Add after_commit and after_rollback callbacks to ActiveRecord that are called after transactions either commit or rollback on all records saved or destroyed in the transaction.

[#2991 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

5 files changed, 466 insertions, 28 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 7864d735ad..ac5bd8e635 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *Rails 3.0.0 [beta 4/release candidate] (unreleased)*
 
+* New callbacks: after_commit and after_rollback. Do expensive operations like image thumbnailing after_commit instead of after_save.  #2991 [Brian Durand]
+
 * Serialized attributes are not converted to YAML if they are any of the formats that can be serialized to XML (like Hash, Array and Strings). [José Valim]
 
 * Destroy uses optimistic locking. If lock_version on the record you're destroying doesn't match lock_version in the database, a StaleObjectError is raised.  #1966 [Curtis Hawthorne]
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
index 0c87e052c4..b9fb452eee 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -122,6 +122,8 @@ module ActiveRecord
         requires_new = options[:requires_new] || !last_transaction_joinable
 
         transaction_open = false
+        @_current_transaction_records ||= []
+
         begin
           if block_given?
             if requires_new || open_transactions == 0
@@ -132,6 +134,7 @@ module ActiveRecord
               end
               increment_open_transactions
               transaction_open = true
+              @_current_transaction_records.push([])
             end
             yield
           end
@@ -141,8 +144,10 @@ module ActiveRecord
             decrement_open_transactions
             if open_transactions == 0
               rollback_db_transaction
+              rollback_transaction_records(true)
             else
               rollback_to_savepoint
+              rollback_transaction_records(false)
             end
           end
           raise unless database_transaction_rollback.is_a?(ActiveRecord::Rollback)
@@ -157,20 +162,35 @@ module ActiveRecord
           begin
             if open_transactions == 0
               commit_db_transaction
+              commit_transaction_records
             else
               release_savepoint
+              save_point_records = @_current_transaction_records.pop
+              unless save_point_records.blank?
+                @_current_transaction_records.push([]) if @_current_transaction_records.empty?
+                @_current_transaction_records.last.concat(save_point_records)
+              end
             end
           rescue Exception => database_transaction_rollback
             if open_transactions == 0
               rollback_db_transaction
+              rollback_transaction_records(true)
             else
               rollback_to_savepoint
+              rollback_transaction_records(false)
             end
             raise
           end
         end
       end
 
+      # Register a record with the current transaction so that its after_commit and after_rollback callbacks
+      # can be called.
+      def add_transaction_record(record)
+        last_batch = @_current_transaction_records.last
+        last_batch << record if last_batch
+      end
+
       # Begins the transaction (and turns off auto-committing).
       def begin_db_transaction()    end
 
@@ -268,6 +288,42 @@ module ActiveRecord
             limit.to_i
           end
         end
+
+        # Send a rollback message to all records after they have been rolled back. If rollback
+        # is false, only rollback records since the last save point.
+        def rollback_transaction_records(rollback) #:nodoc
+          if rollback
+            records = @_current_transaction_records.flatten
+            @_current_transaction_records.clear
+          else
+            records = @_current_transaction_records.pop
+          end
+
+          unless records.blank?
+            records.uniq.each do |record|
+              begin
+                record.rolledback!(rollback)
+              rescue Exception => e
+                record.logger.error(e) if record.respond_to?(:logger)
+              end
+            end
+          end
+        end
+
+        # Send a commit message to all records after they have been committed.
+        def commit_transaction_records #:nodoc
+          records = @_current_transaction_records.flatten
+          @_current_transaction_records.clear
+          unless records.blank?
+            records.uniq.each do |record|
+              begin
+                record.committed!
+              rescue Exception => e
+                record.logger.error(e) if record.respond_to?(:logger)
+              end
+            end
+          end
+        end
     end
   end
 end
diff --git a/activerecord/lib/active_record/transactions.rb b/activerecord/lib/active_record/transactions.rb
index cf0fe8934d..9e48228a40 100644
--- a/activerecord/lib/active_record/transactions.rb
+++ b/activerecord/lib/active_record/transactions.rb
@@ -12,6 +12,9 @@ module ActiveRecord
       [:destroy, :save, :save!].each do |method|
         alias_method_chain method, :transactions
       end
+
+      define_model_callbacks :commit, :commit_on_update, :commit_on_create, :commit_on_destroy, :only => :after
+      define_model_callbacks :rollback, :rollback_on_update, :rollback_on_create, :rollback_on_destroy
     end
 
