This document describes Celery 3.1. For development docs, go here.

Source code for celery.events.state

# -*- coding: utf-8 -*-
"""
    celery.events.state
    ~~~~~~~~~~~~~~~~~~~

    This module implements a datastructure used to keep
    track of the state of a cluster of workers and the tasks
    it is working on (by consuming events).

    For every event consumed the state is updated,
    so the state represents the state of the cluster
    at the time of the last event.

    Snapshots (:mod:`celery.events.snapshot`) can be used to
    take "pictures" of this state at regular intervals
    to e.g. store that in a database.

"""
from __future__ import absolute_import

import sys
import threading

from datetime import datetime
from heapq import heappush, heappop
from itertools import islice
from time import time

from kombu.clocks import timetuple
from kombu.utils import kwdict

from celery import states
from celery.datastructures import AttributeDict
from celery.five import items, values
from celery.utils.functional import LRUCache
from celery.utils.log import get_logger

# The window (in percentage) is added to the workers heartbeat
# frequency.  If the time between updates exceeds this window,
# then the worker is considered to be offline.
HEARTBEAT_EXPIRE_WINDOW = 200

# Max drift between event timestamp and time of event received
# before we alert that clocks may be unsynchronized.
HEARTBEAT_DRIFT_MAX = 16

DRIFT_WARNING = """\
Substantial drift from %s may mean clocks are out of sync.  Current drift is
%s seconds.  [orig: %s recv: %s]
"""

CAN_KWDICT = sys.version_info >= (2, 6, 5)

logger = get_logger(__name__)
warn = logger.warning

R_STATE = '<State: events={0.event_count} tasks={0.task_count}>'
R_WORKER = '<Worker: {0.hostname} ({0.status_string})'
R_TASK = '<Task: {0.name}({0.uuid}) {0.state}>'

