ei: add EI_EVENT_SYNC as opaque event to correctly schedule callbacks

See the corresponding eis commit for details.

Part-of: <https://gitlab.freedesktop.org/libinput/libei/-/merge_requests/316>

src/libei-event.c

@@ -50,6 +50,7 @@ ei_event_type_to_string(enum ei_event_type type)
 	CASE_RETURN_STRING(EI_EVENT_DEVICE_RESUMED);
 	CASE_RETURN_STRING(EI_EVENT_KEYBOARD_MODIFIERS);
 	CASE_RETURN_STRING(EI_EVENT_PONG);
+	CASE_RETURN_STRING(EI_EVENT_SYNC);
 	CASE_RETURN_STRING(EI_EVENT_FRAME);
 	CASE_RETURN_STRING(EI_EVENT_DEVICE_START_EMULATING);
 	CASE_RETURN_STRING(EI_EVENT_DEVICE_STOP_EMULATING);
@@ -100,6 +101,9 @@ ei_event_destroy(struct ei_event *event)
 	case EI_EVENT_PONG:
 		ei_ping_unref(event->pong.ping);
 		break;
+	case EI_EVENT_SYNC:
+		ei_pingpong_unref(event->sync.pingpong);
+		break;
 	}
 	ei_device_unref(event->device);
 	ei_seat_unref(event->seat);

src/libei-event.h

@@ -72,6 +72,9 @@ struct ei_event {
 		struct {
 			struct ei_ping *ping;
 		} pong;
+		struct {
+			struct ei_pingpong *pingpong;
+		} sync;
 	};
 };
 

src/libei-private.h

@@ -171,6 +171,9 @@ ei_queue_disconnect_event(struct ei *ei);
 void
 ei_queue_pong_event(struct ei *ei, struct ei_ping *ping);
 
+void
+ei_queue_sync_event(struct ei *ei, struct ei_pingpong *ping);
+
 void
 ei_queue_device_removed_event(struct ei_device *device);
 

src/libei.c

@@ -336,6 +336,16 @@ ei_queue_pong_event(struct ei *ei, struct ei_ping *ping)
 	queue_event(ei, e);
 }
 
+void
+ei_queue_sync_event(struct ei *ei, struct ei_pingpong *ping)
+{
+	struct ei_event *e = ei_event_new(ei);
+	e->type = EI_EVENT_SYNC;
+	e->sync.pingpong = ei_pingpong_ref(ping);
+
+	queue_event(ei, e);
+}
+
 void
 ei_queue_seat_added_event(struct ei_seat *seat)
 {
@@ -683,6 +693,16 @@ ei_get_event(struct ei *ei)
 	struct ei_event *e = list_first_entry(&ei->event_queue, e, link);
 	list_remove(&e->link);
 
+	if (e->type == EI_EVENT_SYNC) {
+		_unref_(ei_pingpong) *pp = steal(&e->sync.pingpong);
+		log_debug(ei_event_get_context(e),
+			  "object %#" PRIx64 ": ping pong done",
+			  ei_pingpong_get_id(pp));
+
+		if (ei->state < EI_STATE_DISCONNECTED)
+			ei_pingpong_request_done(pp, 0);
+	}
+
 	return e;
 }
 
@@ -764,8 +784,7 @@ handle_msg_ping(struct ei_connection *connection, object_id_t id,  uint32_t vers
 	DISCONNECT_IF_INVALID_VERSION(ei, ei_pingpong, id, version);
 
 	_unref_(ei_pingpong) *pingpong = ei_pingpong_new_for_id(ei, id, version);
-
+	ei_queue_sync_event(ei_connection_get_context(connection), pingpong);
-	ei_pingpong_request_done(pingpong, 0);
 
 	return NULL;
 }

src/libei.h

@@ -431,6 +431,17 @@ enum ei_event_type {
 	 */
 	EI_EVENT_PONG = 90,
 
+	/**
+	 * This event represents a synchronization request (ping) from the EIS
+	 * implementation. The corresponding reply (pong) will be sent when
+	 * it is unref'd. It has no other API.
+	 *
+	 * The caller must ensure that any state changes triggered by messages
+	 * received prior to this event have been resolved and communicated to the
+	 * EIS implementation prior to calling ei_event_unref().
+	 */
+	EI_EVENT_SYNC,
+
 	/**
 	 * "Hardware" frame event. This event **must** be sent by the server
 	 * and notifies the client that the previous set of events belong to

