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import os
import errno
import logging
import time
from threading import Lock
from typing import Dict
from .state_transition import ActionType, PolicyAction, Transition, \
State, StateTransition
from ..exception import MirrorException
log = logging.getLogger(__name__)
class DirectoryState:
def __init__(self, instance_id=None, mapped_time=None):
self.instance_id = instance_id
self.mapped_time = mapped_time
self.state = State.UNASSOCIATED
self.stalled = False
self.transition = Transition(ActionType.NONE)
self.next_state = None
self.purging = False
def __str__(self):
return f'[instance_id={self.instance_id}, mapped_time={self.mapped_time},'\
f' state={self.state}, transition={self.transition}, next_state={self.next_state},'\
f' purging={self.purging}]'
class Policy:
# number of seconds after which a directory can be reshuffled
# to other mirror daemon instances.
DIR_SHUFFLE_THROTTLE_INTERVAL = 300
def __init__(self):
self.dir_states = {}
self.instance_to_dir_map = {}
self.dead_instances = []
self.lock = Lock()
@staticmethod
def is_instance_action(action_type):
return action_type in (ActionType.ACQUIRE,
ActionType.RELEASE)
def is_dead_instance(self, instance_id):
return instance_id in self.dead_instances
def is_state_scheduled(self, dir_state, state):
return dir_state.state == state or dir_state.next_state == state
def is_shuffling(self, dir_path):
log.debug(f'is_shuffling: {dir_path}')
return self.is_state_scheduled(self.dir_states[dir_path], State.SHUFFLING)
def can_shuffle_dir(self, dir_path):
"""Right now, shuffle directories only based on idleness. Later, we
probably want to avoid shuffling images that were recently shuffled.
"""
log.debug(f'can_shuffle_dir: {dir_path}')
dir_state = self.dir_states[dir_path]
return StateTransition.is_idle(dir_state.state) and \
(time.time() - dir_state['mapped_time']) > Policy.DIR_SHUFFLE_THROTTLE_INTERVAL
def set_state(self, dir_state, state, ignore_current_state=False):
if not ignore_current_state and dir_state.state == state:
return False
elif StateTransition.is_idle(dir_state.state):
dir_state.state = state
dir_state.next_state = None
dir_state.transition = StateTransition.transit(
dir_state.state, dir_state.transition.action_type)
return True
dir_state.next_state = state
return False
def init(self, dir_mapping):
with self.lock:
for dir_path, dir_map in dir_mapping.items():
instance_id = dir_map['instance_id']
if instance_id:
if not instance_id in self.instance_to_dir_map:
self.instance_to_dir_map[instance_id] = []
self.instance_to_dir_map[instance_id].append(dir_path)
self.dir_states[dir_path] = DirectoryState(instance_id, dir_map['last_shuffled'])
dir_state = self.dir_states[dir_path]
state = State.INITIALIZING if instance_id else State.ASSOCIATING
purging = dir_map.get('purging', 0)
if purging:
dir_state.purging = True
state = State.DISASSOCIATING
if not instance_id:
dir_state.transition = StateTransition.transit(state,
dir_state.transition.action_type)
log.debug(f'starting state: {dir_path} {state}: {dir_state}')
self.set_state(dir_state, state)
log.debug(f'init dir_state: {dir_state}')
def lookup(self, dir_path):
log.debug(f'looking up {dir_path}')
with self.lock:
dir_state = self.dir_states.get(dir_path, None)
if dir_state:
return {'instance_id': dir_state.instance_id,
'mapped_time': dir_state.mapped_time,
'purging': dir_state.purging}
return None
def map(self, dir_path, dir_state):
log.debug(f'mapping {dir_path}')
min_instance_id = None
current_instance_id = dir_state.instance_id
if current_instance_id and not self.is_dead_instance(current_instance_id):
return True
if self.is_dead_instance(current_instance_id):
self.unmap(dir_path, dir_state)
for instance_id, dir_paths in self.instance_to_dir_map.items():
if self.is_dead_instance(instance_id):
continue
if not min_instance_id or len(dir_paths) < len(self.instance_to_dir_map[min_instance_id]):
min_instance_id = instance_id
if not min_instance_id:
log.debug(f'instance unavailable for {dir_path}')
return False
log.debug(f'dir_path {dir_path} maps to instance {min_instance_id}')
dir_state.instance_id = min_instance_id
dir_state.mapped_time = time.time()
self.instance_to_dir_map[min_instance_id].append(dir_path)
return True
def unmap(self, dir_path, dir_state):
instance_id = dir_state.instance_id
log.debug(f'unmapping {dir_path} from instance {instance_id}')
self.instance_to_dir_map[instance_id].remove(dir_path)
dir_state.instance_id = None
dir_state.mapped_time = None
if self.is_dead_instance(instance_id) and not self.instance_to_dir_map[instance_id]:
self.instance_to_dir_map.pop(instance_id)
self.dead_instances.remove(instance_id)
