2 files changed, 75 insertions, 51 deletions

diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index 5a5548d567..6a1f1fefb8 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -275,34 +275,14 @@ module ActiveSupport
         if block_given?
           options = merged_options(options)
           key = namespaced_key(name, options)
-          unless options[:force]
-            entry = instrument(:read, name, options) do |payload|
-              payload[:super_operation] = :fetch if payload
-              read_entry(key, options)
-            end
-          end
-          if entry && entry.expired?
-            race_ttl = options[:race_condition_ttl].to_i
-            if race_ttl && (Time.now - entry.expires_at <= race_ttl)
-              # When an entry has :race_condition_ttl defined, put the stale entry back into the cache
-              # for a brief period while the entry is begin recalculated.
-              entry.expires_at = Time.now + race_ttl
-              write_entry(key, entry, :expires_in => race_ttl * 2)
-            else
-              delete_entry(key, options)
-            end
-            entry = nil
-          end
+
+          cached_entry = find_cached_entry(key, name, options) unless options[:force]
+          entry = handle_expired_entry(cached_entry, key, options)
 
           if entry
-            instrument(:fetch_hit, name, options) { |payload| }
-            entry.value
+            get_entry_value(entry, name, options)
           else
-            result = instrument(:generate, name, options) do |payload|
-              yield(name)
-            end
-            write(name, result, options)
-            result
+            save_block_result_to_cache(name, options) { |name| yield name }
           end
         else
           read(name, options)
@@ -531,6 +511,42 @@ module ActiveSupport
           return unless logger && logger.debug? && !silence?
           logger.debug("Cache #{operation}: #{key}#{options.blank? ? "" : " (#{options.inspect})"}")
         end
+
+        def find_cached_entry(key, name, options)
+          instrument(:read, name, options) do |payload|
+            payload[:super_operation] = :fetch if payload
+            read_entry(key, options)
+          end
+        end
+
+        def handle_expired_entry(entry, key, options)
+          if entry && entry.expired?
+            race_ttl = options[:race_condition_ttl].to_i
+            if race_ttl && (Time.now - entry.expires_at <= race_ttl)
+              # When an entry has :race_condition_ttl defined, put the stale entry back into the cache
+              # for a brief period while the entry is begin recalculated.
+              entry.expires_at = Time.now + race_ttl
+              write_entry(key, entry, :expires_in => race_ttl * 2)
+            else
+              delete_entry(key, options)
+            end
+            entry = nil
+          end
+          entry
+        end
+
+        def get_entry_value(entry, name, options)
+          instrument(:fetch_hit, name, options) { |payload| }
+          entry.value
+        end
+
+        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
 
     # This class is used to represent cache entries. Cache entries have a value and an optional
diff --git a/activesupport/lib/active_support/testing/isolation.rb b/activesupport/lib/active_support/testing/isolation.rb
index aa87598926..e4f8959e7a 100644
--- a/activesupport/lib/active_support/testing/isolation.rb
+++ b/activesupport/lib/active_support/testing/isolation.rb
@@ -43,32 +43,36 @@ module ActiveSupport
     module Isolation
       require 'thread'
 
-      class ParallelEach
-        include Enumerable
-
-        # default to 2 cores
-        CORES = (ENV['TEST_CORES'] || 2).to_i
-
-        def initialize list
-          @list  = list
-          @queue = SizedQueue.new CORES
-        end
+      # Recent versions of MiniTest (such as the one shipped with Ruby 2.0) already define
+      # a ParallelEach class.
+      unless defined? ParallelEach
+        class ParallelEach
+          include Enumerable
+
+          # default to 2 cores
+          CORES = (ENV['TEST_CORES'] || 2).to_i
+
+          def initialize list
+            @list  = list
+            @queue = SizedQueue.new CORES
+          end
 
-        def grep pattern
-          self.class.new super
-        end
+          def grep pattern
+            self.class.new super
+          end
 
-        def each
-          threads = CORES.times.map {
-            Thread.new {
-              while job = @queue.pop
-                yield job
-              end
+          def each
+            threads = CORES.times.map {
+              Thread.new {
+                while job = @queue.pop
+                  yield job
+                end
+              }
             }
-          }
-          @list.each { |i| @queue << i }
-          CORES.times { @queue << nil }
-          threads.each(&:join)
+            @list.each { |i| @queue << i }
+            CORES.times { @queue << nil }
+            threads.each(&:join)
+          end
         end
       end
 
@@ -84,10 +88,14 @@ module ActiveSupport
         !ENV["NO_FORK"] && ((RbConfig::CONFIG['host_os'] !~ /mswin|mingw/) && (RUBY_PLATFORM !~ /java/))
       end
 
+      @@class_setup_mutex = Mutex.new
+
       def _run_class_setup      # class setup method should only happen in parent
-        unless defined?(@@ran_class_setup) || ENV['ISOLATION_TEST']
-          self.class.setup if self.class.respond_to?(:setup)
-          @@ran_class_setup = true
+        @@class_setup_mutex.synchronize do
+          unless defined?(@@ran_class_setup) || ENV['ISOLATION_TEST']
+            self.class.setup if self.class.respond_to?(:setup)
+            @@ran_class_setup = true
+          end
         end
       end