cache.rb in activesupport-4.1.0.beta1

- old
+ new

@@ -1,23 +1,23 @@
 require 'benchmark'
 require 'zlib'
 require 'active_support/core_ext/array/extract_options'
 require 'active_support/core_ext/array/wrap'
 require 'active_support/core_ext/benchmark'
-require 'active_support/core_ext/class/attribute_accessors'
+require 'active_support/core_ext/module/attribute_accessors'
 require 'active_support/core_ext/numeric/bytes'
 require 'active_support/core_ext/numeric/time'
 require 'active_support/core_ext/object/to_param'
 require 'active_support/core_ext/string/inflections'
 
 module ActiveSupport
   # See ActiveSupport::Cache::Store for documentation.
   module Cache
-    autoload :FileStore, 'active_support/cache/file_store'
-    autoload :MemoryStore, 'active_support/cache/memory_store'
+    autoload :FileStore,     'active_support/cache/file_store'
+    autoload :MemoryStore,   'active_support/cache/memory_store'
     autoload :MemCacheStore, 'active_support/cache/mem_cache_store'
-    autoload :NullStore, 'active_support/cache/null_store'
+    autoload :NullStore,     'active_support/cache/null_store'
 
     # These options mean something to all cache implementations. Individual cache
     # implementations may support additional options.
     UNIVERSAL_OPTIONS = [:namespace, :compress, :compress_threshold, :expires_in, :race_condition_ttl]
 
@@ -86,29 +86,28 @@
         expanded_cache_key << retrieve_cache_key(key)
         expanded_cache_key
       end
 
       private
+        def retrieve_cache_key(key)
+          case
+          when key.respond_to?(:cache_key) then key.cache_key
+          when key.is_a?(Array)            then key.map { |element| retrieve_cache_key(element) }.to_param
+          when key.respond_to?(:to_a)      then retrieve_cache_key(key.to_a)
+          else                                  key.to_param
+          end.to_s
+        end
 
-      def retrieve_cache_key(key)
-        case
-        when key.respond_to?(:cache_key) then key.cache_key
-        when key.is_a?(Array)            then key.map { |element| retrieve_cache_key(element) }.to_param
-        when key.respond_to?(:to_a)      then retrieve_cache_key(key.to_a)
-        else                                  key.to_param
-        end.to_s
-      end
-
-      # Obtains the specified cache store class, given the name of the +store+.
-      # Raises an error when the store class cannot be found.
-      def retrieve_store_class(store)
-        require "active_support/cache/#{store}"
-      rescue LoadError => e
-        raise "Could not find cache store adapter for #{store} (#{e})"
-      else
-        ActiveSupport::Cache.const_get(store.to_s.camelize)
-      end
+        # Obtains the specified cache store class, given the name of the +store+.
+        # Raises an error when the store class cannot be found.
+        def retrieve_store_class(store)
+          require "active_support/cache/#{store}"
+        rescue LoadError => e
+          raise "Could not find cache store adapter for #{store} (#{e})"
+        else
+          ActiveSupport::Cache.const_get(store.to_s.camelize)
+        end
     end
 
     # An abstract cache store class. There are multiple cache store
     # implementations, each having its own additional features. See the classes
     # under the ActiveSupport::Cache module, e.g.
@@ -151,11 +150,10 @@
     # large enough to warrant compression. To turn on compression either pass
     # <tt>compress: true</tt> in the initializer or as an option to +fetch+
     # or +write+. To specify the threshold at which to compress values, set the
     # <tt>:compress_threshold</tt> option. The default threshold is 16K.
     class Store
-
       cattr_accessor :logger, :instance_writer => true
 
       attr_reader :silence, :options
       alias :silence? :silence
 
@@ -226,11 +224,11 @@
       #   cache = ActiveSupport::Cache::MemoryStore.new(expires_in: 5.minutes)
       #   cache.write(key, value, expires_in: 1.minute) # Set a lower value for one entry
       #
       # Setting <tt>:race_condition_ttl</tt> is very useful in situations where
       # a cache entry is used very frequently and is under heavy load. If a
-      # cache expires and due to heavy load seven different processes will try
+      # cache expires and due to heavy load several different processes will try
       # to read data natively and then they all will try to write to cache. To
       # avoid that case the first process to find an expired cache entry will
       # bump the cache expiration time by the value set in <tt>:race_condition_ttl</tt>.
       # Yes, this process is extending the time for a stale value by another few
       # seconds. Because of extended life of the previous cache, other processes
@@ -350,15 +348,44 @@
           end
         end
         results
       end
 