     # Transactions are protective blocks where SQL statements are only permanent
@@ -108,7 +111,7 @@ module ActiveRecord
     #     rescue ActiveRecord::StatementInvalid
     #       # ...which we ignore.
     #     end
-    #     
+    #
     #     # On PostgreSQL, the transaction is now unusable. The following
     #     # statement will cause a PostgreSQL error, even though the unique
     #     # constraint is no longer violated:
@@ -132,7 +135,7 @@ module ActiveRecord
     #       raise ActiveRecord::Rollback
     #     end
     #   end
-    #   
+    #
     #   User.find(:all)  # => empty
     #
     # It is also possible to requires a sub-transaction by passing
@@ -147,7 +150,7 @@ module ActiveRecord
     #       raise ActiveRecord::Rollback
     #     end
     #   end
-    #   
+    #
     #   User.find(:all)  # => Returns only Kotori
     #
     # Most databases don't support true nested transactions. At the time of
@@ -157,6 +160,26 @@ module ActiveRecord
     # http://dev.mysql.com/doc/refman/5.0/en/savepoints.html
     # for more information about savepoints.
     #
+    # === Callbacks
+    #
+    # There are two types of callbacks associated with committing and rolling back transactions:
+    # after_commit and after_rollback.
+    #
+    # The after_commit callbacks are called on every record saved or destroyed within a
+    # transaction immediately after the  transaction is committed. The after_rollback callbacks
+    # are called on every record saved or destroyed within a transaction immediately after the
+    # transaction or savepoint is rolled back.
+    #
+    # Additionally, there are callbacks for after_commit_on_create, after_rollback_on_create,
+    # after_commit_on_update, after_rollback_on_update, after_commit_on_destroy, and
+    # after_rollback_on_destroy which are only called if a record is created, updated or destroyed
+    # in the transaction.
+    #
+    # These callbacks are useful for interacting with other systems since you will be guaranteed
+    # that the callback is only executed when the database is in a permanent state. For example,
+    # after_commit is a good spot to put in a hook to clearing a cache since clearing it from
+    # within a transaction could trigger the cache to be regenerated before the database is updated.
+    #
     # === Caveats
     #
     # If you're on MySQL, then do not use DDL operations in nested transactions
@@ -166,7 +189,7 @@ module ActiveRecord
     # is finished and tries to release the savepoint it created earlier, a
     # database error will occur because the savepoint has already been
     # automatically released. The following example demonstrates the problem:
-    # 
+    #
     #   Model.connection.transaction do                           # BEGIN
     #     Model.connection.transaction(:requires_new => true) do  # CREATE SAVEPOINT active_record_1
     #       Model.connection.create_table(...)                    # active_record_1 now automatically released
@@ -197,24 +220,55 @@ module ActiveRecord
     end
 
     def save_with_transactions! #:nodoc:
-      rollback_active_record_state! { self.class.transaction { save_without_transactions! } }
+      with_transaction_returning_status(:save_without_transactions!)
     end
 
     # Reset id and @new_record if the transaction rolls back.
     def rollback_active_record_state!
-      id_present = has_attribute?(self.class.primary_key)
-      previous_id = id
-      previous_new_record = new_record?
+      remember_transaction_record_state
       yield
     rescue Exception
-      @new_record = previous_new_record
-      if id_present
-        self.id = previous_id
+      restore_transaction_record_state
+      raise
+    ensure
+      clear_transaction_record_state
+    end
+
+    # Call the after_commit callbacks
+    def committed! #:nodoc:
+      if transaction_record_state(:new_record)
+        _run_commit_on_create_callbacks
+      elsif transaction_record_state(:destroyed)
+        _run_commit_on_destroy_callbacks
       else
-        @attributes.delete(self.class.primary_key)
-        @attributes_cache.delete(self.class.primary_key)
+        _run_commit_on_update_callbacks
+      end
+      _run_commit_callbacks
+    ensure
+      clear_transaction_record_state
+    end
+
+    # Call the after rollback callbacks. The restore_state argument indicates if the record
+    # state should be rolled back to the beginning or just to the last savepoint.
+    def rolledback!(force_restore_state = false) #:nodoc:
+      if transaction_record_state(:new_record)
+        _run_rollback_on_create_callbacks
+      elsif transaction_record_state(:destroyed)
+        _run_rollback_on_destroy_callbacks
+      else
+        _run_rollback_on_update_callbacks
+      end
+      _run_rollback_callbacks
+    ensure
+      restore_transaction_record_state(force_restore_state)
+    end
+
+    # Add the record to the current transaction so that the :after_rollback and :after_commit callbacks
+    # can be called.
+    def add_to_transaction
+      if self.class.connection.add_transaction_record(self)
+        remember_transaction_record_state
       end
-      raise
     end
 
