Caching

Introduction to the Cache Interface

Cement defines a Cache Interface, but does not implement caching by default.

Cement often includes multiple handler implementations of an interface that may or may not have additional features or functionality than the interface requires. The documentation below only references usage based on the interface and default handler (not the full capabilities of an implementation).

Cement Extensions That Provide Cache Handlers:

API References:

Configuration

Application Meta Options

The following options under App.Meta modify configuration handling:

Option

Description

cache_handler

The handler that implements the cache interface.

Working with Caches

The following example uses the Memcached Extension, which requires the pylibmc library to be installed, as well as a Memcached server running on localhost:11211.

Example: Working with Caches
Example: Working with Caches
from cement import App
from cement.utils.misc import init_defaults
CONFIG = init_defaults('myapp', 'memcached')
CONFIG['cache.memcached']['expire_time'] = 300 # seconds
CONFIG['cache.memcached']['hosts'] = ['127.0.0.1']
class MyApp(App):
class Meta:
label = 'myapp'
config_defaults = CONFIG
extensions = ['memcached']
cache_handler = 'memcached'
with MyApp() as app:
# Run the app
app.run()
# Set a cached value
app.cache.set('my_key', 'my value')
# Get a cached value
app.cache.get('my_key')
# Delete a cached value
app.cache.delete('my_key')
# Delete the entire cache
app.cache.purge()

Creating a Cache Handler

All interfaces in Cement can be overridden with your own implementation. This can be done either by sub-classing CacheHandler itself, or by sub-classing an existing extension's handlers in order to alter their functionality.

Example: Creating a Cache Handler
Example: Creating a Cache Handler
myapp.py
from cement import App
from cement.core.cache import CacheHandler
class MyCacheHandler(CacheHandler):
class Meta:
label = 'my_cache_handler'
# do something to implement the interface
class MyApp(App):
class Meta:
label = 'myapp'
cache_handler = 'my_cache_handler'
handlers = [
MyCacheHandler,
]