Erector Cache¶ ↑

Widget caching for Erector.

Note: This only works at the widget level as this is essentially a fragment caching utility, and will not work for widgets rendered directly from a controller. (widget vs render_widget)

sudo gem install erector_cache

Checkout redis github.com/antirez/redis and install

MAKE SURE REDIS SERVER IS RUNNING

First, connect to the Redis database. This would most likely go into an environment.rb.

Lawnchair.connectdb

This will connect to a default database on localhost, if you want to connect to a particular database you can do:

Lawnchair.connectdb(Redis.new(:database => 11, :host => "127.0.0.1", :port => 6379))

• cache_for - Use this to tell the widget how long it should be cached for. Defaults to 1 hour

• cache_with - These are the widget parameters you want to use to build the cache key

• expire! - Expire the instances of a widget matching the given parameters

  class Bluth < Erector::Widget
    cache_with :name, :mistake
    cache_for 3.seasons
  
    def content
      div "My name is #{@name} and #{@mistake.to_param}"
    end
  end
  
  class Mistake < ORM::Base
    attr_reader :updated_at
  
    def initialize(size)
      @size = size || :huge
      @updated_at = Time.now
    end
  
    def size
      @size
    end
  
    def to_param
      "I_just_made_a_#{size}_mistake"
    end
  end
  

In the simple case the cache key will be built off of the value of the parameter eg.

widget Bluth, :name => "George Michael", :mistake => "consubrinaphilia"

This will yield a cache key of “Lawnchair:Bluth:name:GeorgeMichael:mistake:consubrinaphilia”

You can also pass whole objects into the widget and build the cache based on this. It will default to using the to_param of the object as the key component value.

@mistake = Mistake.create(:huge)
widget Bluth, :name => "Gob", :mistake => @mistake

This will yield a cache key of “Lawnchair:Bluth:name:Gob:mistake:I_just_made_a_huge_mistake”

This is essentially the same as doing this, which opens up more complex possibilities for generating cache keys

class Bluth < Erector::Widget
  cache_with :name, :mistake => lambda {|mistake| mistake.to_param }
end

@mistake = Mistake.create(:huge)
widget Bluth, :name => "Gob", :mistake => @mistake

Using this, we could set the cache to auto expire every time the associated object is updated.

class Bluth < Erector::Widget
  cache_with :name, :mistake => lambda {|mistake| mistake.updated_at }
end

Widget expiration is possible by calling the widget class’s expire! method and passing in as much information about the keys to expire as you want.

Assume the following have occurred:

widget Bluth, :name => "Tobias", :mistake => "I_just_blue_myself"
widget Bluth, :name => "Tobias", :mistake => "analyst_and_therapist"
widget Bluth, :name => "Buster", :mistake => "swimming_with_seal"

You can expire all Bluth widgets regardless of what the values of the params passed into them with:

Bluth.expire!

You can expire only the Bluth widget with :mistake => “I_just_blue_myself” by using:

Bluth.expire!(:mistake => "I_just_blue_myself")

You can expire all widgets with :name => “Tobias” with:

Bluth.expire!(:name => "Tobias")

Likewise, calling the following will expire only the one cached version of the widget that exists, leaving the other instance in the cache:

Bluth.expire!(:name => "Tobias", :mistake => "I_just_blue_myself")

Any cache key component that is not passed into the expire! method will result in a wildcard match on that component, allowing you to be as specific as you wish.

Note: Lawnchair will automatically condense spaces, so don’t feel constrained to using underscores or dashes in keys.

                        ....:~~~~~~~~~~~~~:~~::::::,..                         
                  ......,~===~=====~~~~~::::::::::::::,.....  ..               
                  ....,~+++=++++++==~~~~:::::::::::::::,...  ..                
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            .....~$$77II7III?+?++++===~~~~::::::::::::::~~=:......             
            ....:ZZ$$7IIIIII???++++++==~~~:::::::::~~~:~~~==,.....             
            ....7OZZ$77I777I????+++++==~~::::::::::~~::~~~===, ..              
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             ,7O8OO$$ZZZ$77$77ZOO8OOZ$II?+++=::,,,:::~===~+++I$Z:.... ..       
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             ,7OOO8OOZ77$I$OZIII~~~~=+???++I7I=:~=~=+I$=~I~=~:~+...=,:,        
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            ..?O88O88OZ$$$$7$Z+?+?77ZOO7III$7$ZI=:::Z7+78ZO8$I~=~++,~=..       
            ..+O88O8OOZ$777=$7=??$ODN$8?+$I?7787=~~:O$?ZN88$Z8?=~...+:..       
            ,:+7ZDDD8OZZ$$7?$Z?IZOII$7?++++?77$??+~:IZ=?+~~=+II=,...+,.        
      .....:II++7O8DOZ$$7$7IIZ??7Z7?~~=+++=+7O7+I?=:+$~=?7I??I?+:..:+..        
      ... .?ZOZ?++$8O$$7777??7$=???I?+===~:~77+I?==~:~=~~~~~~~~==.,:..         
      ... ,+77?7OI78O777777II+?$=~~~~~~~:::II+$7?+~:~:~~~:,:::::~=:.....       
      ....,+77==Z$$8O$7777IIII??I=:::::,,+?II?77I+~,,::=I7~,,.:=++:....        
      .....=7?=?O8$88Z$$$777II?+=+7$IIII=:+$7III77?==~~=+=+?+=~~~~:.....       
      .....~7++7877O8O$$$$77I?+===:~~:::~+IZ$I?+7O$+=~~?++==~::::~:....        
      .....,I+?==?788OZZ$$77II?+==~~~~~===+7ODD8OZ8OZZ8D7+~~++~~~=: ...        
      ......I=+=+I7O8OOZZ$777I??+===~~====+?IOO$7$O88Z$$7+=~=+=~==:.....       
            ,$++7ZIOD8OZ$$$7777I?++=====?I$ZZZ$Z77ZZOOZ$ZZ$I+~+++=.....        
             ~I++?7OO$$$$$$777$77?++=?IZOZOOOOZZOOOOOOZ$ZOZ$Z$+=+~......       
            .,?++?IZO$$Z$$$777777I??I$ZOOOOOOOZZOZZ7II$7IZOOOZI=+~......       
            ..,II=:?Z$$$$$$77I77I?78888888OZZZ$77$III7?+?$O8OO$++,..  .        
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            ........?7$$$$$77II77II=+77Z8NNNNDNNN8DNDNMNO7+?7I++~.    .        
            ........?$$$$$$$7I777I?==+++?IO8OZI==,::,?$7I?==?+==:              
               .....?7$$$$Z$77I7$$7?=++++I??7I+===+?+=?I?===~=+=..             
                  ..?$$ZZZZ$$$77777I?+=+++II++++=====++===~~==+...             
                  . ?$$$ZZZZ$$777777I+=+++?II?+????++?+++=~~==~...             
            .  .  ..I$$ZZOOOZZ$$777777+=+?+=+?++++==+=~~~~~~~~...              
            .......:$$ZZZOOOOOZZ$777$$?+=+++===~~=~~~~~~~~~~=, ..              
             .....,I$7$$$$$ZOOOOZ$$7$Z7I+=====~~:::~:~~~~~=~.....              
            . ....+77777$$$ZOO88OZZ$$Z$I?+=====~~::~~~~~=~=,.. ..              
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. :D88DDDZ7+:.,?7I7$$$7IIIII777$ZOOO888OOZ$II??+====+==++,.                    
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,Z8OOOOOO888888DD8DDD88DDD$?IIII7$ZOZOOOOOOOOZZZZZ$Z$I=.....

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