     # Executes +method+ within a transaction and captures its return value as a
@@ -226,10 +280,59 @@ module ActiveRecord
     def with_transaction_returning_status(method, *args)
       status = nil
       self.class.transaction do
+        add_to_transaction
         status = send(method, *args)
         raise ActiveRecord::Rollback unless status
       end
       status
     end
+
+    protected
+
+    # Save the new record state and id of a record so it can be restored later if a transaction fails.
+    def remember_transaction_record_state #:nodoc
+      @_start_transaction_state ||= {}
+      unless @_start_transaction_state.include?(:new_record)
+        @_start_transaction_state[:id] = id if has_attribute?(self.class.primary_key)
+        @_start_transaction_state[:new_record] = @new_record
+      end
+      unless @_start_transaction_state.include?(:destroyed)
+        @_start_transaction_state[:destroyed] = @new_record
+      end
+      @_start_transaction_state[:level] = (@_start_transaction_state[:level] || 0) + 1
+    end
+
+    # Clear the new record state and id of a record.
+    def clear_transaction_record_state #:nodoc
+      if defined?(@_start_transaction_state)
+        @_start_transaction_state[:level] = (@_start_transaction_state[:level] || 0) - 1
+        remove_instance_variable(:@_start_transaction_state) if @_start_transaction_state[:level] < 1
+      end
+    end
+
+    # Restore the new record state and id of a record that was previously saved by a call to save_record_state.
+    def restore_transaction_record_state(force = false) #:nodoc
+      if defined?(@_start_transaction_state)
+        @_start_transaction_state[:level] = (@_start_transaction_state[:level] || 0) - 1
+        if @_start_transaction_state[:level] < 1
+          restore_state = remove_instance_variable(:@_start_transaction_state)
+          if restore_state
+            @new_record = restore_state[:new_record]
+            @destroyed = restore_state[:destroyed]
+            if restore_state[:id]
+              self.id = restore_state[:id]
+            else
+              @attributes.delete(self.class.primary_key)
+              @attributes_cache.delete(self.class.primary_key)
+            end
+          end
+        end
+      end
+    end
+
+    # Determine if a record was created or destroyed in a transaction. State should be one of :new_record or :destroyed.
+    def transaction_record_state(state) #:nodoc
+      @_start_transaction_state[state] if defined?(@_start_transaction_state)
+    end
   end
 end
diff --git a/activerecord/test/cases/transaction_callbacks_test.rb b/activerecord/test/cases/transaction_callbacks_test.rb
new file mode 100644
index 0000000000..c2c5fd3b05
--- /dev/null
+++ b/activerecord/test/cases/transaction_callbacks_test.rb
@@ -0,0 +1,244 @@
+require "cases/helper"
+require 'models/topic'
+require 'models/reply'
+
+class TransactionCallbacksTest < ActiveRecord::TestCase
+  self.use_transactional_fixtures = false
+  fixtures :topics
+
+  class TopicWithCallbacks < ActiveRecord::Base
+    set_table_name :topics
+
+    after_commit{|record| record.send(:do_after_commit, nil)}
+    after_commit_on_create{|record| record.send(:do_after_commit, :create)}
+    after_commit_on_update{|record| record.send(:do_after_commit, :update)}
+    after_commit_on_destroy{|record| record.send(:do_after_commit, :destroy)}
+    after_rollback{|record| record.send(:do_after_rollback, nil)}
+    after_rollback_on_create{|record| record.send(:do_after_rollback, :create)}
+    after_rollback_on_update{|record| record.send(:do_after_rollback, :update)}
+    after_rollback_on_destroy{|record| record.send(:do_after_rollback, :destroy)}
+
+    def history
+      @history ||= []
+    end
+
+    def after_commit_block(on = nil, &block)
+      @after_commit ||= {}
+      @after_commit[on] ||= []
+      @after_commit[on] << block
+    end
+
+    def after_rollback_block(on = nil, &block)
+      @after_rollback ||= {}
+      @after_rollback[on] ||= []
+      @after_rollback[on] << block
+    end
+
+    def do_after_commit(on)
+      blocks = @after_commit[on] if defined?(@after_commit)
+      blocks.each{|b| b.call(self)} if blocks
+    end
