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Python

# -*- coding: utf-8 -*-
from __future__ import (absolute_import, division, print_function,
unicode_literals)
import uuid
import warnings
from datetime import datetime
from distutils.version import StrictVersion
from redis import WatchError
from .compat import as_text, string_types, total_ordering, utc
from .connections import resolve_connection
from .defaults import DEFAULT_RESULT_TTL
from .exceptions import DequeueTimeout, NoSuchJobError
from .job import Job, JobStatus
from .serializers import resolve_serializer
from .utils import backend_class, get_version, import_attribute, parse_timeout, utcnow
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, serializer=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, serializer=serializer)
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, serializer=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, serializer=serializer)
def __init__(self, name='default', default_timeout=None, connection=None,
is_async=True, job_class=None, serializer=None, **kwargs):
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) or self.DEFAULT_TIMEOUT
self._is_async = is_async
if 'async' in kwargs:
self._is_async = kwargs['async']
warnings.warn('The `async` keyword is deprecated. Use `is_async` instead', DeprecationWarning)
# 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
self.serializer = resolve_serializer(serializer)
self.redis_server_version = None
def __len__(self):
return self.count
def __nonzero__(self):
return True
def __bool__(self):
return True
def __iter__(self):
yield self
def get_redis_server_version(self):
"""Return Redis server version of connection"""
if not self.redis_server_version:
self.redis_server_version = get_version(self.connection)
return self.redis_server_version
@property
def key(self):
"""Returns the Redis key for this Queue."""
return self._key
@property
def registry_cleaning_key(self):
"""Redis key used to indicate this queue has been cleaned."""
return 'rq:clean_registries:%s' % self.name
def acquire_cleaning_lock(self):
"""Returns a boolean indicating whether a lock to clean this queue
is acquired. A lock expires in 899 seconds (15 minutes - 1 second)
"""
return self.connection.set(self.registry_cleaning_key, 1, nx=1, ex=899)
def empty(self):
"""Removes all messages on the queue."""
script = """
local prefix = "{0}"
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
""".format(self.job_class.redis_job_namespace_prefix).encode("utf-8")
script = self.connection.register_script(script)
return script(keys=[self.key])
def delete(self, delete_jobs=True):
"""Deletes the queue. If delete_jobs is true it removes all the associated messages on the queue first."""
if delete_jobs:
self.empty()
with self.connection.pipeline() as pipeline:
pipeline.srem(self.redis_queues_keys, self._key)
pipeline.delete(self._key)
pipeline.execute()
def is_empty(self):
"""Returns whether the current queue is empty."""
return self.count == 0
@property
def is_async(self):
"""Returns whether the current queue is async."""
return bool(self._is_async)
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:
return job
def get_job_position(self, job_or_id):
"""Returns the position of a job within the queue
Using Redis before 6.0.6 and redis-py before 3.5.4 has a complexity of
worse than O(N) and should not be used for very long job queues. Redis
and redis-py version afterwards should support the LPOS command
handling job positions within Redis c implementation.
"""
job_id = job_or_id.id if isinstance(job_or_id, self.job_class) else job_or_id
if self.get_redis_server_version() >= StrictVersion("6.0.6"):
try:
return self.connection.lpos(self.key, job_id)
except AttributeError:
# not yet implemented by redis-py
pass
if job_id in self.job_ids:
return self.job_ids.index(job_id)
return None
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)
@property
def failed_job_registry(self):
"""Returns this queue's FailedJobRegistry."""
from rq.registry import FailedJobRegistry
return FailedJobRegistry(queue=self, job_class=self.job_class)
@property
def started_job_registry(self):
"""Returns this queue's StartedJobRegistry."""
from rq.registry import StartedJobRegistry
return StartedJobRegistry(queue=self, job_class=self.job_class)
@property
def finished_job_registry(self):
"""Returns this queue's FinishedJobRegistry."""
from rq.registry import FinishedJobRegistry
return FinishedJobRegistry(queue=self)
@property
def deferred_job_registry(self):
"""Returns this queue's DeferredJobRegistry."""
from rq.registry import DeferredJobRegistry
return DeferredJobRegistry(queue=self, job_class=self.job_class)
@property
def scheduled_job_registry(self):
"""Returns this queue's ScheduledJobRegistry."""
from rq.registry import ScheduledJobRegistry
return ScheduledJobRegistry(queue=self, job_class=self.job_class)
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 = '{0}_compact:{1}'.format(
self.redis_queue_namespace_prefix, uuid.uuid4()) # noqa
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 create_job(self, func, args=None, kwargs=None, timeout=None,
result_ttl=None, ttl=None, failure_ttl=None,
description=None, depends_on=None, job_id=None,
meta=None, status=JobStatus.QUEUED, retry=None):
"""Creates a job based on parameters given."""