def shuffle(self, dirs_per_instance, include_stalled_dirs):
log.debug(f'directories per instance: {dirs_per_instance}')
shuffle_dirs = []
for instance_id, dir_paths in self.instance_to_dir_map.items():
cut_off = len(dir_paths) - dirs_per_instance
if cut_off > 0:
for dir_path in dir_paths:
if cut_off == 0:
break
if self.is_shuffling(dir_path):
cut_off -= 1
elif self.can_shuffle_dir(dir_path):
cut_off -= 1
shuffle_dirs.append(dir_path)
if include_stalled_dirs:
for dir_path, dir_state in self.dir_states.items():
if dir_state.stalled:
log.debug(f'{dir_path} is stalled: {dir_state} -- trigerring kick')
dir_state.stalled = False
shuffle_dirs.append(dir_path)
return shuffle_dirs
def execute_policy_action(self, dir_path, dir_state, policy_action):
log.debug(f'executing for directory {dir_path} policy_action {policy_action}')
done = True
if policy_action == PolicyAction.MAP:
done = self.map(dir_path, dir_state)
elif policy_action == PolicyAction.UNMAP:
self.unmap(dir_path, dir_state)
elif policy_action == PolicyAction.REMOVE:
if dir_state.state == State.UNASSOCIATED:
self.dir_states.pop(dir_path)
else:
raise Exception()
return done
def start_action(self, dir_path):
log.debug(f'start action: {dir_path}')
with self.lock:
dir_state = self.dir_states.get(dir_path, None)
if not dir_state:
raise Exception()
log.debug(f'dir_state: {dir_state}')
if dir_state.transition.start_policy_action:
stalled = not self.execute_policy_action(dir_path, dir_state,
dir_state.transition.start_policy_action)
if stalled:
next_action = ActionType.NONE
if dir_state.purging:
dir_state.next_state = None
dir_state.state = State.UNASSOCIATED
dir_state.transition = StateTransition.transit(State.DISASSOCIATING, ActionType.NONE)
self.set_state(dir_state, State.DISASSOCIATING)
next_action = dir_state.transition.action_type
else:
dir_state.stalled = True
log.debug(f'state machine stalled')
return next_action
return dir_state.transition.action_type
def finish_action(self, dir_path, r):
log.debug(f'finish action {dir_path} r={r}')
with self.lock:
dir_state = self.dir_states.get(dir_path, None)
if not dir_state:
raise Exception()
if r < 0 and (not Policy.is_instance_action(dir_state.transition.action_type) or
not dir_state.instance_id or
not dir_state.instance_id in self.dead_instances):
return True
log.debug(f'dir_state: {dir_state}')
finish_policy_action = dir_state.transition.finish_policy_action
dir_state.transition = StateTransition.transit(
dir_state.state, dir_state.transition.action_type)
log.debug(f'transitioned to dir_state: {dir_state}')
if dir_state.transition.final_state:
log.debug('reached final state')
dir_state.state = dir_state.transition.final_state
dir_state.transition = Transition(ActionType.NONE)
log.debug(f'final dir_state: {dir_state}')
if StateTransition.is_idle(dir_state.state) and dir_state.next_state:
self.set_state(dir_state, dir_state.next_state)
pending = not dir_state.transition.action_type == ActionType.NONE
if finish_policy_action:
self.execute_policy_action(dir_path, dir_state, finish_policy_action)
return pending
def find_tracked_ancestor_or_subtree(self, dir_path):
for tracked_path, _ in self.dir_states.items():
comp = [dir_path, tracked_path]
cpath = os.path.commonpath(comp)
if cpath in comp:
what = 'subtree' if cpath == tracked_path else 'ancestor'
return (tracked_path, what)
return None
def add_dir(self, dir_path):
log.debug(f'adding dir_path {dir_path}')
with self.lock:
if dir_path in self.dir_states:
return False
as_info = self.find_tracked_ancestor_or_subtree(dir_path)
if as_info:
raise MirrorException(-errno.EINVAL, f'{dir_path} is a {as_info[1]} of tracked path {as_info[0]}')
self.dir_states[dir_path] = DirectoryState()
dir_state = self.dir_states[dir_path]
log.debug(f'add dir_state: {dir_state}')
if dir_state.state == State.INITIALIZING:
return False
return self.set_state(dir_state, State.ASSOCIATING)
def remove_dir(self, dir_path):
log.debug(f'removing dir_path {dir_path}')
with self.lock:
dir_state = self.dir_states.get(dir_path, None)
if not dir_state:
return False
log.debug(f'removing dir_state: {dir_state}')
dir_state.purging = True
# advance the state machine with DISASSOCIATING state for removal
if dir_state.stalled:
dir_state.state = State.UNASSOCIATED
dir_state.transition = StateTransition.transit(State.DISASSOCIATING, ActionType.NONE)
r = self.set_state(dir_state, State.DISASSOCIATING)
log.debug(f'dir_state: {dir_state}')
return r
def add_instances_initial(self, instance_ids):
"""Take care of figuring out instances which no longer exist
and remove them. This is to be done only once on startup to
identify instances which were previously removed but directories
are still mapped (on-disk) to them.
