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Mini Shell
# coding=utf-8
#
# Copyright © Cloud Linux GmbH & Cloud Linux Software, Inc 2010-2023 All Rights Reserved
#
# Licensed under CLOUD LINUX LICENSE AGREEMENT
# http://cloudlinux.com/docs/LICENSE.TXT
import inspect
import contextlib
from dataclasses import dataclass
from datetime import timedelta
from typing import TypeAlias, NamedTuple, AbstractSet, Self
from lvestats.orm import BurstingEventType
from .utils import bootstrap_gen
from ._logs import logger
from .common import (
BurstingMultipliers,
LveId,
Timestamp,
LveLimits,
ApplyLveSettings,
LveStats,
InvalidStateError,
LveUsage,
LveState,
calc_bursted_limits,
infer_lve_state,
)
from .history import LveHistory
from .notify import Emitter, Signal
class LveStateManager:
@dataclass(frozen=True, slots=True)
class Disappered(RuntimeError):
now: Timestamp
@dataclass(frozen=True, slots=True)
class Burst:
now: Timestamp
@dataclass(frozen=True, slots=True)
class Unburst:
now: Timestamp
# NOTE(vlebedev): Seems that namedtuples are ~20% faster to create compared to
# classes - dataclasses or usual ones.
class UpdateReadings(NamedTuple):
now: Timestamp
normal_limits: LveLimits | None
stats: LveStats | None
usage: LveUsage | None
Request: TypeAlias = UpdateReadings | Disappered | Burst | Unburst
@dataclass(frozen=True, slots=True)
class _StateSwitched(RuntimeError):
pass
def __init__(
self,
now: Timestamp,
lve_id: LveId,
bursting_multipliers: BurstingMultipliers,
initial_normal_limits: LveLimits,
initial_stats: LveStats,
initial_usage: LveUsage,
quota: timedelta,
quota_window: timedelta,
apply_lve_settings: ApplyLveSettings,
initial_history: LveHistory = LveHistory(),
fail_fast: bool = True,
):
if quota > quota_window:
raise ValueError('Bursting quota must not exceed bursting quota window!')
# NOTE(vlebedev): Constants start here.
self._lve_id = lve_id
self._bursting_multipliers = bursting_multipliers
self._quota_sec = quota.total_seconds()
self._quota_window_sec = quota_window.total_seconds()
self._fail_fast = fail_fast
# NOTE(vlebedev): Constants end here.
# NOTE(vlebedev): "Input" variables start here.
# "Input" variables are those that are read from external source (Request) and must not
# be altered by internal logic.
self._now = now
self._normal_limits = initial_normal_limits
self._stats = initial_stats
self._usage = initial_usage
self._state = infer_lve_state(
initial_stats,
initial_normal_limits,
initial_usage,
)
# NOTE(vlebedev): "Input" variables end here.
# NOTE(vlebedev): "Output" variables start here.
# "Output" variables are a channel that communicates internal state to external world.
# Internal logic is responsible for mutating these vairables.
self._history = initial_history
# NOTE(vlebedev): "Output" variables end here.
# NOTE(vlebedev): Utility stuff starts here.
# These variables are not supposed to rewritten by internal logic.
def apply_lve_settings_wrapper(cmd) -> None:
if isinstance(cmd, self.Burst):
limits = calc_bursted_limits(self._normal_limits, bursting_multipliers)
elif isinstance(cmd, self.Unburst):
limits = self._normal_limits
else:
raise ValueError(f'Unexpected command: {cmd}')
apply_lve_settings(self._lve_id, limits)
self._apply_lve_settings = apply_lve_settings_wrapper
root_handler_gen = self._create_root_handler_gen()
def step(request):
response = root_handler_gen.send(request)
if isinstance(response, Exception):
raise response
return response
self.step = step
self._on_state_changed = Emitter()
@property
def lve_id(self) -> LveId:
return self._lve_id
@property
def now(self) -> Timestamp:
return self._now
@property
def state(self) -> LveState:
return self._state
@property
def is_bursted(self) -> bool:
return self._state in {LveState.BURSTED, LveState.OVERUSING}
@property
def is_unbursted(self) -> bool:
return self._state == LveState.UNBURSTED
@property
def is_overusing(self) -> bool:
return self._state == LveState.OVERUSING
@property
def history_contains_overusing(self) -> bool:
return self._history.contains_overusing
@property
def history(self) -> LveHistory:
return self._history
def check_quota_exceeded(self, now: float) -> bool:
return self._history.get_overusing_duration(now) >= self._quota_sec
@property
def on_state_changed(self) -> Signal:
return self._on_state_changed
def trim_history(self, now: Timestamp) -> None:
cutoff = Timestamp(int(now - self._quota_window_sec))
self._history = self._history.trim(cutoff)
@bootstrap_gen
def _create_root_handler_gen(self):