test/eierpecken.c

@@ -502,6 +502,7 @@ new_context(enum peck_ei_mode ei_mode)
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTOSEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTOSTART);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_FRAME);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 
 	peck_ei_enable_fatal_bug(peck);
 	peck_eis_enable_fatal_bug(peck);
@@ -655,6 +656,7 @@ peck_enable_ei_behavior(struct peck *peck, enum peck_ei_behavior behavior)
 	case PECK_EI_BEHAVIOR_HANDLE_ADDED_BUTTON:
 	case PECK_EI_BEHAVIOR_HANDLE_ADDED_SCROLL:
 	case PECK_EI_BEHAVIOR_HANDLE_FRAME:
+	case PECK_EI_BEHAVIOR_HANDLE_SYNC:
 		flag_set(peck->ei_behavior, behavior);
 		break;
 	case PECK_EI_BEHAVIOR_HANDLE_RESUMED:
@@ -1076,6 +1078,10 @@ _peck_dispatch_ei(struct peck *peck, int lineno)
 			break;
 		case EI_EVENT_PONG:
 			break;
+		case EI_EVENT_SYNC:
+			if (flag_is_set(peck->ei_behavior, PECK_EI_BEHAVIOR_HANDLE_SYNC))
+				process_event = tristate_yes;
+			break;
 		case EI_EVENT_FRAME:
 			/* Ensure we only expect frames when we expect them */
 			munit_assert_true(need_frame);
@@ -1247,6 +1253,12 @@ _peck_assert_no_ei_events(struct ei *ei, int lineno)
 			continue;
 		}
 
+		if (peck && flag_is_set(peck->ei_behavior, PECK_EI_BEHAVIOR_HANDLE_SYNC) &&
+		    ei_event_get_type(e) == EI_EVENT_SYNC) {
+			log_debug(peck, "Skipping over sync event\n");
+			continue;
+		}
+
 		munit_errorf("Expected empty event queue, have: %s, line %d\n",
 			     peck_ei_event_name(e), lineno);
 	}
@@ -1295,6 +1307,14 @@ _peck_ei_next_event(struct ei *ei, enum ei_event_type type, int lineno)
 		}
 	}
 
+	if (flag_is_set(peck->ei_behavior, PECK_EI_BEHAVIOR_HANDLE_SYNC)) {
+		while (event && ei_event_get_type(event) == EI_EVENT_SYNC) {
+			ei_event_unref(event);
+			log_debug(peck, "Skipping over sync event\n");
+			event = ei_get_event(ei);
+		}
+	}
+
 	if (!event)
 		munit_errorf("Expected ei event type %s, got none, line %d\n",
 			     peck_ei_event_type_name(type),
@@ -1406,6 +1426,7 @@ peck_ei_event_type_name(enum ei_event_type type)
 		CASE_STRING(DEVICE_RESUMED);
 		CASE_STRING(KEYBOARD_MODIFIERS);
 		CASE_STRING(PONG);
+		CASE_STRING(SYNC);
 		CASE_STRING(FRAME);
 		CASE_STRING(DEVICE_START_EMULATING);
 		CASE_STRING(DEVICE_STOP_EMULATING);

test/eierpecken.h

@@ -139,6 +139,10 @@ enum peck_ei_behavior {
 	 * Handle frame events. This behavior is enabled by default.
 	 */
 	PECK_EI_BEHAVIOR_HANDLE_FRAME,
+	/**
+	 * Handle sync events. This behavior is enabled by default.
+	 */
+	PECK_EI_BEHAVIOR_HANDLE_SYNC,
 };
 
 struct peck;

test/test-ei-device.c

@@ -295,6 +295,7 @@ MUNIT_TEST(test_ei_device_close)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_DEVICES);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTODEVICES);
 
 	peck_dispatch_until_stable(peck);
@@ -1873,6 +1874,7 @@ MUNIT_TEST(test_passive_ei_device_start_stop_emulating)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_RESUME_DEVICE);
 
