EEA Cache

EEA Cache

http://ci.eionet.europa.eu/job/eea.cache-www/badge/icon http://ci.eionet.europa.eu/job/eea.cache-plone4/badge/icon

Introduction

This package combines the features from lovely.memcached and plone.memoize.ram. It provides a decorator and utility for Memcaches at EEA. The decorator allows you set dependencies known by eea.cache

Note

This add-on doesn’t do anything by itself. It needs to be integrated by a developer within your own products. For reference you can check the eea.app.visualization package.

Installation

zc.buildout

If you are using zc.buildout and the plone.recipe.zope2instance recipe to manage your project, you can do this:

  • Update your buildout.cfg file:

    parts +=
      libevent
      memcached
      memcached-ctl
    
    effective-user = zope-www
    
    [instance]
    ...
    eggs =
      ...
      eea.cache
    
    zcml =
      ...
      eea.cache-overrides
    
    
    [libevent]
    recipe = zc.recipe.cmmi
    url = http://www.monkey.org/~provos/libevent-1.4.8-stable.tar.gz
    
    [memcached]
    recipe = zc.recipe.cmmi
    url = http://www.danga.com/memcached/dist/memcached-1.2.6.tar.gz
    extra_options = --with-libevent=${libevent:location}
    
    [memcached-ctl]
    recipe = lovely.recipe:mkfile
    path = ${buildout:bin-directory}/memcached
    mode = 0755
    content =
     #!/bin/sh
     export LD_LIBRARY_PATH=${libevent:location}/lib
    
     PIDFILE=${memcached:location}/memcached.pid
        case "$1" in
          start)
           ${memcached:location}/bin/memcached -d -u ${buildout:effective-user} -P $PIDFILE
            ;;
          stop)
            kill `cat $PIDFILE`
            ;;
          restart|force-reload)
            $0 stop
            sleep 1
            $0 start
            ;;
          *)
            echo "Usage: $SCRIPTNAME {start|stop|restart}" >&2
            exit 1
            ;;
        esac
  • Re-run buildout, e.g. with:

    $ bin/buildout -c buildout.cfg
  • Restart memcache and Zope:

    $ bin/memcached restart
    $ bin/instance restart

Dependencies

EEA Cache has the following dependencies:
  • Plone 4+

Source code

Latest source code (Zope 2 compatible):

Cache decorator

>>> def key(method, self):
...     return method.__name__
>>> from eea.cache import cache
>>> @cache(key, dependencies=["frontpage"])
... def myMethod(num):
...     return num*num

Lets clear any running memcache

>>> from eea.cache.event import InvalidateCacheEvent
>>> from zope.event import notify
>>> notify(InvalidateCacheEvent(raw=True, dependencies=['frontpage']))

Our myMethod will now be cached with the key returned from the method ‘key’ and with dependency ‘frontpage’.

>>> myMethod(2)
4
>>> myMethod(3)
4
>>> notify(InvalidateCacheEvent(raw=True, dependencies=['frontpage']))
>>> myMethod(3)
4

Cache lifetime

By default your content is cached in memcache for one hour (3600 seconds). You can change this by adding an int property within: ZMI > portal_properties > site_properties called memcached_defaultLifetime and set it’s value to 86400 (one day) for example.

Cache lifetime override per key

Starting with eea.cache 5.1 you can also pass a lifetime key with the duration in seconds which will override the defaultLifetime either given from the portal property or the default one from lovely.memcached of 3600 seconds

ex: in order to cache the result only for 4 minutes
>>> @cache(key, dependencies=["frontpage"], lifetime=240)
... def myMethod(num):
...     return num*num

Funding and project management

EEA - European Environment Agency (EU)