# NOTE(vlebedev): This coroutine is solely responsible for modifying "input" variables.
# No mutations of "input" variables must happen outside of it.
state_to_handler_factory = {
LveState.EXISTED: self._create_existed_state_handler_gen,
LveState.UNBURSTED: self._create_unbursted_state_handler_gen,
LveState.BURSTED: self._create_bursted_state_handler_gen,
LveState.OVERUSING: self._create_overusing_state_handler_gen,
}
prev_state = next_state = self._state
subhandler = state_to_handler_factory[next_state](next_state)
request, response = None, None
while True:
try:
request, response = (yield response), None
# NOTE(vlebedev): "Input" variables mutations start here.
# It's important that it happens before invoking state handler
# so that state handler sees updated state.
assert request.now >= self._now, "Time is not expected to go backward!"
self._now = request.now
if isinstance(request, self.UpdateReadings):
if request.normal_limits is not None:
self._normal_limits = request.normal_limits
if request.stats is not None:
self._stats = request.stats
if request.usage is not None:
self._usage = request.usage
next_state = infer_lve_state(
self._stats,
self._normal_limits,
self._usage,
)
elif isinstance(request, self.Disappered):
next_state = LveState.EXISTED
self._state = next_state
# NOTE(vlebedev): "Input" variables mutations end here.
# TODO(vlebedev): Refactor subhandler management - it turned out to be quite messy.
if inspect.getgeneratorstate(subhandler) != inspect.GEN_CLOSED:
subhandler_exc = None
if isinstance(request, self.Disappered):
subhandler_exc = request
elif next_state != prev_state:
subhandler_exc = self._StateSwitched()
if subhandler_exc is not None:
try:
with contextlib.suppress(StopIteration, type(subhandler_exc)):
subhandler.throw(subhandler_exc)
except (StopIteration, type(subhandler_exc)):
logger.debug(
'LVE "%s": state subhandler for "%s" state terminated',
self._lve_id, next_state
)
except Exception:
if self._fail_fast:
raise
logger.exception(
'LVE "%s": state subhandler for "%s" state unexpectedly failed during termination!',
self._lve_id, next_state
)
else:
try:
subhandler.close()
except Exception:
if self._fail_fast:
raise
logger.exception(
'LVE "%s": state subhandler for "%s" state did not terminate properly '
'and failed during force-close!',
self._lve_id, next_state
)
if inspect.getgeneratorstate(subhandler) == inspect.GEN_CLOSED and next_state != prev_state:
subhandler = state_to_handler_factory[next_state](next_state)
logger.debug('LVE "%s": state subhandler for "%s" state created', self._lve_id, next_state)
if inspect.getgeneratorstate(subhandler) != inspect.GEN_CLOSED:
try:
response = subhandler.send(request)
except StopIteration:
logger.debug('LVE "%s": state subhandler for "%s" state finished', self._lve_id, next_state)
except Exception:
if self._fail_fast:
raise
logger.exception(
'LVE "%s": state subhandler for "%s" state failed while handling "%s" request!',
self._lve_id, next_state, request,
)
# NOTE(vlebedev): Trigger signal handlers only after all internal state has been updated.
if next_state != prev_state:
logger.debug(
'LVE "%s": transitioned from "%s" to "%s" state',
self._lve_id, prev_state, next_state,
)
try:
self._on_state_changed(prev_state, next_state)
except Exception:
if self._fail_fast:
raise
logger.exception('LVE "%s": some "on_state_changed" listeners failed!', self._lve_id)
prev_state = next_state
except Exception as e:
if self._fail_fast:
raise e
logger.critical('LVE "%s": top handler unexpectadly failed!', self._lve_id, exc_info=e)
@bootstrap_gen
def _create_unbursted_state_handler_gen(self, prev_state: LveState):
request, response = None, None
try:
while True:
request, response = (yield response), None
if isinstance(request, self.Unburst):
response = InvalidStateError('Already unbursted!')
