Module: LowCardTables::LowCardTable::CacheExpiration::HasCacheExpiration::ClassMethods

Defined in:
lib/low_card_tables/low_card_table/cache_expiration/has_cache_expiration.rb

Instance Method Summary collapse

Instance Method Details

#low_card_cache_expiration(type_or_number = nil, options = { }) ⇒ Object

Sets the cache-expiration policy of this class. You can pass:

  • A positive number – sets the cache-expiration policy to be that many seconds.

  • Zero – turns off caching entirely.

  • :unlimited – makes the cache last forever.

  • :exponential, optionally with an options hash as the second argument – sets the cache-expiration policy to be exponential; see ExponentialCacheExpirationPolicy for more details.

If you pass no arguments at all, you’re returned the current cache-expiration policy.

If you do not call this method at all, the cache-expiration policy will be undefined. You should always either call this method, or set up an inheritance chain using #low_card_cache_policy_inherits_from, to a class that does have it defined.



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# File 'lib/low_card_tables/low_card_table/cache_expiration/has_cache_expiration.rb', line 34

def low_card_cache_expiration(type_or_number = nil, options = { })
  if type_or_number.nil?
    @_low_card_cache_expiration_return_value || low_card_cache_expiration_inherited
  else
    if type_or_number == 0
      @_low_card_cache_expiration_policy_object = LowCardTables::LowCardTable::CacheExpiration::NoCachingExpirationPolicy.new
      @_low_card_cache_expiration_return_value = 0
    elsif type_or_number.kind_of?(Numeric)
      @_low_card_cache_expiration_policy_object = LowCardTables::LowCardTable::CacheExpiration::FixedCacheExpirationPolicy.new(type_or_number)
      @_low_card_cache_expiration_return_value = type_or_number
    elsif type_or_number == :unlimited
      @_low_card_cache_expiration_policy_object = LowCardTables::LowCardTable::CacheExpiration::UnlimitedCacheExpirationPolicy.new
      @_low_card_cache_expiration_return_value = :unlimited
    elsif type_or_number == :exponential
      @_low_card_cache_expiration_policy_object = LowCardTables::LowCardTable::CacheExpiration::ExponentialCacheExpirationPolicy.new(options.merge(:start_time => low_card_current_time))
      if options.size > 0
        @_low_card_cache_expiration_return_value = [ :exponential, options ]
      else
        @_low_card_cache_expiration_return_value = :exponential
      end
    else
      raise ArgumentError, "Invalid cache expiration time argumnet '#{type_or_number.inspect}'; you must pass a number, :unlimited, or :exponential."
    end
  end
end

#low_card_cache_expiration_policy_object ⇒ Object

For low_card_tables internal use only. Returns the current cache-expiration policy object – e.g., an instance of LowCardTables::LowCardTable::CacheExpiration::FixedCacheExpirationPolicy.



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# File 'lib/low_card_tables/low_card_table/cache_expiration/has_cache_expiration.rb', line 62

def low_card_cache_expiration_policy_object
  @_low_card_cache_expiration_policy_object || low_card_cache_expiration_policy_object_inherited
end

#low_card_cache_policy_inherits_from(other_class) ⇒ Object

Declares that this class should inherit its cache-expiration policy from the specified other class, which must be a class that has had this module included in it (directly or indirectly) too. In other words, if you don’t set a policy on this class, but have specified that it inherits its policy from the given other class, then it will use whatever policy the other class has set.

We use this because low-card tables’ classes all inherit directly from ::ActiveRecord::Base; they don’t inherit from some parent “it’s a low-card table” class. (This is because inheritance in ActiveRecord is used to denote data in common via STI, not what we’re trying to do here.) So we use this to set up the default policy directly on the ::LowCardTables root module, and ‘inherit’ it into individual low-card tables (via the included block on LowCardTables::LowCardTable::Base) this way.



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# File 'lib/low_card_tables/low_card_table/cache_expiration/has_cache_expiration.rb', line 76

def low_card_cache_policy_inherits_from(other_class)
  @_low_card_cache_policy_inherits_from = other_class
end