Extract #sync_timezone_changes method in AbstractMysqlAdapter

This enables subclasses to sync database timezone changes without overriding `#raw_execute`,
which removes the need to redefine `#raw_execute` in the `Mysql2Adapter` and other
adapters subclassing `AbstractMysqlAdapter`.

Co-authored-by: Paarth Madan <paarth.madan@shopify.com>

activerecord/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   Extract `#sync_timezone_changes` method in AbstractMysqlAdapter to enable subclasses
+    to sync database timezone changes without overriding `#raw_execute`.
+
+    *Adrianna Chang*, *Paarth Madan*
+
 *   Do not write additional new lines when dumping sql migration versions
 
     This change updates the `insert_versions_sql` function so that the database insert string containing the current database migration versions does not end with two additional new lines.

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -731,11 +731,17 @@ def raw_execute(sql, name, async: false, allow_retry: false, uses_transaction: t
 
           log(sql, name, async: async) do
             with_raw_connection(allow_retry: allow_retry, uses_transaction: uses_transaction) do |conn|
+              sync_timezone_changes(conn)
               conn.query(sql)
             end
           end
         end
 
+        # Make sure we carry over any changes to ActiveRecord.default_timezone that have been
+        # made since we established the connection
+        def sync_timezone_changes(raw_connection)
+        end
+
         def internal_execute(sql, name = "SCHEMA", allow_retry: true, uses_transaction: false)
           raw_execute(sql, name, allow_retry: allow_retry, uses_transaction: uses_transaction)
         end

activerecord/lib/active_record/connection_adapters/mysql/database_statements.rb

@@ -83,18 +83,8 @@ def high_precision_current_timestamp
         end
 
         private
-          def raw_execute(sql, name, async: false, allow_retry: false, uses_transaction: true)
-            mark_transaction_written_if_write(sql)
-
-            log(sql, name, async: async) do
-              with_raw_connection(allow_retry: allow_retry, uses_transaction: uses_transaction) do |conn|
-                # make sure we carry over any changes to ActiveRecord.default_timezone that have been
-                # made since we established the connection
-                conn.query_options[:database_timezone] = default_timezone
-
-                conn.query(sql)
-              end
-            end
+          def sync_timezone_changes(raw_connection)
+            raw_connection.query_options[:database_timezone] = default_timezone
           end
 
           def execute_batch(statements, name = nil)
@@ -176,9 +166,7 @@ def exec_stmt_and_free(sql, name, binds, cache_stmt: false, async: false)
 
             log(sql, name, binds, type_casted_binds, async: async) do
               with_raw_connection do |conn|
-                # make sure we carry over any changes to ActiveRecord.default_timezone that have been
-                # made since we established the connection
-                conn.query_options[:database_timezone] = default_timezone
+                sync_timezone_changes(conn)
 
                 if cache_stmt
                   stmt = @statements[sql] ||= conn.prepare(sql)

activerecord/test/cases/adapters/mysql2/mysql2_adapter_test.rb

@@ -314,6 +314,14 @@ def test_statement_timeout_error_codes
     end
   end
 
+  def test_database_timezone_changes_synced_to_connection
+    with_timezone_config default: :local do
+      assert_changes(-> { @conn.raw_connection.query_options[:database_timezone] }, from: :utc, to: :local) do
+        @conn.execute("SELECT 1")
+      end
+    end
+  end
+
   private
     def with_example_table(definition = "id int auto_increment primary key, number int, data varchar(255)", &block)
       super(@conn, "ex", definition, &block)