vendor/rails/activesupport/lib/active_support/cache/strategy/local_cache.rb

   1 module ActiveSupport
   2   module Cache
   3     module Strategy
   4       module LocalCache
   5         # this allows caching of the fact that there is nothing in the remote cache
   6         NULL = 'remote_cache_store:null'
   7
   8         def with_local_cache
   9           Thread.current[thread_local_key] = MemoryStore.new
  10           yield
  11         ensure
  12           Thread.current[thread_local_key] = nil
  13         end
  14
  15         def middleware
  16           @middleware ||= begin
  17             klass = Class.new
  18             klass.class_eval(<<-EOS, __FILE__, __LINE__)
  19               def initialize(app)
  20                 @app = app
  21               end
  22
  23               def call(env)
  24                 Thread.current[:#{thread_local_key}] = MemoryStore.new
  25                 @app.call(env)
  26               ensure
  27                 Thread.current[:#{thread_local_key}] = nil
  28               end
  29             EOS
  30             klass
  31           end
  32         end
  33
  34         def read(key, options = nil)
  35           value = local_cache && local_cache.read(key)
  36           if value == NULL
  37             nil
  38           elsif value.nil?
  39             value = super
  40             local_cache.write(key, value || NULL) if local_cache
  41             value
  42           else
  43             # forcing the value to be immutable
  44             value.duplicable? ? value.dup : value
  45           end
  46         end
  47
  48         def write(key, value, options = nil)
  49           value = value.to_s if respond_to?(:raw?) && raw?(options)
  50           local_cache.write(key, value || NULL) if local_cache
  51           super
  52         end
  53
  54         def delete(key, options = nil)
  55           local_cache.write(key, NULL) if local_cache
  56           super
  57         end
  58
  59         def exist(key, options = nil)
  60           value = local_cache.read(key) if local_cache
  61           if value == NULL
  62             false
  63           elsif value
  64             true
  65           else
  66             super
  67           end
  68         end
  69
  70         def increment(key, amount = 1)
  71           if value = super
  72             local_cache.write(key, value.to_s) if local_cache
  73             value
  74           else
  75             nil
  76           end
  77         end
  78
  79         def decrement(key, amount = 1)
  80           if value = super
  81             local_cache.write(key, value.to_s) if local_cache
  82             value
  83           else
  84             nil
  85           end
  86         end
  87
  88         def clear
  89           local_cache.clear if local_cache
  90           super
  91         end
  92
  93         private
  94           def thread_local_key
  95             @thread_local_key ||= "#{self.class.name.underscore}_local_cache".gsub("/", "_").to_sym
  96           end
  97
  98           def local_cache
  99             Thread.current[thread_local_key]
 100           end
 101       end
 102     end
 103   end
 104 end