# -*- coding: utf-8 -*-
from __future__ import (absolute_import, division, print_function,
unicode_literals)
import uuid
from redis import WatchError
from .compat import as_text, string_types, total_ordering
from .connections import resolve_connection
from .defaults import DEFAULT_RESULT_TTL
from .exceptions import (DequeueTimeout, InvalidJobDependency,
InvalidJobOperationError, NoSuchJobError, UnpickleError)
from .job import Job, JobStatus
from .utils import backend_class, import_attribute, utcnow, parse_timeout
def get_failed_queue(connection=None, job_class=None):
"""Returns a handle to the special failed queue."""
return FailedQueue(connection=connection, job_class=job_class)
def compact(lst):
return [item for item in lst if item is not None]
@total_ordering
class Queue(object):
job_class = Job
DEFAULT_TIMEOUT = 180 # Default timeout seconds.
redis_queue_namespace_prefix = 'rq:queue:'
redis_queues_keys = 'rq:queues'
@classmethod
def all(cls, connection=None, job_class=None):
"""Returns an iterable of all Queues.
"""
connection = resolve_connection(connection)
def to_queue(queue_key):
return cls.from_queue_key(as_text(queue_key),
connection=connection,
job_class=job_class)
return [to_queue(rq_key)
for rq_key in connection.smembers(cls.redis_queues_keys)
if rq_key]
@classmethod
def from_queue_key(cls, queue_key, connection=None, job_class=None):
"""Returns a Queue instance, based on the naming conventions for naming
the internal Redis keys. Can be used to reverse-lookup Queues by their
Redis keys.
"""
prefix = cls.redis_queue_namespace_prefix
if not queue_key.startswith(prefix):
raise ValueError('Not a valid RQ queue key: {0}'.format(queue_key))
name = queue_key[len(prefix):]
return cls(name, connection=connection, job_class=job_class)
def __init__(self, name='default', default_timeout=None, connection=None,
async=True, job_class=None):
self.connection = resolve_connection(connection)
prefix = self.redis_queue_namespace_prefix
self.name = name
self._key = '{0}{1}'.format(prefix, name)
self._default_timeout = parse_timeout(default_timeout)
self._async = async
# override class attribute job_class if one was passed
if job_class is not None:
if isinstance(job_class, string_types):
job_class = import_attribute(job_class)
self.job_class = job_class
def __len__(self):
return self.count
def __nonzero__(self):
return True
def __bool__(self):
return True
def __iter__(self):
yield self
@property
def key(self):
"""Returns the Redis key for this Queue."""
return self._key
def empty(self):
"""Removes all messages on the queue."""
script = b"""
local prefix = "rq:job:"
local q = KEYS[1]
local count = 0
while true do
local job_id = redis.call("lpop", q)
if job_id == false then
break
end
-- Delete the relevant keys
redis.call("del", prefix..job_id)
redis.call("del", prefix..job_id..":dependents")
count = count + 1
end
return count
"""
script = self.connection.register_script(script)
return script(keys=[self.key])
def is_empty(self):
"""Returns whether the current queue is empty."""
return self.count == 0
def fetch_job(self, job_id):
try:
job = self.job_class.fetch(job_id, connection=self.connection)
except NoSuchJobError:
self.remove(job_id)
else:
if job.origin == self.name or (job.is_failed and self == get_failed_queue(connection=self.connection, job_class=self.job_class)):
return job
def get_job_ids(self, offset=0, length=-1):
"""Returns a slice of job IDs in the queue."""
start = offset
if length >= 0:
end = offset + (length - 1)
else:
end = length
return [as_text(job_id) for job_id in
self.connection.lrange(self.key, start, end)]
def get_jobs(self, offset=0, length=-1):
"""Returns a slice of jobs in the queue."""
job_ids = self.get_job_ids(offset, length)
return compact([self.fetch_job(job_id) for job_id in job_ids])
@property
def job_ids(self):
"""Returns a list of all job IDS in the queue."""
