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"""LivenessManager.""" |
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from typing import Optional, Tuple |
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from datetime import datetime |
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from kytos.core import KytosEvent, log |
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from kytos.core.common import EntityStatus |
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class ILSM: |
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"""InterfaceLivenessStateMachine. |
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This state machine represents the logical liveness state of the interface. |
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If an interface is admin disabled or isn't active then a manager that uses |
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this state machine should call the transition accordingly. |
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""" |
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def __init__(self, state="init") -> None: |
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"""InterfaceLivenessStateMachine.""" |
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self.transitions = { |
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"init": ["up", "down"], |
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"up": ["down", "init"], |
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"down": ["up", "init"], |
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} |
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self.state = state |
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self.last_hello_at: Optional[datetime] = None |
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def __repr__(self) -> str: |
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"""Repr.""" |
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return f"ILSM({self.state}, {self.last_hello_at})" |
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def transition_to(self, to_state: str) -> Optional[str]: |
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"""Try to transition to a state.""" |
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if to_state not in self.transitions[self.state]: |
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return None |
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self.state = to_state |
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return self.state |
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def reaper_check(self, dead_interval: int) -> Optional[str]: |
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"""Try to transition to down. It must be called every dead_interval.""" |
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if ( |
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self.last_hello_at and |
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(datetime.utcnow() - self.last_hello_at).seconds > dead_interval |
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): |
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return self.transition_to("down") |
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return None |
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def consume_hello(self, received_at: datetime) -> Optional[str]: |
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"""Consume hello. It must be called on every received hello.""" |
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self.last_hello_at = received_at |
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if self.transition_to("up"): |
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return "up" |
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return None |
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class LSM: |
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"""LivenessStateMachine aggregates two resulting ILSM acts like a link.""" |
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def __init__(self, ilsm_a: ILSM, ilsm_b: ILSM, state="init") -> None: |
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"""LinkLivenessStateMachine.""" |
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self.ilsm_a = ilsm_a |
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self.ilsm_b = ilsm_b |
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self.state = state |
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self.transitions = self.ilsm_a.transitions |
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def __repr__(self) -> str: |
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"""Repr.""" |
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return f"LSM({self.agg_state()}, {self.ilsm_a}, {self.ilsm_b})" |
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def agg_state(self) -> str: |
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"""Aggregated state.""" |
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if self.ilsm_a.state == "init" or self.ilsm_b.state == "init": |
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return "init" |
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if self.ilsm_a.state == "down" or self.ilsm_b.state == "down": |
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return "down" |
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if self.ilsm_a.state == "up" and self.ilsm_b.state == "up": |
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return "up" |
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return "init" |
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def _transition_to(self, to_state: str) -> Optional[str]: |
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"""Try to transition to a state.""" |
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if to_state not in self.transitions[self.state]: |
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return None |
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self.state = to_state |
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return self.state |
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def next_state(self) -> Optional[str]: |
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"""Next state.""" |
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return self._transition_to(self.agg_state()) |
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class LivenessManager: |
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"""LivenessManager.""" |
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def __init__(self, controller) -> None: |
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"""LivenessManager.""" |
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self.controller = controller |
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self.interfaces = {} # liveness enabled |
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self.liveness = {} # indexed by the lowest interface id of the pair |
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self.liveness_ids = {} # interface id to lowest id of the pair |
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@classmethod |
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def link_status_hook_liveness(cls, link) -> Optional[EntityStatus]: |
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"""Link status hook liveness.""" |
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if ( |
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link.is_active() |
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and link.is_enabled() |
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and "liveness_status" in link.metadata |
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and link.metadata["liveness_status"] != "up" |
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): |
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return EntityStatus.DOWN |
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return None |
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def is_enabled(self, *interfaces) -> bool: |
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"""Check if liveness is enabled on an interface.""" |
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for interface in interfaces: |
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if interface.id not in self.interfaces: |
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return False |
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return True |
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def enable(self, *interfaces) -> None: |
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"""Enable liveness on interface.""" |
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for interface in interfaces: |
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self.interfaces[interface.id] = interface |
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def disable(self, *interfaces) -> None: |
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"""Disable liveness interface.""" |
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for interface in interfaces: |
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self.interfaces.pop(interface.id, None) |
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min_id = self.liveness_ids.pop(interface.id, None) |
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self.liveness.pop(min_id, None) |
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async def atry_to_publish_lsm_event( |