+
+    def do_after_rollback(on)
+      blocks = @after_rollback[on] if defined?(@after_rollback)
+      blocks.each{|b| b.call(self)} if blocks
+    end
+  end
+
+  def setup
+    @first, @second = TopicWithCallbacks.find(1, 3).sort_by { |t| t.id }
+  end
+
+  def test_call_after_commit_after_transaction_commits
+    @first.after_commit_block{|r| r.history << :after_commit}
+    @first.after_rollback_block{|r| r.history << :after_rollback}
+
+    @first.save!
+    assert @first.history, [:after_commit]
+  end
+
+  def test_only_call_after_commit_on_update_after_transaction_commits_for_existing_record
+    commit_callback = []
+    @first.after_commit_block(:create){|r| r.history << :commit_on_create}
+    @first.after_commit_block(:update){|r| r.history << :commit_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :commit_on_destroy}
+    @first.after_commit_block(:create){|r| r.history << :rollback_on_create}
+    @first.after_commit_block(:update){|r| r.history << :rollback_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :rollback_on_destroy}
+
+    @first.save!
+    assert @first.history, [:commit_on_update]
+  end
+
+  def test_only_call_after_commit_on_destroy_after_transaction_commits_for_destroyed_record
+    commit_callback = []
+    @first.after_commit_block(:create){|r| r.history << :commit_on_create}
+    @first.after_commit_block(:update){|r| r.history << :commit_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :commit_on_destroy}
+    @first.after_commit_block(:create){|r| r.history << :rollback_on_create}
+    @first.after_commit_block(:update){|r| r.history << :rollback_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :rollback_on_destroy}
+
+    @first.destroy
+    assert @first.history, [:commit_on_destroy]
+  end
+
+  def test_only_call_after_commit_on_create_after_transaction_commits_for_new_record
+    @new_record = TopicWithCallbacks.new(:title => "New topic", :written_on => Date.today)
+    @new_record.after_commit_block(:create){|r| r.history << :commit_on_create}
+    @new_record.after_commit_block(:update){|r| r.history << :commit_on_update}
+    @new_record.after_commit_block(:destroy){|r| r.history << :commit_on_destroy}
+    @new_record.after_commit_block(:create){|r| r.history << :rollback_on_create}
+    @new_record.after_commit_block(:update){|r| r.history << :rollback_on_update}
+    @new_record.after_commit_block(:destroy){|r| r.history << :rollback_on_destroy}
+
+    @new_record.save!
+    assert @new_record.history, [:commit_on_create]
+  end
+
+  def test_call_after_rollback_after_transaction_rollsback
+    @first.after_commit_block{|r| r.history << :after_commit}
+    @first.after_rollback_block{|r| r.history << :after_rollback}
+
+    Topic.transaction do
+      @first.save!
+      raise ActiveRecord::Rollback
+    end
+
+    assert @first.history, [:after_rollback]
+  end
+
+  def test_only_call_after_rollback_on_update_after_transaction_rollsback_for_existing_record
+    commit_callback = []
+    @first.after_commit_block(:create){|r| r.history << :commit_on_create}
+    @first.after_commit_block(:update){|r| r.history << :commit_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :commit_on_destroy}
+    @first.after_commit_block(:create){|r| r.history << :rollback_on_create}
+    @first.after_commit_block(:update){|r| r.history << :rollback_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :rollback_on_destroy}
+
+    Topic.transaction do
+      @first.save!
+      raise ActiveRecord::Rollback
+    end
+
+    assert @first.history, [:rollback_on_update]
+  end
+
+  def test_only_call_after_rollback_on_destroy_after_transaction_rollsback_for_destroyed_record
+    commit_callback = []
+    @first.after_commit_block(:create){|r| r.history << :commit_on_create}
+    @first.after_commit_block(:update){|r| r.history << :commit_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :commit_on_update}
+    @first.after_commit_block(:create){|r| r.history << :rollback_on_create}
+    @first.after_commit_block(:update){|r| r.history << :rollback_on_update}
+    @first.after_commit_block(:destroy){|r| r.history << :rollback_on_destroy}
+
+    Topic.transaction do
+      @first.destroy