__all__ = ['Worker', 'Task', 'State', 'heartbeat_expires']


[docs]def heartbeat_expires(timestamp, freq=60, expire_window=HEARTBEAT_EXPIRE_WINDOW): return timestamp + freq * (expire_window / 1e2)
def with_unique_field(attr): def _decorate_cls(cls): def __eq__(this, other): if isinstance(other, this.__class__): return getattr(this, attr) == getattr(other, attr) return NotImplemented cls.__eq__ = __eq__ def __ne__(this, other): return not this.__eq__(other) cls.__ne__ = __ne__ def __hash__(this): return hash(getattr(this, attr)) cls.__hash__ = __hash__ return cls return _decorate_cls @with_unique_field('hostname')
[docs]class Worker(AttributeDict): """Worker State.""" heartbeat_max = 4 expire_window = HEARTBEAT_EXPIRE_WINDOW pid = None _defaults = {'hostname': None, 'pid': None, 'freq': 60} def __init__(self, **fields): dict.__init__(self, self._defaults, **fields) self.heartbeats = []
[docs] def on_online(self, timestamp=None, local_received=None, **kwargs): """Callback for the :event:`worker-online` event.""" self.update(**kwargs) self.update_heartbeat(local_received, timestamp)
[docs] def on_offline(self, **kwargs): """Callback for the :event:`worker-offline` event.""" self.update(**kwargs) self.heartbeats = []
[docs] def on_heartbeat(self, timestamp=None, local_received=None, **kwargs): """Callback for the :event:`worker-heartbeat` event.""" self.update(**kwargs) self.update_heartbeat(local_received, timestamp)
[docs] def update_heartbeat(self, received, timestamp): if not received or not timestamp: return drift = abs(int(received) - int(timestamp)) if drift > HEARTBEAT_DRIFT_MAX: warn(DRIFT_WARNING, self.hostname, drift, datetime.fromtimestamp(received), datetime.fromtimestamp(timestamp)) heartbeats, hbmax = self.heartbeats, self.heartbeat_max if not heartbeats or (received and received > heartbeats[-1]): heappush(heartbeats, received) if len(heartbeats) > hbmax: heartbeats[:] = heartbeats[hbmax:]
def __repr__(self): return R_WORKER.format(self) @property
[docs] def status_string(self): return 'ONLINE' if self.alive else 'OFFLINE'
@property
[docs] def heartbeat_expires(self): return heartbeat_expires(self.heartbeats[-1], self.freq, self.expire_window)
@property
[docs] def alive(self): return bool(self.heartbeats and time() < self.heartbeat_expires)
@property
[docs] def id(self): return '{0.hostname}.{0.pid}'.format(self)
@with_unique_field('uuid')
[docs]class Task(AttributeDict): """Task State.""" #: How to merge out of order events. #: Disorder is detected by logical ordering (e.g. :event:`task-received` #: must have happened before a :event:`task-failed` event). #: #: A merge rule consists of a state and a list of fields to keep from #: that state. ``(RECEIVED, ('name', 'args')``, means the name and args #: fields are always taken from the RECEIVED state, and any values for #: these fields received before or after is simply ignored. merge_rules = {states.RECEIVED: ('name', 'args', 'kwargs', 'retries', 'eta', 'expires')} #: meth:`info` displays these fields by default. _info_fields = ('args', 'kwargs', 'retries', 'result', 'eta', 'runtime', 'expires', 'exception', 'exchange', 'routing_key') #: Default values. _defaults = dict(uuid=None, name=None, state=states.PENDING, received=False, sent=False, started=False, succeeded=False, failed=False, retried=False, revoked=False, args=None, kwargs=None, eta=None, expires=None, retries=None, worker=None, result=None, exception=None, timestamp=None, runtime=None, traceback=None, exchange=None, routing_key=None, clock=0) def __init__(self, **fields): dict.__init__(self, self._defaults, **fields)
[docs] def update(self, state, timestamp, fields, _state=states.state): """Update state from new event. :param state: State from event. :param timestamp: Timestamp from event. :param fields: Event data. """ time_received = fields.get('local_received') or 0 if self.worker and time_received: self.worker.update_heartbeat(time_received, timestamp) if state != states.RETRY and self.state != states.RETRY and \ _state(state) < _state(self.state): # this state logically happens-before the current state, so merge. self.merge(state, timestamp, fields) else: self.state = state self.timestamp = timestamp super(Task, self).update(fields)
[docs] def merge(self, state, timestamp, fields): """Merge with out of order event.""" keep = self.merge_rules.get(state) if keep is not None: fields = dict((key, fields.get(key)) for key in keep) super(Task, self).update(fields)
[docs] def on_sent(self, timestamp=None, **fields): """Callback for the :event:`task-sent` event.""" self.sent = timestamp self.update(states.PENDING, timestamp, fields)
[docs] def on_received(self, timestamp=None, **fields): """Callback for the :event:`task-received` event.""" self.received = timestamp self.update(states.RECEIVED, timestamp, fields)
[docs] def on_started(self, timestamp=None, **fields): """Callback for the :event:`task-started` event.""" self.started = timestamp self.update(states.STARTED, timestamp, fields)
[docs] def on_failed(self, timestamp=None, **fields): """Callback for the :event:`task-failed` event.""" self.failed = timestamp self.update(states.FAILURE, timestamp, fields)
[docs] def on_retried(self, timestamp=None, **fields): """Callback for the :event:`task-retried` event.""" self.retried = timestamp self.update(states.RETRY, timestamp, fields)
[docs] def on_succeeded(self, timestamp=None, **fields): """Callback for the :event:`task-succeeded` event.""" self.succeeded = timestamp self.update(states.SUCCESS, timestamp, fields)
