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"""Classes related to paths""" |
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import requests |
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from kytos.core import log |
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from kytos.core.common import EntityStatus, GenericEntity |
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from kytos.core.link import Link |
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from napps.kytos.mef_eline import settings |
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from napps.kytos.mef_eline.exceptions import DisabledSwitch, InvalidPath |
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class Path(list, GenericEntity): |
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"""Class to represent a Path.""" |
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def __eq__(self, other=None): |
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"""Compare paths.""" |
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if not other or not isinstance(other, Path): |
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return False |
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return super().__eq__(other) |
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def is_affected_by_link(self, link=None): |
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"""Verify if the current path is affected by link.""" |
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if not link: |
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return False |
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return link in self |
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def link_affected_by_interface(self, interface=None): |
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"""Return the link using this interface, if any, or None otherwise.""" |
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if not interface: |
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return None |
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for link in self: |
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if interface in (link.endpoint_a, link.endpoint_b): |
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return link |
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return None |
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def choose_vlans(self): |
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"""Choose the VLANs to be used for the circuit.""" |
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for link in self: |
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tag = link.get_next_available_tag() |
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link.add_metadata("s_vlan", tag) |
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def make_vlans_available(self): |
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"""Make the VLANs used in a path available when undeployed.""" |
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for link in self: |
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link.make_tag_available(link.get_metadata("s_vlan")) |
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link.remove_metadata("s_vlan") |
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def is_valid(self, switch_a, switch_z, is_scheduled=False): |
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"""Check if this is a valid path.""" |
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if not self: |
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return True |
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previous = switch_a |
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for link in self: |
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if link.endpoint_a.switch.status == EntityStatus.DISABLED: |
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switch = link.endpoint_a.switch.dpid |
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raise DisabledSwitch(f"{switch} is disabled") |
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if link.endpoint_b.switch.status == EntityStatus.DISABLED: |
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switch = link.endpoint_b.switch.dpid |
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raise DisabledSwitch(f"{switch} is disabled") |
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if link.endpoint_a.switch != previous: |
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raise InvalidPath( |
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f"{link.endpoint_a} switch is different" f" from previous." |
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) |
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if is_scheduled is False and ( |
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link.endpoint_a.link is None |
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or link.endpoint_a.link != link |
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or link.endpoint_b.link is None |
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or link.endpoint_b.link != link |
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): |
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raise InvalidPath(f"Link {link} is not available.") |
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previous = link.endpoint_b.switch |
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if previous == switch_z: |
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return True |
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raise InvalidPath("Last endpoint is different from uni_z") |
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@property |
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def status(self): |
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"""Check for the status of a path. |
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If any link in this path is down, the path is considered down. |
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""" |
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if not self: |
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return EntityStatus.DISABLED |
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endpoint = f"{settings.TOPOLOGY_URL}/links" |
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api_reply = requests.get(endpoint) |
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if api_reply.status_code != getattr(requests.codes, "ok"): |
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log.error( |
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"Failed to get links at %s. Returned %s", |
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endpoint, |
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api_reply.status_code, |
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) |
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return None |
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links = api_reply.json()["links"] |
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return_status = EntityStatus.UP |
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for path_link in self: |
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try: |
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link = links[path_link.id] |
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except KeyError: |
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return EntityStatus.DISABLED |
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if link["enabled"] is False: |
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return EntityStatus.DISABLED |
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if link["active"] is False: |
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return_status = EntityStatus.DOWN |
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return return_status |
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def as_dict(self): |
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"""Return list comprehension of links as_dict.""" |
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return [link.as_dict() for link in self if link] |
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class DynamicPathManager: |
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"""Class to handle and create paths.""" |
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controller = None |
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@classmethod |
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def set_controller(cls, controller=None): |
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"""Set the controller to discovery news paths.""" |
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cls.controller = controller |
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@staticmethod |
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def get_paths(circuit, max_paths=2, **kwargs): |
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"""Get a valid path for the circuit from the Pathfinder.""" |
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endpoint = settings.PATHFINDER_URL |
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request_data = { |
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"source": circuit.uni_a.interface.id, |