+      raise ActiveRecord::Rollback
+    end
+
+    assert @first.history, [:rollback_on_destroy]
+  end
+
+  def test_only_call_after_rollback_on_create_after_transaction_rollsback_for_new_record
+    @new_record = TopicWithCallbacks.new(:title => "New topic", :written_on => Date.today)
+    @new_record.after_commit_block(:create){|r| r.history << :commit_on_create}
+    @new_record.after_commit_block(:update){|r| r.history << :commit_on_update}
+    @new_record.after_commit_block(:destroy){|r| r.history << :commit_on_destroy}
+    @new_record.after_commit_block(:create){|r| r.history << :rollback_on_create}
+    @new_record.after_commit_block(:update){|r| r.history << :rollback_on_update}
+    @new_record.after_commit_block(:destroy){|r| r.history << :rollback_on_destroy}
+
+    Topic.transaction do
+      @new_record.save!
+      raise ActiveRecord::Rollback
+    end
+
+    assert @new_record.history, [:rollback_on_create]
+  end
+
+  def test_call_after_rollback_when_commit_fails
+    @first.connection.class.send(:alias_method, :real_method_commit_db_transaction, :commit_db_transaction)
+    begin
+      @first.connection.class.class_eval do
+        def commit_db_transaction; raise "boom!"; end
+      end
+
+      @first.after_commit_block{|r| r.history << :after_commit}
+      @first.after_rollback_block{|r| r.history << :after_rollback}
+
+      assert !@first.save rescue nil
+      assert @first.history == [:after_rollback]
+    ensure
+      @first.connection.class.send(:remove_method, :commit_db_transaction)
+      @first.connection.class.send(:alias_method, :commit_db_transaction, :real_method_commit_db_transaction)
+    end
+  end
+
+  def test_only_call_after_rollback_on_records_rolled_back_to_a_savepoint
+    def @first.rollbacks(i=0); @rollbacks ||= 0; @rollbacks += i if i; end
+    def @first.commits(i=0); @commits ||= 0; @commits += i if i; end
+    @first.after_rollback_block{|r| r.rollbacks(1)}
+    @first.after_commit_block{|r| r.commits(1)}
+
+    def @second.rollbacks(i=0); @rollbacks ||= 0; @rollbacks += i if i; end
+    def @second.commits(i=0); @commits ||= 0; @commits += i if i; end
+    @second.after_rollback_block{|r| r.rollbacks(1)}
+    @second.after_commit_block{|r| r.commits(1)}
+
+    Topic.transaction do
+      @first.save!
+      Topic.transaction(:requires_new => true) do
+        @second.save!
+        raise ActiveRecord::Rollback
+      end
+    end
+
+    assert 1, @first.commits
+    assert 0, @first.rollbacks
+    assert 1, @second.commits
+    assert 1, @second.rollbacks
+  end
+
+  def test_only_call_after_rollback_on_records_rolled_back_to_a_savepoint_when_release_savepoint_fails
+    def @first.rollbacks(i=0); @rollbacks ||= 0; @rollbacks += i if i; end
+    def @first.commits(i=0); @commits ||= 0; @commits += i if i; end
+
+    @second.after_rollback_block{|r| r.rollbacks(1)}
+    @second.after_commit_block{|r| r.commits(1)}
+
+    Topic.transaction do
+      @first.save
+      Topic.transaction(:requires_new => true) do
+        @first.save!
+        raise ActiveRecord::Rollback
+      end
+      Topic.transaction(:requires_new => true) do
+        @first.save!
+        raise ActiveRecord::Rollback
+      end
+    end
+
+    assert 1, @first.commits
+    assert 2, @first.rollbacks
+  end
+
+  def test_after_transaction_callbacks_should_not_raise_errors
+    def @first.last_after_transaction_error=(e); @last_transaction_error = e; end
+    def @first.last_after_transaction_error; @last_transaction_error; end
+    @first.after_commit_block{|r| r.last_after_transaction_error = :commit; raise "fail!";}
+    @first.after_rollback_block{|r| r.last_after_transaction_error = :rollback; raise "fail!";}
+
+    @first.save!
+    assert_equal @first.last_after_transaction_error, :commit
+
+    Topic.transaction do
+      @first.save!
+      raise ActiveRecord::Rollback
+    end
+
+    assert_equal @first.last_after_transaction_error, :rollback
+  end
+end
diff --git a/activerecord/test/cases/transactions_test.rb b/activerecord/test/cases/transactions_test.rb
index c550030329..958a4e4f94 100644
--- a/activerecord/test/cases/transactions_test.rb
+++ b/activerecord/test/cases/transactions_test.rb
