Remove our use of #outside_transaction?

This method was first seen in 045713ee240fff815edb5962b25d668512649478,
and subsequently reimplemented in
fb2325e35855d62abd2c76ce03feaa3ca7992e4f.

According to @jeremy, this is okay to remove. He thinks it was added
because at the time we didn't have much transaction state to keep track
of, and he viewed it as a hack for us to track it internally, thinking
it was better to ask the connection for the transaction state.

Over the years we have added more and more state to track, a lot of
which is impossible to ask the connection for. So it seems that this is
just a relic of the passed and we will just track the state internally
only.

2 files changed, 14 insertions, 32 deletions

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 0589e6b447..c8c3fcb22a 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/database_statements.rb
@@ -107,20 +107,6 @@ module ActiveRecord
         exec_delete(to_sql(arel, binds), name, binds)
       end
 
-      # Checks whether there is currently no transaction active. This is done
-      # by querying the database driver, and does not use the transaction
-      # house-keeping information recorded by #increment_open_transactions and
-      # friends.
-      #
-      # Returns true if there is no transaction active, false if there is a
-      # transaction active, and nil if this information is unknown.
-      #
-      # Not all adapters supports transaction state introspection. Currently,
-      # only the PostgreSQL adapter supports this.
-      def outside_transaction?
-        nil
-      end
-
       # Returns +true+ when the connection adapter supports prepared statement
       # caching, otherwise returns +false+
       def supports_statement_cache?
@@ -173,7 +159,7 @@ module ActiveRecord
         options.assert_valid_keys :requires_new, :joinable
 
         if !options[:requires_new] && current_transaction.joinable?
-          within_existing_transaction { yield }
+          yield
         else
           within_new_transaction(options) { yield }
         end
@@ -185,27 +171,17 @@ module ActiveRecord
         begin_transaction(options)
         yield
       rescue Exception => error
-        rollback_transaction unless outside_transaction?
+        rollback_transaction
         raise
       ensure
-        if outside_transaction?
-          reset_transaction
-        else
-          begin
-            commit_transaction unless error
-          rescue Exception => e
-            rollback_transaction
-            raise
-          end
+        begin
+          commit_transaction unless error
+        rescue Exception => e
+          rollback_transaction
+          raise
         end
       end
 
-      def within_existing_transaction #:nodoc:
-        yield
-      ensure
-        reset_transaction if outside_transaction?
-      end
-
       def current_transaction #:nodoc:
         @transaction
       end
@@ -228,7 +204,7 @@ module ActiveRecord
         @transaction = @transaction.rollback
       end
 
-      def reset_transaction
+      def reset_transaction #:nodoc:
         @transaction = ClosedTransaction.new(self)
       end
 
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
index eb3084e066..c8437c18cc 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb
@@ -1,3 +1,5 @@
+require 'active_support/deprecation'
+
 module ActiveRecord
   module ConnectionAdapters
     class PostgreSQLAdapter < AbstractAdapter
@@ -214,6 +216,10 @@ module ActiveRecord
         end
 
         def outside_transaction?
+          ActiveSupport::Deprecation.warn(
+            "#outside_transaction? is deprecated. This method was only really used " \
+            "internally, but you can use #transaction_open? instead."
+          )
           @connection.transaction_status == PGconn::PQTRANS_IDLE
         end