0_system_config_cache.md

See https://gist.github.com/tsnow/9278946

new.rb

## New
class SystemConfig < ActiveRecord::Base

  validates_uniqueness_of :name, :case_sensitive => :db

  def self.cache
    @cache ||= CachedMethod.new('system_config', :expires_in => 10.minutes) do 
      all
    end
  end
  
  def self.fetch(name)
    @cache.get.find{|i| i.name == name.to_s}
  end
  
  def self.fetch_value(name)
    found = fetch(name)
    return nil unless found
    found.to_value
  end
  
  def self.fetch_value!(name)
    err_msg = "SystemConfig.find_by_name(#{name.inspect}) doesn't exist"
    raise ArgumentError.new(err_msg) unless found(name)
    fetch_value(name)
  end
  
  def self.[](name)
    fetch_value(name)
  end

  def self.[]=(name, value)
    existing = SystemConfig.find(:first, :conditions => {:name => name})
    new_config = SystemConfig.new(:name => name, :value => value)
    SystemConfig.transaction do
      existing.delete if existing.present?
      raise ActiveRecord::Rollback unless new_config.valid?
      new_config.save
    end
    delete_cache
    new_config.to_value
  end

  def self.method_missing(method, *args, &block)
    return super unless has_key?(method.to_s)
    fetch_value!(method.to_s) 
  end

  def self.respond_to?(name)
    super or fetch(name)
  end

  def self.delete_cache
    cache.delete
  end
  
  def to_value
    if name =~ /\?$/
      return (value == "0" || value == "false") ? false : true
    end
    
    case config.value 
    when /^\d*$/ then
      value.to_i
    when /^\d*\.\d*$/ then
      value.to_f
    else
      value
    end
  end
  
end

old.rb

## Old

class SystemConfig < ActiveRecord::Base
  SYSTEM_CONFIG_CACHE_KEY = 'system_config'
  validates_uniqueness_of :name, :case_sensitive => :db
  def self.[](name)
    if system_config = Rails.cache.read(SYSTEM_CONFIG_CACHE_KEY) 
      return system_config[name]
    else
      cache_system_config[name]
    end
  end

  def self.[]=(name, value)
    existing = SystemConfig.find(:first, :conditions => {:name => name})
    new_config = SystemConfig.new(:name => name, :value => value)
    SystemConfig.transaction do
      existing.delete if existing.present?
      raise ActiveRecord::Rollback unless new_config.valid?
      new_config.save
    end
    delete_cache
  end

  def self.method_missing(method, *args, &block)
    if !(value = SystemConfig.send(:[], method.to_s)).nil?
      return value
    elsif SystemConfig.respond_to? method.to_s
      return
    else
      super
    end 
  end

  def self.respond_to?(name)
    super or key_exists?(name)
  end

  def self.delete_cache
    Rails.cache.delete(SYSTEM_CONFIG_CACHE_KEY)
  end

  private
    def self.key_exists?(name)
      if keys = Rails.cache.read(SYSTEM_CONFIG_CACHE_KEY).try(:keys)
        return keys.any?{ |k| k == name}
      end
      return false
    end

    def self.cache_system_config
      system_config = {}
      SystemConfig.all.each do |config|
        if config.name =~ /\?$/
          value = (config.value == "0" || config.value == "false") ? false : true
        elsif config.value =~ /^\d*$/
          value = config.value.to_i
        elsif config.value =~ /^\d*\.\d*$/
          value = config.value.to_f
        else
          value = config.value
        end
        system_config[config.name] = value
      end
      Rails.cache.write(SYSTEM_CONFIG_CACHE_KEY, system_config, :expires_in => 10.minutes)
      system_config
    end
end