add status_update_serial to webxdc_status_update event (#3215)

this bypasses the replication safety introduced by letting the caller track the last serial,
however, in case of bots that do not track much state and do not playback updates anyway,
it is still useful.

CHANGELOG.md

@@ -10,6 +10,7 @@
 
 - Further improve finding the correct server after logging in #3208
 - `get_connectivity_html()` returns HTML as non-scalable #3213
+- add update-serial to `DC_EVENT_WEBXDC_STATUS_UPDATE` #3215
 
 
 ## 1.77.0

deltachat-ffi/deltachat.h

@@ -5606,11 +5606,16 @@ void dc_event_unref(dc_event_t* event);
 /**
  * webxdc status update received.
  * To get the received status update, use dc_get_webxdc_status_updates() with
- * `serial` set to the last known update.
+ * `serial` set to the last known update
+ * (in case of special bots, `status_update_serial` from `data2`
+ * may help to calculate the last known update for dc_get_webxdc_status_updates();
+ * UIs must not peek at this parameter to avoid races in the status replication
+ * eg. when events arrive while initial updates are played back).
+ *
  * To send status updates, use dc_send_webxdc_status_update().
  *
  * @param data1 (int) msg_id
- * @param data2 (int) 0
+ * @param data2 (int) status_update_serial - must not be used by UI implementations.
  */
 #define DC_EVENT_WEBXDC_STATUS_UPDATE                2120
 

deltachat-ffi/src/lib.rs

@@ -503,7 +503,7 @@ pub unsafe extern "C" fn dc_event_get_data1_int(event: *mut dc_event_t) -> libc:
         | EventType::SecurejoinJoinerProgress { contact_id, .. } => {
             contact_id.to_u32() as libc::c_int
         }
-        EventType::WebxdcStatusUpdate(msg_id) => msg_id.to_u32() as libc::c_int,
+        EventType::WebxdcStatusUpdate { msg_id, .. } => msg_id.to_u32() as libc::c_int,
     }
 }
 
@@ -535,9 +535,8 @@ pub unsafe extern "C" fn dc_event_get_data2_int(event: *mut dc_event_t) -> libc:
         | EventType::ImexFileWritten(_)
         | EventType::MsgsNoticed(_)
         | EventType::ConnectivityChanged
-        | EventType::SelfavatarChanged
-        | EventType::WebxdcStatusUpdate(_)
-        | EventType::ChatModified(_) => 0,
+        | EventType::SelfavatarChanged => 0,
+        EventType::ChatModified(_) => 0,
         EventType::MsgsChanged { msg_id, .. }
         | EventType::IncomingMsg { msg_id, .. }
         | EventType::MsgDelivered { msg_id, .. }
@@ -546,6 +545,10 @@ pub unsafe extern "C" fn dc_event_get_data2_int(event: *mut dc_event_t) -> libc:
         EventType::SecurejoinInviterProgress { progress, .. }
         | EventType::SecurejoinJoinerProgress { progress, .. } => *progress as libc::c_int,
         EventType::ChatEphemeralTimerModified { timer, .. } => timer.to_u32() as libc::c_int,
+        EventType::WebxdcStatusUpdate {
+            status_update_serial,
+            ..
+        } => status_update_serial.to_u32() as libc::c_int,
     }
 }
 
@@ -587,7 +590,7 @@ pub unsafe extern "C" fn dc_event_get_data2_str(event: *mut dc_event_t) -> *mut
         | EventType::SecurejoinJoinerProgress { .. }
         | EventType::ConnectivityChanged
         | EventType::SelfavatarChanged
-        | EventType::WebxdcStatusUpdate(_)
+        | EventType::WebxdcStatusUpdate { .. }
         | EventType::ChatEphemeralTimerModified { .. } => ptr::null_mut(),
         EventType::ConfigureProgress { comment, .. } => {
             if let Some(comment) = comment {

src/events.rs

@@ -10,6 +10,7 @@ use crate::chat::ChatId;
 use crate::contact::ContactId;
 use crate::ephemeral::Timer as EphemeralTimer;
 use crate::message::MsgId;
+use crate::webxdc::StatusUpdateSerial;
 
 #[derive(Debug)]
 pub struct Events {
@@ -335,5 +336,8 @@ pub enum EventType {
     SelfavatarChanged,
 
     #[strum(props(id = "2120"))]
-    WebxdcStatusUpdate(MsgId),
+    WebxdcStatusUpdate {
+        msg_id: MsgId,
+        status_update_serial: StatusUpdateSerial,
+    },
 }

src/webxdc.rs

@@ -254,9 +254,14 @@ impl Context {
             )
             .await?;
 
-        self.emit_event(EventType::WebxdcStatusUpdate(instance.id));
+        let status_update_serial = StatusUpdateSerial(u32::try_from(rowid)?);
 
-        Ok(StatusUpdateSerial(u32::try_from(rowid)?))
+        self.emit_event(EventType::WebxdcStatusUpdate {
+            msg_id: instance.id,
+            status_update_serial,
+        });
+
+        Ok(status_update_serial)
     }
 
     /// Sends a status update for an webxdc instance.
@@ -1016,7 +1021,10 @@ mod tests {
             .get_matching(|evt| matches!(evt, EventType::WebxdcStatusUpdate { .. }))
             .await;
         match event {
-            EventType::WebxdcStatusUpdate(msg_id) => {
+            EventType::WebxdcStatusUpdate {
+                msg_id,
+                status_update_serial: _,
+            } => {
                 assert_eq!(msg_id, instance_id);
             }
             _ => unreachable!(),