return self.get_job_ids()
@property
def jobs(self):
"""Returns a list of all (valid) jobs in the queue."""
return self.get_jobs()
@property
def count(self):
"""Returns a count of all messages in the queue."""
return self.connection.llen(self.key)
def remove(self, job_or_id, pipeline=None):
"""Removes Job from queue, accepts either a Job instance or ID."""
job_id = job_or_id.id if isinstance(job_or_id, self.job_class) else job_or_id
if pipeline is not None:
pipeline.lrem(self.key, 1, job_id)
return
return self.connection._lrem(self.key, 1, job_id)
def compact(self):
"""Removes all "dead" jobs from the queue by cycling through it, while
guaranteeing FIFO semantics.
"""
COMPACT_QUEUE = 'rq:queue:_compact:{0}'.format(uuid.uuid4())
self.connection.rename(self.key, COMPACT_QUEUE)
while True:
job_id = as_text(self.connection.lpop(COMPACT_QUEUE))
if job_id is None:
break
if self.job_class.exists(job_id, self.connection):
self.connection.rpush(self.key, job_id)
def push_job_id(self, job_id, pipeline=None, at_front=False):
"""Pushes a job ID on the corresponding Redis queue.
'at_front' allows you to push the job onto the front instead of the back of the queue"""
connection = pipeline if pipeline is not None else self.connection
if at_front:
connection.lpush(self.key, job_id)
else:
connection.rpush(self.key, job_id)
def enqueue_call(self, func, args=None, kwargs=None, timeout=None,
result_ttl=None, ttl=None, description=None,
depends_on=None, job_id=None, at_front=False, meta=None):
"""Creates a job to represent the delayed function call and enqueues
it.
It is much like `.enqueue()`, except that it takes the function's args
and kwargs as explicit arguments. Any kwargs passed to this function
contain options for RQ itself.
"""
timeout = parse_timeout(timeout) or self._default_timeout
result_ttl = parse_timeout(result_ttl)
ttl = parse_timeout(ttl)
job = self.job_class.create(
func, args=args, kwargs=kwargs, connection=self.connection,
result_ttl=result_ttl, ttl=ttl, status=JobStatus.QUEUED,
description=description, depends_on=depends_on,
timeout=timeout, id=job_id, origin=self.name, meta=meta)
# If job depends on an unfinished job, register itself on it's
# parent's dependents instead of enqueueing it.
# If WatchError is raised in the process, that means something else is
# modifying the dependency. In this case we simply retry
if depends_on is not None:
if not isinstance(depends_on, self.job_class):
depends_on = self.job_class(id=depends_on,
connection=self.connection)
with self.connection._pipeline() as pipe:
while True:
try:
pipe.watch(depends_on.key)
# If the dependency does not exist, raise an
# exception to avoid creating an orphaned job.
if not self.job_class.exists(depends_on.id,
self.connection):
raise InvalidJobDependency('Job {0} does not exist'.format(depends_on.id))
if depends_on.get_status() != JobStatus.FINISHED:
pipe.multi()
job.set_status(JobStatus.DEFERRED)
job.register_dependency(pipeline=pipe)
job.save(pipeline=pipe)
job.cleanup(ttl=job.ttl, pipeline=pipe)
pipe.execute()
return job
break
except WatchError:
continue
job = self.enqueue_job(job, at_front=at_front)
return job
def run_job(self, job):
job.perform()
job.set_status(JobStatus.FINISHED)
job.save(include_meta=False)
job.cleanup(DEFAULT_RESULT_TTL)
return job
def enqueue(self, f, *args, **kwargs):
"""Creates a job to represent the delayed function call and enqueues
it.
Expects the function to call, along with the arguments and keyword
arguments.
