build.models.path.DynamicPathManager.get_disjoint_paths() - Code Metrics - Inspection of "feature: Added uni tag usage" - kytos-ng/mef_eline - Measure and Improve Code Quality continuously with Scrutinizer

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Pull Request — master (#371)

by Vinicius

created 2023-10-11 13:16 UTC

DynamicPathManager.get_disjoint_paths() C

↳ Parent: build.models.path

Complexity

Conditions

Size

Total Lines	65
Code Lines	24

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	20
CRAP Score	9

Importance

Changes

Metric	Value
eloc	24
dl	0
loc	65
ccs	20
cts	20
cp	1
rs	6.6666
c	0
b	0
f	0
cc	9
nop	4
crap	9

How to fix Long Method

"""Classes related to paths"""
import requests

from kytos.core import log
from kytos.core.common import EntityStatus, GenericEntity
from kytos.core.interface import TAG
from kytos.core.link import Link
from napps.kytos.mef_eline import settings
from napps.kytos.mef_eline.exceptions import InvalidPath


class Path(list, GenericEntity):
    """Class to represent a Path."""

    def __eq__(self, other=None):
        """Compare paths."""
        if not other or not isinstance(other, Path):
            return False
        return super().__eq__(other)

    def is_affected_by_link(self, link=None):
        """Verify if the current path is affected by link."""
        if not link:
            return False
        return link in self

    def link_affected_by_interface(self, interface=None):
        """Return the link using this interface, if any, or None otherwise."""
        if not interface:
            return None
        for link in self:
            if interface in (link.endpoint_a, link.endpoint_b):
                return link
        return None

    def choose_vlans(self, controller):
        """Choose the VLANs to be used for the circuit."""
        for link in self:
            tag_value = link.get_next_available_tag(controller, link.id)
            tag = TAG('vlan', tag_value)
            link.add_metadata("s_vlan", tag)

    def make_vlans_available(self, controller):
        """Make the VLANs used in a path available when undeployed."""
        for link in self:
            tag = link.get_metadata("s_vlan")
            result_a, result_b = link.make_tags_available(
                controller, tag.value, link.id, tag.tag_type
            )
            if result_a is False:
                log.error(f"Tag {tag} was already available in"
                          f"{link.endpoint_a.id}")
            if result_b is False:
                log.error(f"Tag {tag} was already available in"
                          f"{link.endpoint_b.id}")
            link.remove_metadata("s_vlan")

    def is_valid(self, switch_a, switch_z, is_scheduled=False):
        """Check if this is a valid path."""
        if not self:
            return True
        previous = visited = {switch_a}
        for link in self:
            current = {link.endpoint_a.switch, link.endpoint_b.switch} \
                      - previous
            if len(current) != 1:
                raise InvalidPath(
                    f"Previous switch {previous} is not connected to "
                    f"current link with switches {current}."
                )
            if current & visited:
                raise InvalidPath(
                    f"Loop detected in path, switch {current} was visited"
                    f" more than once."
                )
            if is_scheduled is False and (
                link.endpoint_a.link is None
                or link.endpoint_a.link != link
                or link.endpoint_b.link is None
                or link.endpoint_b.link != link
            ):
                raise InvalidPath(f"Link {link} is not available.")
            previous = current
            visited |= current
        if previous & {switch_z}:
            return True
        raise InvalidPath("Last link does not contain uni_z switch")

    @property
    def status(self):
        """Check for the  status of a path.

        If any link in this path is down, the path is considered down.
        """
        if not self:
            return EntityStatus.DISABLED

        endpoint = f"{settings.TOPOLOGY_URL}/links"
        api_reply = requests.get(endpoint)
        if api_reply.status_code != getattr(requests.codes, "ok"):
            log.error(
                "Failed to get links at %s. Returned %s",
                endpoint,
                api_reply.status_code,
            )
            return None
        links = api_reply.json()["links"]
        return_status = EntityStatus.UP
        for path_link in self:
            try:
                link = links[path_link.id]
            except KeyError:
                return EntityStatus.DISABLED
            if link["enabled"] is False:
                return EntityStatus.DISABLED
            if link["active"] is False:
                return_status = EntityStatus.DOWN
        return return_status

    def as_dict(self):
        """Return list comprehension of links as_dict."""
        return [link.as_dict() for link in self if link]


class DynamicPathManager:
    """Class to handle and create paths."""

    controller = None

    @classmethod
    def set_controller(cls, controller=None):
        """Set the controller to discovery news paths."""
        cls.controller = controller

