some Queue subclasses and ducktypes
Project description
Queue-like items: iterable queues, channels, etc.
Latest release 20221228: Minor doc update.
Class Channel
A zero-storage data passage.
Unlike a Queue
, put(item)
blocks waiting for the matching get()
.
Method Channel.__init__(self)
:
pylint: disable=consider-using-with
Function IterablePriorityQueue(capacity=0, name=None)
Factory to create an iterable PriorityQueue
.
Function IterableQueue(capacity=0, name=None)
Factory to create an iterable queue. Note that the returned queue is already open and needs a close.
Class ListQueue
A simple iterable queue based on a list
.
Method ListQueue.__init__(self, queued=None)
:
Initialise the queue.
queued
is an optional iterable of initial items for the queue.
NullQ = <NullQueue:NullQ blocking=False>
A queue-like object that discards its inputs.
Calls to .get()
raise Queue_Empty
.
Class NullQueue(cs.resources.MultiOpenMixin, cs.context.ContextManagerMixin)
A queue-like object that discards its inputs.
Calls to .get()
raise Queue_Empty
.
Method NullQueue.__init__(self, blocking=False, name=None)
:
Initialise the NullQueue
.
Parameters:
blocking
: optional; if true, calls to.get()
block until.shutdown()
; default:False
.name
: optional name for thisNullQueue
.
Class PushQueue(cs.resources.MultiOpenMixin, cs.context.ContextManagerMixin)
A puttable object which looks like an iterable Queue
.
In this base class,
calling .put(item)
calls functor
supplied at initialisation
to trigger a function on data arrival
whose iterable of results are put onto the output queue.
As an example, the cs.pipeline.Pipeline
class
uses subclasses of PushQueue
for each pipeline stage,
overriding the .put(item)
method
to mediate the call of functor
through cs.later.Later
as resource controlled concurrency.
Method PushQueue.__init__(self, name, functor, outQ)
:
Initialise the PushQueue with the callable functor
and the output queue outQ
.
Parameters:
functor
is a one-to-many function which accepts a single item of input and returns an iterable of outputs; it may be a generator. These outputs are passed tooutQ.put
individually as received.outQ
is aMultiOpenMixin
which accepts via its.put()
method.
Class QueueIterator(cs.resources.MultiOpenMixin, cs.context.ContextManagerMixin)
A QueueIterator
is a wrapper for a Queue
(or ducktype) which
presents an iterator interface to collect items.
It does not offer the .get
or .get_nowait
methods.
Class TimerQueue
Class to run a lot of "in the future" jobs without using a bazillion Timer threads.
Release Log
Release 20221228: Minor doc update.
Release 20221207: PushQueue: modernise the MutiOpenMixin startup_shutdown, do both open and close of self.outQ.
Release 20220918: Expose formerly private _QueueIterator as QueueIterator, use a per-queue sentinel from cs.obj.Sentinel.
Release 20220805: ListQueue: add "append" synonym for "put" in keeping with the list-ish flavour.
Release 20220605: ListQueue: extend/prepend: reject str explicitly - although iterable, it is almost never what is intended.
Release 20220317: Add missed import.
Release 20220313: New ListQueue.prepend(items[,offset=0]) method.
Release 20211116: ListQueue: new insert() method.
Release 20210924: Channel: make a Channel iterable.
Release 20210913: New ListQueue simple iterable queue based on a list with list-like .append and .extend.
Release 20201025: Drop obsolete call to MultiOpenMixin.init.
Release 20200718: _QueueIterator: set finalise_later via new MultiOpenMixin property, required by recent MultiOpenMixin change.
Release 20200521: IterableQueue,IterablePriorityQueue: simplify wrappers, bypasses weird bug from overengineering these.
Release 20191007:
- PushQueue: improve str.
- Clean lint, drop cs.obj dependency.
Release 20190812: _QueueIterator: do MultiOpenMixin.init so that str is functional.
Release 20181022: Bugfix Channel, drasticly simplify PushQueue, other minor changes.
Release 20160828:
- Use "install_requires" instead of "requires" in DISTINFO.
- TimerQueue.add: support optional *a and **kw arguments for func.
- Many bugfixes and internal changes.
Release 20150115: More PyPI metadata fixups.
Release 20150111: Initial PyPI release.
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