"""
for instance_id in instance_ids:
if not instance_id in self.instance_to_dir_map:
self.instance_to_dir_map[instance_id] = []
dead_instances = []
for instance_id, _ in self.instance_to_dir_map.items():
if not instance_id in instance_ids:
dead_instances.append(instance_id)
if dead_instances:
self._remove_instances(dead_instances)
def add_instances(self, instance_ids, initial_update=False):
log.debug(f'adding instances: {instance_ids} initial_update {initial_update}')
with self.lock:
if initial_update:
self.add_instances_initial(instance_ids)
else:
nr_instances = len(self.instance_to_dir_map)
nr_dead_instances = len(self.dead_instances)
if nr_instances > 0:
# adjust dead instances
nr_instances -= nr_dead_instances
include_stalled_dirs = nr_instances == 0
for instance_id in instance_ids:
if not instance_id in self.instance_to_dir_map:
self.instance_to_dir_map[instance_id] = []
dirs_per_instance = int(len(self.dir_states) /
(len(self.instance_to_dir_map) - nr_dead_instances))
if dirs_per_instance == 0:
dirs_per_instance += 1
shuffle_dirs = []
# super set of directories which are candidates for shuffling -- choose
# those which can be shuffle rightaway (others will be shuffled when
# they reach idle state).
shuffle_dirs_ss = self.shuffle(dirs_per_instance, include_stalled_dirs)
if include_stalled_dirs:
return shuffle_dirs_ss
for dir_path in shuffle_dirs_ss:
dir_state = self.dir_states[dir_path]
if self.set_state(dir_state, State.SHUFFLING):
shuffle_dirs.append(dir_path)
log.debug(f'remapping directories: {shuffle_dirs}')
return shuffle_dirs
def remove_instances(self, instance_ids):
with self.lock:
return self._remove_instances(instance_ids)
def _remove_instances(self, instance_ids):
log.debug(f'removing instances: {instance_ids}')
shuffle_dirs = []
for instance_id in instance_ids:
if not instance_id in self.instance_to_dir_map:
continue
if not self.instance_to_dir_map[instance_id]:
self.instance_to_dir_map.pop(instance_id)
continue
self.dead_instances.append(instance_id)
dir_paths = self.instance_to_dir_map[instance_id]
log.debug(f'force shuffling instance_id {instance_id}, directories {dir_paths}')
for dir_path in dir_paths:
dir_state = self.dir_states[dir_path]
if self.is_state_scheduled(dir_state, State.DISASSOCIATING):
log.debug(f'dir_path {dir_path} is disassociating, ignoring...')
continue
log.debug(f'shuffling dir_path {dir_path}')
if self.set_state(dir_state, State.SHUFFLING, True):
shuffle_dirs.append(dir_path)
log.debug(f'shuffling {shuffle_dirs}')
return shuffle_dirs
def dir_status(self, dir_path):
with self.lock:
dir_state = self.dir_states.get(dir_path, None)
if not dir_state:
raise MirrorException(-errno.ENOENT, f'{dir_path} is not tracked')
res = {} # type: Dict
if dir_state.stalled:
res['state'] = 'stalled'
res['reason'] = 'no mirror daemons running'
elif dir_state.state == State.ASSOCIATING:
res['state'] = 'mapping'
else:
state = None
dstate = dir_state.state
if dstate == State.ASSOCIATING:
state = 'mapping'
elif dstate == State.DISASSOCIATING:
state = 'unmapping'
elif dstate == State.SHUFFLING:
state = 'shuffling'
elif dstate == State.ASSOCIATED:
state = 'mapped'
elif dstate == State.INITIALIZING:
state = 'resolving'
res['state'] = state
res['instance_id'] = dir_state.instance_id
res['last_shuffled'] = dir_state.mapped_time
return res
def instance_summary(self):
with self.lock:
res = {
'mapping': {}
} # type: Dict
for instance_id, dir_paths in self.instance_to_dir_map.items():
res['mapping'][instance_id] = f'{len(dir_paths)} directories'
return res
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