    @staticmethod
    def get_paths(circuit, max_paths=2, **kwargs):
        """Get a valid path for the circuit from the Pathfinder."""
        endpoint = settings.PATHFINDER_URL
        spf_attribute = kwargs.get("spf_attribute") or settings.SPF_ATTRIBUTE
        request_data = {
            "source": circuit.uni_a.interface.id,
            "destination": circuit.uni_z.interface.id,
            "spf_max_paths": max_paths,
            "spf_attribute": spf_attribute
        }
        request_data.update(kwargs)
        api_reply = requests.post(endpoint, json=request_data)

        if api_reply.status_code != getattr(requests.codes, "ok"):
            log.error(
                "Failed to get paths at %s. Returned %s",
                endpoint,
                api_reply.text,
            )
            return None
        reply_data = api_reply.json()
        return reply_data.get("paths")

    @staticmethod
    def _clear_path(path):
        """Remove switches from a path, returning only interfaces."""
        return [endpoint for endpoint in path if len(endpoint) > 23]

    @classmethod
    def get_best_path(cls, circuit):
        """Return the best path available for a circuit, if exists."""
        paths = cls.get_paths(circuit)
        if paths:
            return cls.create_path(cls.get_paths(circuit)[0]["hops"])
        return None

    @classmethod
    def get_best_paths(cls, circuit, **kwargs):
        """Return the best paths available for a circuit, if they exist."""
        for path in cls.get_paths(circuit, **kwargs):
            yield cls.create_path(path["hops"])

    @classmethod
    def get_disjoint_paths(
        cls, circuit, unwanted_path, cutoff=settings.DISJOINT_PATH_CUTOFF
    ):
        """Computes the maximum disjoint paths from the unwanted_path for a EVC

        Maximum disjoint paths from the unwanted_path are the paths from the
        source node to the target node that share the minimum number os links
        contained in unwanted_path. In other words, unwanted_path is the path
        we want to avoid: we want the maximum possible disjoint path from it.
        The disjointness of a path in regards to unwanted_path is calculated
        by the complementary percentage of shared links between them. As an
        example, if the unwanted_path has 3 links, a given path P1 has 1 link
        shared with unwanted_path, and a given path P2 has 2 links shared with
        unwanted_path, then the disjointness of P1 is 0.67 and the disjointness
        of P2 is 0.33. In this example, P1 is preferable over P2 because it
        offers a better disjoint path. When two paths have the same
        disjointness they are ordered by 'cost' attributed as returned from
        Pathfinder. When the disjointness of a path is equal to 0 (i.e., it
        shares all the links with unwanted_path), that particular path is not
        considered a candidate.

        Parameters:
        -----------

        circuit : EVC
            The EVC providing source node (uni_a) and target node (uni_z)

        unwanted_path : Path
            The Path which we want to avoid.

        cutoff: int
            Maximum number of paths to consider when calculating the disjoint
            paths (number of paths to request from pathfinder)

        Returns:
        --------
        paths : generator
            Generator of unwanted_path disjoint paths. If unwanted_path is
            not provided or empty, we return an empty list.
        """
        unwanted_links = [
            (link.endpoint_a.id, link.endpoint_b.id) for link in unwanted_path
        ]
        if not unwanted_links:
            return None

        paths = cls.get_paths(circuit, max_paths=cutoff,
                              **circuit.secondary_constraints)
        for path in paths:
            head = path["hops"][:-1]
            tail = path["hops"][1:]
            shared_edges = 0
            for (endpoint_a, endpoint_b) in unwanted_links:
                if ((endpoint_a, endpoint_b) in zip(head, tail)) or (
                    (endpoint_b, endpoint_a) in zip(head, tail)
                ):
                    shared_edges += 1
            path["disjointness"] = 1 - shared_edges / len(unwanted_links)
        paths = sorted(paths, key=lambda x: (-x['disjointness'], x['cost']))
        for path in paths:
            if path["disjointness"] == 0:
                continue
            yield cls.create_path(path["hops"])
        return None

    @classmethod
    def create_path(cls, path):
        """Return the path containing only the interfaces."""
        new_path = Path()
        clean_path = cls._clear_path(path)

        if len(clean_path) % 2:
            return None

        for link in zip(clean_path[1:-1:2], clean_path[2::2]):
            interface_a = cls.controller.get_interface_by_id(link[0])
            interface_b = cls.controller.get_interface_by_id(link[1])
            if interface_a is None or interface_b is None:
                return None
            new_path.append(Link(interface_a, interface_b))

