vendor/rails/activerecord/lib/active_record/connection_adapters/abstract/query_cache.rb

   1 module ActiveRecord
   2   module ConnectionAdapters # :nodoc:
   3     module QueryCache
   4       class << self
   5         def included(base)
   6           base.class_eval do
   7             attr_accessor :query_cache_enabled
   8             alias_method_chain :columns, :query_cache
   9             alias_method_chain :select_all, :query_cache
  10           end
  11
  12           dirties_query_cache base, :insert, :update, :delete
  13         end
  14
  15         def dirties_query_cache(base, *method_names)
  16           method_names.each do |method_name|
  17             base.class_eval <<-end_code, __FILE__, __LINE__
  18               def #{method_name}_with_query_dirty(*args)
  19                 clear_query_cache if @query_cache_enabled
  20                 #{method_name}_without_query_dirty(*args)
  21               end
  22
  23               alias_method_chain :#{method_name}, :query_dirty
  24             end_code
  25           end
  26         end
  27       end
  28
  29       # Enable the query cache within the block.
  30       def cache
  31         old, @query_cache_enabled = @query_cache_enabled, true
  32         @query_cache ||= {}
  33         yield
  34       ensure
  35         clear_query_cache
  36         @query_cache_enabled = old
  37       end
  38
  39       # Disable the query cache within the block.
  40       def uncached
  41         old, @query_cache_enabled = @query_cache_enabled, false
  42         yield
  43       ensure
  44         @query_cache_enabled = old
  45       end
  46
  47       def clear_query_cache
  48         @query_cache.clear if @query_cache
  49       end
  50
  51       def select_all_with_query_cache(*args)
  52         if @query_cache_enabled
  53           cache_sql(args.first) { select_all_without_query_cache(*args) }
  54         else
  55           select_all_without_query_cache(*args)
  56         end
  57       end
  58
  59       def columns_with_query_cache(*args)
  60         if @query_cache_enabled
  61           @query_cache["SHOW FIELDS FROM #{args.first}"] ||= columns_without_query_cache(*args)
  62         else
  63           columns_without_query_cache(*args)
  64         end
  65       end
  66
  67       private
  68         def cache_sql(sql)
  69           result =
  70             if @query_cache.has_key?(sql)
  71               log_info(sql, "CACHE", 0.0)
  72               @query_cache[sql]
  73             else
  74               @query_cache[sql] = yield
  75             end
  76
  77           if Array === result
  78             result.collect { |row| row.dup }
  79           else
  80             result.duplicable? ? result.dup : result
  81           end
  82         rescue TypeError
  83           result
  84         end
  85     end
  86   end
  87 end