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"destination": circuit.uni_z.interface.id, |
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"spf_max_paths": max_paths, |
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} |
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request_data.update(kwargs) |
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api_reply = requests.post(endpoint, json=request_data) |
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if api_reply.status_code != getattr(requests.codes, "ok"): |
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log.error( |
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"Failed to get paths at %s. Returned %s", |
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endpoint, |
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api_reply.text, |
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) |
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return None |
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reply_data = api_reply.json() |
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return reply_data.get("paths") |
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@staticmethod |
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def _clear_path(path): |
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"""Remove switches from a path, returning only interfaces.""" |
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return [endpoint for endpoint in path if len(endpoint) > 23] |
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@classmethod |
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def get_best_path(cls, circuit): |
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"""Return the best path available for a circuit, if exists.""" |
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paths = cls.get_paths(circuit) |
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if paths: |
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return cls.create_path(cls.get_paths(circuit)[0]["hops"]) |
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return None |
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@classmethod |
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def get_best_paths(cls, circuit, **kwargs): |
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"""Return the best paths available for a circuit, if they exist.""" |
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for path in cls.get_paths(circuit, **kwargs): |
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yield cls.create_path(path["hops"]) |
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@classmethod |
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def get_disjoint_paths( |
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cls, circuit, unwanted_path, cutoff=settings.DISJOINT_PATH_CUTOFF |
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): |
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"""Computes the maximum disjoint paths from the unwanted_path for a EVC |
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Maximum disjoint paths from the unwanted_path are the paths from the |
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source node to the target node that share the minimum number os links |
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contained in unwanted_path. In other words, unwanted_path is the path |
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we want to avoid: we want the maximum possible disjoint path from it. |
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The disjointness of a path in regards to unwanted_path is calculated |
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by the complementary percentage of shared links between them. As an |
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example, if the unwanted_path has 3 links, a given path P1 has 1 link |
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shared with unwanted_path, and a given path P2 has 2 links shared with |
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unwanted_path, then the disjointness of P1 is 0.67 and the disjointness |
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of P2 is 0.33. In this example, P1 is preferable over P2 because it |
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offers a better disjoint path. When two paths have the same |
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disjointness they are ordered by 'cost' attributed as returned from |
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Pathfinder. When the disjointness of a path is equal to 0 (i.e., it |
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shares all the links with unwanted_path), that particular path is not |
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considered a candidate. |
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Parameters: |
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----------- |
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circuit : EVC |
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The EVC providing source node (uni_a) and target node (uni_z) |
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unwanted_path : Path |
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The Path which we want to avoid. |
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cutoff: int |
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Maximum number of paths to consider when calculating the disjoint |
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paths (number of paths to request from pathfinder) |
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Returns: |
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-------- |
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paths : generator |
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Generator of unwanted_path disjoint paths. If unwanted_path is |
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not provided or empty, we return an empty list. |
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""" |
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unwanted_links = [ |
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(link.endpoint_a.id, link.endpoint_b.id) for link in unwanted_path |
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] |
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if not unwanted_links: |
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return None |
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paths = cls.get_paths(circuit, max_paths=cutoff, |
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**circuit.secondary_constraints) |
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for path in paths: |
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head = path["hops"][:-1] |
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tail = path["hops"][1:] |
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shared_edges = 0 |
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for (endpoint_a, endpoint_b) in unwanted_links: |
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if ((endpoint_a, endpoint_b) in zip(head, tail)) or ( |
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(endpoint_b, endpoint_a) in zip(head, tail) |
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): |
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shared_edges += 1 |
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path["disjointness"] = 1 - shared_edges / len(unwanted_links) |
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paths = sorted(paths, key=lambda x: (-x['disjointness'], x['cost'])) |
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for path in paths: |
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if path["disjointness"] == 0: |
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continue |
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yield cls.create_path(path["hops"]) |
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return None |
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@classmethod |
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def create_path(cls, path): |
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"""Return the path containing only the interfaces.""" |
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new_path = Path() |
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clean_path = cls._clear_path(path) |
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if len(clean_path) % 2: |
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return None |
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for link in zip(clean_path[1:-1:2], clean_path[2::2]): |
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interface_a = cls.controller.get_interface_by_id(link[0]) |
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interface_b = cls.controller.get_interface_by_id(link[1]) |
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if interface_a is None or interface_b is None: |
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return None |
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new_path.append(Link(interface_a, interface_b)) |
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return new_path |
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kytos-ng /
mef_eline