The function argument `f` may be any of the following:
* A reference to a function
* A reference to an object's instance method
* A string, representing the location of a function (must be
meaningful to the import context of the workers)
"""
if not isinstance(f, string_types) and f.__module__ == '__main__':
raise ValueError('Functions from the __main__ module cannot be processed '
'by workers')
# Detect explicit invocations, i.e. of the form:
# q.enqueue(foo, args=(1, 2), kwargs={'a': 1}, timeout=30)
timeout = kwargs.pop('timeout', None)
description = kwargs.pop('description', None)
result_ttl = kwargs.pop('result_ttl', None)
ttl = kwargs.pop('ttl', None)
depends_on = kwargs.pop('depends_on', None)
job_id = kwargs.pop('job_id', None)
at_front = kwargs.pop('at_front', False)
meta = kwargs.pop('meta', None)
if 'args' in kwargs or 'kwargs' in kwargs:
assert args == (), 'Extra positional arguments cannot be used when using explicit args and kwargs' # noqa
args = kwargs.pop('args', None)
kwargs = kwargs.pop('kwargs', None)
return self.enqueue_call(func=f, args=args, kwargs=kwargs,
timeout=timeout, result_ttl=result_ttl, ttl=ttl,
description=description, depends_on=depends_on,
job_id=job_id, at_front=at_front, meta=meta)
def enqueue_job(self, job, pipeline=None, at_front=False):
"""Enqueues a job for delayed execution.
If Queue is instantiated with async=False, job is executed immediately.
"""
pipe = pipeline if pipeline is not None else self.connection._pipeline()
# Add Queue key set
pipe.sadd(self.redis_queues_keys, self.key)
job.set_status(JobStatus.QUEUED, pipeline=pipe)
job.origin = self.name
job.enqueued_at = utcnow()
if job.timeout is None:
job.timeout = self.DEFAULT_TIMEOUT
job.save(pipeline=pipe)
job.cleanup(ttl=job.ttl, pipeline=pipe)
if self._async:
self.push_job_id(job.id, pipeline=pipe, at_front=at_front)
if pipeline is None:
pipe.execute()
if not self._async:
job = self.run_job(job)
return job
def enqueue_dependents(self, job, pipeline=None):
"""Enqueues all jobs in the given job's dependents set and clears it.
When called without a pipeline, this method uses WATCH/MULTI/EXEC.
If you pass a pipeline, only MULTI is called. The rest is up to the
caller.
"""
from .registry import DeferredJobRegistry
pipe = pipeline if pipeline is not None else self.connection._pipeline()
dependents_key = job.dependents_key
while True:
try:
# if a pipeline is passed, the caller is responsible for calling WATCH
# to ensure all jobs are enqueued
if pipeline is None:
pipe.watch(dependents_key)
dependent_jobs = [self.job_class.fetch(as_text(job_id), connection=self.connection)
for job_id in pipe.smembers(dependents_key)]
pipe.multi()
for dependent in dependent_jobs:
registry = DeferredJobRegistry(dependent.origin,
self.connection,
job_class=self.job_class)
registry.remove(dependent, pipeline=pipe)
if dependent.origin == self.name:
self.enqueue_job(dependent, pipeline=pipe)
else:
queue = Queue(name=dependent.origin, connection=self.connection)
queue.enqueue_job(dependent, pipeline=pipe)
pipe.delete(dependents_key)
if pipeline is None:
pipe.execute()
break
except WatchError:
if pipeline is None:
continue
else:
# if the pipeline comes from the caller, we re-raise the
# exception as it it the responsibility of the caller to
# handle it
raise
def pop_job_id(self):
"""Pops a given job ID from this Redis queue."""
return as_text(self.connection.lpop(self.key))
@classmethod
def lpop(cls, queue_keys, timeout, connection=None):
"""Helper method. Intermediate method to abstract away from some
Redis API details, where LPOP accepts only a single key, whereas BLPOP
accepts multiple. So if we want the non-blocking LPOP, we need to
iterate over all queues, do individual LPOPs, and return the result.
Until Redis receives a specific method for this, we'll have to wrap it
this way.