+      # Fetches data from the cache, using the given keys. If there is data in
+      # the cache with the given keys, then that data is returned. Otherwise,
+      # the supplied block is called for each key for which there was no data,
+      # and the result will be written to the cache and returned.
+      #
+      # Options are passed to the underlying cache implementation.
+      #
+      # Returns an array with the data for each of the names. For example:
+      #
+      #   cache.write("bim", "bam")
+      #   cache.fetch_multi("bim", "boom") {|key| key * 2 }
+      #   # => ["bam", "boomboom"]
+      #
+      def fetch_multi(*names)
+        options = names.extract_options!
+        options = merged_options(options)
+
+        results = read_multi(*names, options)
+
+        names.map do |name|
+          results.fetch(name) do
+            value = yield name
+            write(name, value, options)
+            value
+          end
+        end
+      end
+
       # Writes the value to the cache, with the key.
       #
       # Options are passed to the underlying cache implementation.
       def write(name, value, options = nil)
         options = merged_options(options)
+
         instrument(:write, name, options) do
           entry = Entry.new(value, options)
           write_entry(namespaced_key(name, options), entry, options)
         end
       end
@@ -366,23 +393,25 @@
       # Deletes an entry in the cache. Returns +true+ if an entry is deleted.
       #
       # Options are passed to the underlying cache implementation.
       def delete(name, options = nil)
         options = merged_options(options)
+
         instrument(:delete, name) do
           delete_entry(namespaced_key(name, options), options)
         end
       end
 
       # Return +true+ if the cache contains an entry for the given key.
       #
       # Options are passed to the underlying cache implementation.
       def exist?(name, options = nil)
         options = merged_options(options)
+
         instrument(:exist?, name) do
           entry = read_entry(namespaced_key(name, options), options)
-          entry && !entry.expired?
+          (entry && !entry.expired?) || false
         end
       end
 
       # Delete all entries with keys matching the pattern.
       #
@@ -555,10 +584,11 @@
 
         def save_block_result_to_cache(name, options)
           result = instrument(:generate, name, options) do |payload|
             yield(name)
           end
+
           write(name, result, options)
           result
         end
     end
 
@@ -578,10 +608,11 @@
           @value = compress(value)
           @compressed = true
         else
           @value = value
         end
+
         @created_at = Time.now.to_f
         @expires_in = options[:expires_in]
         @expires_in = @expires_in.to_f if @expires_in
       end
 
@@ -591,11 +622,11 @@
       end
 
       # Check if the entry is expired. The +expires_in+ parameter can override
       # the value set when the entry was created.
       def expired?
-        convert_version_4beta1_entry! if defined?(@v)
+        convert_version_4beta1_entry! if defined?(@value)
         @expires_in && @created_at + @expires_in <= Time.now.to_f
       end
 
       def expires_at
         @expires_in ? @created_at + @expires_in : nil
@@ -628,10 +659,11 @@
 
       # Duplicate the value in a class. This is used by cache implementations that don't natively
       # serialize entries to protect against accidental cache modifications.
       def dup_value!
         convert_version_4beta1_entry! if defined?(@v)
+
         if @value && !compressed? && !(@value.is_a?(Numeric) || @value == true || @value == false)
           if @value.is_a?(String)
             @value = @value.dup
           else
             @value = Marshal.load(Marshal.dump(@value))
@@ -642,12 +674,14 @@
       private
         def should_compress?(value, options)
           if value && options[:compress]
             compress_threshold = options[:compress_threshold] || DEFAULT_COMPRESS_LIMIT
             serialized_value_size = (value.is_a?(String) ? value : Marshal.dump(value)).bytesize
+
             return true if serialized_value_size >= compress_threshold
           end
+
           false
         end
 
         def compressed?
           defined?(@compressed) ? @compressed : false
@@ -666,13 +700,15 @@
         def convert_version_4beta1_entry!
           if defined?(@v)
             @value = @v
             remove_instance_variable(:@v)
           end
+
           if defined?(@c)
             @compressed = @c
             remove_instance_variable(:@c)
           end
+
           if defined?(@x) && @x
             @created_at ||= Time.now.to_f
             @expires_in = @x - @created_at
             remove_instance_variable(:@x)
           end