timeout = parse_timeout(timeout)
if timeout is None:
timeout = self._default_timeout
elif timeout == 0:
raise ValueError('0 timeout is not allowed. Use -1 for infinite timeout')
result_ttl = parse_timeout(result_ttl)
failure_ttl = parse_timeout(failure_ttl)
ttl = parse_timeout(ttl)
if ttl is not None and ttl <= 0:
raise ValueError('Job ttl must be greater than 0')
job = self.job_class.create(
func, args=args, kwargs=kwargs, connection=self.connection,
result_ttl=result_ttl, ttl=ttl, failure_ttl=failure_ttl,
status=status, description=description,
depends_on=depends_on, timeout=timeout, id=job_id,
origin=self.name, meta=meta, serializer=self.serializer
)
if retry:
job.retries_left = retry.max
job.retry_intervals = retry.intervals
return job
def enqueue_call(self, func, args=None, kwargs=None, timeout=None,
result_ttl=None, ttl=None, failure_ttl=None,
description=None, depends_on=None, job_id=None,
at_front=False, meta=None, retry=None):
"""Creates a job to represent the delayed function call and enqueues
it.
nd
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.
"""
job = self.create_job(
func, args=args, kwargs=kwargs, result_ttl=result_ttl, ttl=ttl,
failure_ttl=failure_ttl, description=description, depends_on=depends_on,
job_id=job_id, meta=meta, status=JobStatus.QUEUED, timeout=timeout,
retry=retry
)
# If a _dependent_ job depends on any unfinished job, register all the
# _dependent_ job's dependencies instead of enqueueing it.
#
# `Job#fetch_dependencies` sets WATCH on all dependencies. If
# WatchError is raised in the when the pipeline is executed, that means
# something else has modified either the set of dependencies or the
# status of one of them. In this case, we simply retry.
if depends_on is not None:
with self.connection.pipeline() as pipe:
while True:
try:
pipe.watch(job.dependencies_key)
dependencies = job.fetch_dependencies(
watch=True,
pipeline=pipe
)
pipe.multi()
for dependency in dependencies:
if dependency.get_status(refresh=False) != JobStatus.FINISHED:
job.set_status(JobStatus.DEFERRED, pipeline=pipe)
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
@classmethod
def parse_args(cls, f, *args, **kwargs):
"""
Parses arguments passed to `queue.enqueue()` and `queue.enqueue_at()`
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}, job_timeout=30)
timeout = kwargs.pop('job_timeout', None)
description = kwargs.pop('description', None)
result_ttl = kwargs.pop('result_ttl', None)
ttl = kwargs.pop('ttl', None)
failure_ttl = kwargs.pop('failure_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)
retry = kwargs.pop('retry', 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 (f, timeout, description, result_ttl, ttl, failure_ttl,
depends_on, job_id, at_front, meta, retry, args, kwargs)
def enqueue(self, f, *args, **kwargs):
"""Creates a job to represent the delayed function call and enqueues it."""
(f, timeout, description, result_ttl, ttl, failure_ttl,
depends_on, job_id, at_front, meta, retry, args, kwargs) = Queue.parse_args(f, *args, **kwargs)
return self.enqueue_call(
func=f, args=args, kwargs=kwargs, timeout=timeout,
result_ttl=result_ttl, ttl=ttl, failure_ttl=failure_ttl,
description=description, depends_on=depends_on, job_id=job_id,
at_front=at_front, meta=meta, retry=retry
)
def enqueue_at(self, datetime, f, *args, **kwargs):
"""Schedules a job to be enqueued at specified time"""
(f, timeout, description, result_ttl, ttl, failure_ttl,
depends_on, job_id, at_front, meta, retry, args, kwargs) = Queue.parse_args(f, *args, **kwargs)
job = self.create_job(f, status=JobStatus.SCHEDULED, args=args, kwargs=kwargs,
timeout=timeout, result_ttl=result_ttl, ttl=ttl,
failure_ttl=failure_ttl, description=description,
depends_on=depends_on, job_id=job_id, meta=meta)
return self.schedule_job(job, datetime)
def schedule_job(self, job, datetime, pipeline=None):
"""Puts job on ScheduledJobRegistry"""
from .registry import ScheduledJobRegistry
registry = ScheduledJobRegistry(queue=self)
pipe = pipeline if pipeline is not None else self.connection.pipeline()
# Add Queue key set
pipe.sadd(self.redis_queues_keys, self.key)
job.save(pipeline=pipe)
registry.schedule(job, datetime, pipeline=pipe)
if pipeline is None:
pipe.execute()
return job
def enqueue_in(self, time_delta, func, *args, **kwargs):
"""Schedules a job to be executed in a given `timedelta` object"""
return self.enqueue_at(datetime.now(utc) + time_delta,
func, *args, **kwargs)
def enqueue_job(self, job, pipeline=None, at_front=False):
"""Enqueues a job for delayed execution.
If Queue is instantiated with is_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._is_async:
self.push_job_id(job.id, pipeline=pipe, at_front=at_front)
if pipeline is None:
pipe.execute()
if not self._is_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_job_ids = [as_text(_id)
for _id in pipe.smembers(dependents_key)]
jobs_to_enqueue = [
dependent_job for dependent_job
in self.job_class.fetch_many(
dependent_job_ids,
connection=self.connection
) if dependent_job.dependencies_are_met(
exclude_job_id=job.id,
pipeline=pipe
)
]
pipe.multi()
for dependent in jobs_to_enqueue:
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 = self.__class__(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
@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 Exception 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)