celery/celery/app/control.py

# -*- coding: utf-8 -*-
"""Worker Remote Control Client.

Client for worker remote control commands.
Server implementation is in :mod:`celery.worker.control`.
"""
from __future__ import absolute_import, unicode_literals

import warnings

from billiard.common import TERM_SIGNAME

from kombu.pidbox import Mailbox
from kombu.utils.functional import lazy
from kombu.utils.objects import cached_property

from celery.exceptions import DuplicateNodenameWarning
from celery.utils.text import pluralize

__all__ = ['Inspect', 'Control', 'flatten_reply']

W_DUPNODE = """\
Received multiple replies from node {0}: {1}.
Please make sure you give each node a unique nodename using
the celery worker `-n` option.\
"""


def flatten_reply(reply):
    """Flatten node replies.

    Convert from a list of replies in this format::

        [{'a@example.com': reply},
         {'b@example.com': reply}]

    into this format::

        {'a@example.com': reply,
         'b@example.com': reply}
    """
    nodes, dupes = {}, set()
    for item in reply:
        [dupes.add(name) for name in item if name in nodes]
        nodes.update(item)
    if dupes:
        warnings.warn(DuplicateNodenameWarning(
            W_DUPNODE.format(
                pluralize(len(dupes), 'name'), ', '.join(sorted(dupes)),
            ),
        ))
    return nodes


class Inspect(object):
    """API for app.control.inspect."""

    app = None

    def __init__(self, destination=None, timeout=1, callback=None,
                 connection=None, app=None, limit=None):
        self.app = app or self.app
        self.destination = destination
        self.timeout = timeout
        self.callback = callback
        self.connection = connection
        self.limit = limit

    def _prepare(self, reply):
        if reply:
            by_node = flatten_reply(reply)
            if (self.destination and
                    not isinstance(self.destination, (list, tuple))):
                return by_node.get(self.destination)
            return by_node

    def _request(self, command, **kwargs):
        return self._prepare(self.app.control.broadcast(
            command,
            arguments=kwargs,
            destination=self.destination,
            callback=self.callback,
            connection=self.connection,
            limit=self.limit,
            timeout=self.timeout, reply=True,
        ))

    def report(self):
        return self._request('report')

    def clock(self):
        return self._request('clock')

    def active(self, safe=None):
        # safe is ignored since 4.0
        # as no objects will need serialization now that we
        # have argsrepr/kwargsrepr.
        return self._request('active')

    def scheduled(self, safe=None):
        return self._request('scheduled')

    def reserved(self, safe=None):
        return self._request('reserved')

    def stats(self):
        return self._request('stats')

    def revoked(self):
        return self._request('revoked')

    def registered(self, *taskinfoitems):
        return self._request('registered', taskinfoitems=taskinfoitems)
    registered_tasks = registered

    def ping(self):
        return self._request('ping')

    def active_queues(self):
        return self._request('active_queues')

    def query_task(self, ids):
        return self._request('query_task', ids=ids)

    def conf(self, with_defaults=False):
        return self._request('conf', with_defaults=with_defaults)

    def hello(self, from_node, revoked=None):
        return self._request('hello', from_node=from_node, revoked=revoked)

    def memsample(self):
        return self._request('memsample')

    def memdump(self, samples=10):
        return self._request('memdump', samples=samples)

    def objgraph(self, type='Request', n=200, max_depth=10):
        return self._request('objgraph', num=n, max_depth=max_depth, type=type)


class Control(object):
    """Worker remote control client."""

    Mailbox = Mailbox

    def __init__(self, app=None):
        self.app = app
        self.mailbox = self.Mailbox(
            'celery',
            type='fanout',
            accept=['json'],
            producer_pool=lazy(lambda: self.app.amqp.producer_pool),
        )

    @cached_property
    def inspect(self):
        return self.app.subclass_with_self(Inspect, reverse='control.inspect')

    def purge(self, connection=None):
        """Discard all waiting tasks.

        This will ignore all tasks waiting for execution, and they will
        be deleted from the messaging server.

        Arguments:
            connection (kombu.Connection): Optional specific connection
                instance to use.  If not provided a connection will
                be acquired from the connection pool.

        Returns:
            int: the number of tasks discarded.
        """
        with self.app.connection_or_acquire(connection) as conn:
            return self.app.amqp.TaskConsumer(conn).purge()
    discard_all = purge

    def election(self, id, topic, action=None, connection=None):
        self.broadcast('election', connection=connection, arguments={
            'id': id, 'topic': topic, 'action': action,
        })

    def revoke(self, task_id, destination=None, terminate=False,
               signal=TERM_SIGNAME, **kwargs):
        """Tell all (or specific) workers to revoke a task by id.

        If a task is revoked, the workers will ignore the task and
        not execute it after all.

        Arguments:
            task_id (str): Id of the task to revoke.
            terminate (bool): Also terminate the process currently working
                on the task (if any).
            signal (str): Name of signal to send to process if terminate.
                Default is TERM.

