to handle very specific errors in the exception handler. This ensure that you do not hide other types of errors which should be fixed. So, unless you specifically plan to handle any error, consider adding a more specific exception. Loading history...
222		warn("error caught while processing notification '%s %s': %s",
223		name, args, format_exc())
224
225		debug('greenlet %s is now dying...', gr)
226
227		gr = greenlet.greenlet(handler)
228		debug('received rpc notification, greenlet %s will handle it', gr)
229	5	gr.switch()
230
231
232		class ErrorResponse(BaseException):
233
234		"""Raise this in a request handler to respond with a given error message.
235
236		Unlike when other exceptions are caught, this gives full control off the
237		error response sent. When "ErrorResponse(msg)" is caught "msg" will be
238		sent verbatim as the error response.No traceback will be appended.
239		"""
240
241		pass
242

neovim / python-client

Pull Request — master (#274)

Session._enqueue_request() A

Complexity

Size

Duplication

Code Coverage

Importance

1. Missing Dependencies

2. Missing __init__.py files

Duplication Side-by-Side

Filter issues like

2. Missing init.py files