mirror of
https://github.com/django-q2/django-q2.git
synced 2026-09-21 11:18:12 +08:00
Pierre-Elliott Bécue
ae75a84f7f
* async is now a reserved word in python3.7 * Rename async function to enqueue * Rename all async_ functions to enqueue_ * Rename Async class to AsyncTask * Updates the docs.
106 lines
3.0 KiB
ReStructuredText
106 lines
3.0 KiB
ReStructuredText
.. py:currentmodule:: django_q
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Chains
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======
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Sometimes you want to run tasks sequentially. For that you can use the :func:`enqueue_chain` function:
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.. code-block:: python
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# enqueue a chain of tasks
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from django_q.tasks import enqueue_chain, result_group
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# the chain must be in the format
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# [(func,(args),{kwargs}),(func,(args),{kwargs}),..]
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group_id = enqueue_chain([('math.copysign', (1, -1)),
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('math.floor', (1,))])
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# get group result
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result_group(group_id, count=2)
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A slightly more convenient way is to use a :class:`Chain` instance:
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.. code-block:: python
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# Chain enqueue
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from django_q.tasks import Chain
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# create a chain that uses the cache backend
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chain = Chain(cached=True)
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# add some tasks
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chain.append('math.copysign', 1, -1)
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chain.append('math.floor', 1)
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# run it
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chain.run()
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print(chain.result())
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.. code-block:: python
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[-1.0, 1]
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Reference
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---------
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.. py:function:: enqueue_chain(chain, group=None, cached=Conf.CACHED, sync=Conf.SYNC, broker=None)
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enqueue a chain of tasks. See also the :class:`Chain` class.
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:param list chain: a list of tasks in the format [(func,(args),{kwargs}), (func,(args),{kwargs})]
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:param str group: an optional group name.
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:param bool cached: run this against the cache backend
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:param bool sync: execute this inline instead of asynchronous
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.. py:class:: Chain(chain=None, group=None, cached=Conf.CACHED, sync=Conf.SYNC)
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A sequential chain of tasks. Acts as a convenient wrapper for :func:`enqueue_chain`
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You can pass the task chain at construction or you can append individual tasks before running them.
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:param list chain: a list of task in the format [(func,(args),{kwargs}), (func,(args),{kwargs})]
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:param str group: an optional group name.
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:param bool cached: run this against the cache backend
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:param bool sync: execute this inline instead of asynchronous
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.. py:method:: append(func, *args, **kwargs)
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Append a task to the chain. Takes the same arguments as :func:`enqueue`
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:return: the current number of tasks in the chain
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:rtype: int
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.. py:method:: run()
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Start queueing the chain to the worker cluster.
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:return: the chains group id
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.. py:method:: result(wait=0)
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return the full list of results from the chain when it finishes. Blocks until timeout or result.
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:param int wait: how many milliseconds to wait for a result
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:return: an unsorted list of results
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.. py:method:: fetch(failures=True, wait=0)
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get the task result objects from the chain when it finishes. Blocks until timeout or result.
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:param failures: include failed tasks
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:param int wait: how many milliseconds to wait for a result
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:return: an unsorted list of task objects
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.. py:method:: current()
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get the index of the currently executing chain element
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:return int: current chain index
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.. py:method:: length()
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get the length of the chain
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:return int: length of the chain
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