elif isinstance(request, self.Burst):
try:
self._apply_lve_settings(request)
except Exception as e:
response = e
else:
break
except self._StateSwitched:
if self._state == LveState.BURSTED:
logger.warn(
'LVE "%s": was set to bursted externally, without internal request from adjuster',
self._lve_id,
)
raise
logger.debug('LVE "%s": waiting for bursting enabled confirmation', self._lve_id)
try:
yield from self._wait_for_confirmation_from_readings({LveState.BURSTED, LveState.OVERUSING})
except self.Disappered:
logger.debug(
'LVE "%s": disappeared while waiting for bursting enabled or overusing started confirmation',
self._lve_id,
)
raise
except self._StateSwitched:
logger.warn(
'LVE "%s": was switched to "%s" while waiting for bursting enabled or overusing started confirmation',
self._lve_id, self._state,
)
raise
assert self._state in {LveState.BURSTED, LveState.OVERUSING}
logger.debug(
'LVE "%s": confirmed from readings that bursting switched to enabled' + (
" and overusing has started" if self._state == LveState.OVERUSING else ""
), self._lve_id,
)
@bootstrap_gen
def _create_bursted_state_handler_gen(self, prev_state: LveState):
request, response = None, None
try:
while True:
request, response = (yield response), None
if isinstance(request, self.Unburst):
try:
self._apply_lve_settings(request)
except Exception as e :
response = e
else:
break
elif isinstance(request, self.Burst):
response = InvalidStateError(f'Already bursted!')
except self._StateSwitched:
if self._state == LveState.UNBURSTED:
logger.warn(
'LVE "%s": was set to unbursted externally, without internal request from adjuster',
self._lve_id,
)
raise
logger.debug('LVE "%s": waiting for bursting disabled confirmation', self._lve_id)
try:
yield from self._wait_for_confirmation_from_readings({LveState.UNBURSTED})
except self.Disappered:
logger.debug('LVE "%s": disappeared while waiting for bursting disabled confirmation', self._lve_id)
raise
except self._StateSwitched:
logger.warn(
'LVE "%s": was switched to "%s" while waiting for bursting disabled confirmation',
self._lve_id, self._state,
)
raise
logger.debug('LVE "%s": confirmed from readings that bursting switched to disabled', self._lve_id)
@bootstrap_gen
def _create_overusing_state_handler_gen(self, prev_state: LveState):
# TODO(vlebedev): Do not use absolute time but relative to the latest event with `now`.
self._history = self._history.append(self._now, BurstingEventType.STARTED)
request, response = None, None
try:
try:
while True:
request, response = (yield response), None
if isinstance(request, self.Unburst):
try:
self._apply_lve_settings(request)
except Exception as e:
response = e
else:
break
elif isinstance(request, self.Burst):
response = InvalidStateError('LVE is overusing i.e. is also already bursted!')
except self._StateSwitched:
if self._state == LveState.UNBURSTED:
logger.warn(
'LVE "%s": was set to unbursted externally, without internal request from adjuster',
self._lve_id,
)
raise
yield from self._wait_for_unbursted_confirmation_from_readings(prev_state)
finally:
self._history = self._history.append(self._now, BurstingEventType.STOPPED)
@bootstrap_gen
def _create_existed_state_handler_gen(self, prev_state: LveState):
request, response = None, None
try:
while True:
try:
request, response = (yield response), None
except self.Disappered:
logger.warn(
'LVE "%s": disappeared again while waiting for LVE to re-appear',
self._lve_id,
)
if isinstance(request, (self.Burst, self.Unburst)):
response = InvalidStateError('LVE does not exist!')
except self._StateSwitched:
logger.debug('LVE "%s": got back from the dead', self._lve_id)
return
def _wait_for_unbursted_confirmation_from_readings(self, prev_state: LveState):
try:
yield from self._wait_for_confirmation_from_readings({LveState.UNBURSTED})
except self.Disappered:
logger.debug('LVE "%s": disappeared while waiting for bursting disabled confirmation', self._lve_id)
raise
except self._StateSwitched:
logger.warn(
'LVE "%s": was switched to "%s" while waiting for bursting disabled confirmation',
self._lve_id, self._state,
)
raise
logger.debug('LVE "%s": confirmed from readings that bursting switched to disabled', self._lve_id)
def _wait_for_confirmation_from_readings(self, expected_states: AbstractSet[LveState]):
request, response = None, None
try:
while True:
request, response = (yield response), None
if isinstance(request, (self.Burst, self.Unburst)):
response = InvalidStateError('Waiting for confirmation from readings that limits have switched!')
except self._StateSwitched:
if self._state not in expected_states:
raise
_state_to_code = {
LveState.EXISTED: "X",
LveState.UNBURSTED: "U",
LveState.BURSTED: "B",
LveState.OVERUSING: "O",
}
assert _state_to_code.keys() == set(LveState)
class LveStateSummary(NamedTuple):
@classmethod
def for_lve(cls, manager: LveStateManager) -> Self:
return cls(manager.state, manager.history, manager.now)
state: LveState
history: LveHistory
now: Timestamp
def __str__(self) -> str:
intervals = self.history.get_overusing_intervals(self.now)
duration = self.history.get_overusing_duration(self.now)
state_code = _state_to_code[self.state]
return f"{state_code};[{intervals}~={round(duration)}s]"
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