        return new_path


1		"""Classes related to paths"""
2	1	import requests
3
4	1	from kytos.core import log
5	1	from kytos.core.common import EntityStatus, GenericEntity
6	1	from kytos.core.interface import TAG
7	1	from kytos.core.link import Link
8	1	from napps.kytos.mef_eline import settings
9	1	from napps.kytos.mef_eline.exceptions import InvalidPath
10
11
12	1	class Path(list, GenericEntity):
13		"""Class to represent a Path."""
14
15	1	def __eq__(self, other=None):
16		"""Compare paths."""
17	1	if not other or not isinstance(other, Path):
18	1	return False
19	1	return super().__eq__(other)
20
21	1	def is_affected_by_link(self, link=None):
22		"""Verify if the current path is affected by link."""
23	1	if not link:
24	1	return False
25	1	return link in self
26
27	1	def link_affected_by_interface(self, interface=None):
28		"""Return the link using this interface, if any, or None otherwise."""
29	1	if not interface:
30	1	return None
31	1	for link in self:
32	1	if interface in (link.endpoint_a, link.endpoint_b):
33	1	return link
34		return None
35
36	1	def choose_vlans(self, controller):
37		"""Choose the VLANs to be used for the circuit."""
38	1	for link in self:
39	1	tag_value = link.get_next_available_tag(controller, link.id)
40	1	tag = TAG('vlan', tag_value)
41	1	link.add_metadata("s_vlan", tag)
42
43	1	def make_vlans_available(self, controller):
44		"""Make the VLANs used in a path available when undeployed."""
45	1	for link in self:
46	1	tag = link.get_metadata("s_vlan")
47	1	result_a, result_b = link.make_tags_available(
48		controller, tag.value, link.id, tag.tag_type
49		)
50	1	if result_a is False:
51		log.error(f"Tag {tag} was already available in"
52		f"{link.endpoint_a.id}")
53	1	if result_b is False:
54		log.error(f"Tag {tag} was already available in"
55		f"{link.endpoint_b.id}")
56	1	link.remove_metadata("s_vlan")
57
58	1	def is_valid(self, switch_a, switch_z, is_scheduled=False):
59		"""Check if this is a valid path."""
60	1	if not self:
61	1	return True
62	1	previous = visited = {switch_a}
63	1	for link in self:
64	1	current = {link.endpoint_a.switch, link.endpoint_b.switch} \
65		- previous
66	1	if len(current) != 1:
67	1	raise InvalidPath(
68		f"Previous switch {previous} is not connected to "
69		f"current link with switches {current}."
70		)
71	1	if current & visited:
72	1	raise InvalidPath(
73		f"Loop detected in path, switch {current} was visited"
74		f" more than once."
75		)
76	1	if is_scheduled is False and (
77		link.endpoint_a.link is None
78		or link.endpoint_a.link != link
79		or link.endpoint_b.link is None
80		or link.endpoint_b.link != link
81		):
82		raise InvalidPath(f"Link {link} is not available.")
83	1	previous = current
84	1	visited \|= current
85	1	if previous & {switch_z}:
86	1	return True
87		raise InvalidPath("Last link does not contain uni_z switch")
88
89	1	@property
90	1	def status(self):
91		"""Check for the status of a path.
92
93		If any link in this path is down, the path is considered down.
94		"""
95	1	if not self:
96	1	return EntityStatus.DISABLED
97
98	1	endpoint = f"{settings.TOPOLOGY_URL}/links"
99	1	api_reply = requests.get(endpoint)
100	1	if api_reply.status_code != getattr(requests.codes, "ok"):
101		log.error(
102		"Failed to get links at %s. Returned %s",
103		endpoint,
104		api_reply.status_code,
105		)
106		return None
107	1	links = api_reply.json()["links"]
108	1	return_status = EntityStatus.UP
109	1	for path_link in self:
110	1	try:
111	1	link = links[path_link.id]
112		except KeyError:
113		return EntityStatus.DISABLED
114	1	if link["enabled"] is False:
115	1	return EntityStatus.DISABLED
116	1	if link["active"] is False:
117	1	return_status = EntityStatus.DOWN
118	1	return return_status
119
120	1	def as_dict(self):
121		"""Return list comprehension of links as_dict."""
122	1	return [link.as_dict() for link in self if link]
123
124
125	1	class DynamicPathManager:
126		"""Class to handle and create paths."""
127
128	1	controller = None
129
130	1	@classmethod
131	1	def set_controller(cls, controller=None):
132		"""Set the controller to discovery news paths."""
133	1	cls.controller = controller
134
135	1	@staticmethod
136	1	def get_paths(circuit, max_paths=2, **kwargs):
137		"""Get a valid path for the circuit from the Pathfinder."""
138	1	endpoint = settings.PATHFINDER_URL
139	1	spf_attribute = kwargs.get("spf_attribute") or settings.SPF_ATTRIBUTE
140	1	request_data = {
141		"source": circuit.uni_a.interface.id,
142		"destination": circuit.uni_z.interface.id,