@@ -262,22 +262,22 @@ class TransactionTest < ActiveRecord::TestCase
     assert !@first.reload.approved?
     assert !@second.reload.approved?
   end if Topic.connection.supports_savepoints?
-  
+
   def test_many_savepoints
     Topic.transaction do
       @first.content = "One"
       @first.save!
-      
+
       begin
         Topic.transaction :requires_new => true do
           @first.content = "Two"
           @first.save!
-          
+
           begin
             Topic.transaction :requires_new => true do
               @first.content = "Three"
               @first.save!
-              
+
               begin
                 Topic.transaction :requires_new => true do
                   @first.content = "Four"
@@ -286,22 +286,22 @@ class TransactionTest < ActiveRecord::TestCase
                 end
               rescue
               end
-              
+
               @three = @first.reload.content
               raise
             end
           rescue
           end
-          
+
           @two = @first.reload.content
           raise
         end
       rescue
       end
-      
+
       @one = @first.reload.content
     end
-    
+
     assert_equal "One", @one
     assert_equal "Two", @two
     assert_equal "Three", @three
@@ -319,7 +319,34 @@ class TransactionTest < ActiveRecord::TestCase
       end
     end
   end
-  
+
+  def test_restore_active_record_state_for_all_records_in_a_transaction
+    topic_1 = Topic.new(:title => 'test_1')
+    topic_2 = Topic.new(:title => 'test_2')
+    Topic.transaction do
+      assert topic_1.save
+      assert topic_2.save
+      @first.save
+      @second.destroy
+      assert_equal false, topic_1.new_record?
+      assert_not_nil topic_1.id
+      assert_equal false, topic_2.new_record?
+      assert_not_nil topic_2.id
+      assert_equal false, @first.new_record?
+      assert_not_nil @first.id
+      assert_equal true, @second.destroyed?
+      raise ActiveRecord::Rollback
+    end
+
+    assert_equal true, topic_1.new_record?
+    assert_nil topic_1.id
+    assert_equal true, topic_2.new_record?
+    assert_nil topic_2.id
+    assert_equal false, @first.new_record?
+    assert_not_nil @first.id
+    assert_equal false, @second.destroyed?
+  end
+
   if current_adapter?(:PostgreSQLAdapter) && defined?(PGconn::PQTRANS_IDLE)
     def test_outside_transaction_works
       assert Topic.connection.outside_transaction?
@@ -328,7 +355,7 @@ class TransactionTest < ActiveRecord::TestCase
       Topic.connection.rollback_db_transaction
       assert Topic.connection.outside_transaction?
     end
-    
+
     def test_rollback_wont_be_executed_if_no_transaction_active
       assert_raise RuntimeError do
         Topic.transaction do
@@ -338,7 +365,7 @@ class TransactionTest < ActiveRecord::TestCase
         end
       end
     end
-    
+
     def test_open_transactions_count_is_reset_to_zero_if_no_transaction_active
       Topic.transaction do
         Topic.transaction do
@@ -358,12 +385,12 @@ class TransactionTest < ActiveRecord::TestCase
     #
     # We go back to the connection for the column queries because
     # Topic.columns is cached and won't report changes to the DB
-    
+
     assert_nothing_raised do
       Topic.reset_column_information
       Topic.connection.add_column('topics', 'stuff', :string)
       assert Topic.column_names.include?('stuff')
-      
+
       Topic.reset_column_information
       Topic.connection.remove_column('topics', 'stuff')
       assert !Topic.column_names.include?('stuff')
@@ -382,6 +409,12 @@ class TransactionTest < ActiveRecord::TestCase
   end
 
   private
+    def define_callback_method(callback_method)
+      define_method(callback_method) do
+        self.history << [callback_method, :method]
+      end
+    end
+
     def add_exception_raising_after_save_callback_to_topic
       Topic.class_eval <<-eoruby, __FILE__, __LINE__ + 1
         remove_method(:after_save_for_transaction)
@@ -440,7 +473,7 @@ class TransactionsWithTransactionalFixturesTest < ActiveRecord::TestCase
 
   def test_automatic_savepoint_in_outer_transaction
     @first = Topic.find(1)
-    
+
     begin
       Topic.transaction do
         @first.approved = true