[docs] def on_revoked(self, timestamp=None, **fields): """Callback for the :event:`task-revoked` event.""" self.revoked = timestamp self.update(states.REVOKED, timestamp, fields)
[docs] def on_unknown_event(self, shortype, timestamp=None, **fields): self.update(shortype.upper(), timestamp, fields)
[docs] def info(self, fields=None, extra=[]): """Information about this task suitable for on-screen display.""" fields = self._info_fields if fields is None else fields def _keys(): for key in list(fields) + list(extra): value = getattr(self, key, None) if value is not None: yield key, value return dict(_keys())
def __repr__(self): return R_TASK.format(self) @property
[docs] def ready(self): return self.state in states.READY_STATES
[docs]class State(object): """Records clusters state.""" event_count = 0 task_count = 0 def __init__(self, callback=None, workers=None, tasks=None, taskheap=None, max_workers_in_memory=5000, max_tasks_in_memory=10000): self.event_callback = callback self.workers = (LRUCache(max_workers_in_memory) if workers is None else workers) self.tasks = (LRUCache(max_tasks_in_memory) if tasks is None else tasks) self._taskheap = [] if taskheap is None else taskheap self.max_workers_in_memory = max_workers_in_memory self.max_tasks_in_memory = max_tasks_in_memory self._mutex = threading.Lock() self.handlers = {'task': self.task_event, 'worker': self.worker_event} self._get_handler = self.handlers.__getitem__
[docs] def freeze_while(self, fun, *args, **kwargs): clear_after = kwargs.pop('clear_after', False) with self._mutex: try: return fun(*args, **kwargs) finally: if clear_after: self._clear()
[docs] def clear_tasks(self, ready=True): with self._mutex: return self._clear_tasks(ready)
def _clear_tasks(self, ready=True): if ready: in_progress = dict( (uuid, task) for uuid, task in self.itertasks() if task.state not in states.READY_STATES) self.tasks.clear() self.tasks.update(in_progress) else: self.tasks.clear() self._taskheap[:] = [] def _clear(self, ready=True): self.workers.clear() self._clear_tasks(ready) self.event_count = 0 self.task_count = 0
[docs] def clear(self, ready=True): with self._mutex: return self._clear(ready)
[docs] def get_or_create_worker(self, hostname, **kwargs): """Get or create worker by hostname. Return tuple of ``(worker, was_created)``. """ try: worker = self.workers[hostname] worker.update(kwargs) return worker, False except KeyError: worker = self.workers[hostname] = Worker( hostname=hostname, **kwargs) return worker, True
[docs] def get_or_create_task(self, uuid): """Get or create task by uuid.""" try: return self.tasks[uuid], False except KeyError: task = self.tasks[uuid] = Task(uuid=uuid) return task, True
[docs] def worker_event(self, type, fields): """Process worker event.""" try: hostname = fields['hostname'] except KeyError: pass else: worker, created = self.get_or_create_worker(hostname) handler = getattr(worker, 'on_' + type, None) if handler: handler(**(fields if CAN_KWDICT else kwdict(fields))) return worker, created
[docs] def task_event(self, type, fields, timetuple=timetuple): """Process task event.""" uuid = fields['uuid'] hostname = fields['hostname'] worker, _ = self.get_or_create_worker(hostname) task, created = self.get_or_create_task(uuid) task.worker = worker maxtasks = self.max_tasks_in_memory * 2 taskheap = self._taskheap timestamp = fields.get('timestamp') or 0 clock = 0 if type == 'sent' else fields.get('clock') heappush(taskheap, timetuple(clock, timestamp, worker.id, task)) if len(taskheap) > maxtasks: heappop(taskheap) handler = getattr(task, 'on_' + type, None) if type == 'received': self.task_count += 1 if handler: handler(**fields) else: task.on_unknown_event(type, **fields) return created
[docs] def event(self, event): with self._mutex: return self._dispatch_event(event)
def _dispatch_event(self, event, kwdict=kwdict): self.event_count += 1 event = kwdict(event) group, _, subject = event['type'].partition('-') try: self._get_handler(group)(subject, event) except KeyError: pass if self.event_callback: self.event_callback(self, event)
[docs] def itertasks(self, limit=None): for index, row in enumerate(items(self.tasks)): yield row if limit and index + 1 >= limit: break
[docs] def tasks_by_time(self, limit=None): """Generator giving tasks ordered by time, in ``(uuid, Task)`` tuples.""" seen = set() for evtup in islice(reversed(self._taskheap), 0, limit): uuid = evtup[3].uuid if uuid not in seen: yield uuid, evtup[3] seen.add(uuid)
tasks_by_timestamp = tasks_by_time
[docs] def tasks_by_type(self, name, limit=None): """Get all tasks by type. Return a list of ``(uuid, Task)`` tuples. """ return islice( ((uuid, task) for uuid, task in self.tasks_by_time() if task.name == name), 0, limit, )
[docs] def tasks_by_worker(self, hostname, limit=None): """Get all tasks by worker. """ return islice( ((uuid, task) for uuid, task in self.tasks_by_time() if task.worker.hostname == hostname), 0, limit, )
[docs] def task_types(self): """Return a list of all seen task types.""" return list(sorted(set(task.name for task in values(self.tasks) if task.name is not None)))
[docs] def alive_workers(self): """Return a list of (seemingly) alive workers.""" return [w for w in values(self.workers) if w.alive]
def __repr__(self): return R_STATE.format(self) def __reduce__(self): return self.__class__, ( self.event_callback, self.workers, self.tasks, self._taskheap, self.max_workers_in_memory, self.max_tasks_in_memory, )