The timeout parameter is interpreted as follows:
None - non-blocking (return immediately)
> 0 - maximum number of seconds to block
"""
connection = resolve_connection(connection)
if timeout is not None: # blocking variant
if timeout == 0:
raise ValueError('RQ does not support indefinite timeouts. Please pick a timeout value > 0')
result = connection.blpop(queue_keys, timeout)
if result is None:
raise DequeueTimeout(timeout, queue_keys)
queue_key, job_id = result
return queue_key, job_id
else: # non-blocking variant
for queue_key in queue_keys:
blob = connection.lpop(queue_key)
if blob is not None:
return queue_key, blob
return None
def dequeue(self):
"""Dequeues the front-most job from this queue.
Returns a job_class instance, which can be executed or inspected.
"""
while True:
job_id = self.pop_job_id()
if job_id is None:
return None
try:
job = self.job_class.fetch(job_id, connection=self.connection)
except NoSuchJobError as e:
# Silently pass on jobs that don't exist (anymore),
continue
except UnpickleError as e:
# Attach queue information on the exception for improved error
# reporting
e.job_id = job_id
e.queue = self
raise e
return job
@classmethod
def dequeue_any(cls, queues, timeout, connection=None, job_class=None):
"""Class method returning the job_class instance at the front of the given
set of Queues, where the order of the queues is important.
When all of the Queues are empty, depending on the `timeout` argument,
either blocks execution of this function for the duration of the
timeout or until new messages arrive on any of the queues, or returns
None.
See the documentation of cls.lpop for the interpretation of timeout.
"""
job_class = backend_class(cls, 'job_class', override=job_class)
while True:
queue_keys = [q.key for q in queues]
result = cls.lpop(queue_keys, timeout, connection=connection)
if result is None:
return None
queue_key, job_id = map(as_text, result)
queue = cls.from_queue_key(queue_key,
connection=connection,
job_class=job_class)
try:
job = job_class.fetch(job_id, connection=connection)
except NoSuchJobError:
# Silently pass on jobs that don't exist (anymore),
# and continue in the look
continue
except UnpickleError as e:
# Attach queue information on the exception for improved error
# reporting
e.job_id = job_id
e.queue = queue
raise e
return job, queue
return None, None
# Total ordering defition (the rest of the required Python methods are
# auto-generated by the @total_ordering decorator)
def __eq__(self, other): # noqa
if not isinstance(other, Queue):
raise TypeError('Cannot compare queues to other objects')
return self.name == other.name
def __lt__(self, other):
if not isinstance(other, Queue):
raise TypeError('Cannot compare queues to other objects')
return self.name < other.name
def __hash__(self): # pragma: no cover
return hash(self.name)
def __repr__(self): # noqa # pragma: no cover
return '{0}({1!r})'.format(self.__class__.__name__, self.name)
def __str__(self):
return '<{0} {1}>'.format(self.__class__.__name__, self.name)
class FailedQueue(Queue):
def __init__(self, connection=None, job_class=None):
super(FailedQueue, self).__init__(JobStatus.FAILED,
connection=connection,
job_class=job_class)
def quarantine(self, job, exc_info):
"""Puts the given Job in quarantine (i.e. put it on the failed
queue).
"""
with self.connection._pipeline() as pipeline:
# Add Queue key set
self.connection.sadd(self.redis_queues_keys, self.key)
job.ended_at = utcnow()
job.exc_info = exc_info
job.save(pipeline=pipeline, include_meta=False)
job.cleanup(ttl=-1, pipeline=pipeline) # failed job won't expire
self.push_job_id(job.id, pipeline=pipeline)
pipeline.execute()
return job
def requeue(self, job_id):
"""Requeues the job with the given job ID."""
try:
job = self.job_class.fetch(job_id, connection=self.connection)
except NoSuchJobError:
# Silently ignore/remove this job and return (i.e. do nothing)
self.remove(job_id)
return
# Delete it from the failed queue (raise an error if that failed)
if self.remove(job) == 0:
raise InvalidJobOperationError('Cannot requeue non-failed jobs')
job.set_status(JobStatus.QUEUED)
job.exc_info = None
queue = Queue(job.origin,
connection=self.connection,
job_class=self.job_class)
return queue.enqueue_job(job)