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155 lines
3.8 KiB
ReStructuredText
155 lines
3.8 KiB
ReStructuredText
Tasks
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=====
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Use :py:func:`async` from your code to quickly offload tasks to the :mod:`cluster`:
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.. code:: python
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from django_q import async, result
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# create the task
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async('math.copysign', 2, -2)
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# or with import and storing the id
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import math.copysign
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task_id = async(copysign, 2, -2)
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# get the result
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task_result = result(task_id)
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# result returns None if the task has not been executed yet
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# so in most cases you will want to use a hook:
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async('math.modf', 2.5, hook='hooks.print_result')
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# hooks.py
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def print_result(task):
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print(task.result)
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Connection pooling
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------------------
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Django Q tries to pass redis connections around its parts as much as possible to save you from running out of connections.
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When you are making individual calls to :func:`async` a lot though, it can help to set up a redis connection to pass to :func:`async`:
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.. code:: python
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# redis connection economy example
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from django_q import async
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from django_q.conf import redis_client
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for i in range(50):
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async('math.modf', 2.5, redis=redis_client)
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.. tip::
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If you are using `django-redis <https://github.com/niwinz/django-redis>`__ , you can :ref:`configure <django_redis>` Django Q to use its connection pool.
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Reference
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---------
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.. py:function:: async(func, *args, hook=None, redis=None, **kwargs)
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Puts a task in the cluster queue
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:param func: The task function to execute
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:param args: The arguments for the task function
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:type func: str or object
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:param hook: Optional function to call after execution
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:type hook: str or object
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:param redis: Optional redis connection
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:param kwargs: Keyword arguments for the task function
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:returns: The uuid of the task
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:rtype: str
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.. py:function:: result(task_id)
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Gets the result of a previously executed task
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:param str task_id: the uuid or name of the task
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:returns: The result of the executed task
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.. py:function:: fetch(task_id)
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Returns a previously executed task
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:param str name: the uuid or name of the task
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:returns: The task
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:rtype: Task
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.. versionchanged:: 0.2.0
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Renamed from get_task
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.. py:class:: Task
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Database model describing an executed task
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.. py:attribute:: id
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An :func:`uuid.uuid4()` identifier
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.. py:attribute:: name
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The name of the task as a humanized version of the :attr:`id`
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.. note::
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This is for convenience and can be used as a parameter for most functions that take a `task_id`.
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Keep in mind however that it is not guaranteed to be unique if you store very large amounts of tasks in the database.
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.. py:attribute:: func
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The function or reference that was executed
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.. py:attribute:: hook
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The function to call after execution.
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.. py:attribute:: args
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Positional arguments for the function.
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.. py:attribute:: kwargs
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Keyword arguments for the function.
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.. py:attribute:: result
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The result object. Contains the error if any occur.
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.. py:attribute:: started
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The moment the task was created by an async command
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.. py:attribute:: stopped
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The moment a worker finished this task
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.. py:attribute:: success
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Was the task executed without problems?
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.. py:method:: time_taken
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Calculates the difference in seconds between started and stopped.
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.. note::
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Time taken represents the time a task spends in the cluster, this includes any time it may have waited in the queue.
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.. py:classmethod:: get_result(task_id)
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Get a result directly by task uuid or name
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.. py:class:: Success
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A proxy model of :class:`Task` with the queryset filtered on :attr:`Task.success` is True.
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.. py:class:: Failure
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A proxy model of :class:`Task` with the queryset filtered on :attr:`Task.success` is False. |