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self, event_suffix: str, interface_a, interface_b |
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) -> None: |
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"""Async try to publish a LSM event.""" |
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if not event_suffix: |
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return |
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name = f"kytos/of_lldp.liveness.{event_suffix}" |
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content = {"interface_a": interface_a, "interface_b": interface_b} |
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event = KytosEvent(name=name, content=content) |
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await self.controller.buffers.app.aput(event) |
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def try_to_publish_lsm_event( |
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self, event_suffix: str, interface_a, interface_b |
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) -> None: |
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"""Try to publish a LSM event.""" |
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if not event_suffix: |
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return |
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name = f"kytos/of_lldp.liveness.{event_suffix}" |
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content = {"interface_a": interface_a, "interface_b": interface_b} |
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event = KytosEvent(name=name, content=content) |
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self.controller.buffers.app.put(event) |
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async def consume_hello_if_enabled(self, interface_a, interface_b): |
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"""Consume liveness hello if enabled.""" |
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if not self.is_enabled(interface_a, interface_b): |
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return |
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await self.consume_hello(interface_a, interface_b, datetime.utcnow()) |
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def get_interface_status( |
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self, interface_id |
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) -> Tuple[Optional[str], Optional[datetime]]: |
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"""Get interface status.""" |
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if interface_id not in self.interfaces: |
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return None, None |
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min_id = self.liveness_ids.get(interface_id) |
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if min_id and min_id in self.liveness: |
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lsm = self.liveness[min_id]["lsm"] |
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if interface_id == min_id: |
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return lsm.ilsm_a.state, lsm.ilsm_a.last_hello_at |
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else: |
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return lsm.ilsm_b.state, lsm.ilsm_b.last_hello_at |
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return "init", None |
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async def consume_hello( |
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self, interface_a, interface_b, received_at: datetime |
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) -> None: |
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"""Consume liveness hello event.""" |
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min_id = min(interface_a.id, interface_b.id) |
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is_interface_a_min_id = min_id == interface_a.id |
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if min_id not in self.liveness: |
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lsm = LSM(ILSM(state="init"), ILSM(state="init")) |
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entry = { |
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"lsm": lsm, |
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} |
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if is_interface_a_min_id: |
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entry["interface_a"], entry["interface_b"] = interface_a, interface_b |
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else: |
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entry["interface_a"], entry["interface_b"] = interface_b, interface_a |
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self.liveness[min_id] = entry |
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self.liveness_ids[interface_a.id] = min_id |
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self.liveness_ids[interface_b.id] = min_id |
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entry = self.liveness[min_id] |
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lsm = entry["lsm"] |
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if is_interface_a_min_id: |
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lsm.ilsm_a.consume_hello(received_at) |
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if entry["interface_b"].id != interface_b.id: |
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""" |
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Implies that the topology connection has changed, needs new ref |
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""" |
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entry["interface_b"] = interface_b |
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entry["lsm"].ilsm_b = ILSM(state="init") |
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else: |
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lsm.ilsm_b.consume_hello(received_at) |
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lsm_next_state = lsm.next_state() |
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log.debug( |
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f"Liveness hello {interface_a.id} <- {interface_b.id}" |
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f" next state: {lsm_next_state}, lsm: {lsm}" |
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) |
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await self.atry_to_publish_lsm_event(lsm_next_state, interface_a, interface_b) |
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def should_call_reaper(self, interface) -> bool: |
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"""Should call reaper.""" |
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if all( |
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( |
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interface.switch.is_connected(), |
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interface.lldp, |
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self.is_enabled(interface), |
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) |
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): |
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return True |
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return False |
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def reaper(self, dead_interval: int): |
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"""Reaper check processable interfaces.""" |
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for value in list(self.liveness.values()): |
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lsm, intf_a, intf_b = ( |
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value["lsm"], |
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value["interface_a"], |
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value["interface_b"], |
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) |
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if any( |
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( |
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lsm.state == "down", |
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not self.should_call_reaper(intf_a), |
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not self.should_call_reaper(intf_b), |
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) |
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): |
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continue |
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lsm.ilsm_a.reaper_check(dead_interval) |
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lsm.ilsm_b.reaper_check(dead_interval) |
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lsm_next_state = lsm.next_state() |
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if all( |
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( |
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intf_a.status == EntityStatus.UP, |
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intf_b.status == EntityStatus.UP, |
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) |
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): |
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self.try_to_publish_lsm_event( |
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lsm_next_state, value["interface_a"], value["interface_b"] |
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) |
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