oslo.cache/doc/source/usage.rst
George Silvis, III 92a979b689 Add usage example to documentation
This example is cobbled together from Keystone's use-case.

Change-Id: Ib0ab0926f2cc86e2b45dfccbf8f73c638ec90a6f
2016-08-20 09:37:46 -04:00

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=======
Usage
=======
A simple example of oslo.cache in use::
from oslo_cache import core as cache
from oslo_config import cfg
CONF = cfg.CONF
caching = cfg.BoolOpt('caching', default=True)
cache_time = cfg.IntOpt('cache_time', default=3600)
CONF.register_opts([caching, cache_time], "feature-name")
cache.configure(CONF)
example_cache_region = cache.create_region()
MEMOIZE = cache.get_memoization_decorator(
CONF, example_cache_region, "feature-name")
# Load config file here
cache.configure_cache_region(example_cache_region)
@MEMOIZE
def f(x):
print x
return x
An example config file for this is::
[cache]
enabled = true
backend = dogpile.cache.memory
[feature-name]
caching = True
cache_time = 7200
There is some subtlety in the order of the calls in the example above. The
requirements are: ``configure`` must be done first; ``create_region`` must be
before both ``get_memoization_decorator`` and ``configure_cache_region``
(because they use the output); the config file must be fully loaded before
``configure_cache_region`` is called; all these calls must complete before a
decorated function is actually invoked. In principle, there are several
different orders this can happen in. In practice, the decorator will be used
at import time, and the config file will be loaded later, so the above order is
the only possible one.