        See Also:
            :meth:`broadcast` for supported keyword arguments.
        """
        return self.broadcast('revoke', destination=destination,
                              arguments={'task_id': task_id,
                                         'terminate': terminate,
                                         'signal': signal}, **kwargs)

    def ping(self, destination=None, timeout=1, **kwargs):
        """Ping all (or specific) workers.

        Returns:
            List[Dict]: List of ``{'hostname': reply}`` dictionaries.

        See Also:
            :meth:`broadcast` for supported keyword arguments.
        """
        return self.broadcast('ping', reply=True, destination=destination,
                              timeout=timeout, **kwargs)

    def rate_limit(self, task_name, rate_limit, destination=None, **kwargs):
        """Tell workers to set a new rate limit for task by type.

        Arguments:
            task_name (str): Name of task to change rate limit for.
            rate_limit (int, str): The rate limit as tasks per second,
                or a rate limit string (`'100/m'`, etc.
                see :attr:`celery.task.base.Task.rate_limit` for
                more information).

        See Also:
            :meth:`broadcast` for supported keyword arguments.
        """
        return self.broadcast('rate_limit', destination=destination,
                              arguments={'task_name': task_name,
                                         'rate_limit': rate_limit},
                              **kwargs)

    def add_consumer(self, queue, exchange=None, exchange_type='direct',
                     routing_key=None, options=None, **kwargs):
        """Tell all (or specific) workers to start consuming from a new queue.

        Only the queue name is required as if only the queue is specified
        then the exchange/routing key will be set to the same name (
        like automatic queues do).

        Note:
            This command does not respect the default queue/exchange
            options in the configuration.

        Arguments:
            queue (str): Name of queue to start consuming from.
            exchange (str): Optional name of exchange.
            exchange_type (str): Type of exchange (defaults to 'direct')
                command to, when empty broadcast to all workers.
            routing_key (str): Optional routing key.
            options (Dict): Additional options as supported
                by :meth:`kombu.entitiy.Queue.from_dict`.

        See Also:
            :meth:`broadcast` for supported keyword arguments.
        """
        return self.broadcast(
            'add_consumer',
            arguments=dict({'queue': queue, 'exchange': exchange,
                            'exchange_type': exchange_type,
                            'routing_key': routing_key}, **options or {}),
            **kwargs
        )

    def cancel_consumer(self, queue, **kwargs):
        """Tell all (or specific) workers to stop consuming from ``queue``.

        See Also:
            Supports the same arguments as :meth:`broadcast`.
        """
        return self.broadcast(
            'cancel_consumer', arguments={'queue': queue}, **kwargs
        )

    def time_limit(self, task_name, soft=None, hard=None, **kwargs):
        """Tell workers to set time limits for a task by type.

        Arguments:
            task_name (str): Name of task to change time limits for.
            soft (float): New soft time limit (in seconds).
            hard (float): New hard time limit (in seconds).
            **kwargs (Any): arguments passed on to :meth:`broadcast`.
        """
        return self.broadcast(
            'time_limit',
            arguments={'task_name': task_name,
                       'hard': hard, 'soft': soft}, **kwargs)

    def enable_events(self, destination=None, **kwargs):
        """Tell all (or specific) workers to enable events.

        See Also:
            Supports the same arguments as :meth:`broadcast`.
        """
        return self.broadcast('enable_events', {}, destination, **kwargs)

    def disable_events(self, destination=None, **kwargs):
        """Tell all (or specific) workers to disable events.

        See Also:
            Supports the same arguments as :meth:`broadcast`.
        """
        return self.broadcast('disable_events', {}, destination, **kwargs)

    def pool_grow(self, n=1, destination=None, **kwargs):
        """Tell all (or specific) workers to grow the pool by ``n``.

        See Also:
            Supports the same arguments as :meth:`broadcast`.
        """
        return self.broadcast('pool_grow', {'n': n}, destination, **kwargs)

    def pool_shrink(self, n=1, destination=None, **kwargs):
        """Tell all (or specific) workers to shrink the pool by ``n``.

        See Also:
            Supports the same arguments as :meth:`broadcast`.
        """
        return self.broadcast('pool_shrink', {'n': n}, destination, **kwargs)

    def broadcast(self, command, arguments=None, destination=None,
                  connection=None, reply=False, timeout=1, limit=None,
                  callback=None, channel=None, **extra_kwargs):
        """Broadcast a control command to the celery workers.

        Arguments:
            command (str): Name of command to send.
            arguments (Dict): Keyword arguments for the command.
            destination (List): If set, a list of the hosts to send the
                command to, when empty broadcast to all workers.
            connection (kombu.Connection): Custom broker connection to use,
                if not set, a connection will be acquired from the pool.
            reply (bool): Wait for and return the reply.
            timeout (float): Timeout in seconds to wait for the reply.
            limit (int): Limit number of replies.
            callback (Callable): Callback called immediately for
                each reply received.
        """
        with self.app.connection_or_acquire(connection) as conn:
            arguments = dict(arguments or {}, **extra_kwargs)
            return self.mailbox(conn)._broadcast(
                command, arguments, destination, reply, timeout,
                limit, callback, channel=channel,
            )