143		"spf_max_paths": max_paths,
144		"spf_attribute": spf_attribute
145		}
146	1	request_data.update(kwargs)
147	1	api_reply = requests.post(endpoint, json=request_data)
148
149	1	if api_reply.status_code != getattr(requests.codes, "ok"):
150	1	log.error(
151		"Failed to get paths at %s. Returned %s",
152		endpoint,
153		api_reply.text,
154		)
155	1	return None
156	1	reply_data = api_reply.json()
157	1	return reply_data.get("paths")
158
159	1	@staticmethod
160	1	def _clear_path(path):
161		"""Remove switches from a path, returning only interfaces."""
162	1	return [endpoint for endpoint in path if len(endpoint) > 23]
163
164	1	@classmethod
165	1	def get_best_path(cls, circuit):
166		"""Return the best path available for a circuit, if exists."""
167	1	paths = cls.get_paths(circuit)
168	1	if paths:
169	1	return cls.create_path(cls.get_paths(circuit)[0]["hops"])
170	1	return None
171
172	1	@classmethod
173	1	def get_best_paths(cls, circuit, **kwargs):
174		"""Return the best paths available for a circuit, if they exist."""
175	1	for path in cls.get_paths(circuit, **kwargs):
176	1	yield cls.create_path(path["hops"])
177
178	1	@classmethod
179	1	def get_disjoint_paths(
180		cls, circuit, unwanted_path, cutoff=settings.DISJOINT_PATH_CUTOFF
181		):
182		"""Computes the maximum disjoint paths from the unwanted_path for a EVC
183
184		Maximum disjoint paths from the unwanted_path are the paths from the
185		source node to the target node that share the minimum number os links
186		contained in unwanted_path. In other words, unwanted_path is the path
187		we want to avoid: we want the maximum possible disjoint path from it.
188		The disjointness of a path in regards to unwanted_path is calculated
189		by the complementary percentage of shared links between them. As an
190		example, if the unwanted_path has 3 links, a given path P1 has 1 link
191		shared with unwanted_path, and a given path P2 has 2 links shared with
192		unwanted_path, then the disjointness of P1 is 0.67 and the disjointness
193		of P2 is 0.33. In this example, P1 is preferable over P2 because it
194		offers a better disjoint path. When two paths have the same
195		disjointness they are ordered by 'cost' attributed as returned from
196		Pathfinder. When the disjointness of a path is equal to 0 (i.e., it
197		shares all the links with unwanted_path), that particular path is not
198		considered a candidate.
199
200		Parameters:
201		-----------
202
203		circuit : EVC
204		The EVC providing source node (uni_a) and target node (uni_z)
205
206		unwanted_path : Path
207		The Path which we want to avoid.
208
209		cutoff: int
210		Maximum number of paths to consider when calculating the disjoint
211		paths (number of paths to request from pathfinder)
212
213		Returns:
214		--------
215		paths : generator
216		Generator of unwanted_path disjoint paths. If unwanted_path is
217		not provided or empty, we return an empty list.
218		"""
219	1	unwanted_links = [
220		(link.endpoint_a.id, link.endpoint_b.id) for link in unwanted_path
221		]
222	1	if not unwanted_links:
223	1	return None
224
225	1	paths = cls.get_paths(circuit, max_paths=cutoff,
226		**circuit.secondary_constraints)
227	1	for path in paths:
228	1	head = path["hops"][:-1]
229	1	tail = path["hops"][1:]
230	1	shared_edges = 0
231	1	for (endpoint_a, endpoint_b) in unwanted_links:
232	1	if ((endpoint_a, endpoint_b) in zip(head, tail)) or (
233		(endpoint_b, endpoint_a) in zip(head, tail)
234		):
235	1	shared_edges += 1
236	1	path["disjointness"] = 1 - shared_edges / len(unwanted_links)
237	1	paths = sorted(paths, key=lambda x: (-x['disjointness'], x['cost']))
238	1	for path in paths:
239	1	if path["disjointness"] == 0:
240	1	continue
241	1	yield cls.create_path(path["hops"])
242	1	return None
243
244	1	@classmethod
245	1	def create_path(cls, path):
246		"""Return the path containing only the interfaces."""
247	1	new_path = Path()
248	1	clean_path = cls._clear_path(path)
249
250	1	if len(clean_path) % 2:
251	1	return None
252
253	1	for link in zip(clean_path[1:-1:2], clean_path[2::2]):
254	1	interface_a = cls.controller.get_interface_by_id(link[0])
255	1	interface_b = cls.controller.get_interface_by_id(link[1])
256	1	if interface_a is None or interface_b is None:
257	1	return None
258	1	new_path.append(Link(interface_a, interface_b))
259
260		return new_path
261

kytos-ng / mef_eline

Pull Request — master (#371)

DynamicPathManager.get_disjoint_paths() C

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