write_entry

# File activesupport/lib/active_support/cache/memory_store.rb, line 145
        def write_entry(key, entry, options) # :nodoc:
          entry.dup_value!
          synchronize do
            old_entry = @data[key]
            return false if @data.key?(key) && options[:unless_exist]
            if old_entry
              @cache_size -= (old_entry.size - entry.size)
            else
              @cache_size += cached_size(key, entry)
            end
            @key_access[key] = Time.now.to_f
            @data[key] = entry
            prune(@max_size * 0.75, @max_prune_time) if @cache_size > @max_size
            true
          end
        end