eea.cache 5.1

Tools and config for memcache related caching

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 lovely.memcached

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.

Contents

Contents

• Introduction

• Contents

• Installation

• Dependencies

• Source code

• Cache decorator

• Cache lifetime

  • Cache lifetime override per key

• Copyright and license

• Funding and project management

• Changelog

  • 5.1 - (2013-02-04)

  • 5.0 - (2012-10-08)

  • 4.3 - (2012-07-13)

  • 4.2 - (2012-02-06)

  • 4.0 - (2011-11-07)

  • 0.3 - (2010-11-22)

  • 0.2 - (2010-11-10)

  • 0.1 - (2009-11-10)

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:

  • Add eea.cache to the list of eggs to install

  • Tell the plone.recipe.zope2instance recipe to install a ZCML slug

  • Add memcache

  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+

• lovely.memcached

Source code

Latest source code (Zope 2 compatible):

• Plone Collective on Github

• EEA on Github

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 lovely.memcached.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

Copyright and license

The Initial Owner of the Original Code is European Environment Agency (EEA). All Rights Reserved.

The eea.cache (the Original Code) is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

More details under docs/License.txt

Funding and project management

EEA - European Environment Agency (EU)

Changelog

5.1 - (2013-02-04)

• Feature: added ability to pass a lifetime key to the cache decorator in order to cache it for a determined period different from the default lifetime [ichimdav #13677]

• Upgrade step: (optional) Within ZMI > portal_properties > site_properties add an int property called memcached_defaultLifetime and set it’s value to 86400 (one day) or any value that fits your needs.

• Feature: Ability to set memcached default lifetime, which by now was hardcoded to one hour (3600 seconds) [voineali refs #13677]

5.0 - (2012-10-08)

• Change: Updated README and egg’s metadata [voineali refs #5434]

4.3 - (2012-07-13)

• Bug fix: fixed markup of HISTORY.txt file [ciobabog refs #5231]

4.2 - (2012-02-06)

• no changes

4.0 - (2011-11-07)

• Feature: Plone 4.x compatible release [ghicaale #4309]

0.3 - (2010-11-22)

• Bug fix: fixed tests namespace in order to be used within hudson [voineali #3821]

0.2 - (2010-11-10)

• Bug fix: added fake memcache client in order to fix broken doctests [voineali]

0.1 - (2009-11-10)

• Initial release