Merge pull request rails#55722 from kozy4324/fix-lease-sticky-flag-timing

Fix lease_connection to preserve pool state when checkout callbacks fail

Author: byroot

activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb

@@ -344,8 +344,9 @@ def activated?
       # held in a cache keyed by a thread.
       def lease_connection
         lease = connection_lease
-        lease.sticky = true
         lease.connection ||= checkout
+        lease.sticky = true
+        lease.connection
       end
 
       def permanent_lease? # :nodoc:

activerecord/test/cases/connection_pool_test.rb

@@ -1477,6 +1477,25 @@ def test_inspect_does_not_show_secrets
         pool&.disconnect!
       end
 
+      def test_checkout_callback_error_does_not_affect_permanent_lease_and_active_connection_state
+        checkout_error = StandardError.new("error during checkout")
+        proc_to_raise = -> { raise checkout_error }
+        ActiveRecord::ConnectionAdapters::AbstractAdapter.set_callback(:checkout, :after, proc_to_raise)
+
+        assert_predicate @pool, :permanent_lease?
+        assert_not_predicate @pool, :active_connection?
+
+        error = assert_raises StandardError do
+          @pool.lease_connection
+        end
+        assert_same checkout_error, error
+
+        assert_predicate @pool, :permanent_lease?
+        assert_not_predicate @pool, :active_connection?
+      ensure
+        ActiveRecord::ConnectionAdapters::AbstractAdapter.skip_callback(:checkout, :after, proc_to_raise)
+      end
+
       private
         def active_connections(pool)
           pool.connections.find_all(&:in_use?)