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTOSEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_ADDED_POINTER);
@@ -1914,6 +1916,7 @@ MUNIT_TEST(test_passive_ei_device_stop_emulating_when_removing)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_RESUME_DEVICE);
 
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTOSEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_ADDED_POINTER);
@@ -2901,6 +2904,7 @@ MUNIT_TEST(test_passive_ei_frame_timestamp)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_RESUME_DEVICE);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_KEYBOARD);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTODEVICES);
 	peck_dispatch_until_stable(peck);
@@ -2960,6 +2964,7 @@ MUNIT_TEST(test_passive_ei_flush_frame)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_RESUME_DEVICE);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_KEYBOARD);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTODEVICES);
 	peck_dispatch_until_stable(peck);

test/test-ei-seat.c

@@ -38,6 +38,7 @@ MUNIT_TEST(test_ei_seat_bind_unbind)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_POINTER);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_KEYBOARD);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -95,6 +96,7 @@ MUNIT_TEST(test_ei_seat_bind_unbind_noref)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_POINTER);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_KEYBOARD);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -144,6 +146,7 @@ MUNIT_TEST(test_ei_seat_bind_unbind_immediately)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_POINTER);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ADD_KEYBOARD);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 

test/test-ei.c

@@ -126,6 +126,7 @@ MUNIT_TEST(test_ei_disconnect_after_connect)
 	_unref_(eis_client) *client = NULL;
 
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 
 	peck_dispatch_until_stable(peck);
 
@@ -212,6 +213,7 @@ MUNIT_TEST(test_ei_disconnect_after_seat)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 
 	peck_dispatch_until_stable(peck);
 
@@ -246,6 +248,7 @@ MUNIT_TEST(test_ei_disconnect_self_after_seat)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 
 	peck_dispatch_until_stable(peck);
 
@@ -283,6 +286,7 @@ MUNIT_TEST(test_ei_disconnect_after_bind_before_received)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -317,6 +321,7 @@ MUNIT_TEST(test_ei_disconnect_self_after_bind_before_received)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -355,6 +360,7 @@ MUNIT_TEST(test_ei_disconnect_after_bind_after_received)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -391,6 +397,7 @@ MUNIT_TEST(test_ei_disconnect_self_after_bind_after_received)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -432,6 +439,7 @@ MUNIT_TEST(test_ei_disconnect_after_unbind_before_received)
 
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_ALL);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -477,6 +485,7 @@ MUNIT_TEST(test_ei_disconnect_after_unbind_after_received)
 
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_ALL);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -520,6 +529,7 @@ MUNIT_TEST(test_client_is_sender)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_NONE);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -539,6 +549,7 @@ MUNIT_TEST(test_client_is_receiver)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_NONE);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 	peck_dispatch_until_stable(peck);
 
@@ -922,6 +933,7 @@ MUNIT_TEST(test_ei_ping_within_frame)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_RESUME_DEVICE);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTODEVICES);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_AUTOSTART);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_ADDED);

test/test-eis.c

@@ -53,6 +53,7 @@ MUNIT_TEST(eistest_name)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_NONE);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 
 	/* The name is set by peck_new() and immutable after the
 	 * backend was set, which peck_new() does for us as well.
@@ -85,6 +86,7 @@ MUNIT_TEST(eistest_cliend_bind_all_caps)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 
 	peck_dispatch_until_stable(peck);
@@ -122,6 +124,7 @@ MUNIT_TEST(eistest_cliend_bind_some_caps)
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_ACCEPT_CLIENT);
 	peck_enable_eis_behavior(peck, PECK_EIS_BEHAVIOR_DEFAULT_SEAT);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_NONE);
+	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_SYNC);
 	peck_enable_ei_behavior(peck, PECK_EI_BEHAVIOR_HANDLE_CONNECT);
 
 	peck_dispatch_until_stable(peck);

tools/ei-debug-events.c

@@ -455,6 +455,8 @@ int main(int argc, char **argv)
 			case EI_EVENT_PONG:
 				print_pong_event(e);
 				break;
+			case EI_EVENT_SYNC:
+				break;
 			}
 		}
 	}