Add further incremental replication tests (#1707)

server/lib/src/entry.rs

@@ -665,9 +665,20 @@ impl Entry<EntryIncremental, EntryNew> {
     }
 
     pub(crate) fn is_add_conflict(&self, db_entry: &EntrySealedCommitted) -> bool {
+        use crate::repl::entry::State;
         debug_assert!(self.valid.uuid == db_entry.valid.uuid);
         // This is a conflict if the state 'at' is not identical
-        self.valid.ecstate.at() != db_entry.valid.ecstate.at()
+        let self_cs = &self.valid.ecstate;
+        let db_cs = db_entry.get_changestate();
+
+        // Can only add conflict on live entries.
+        match (self_cs.current(), db_cs.current()) {
+            (State::Live { at: at_left, .. }, State::Live { at: at_right, .. }) => {
+                at_left != at_right
+            }
+            // Tombstone will always overwrite.
+            _ => false,
+        }
     }
 
     pub(crate) fn merge_state(
@@ -805,10 +816,7 @@ impl Entry<EntryIncremental, EntryNew> {
                     attrs: eattrs,
                 }
             }
-            (State::Tombstone { at: left_at }, State::Tombstone { at: right_at }) => {
+            (State::Tombstone { at: left_at }, State::Live { .. }) => {
-                // Due to previous checks, this must be equal!
-                debug_assert!(left_at == right_at);
-                debug_assert!(self.attrs == db_ent.attrs);
                 // We have to generate the attrs here, since on replication
                 // we just send the tombstone ecstate rather than attrs. Our
                 // db stub also lacks these attributes too.
@@ -831,23 +839,14 @@ impl Entry<EntryIncremental, EntryNew> {
                     attrs: attrs_new,
                 }
             }
-            (State::Tombstone { .. }, State::Live { .. }) => {
-                debug_assert!(false);
-                // Keep the left side.
-                Entry {
-                    valid: EntryIncremental {
-                        uuid: self.valid.uuid,
-                        ecstate: self.valid.ecstate.clone(),
-                    },
-                    state: EntryCommitted {
-                        id: db_ent.state.id,
-                    },
-                    attrs: self.attrs.clone(),
-                }
-            }
             (State::Live { .. }, State::Tombstone { .. }) => {
-                debug_assert!(false);
+                // Our current DB entry is a tombstone - ignore the incoming live
-                // Keep the right side
+                // entry and just retain our DB tombstone.
+                //
+                // Note we don't need to gen the attrs here since if a stub was made then
+                // we'd be live:live. To be in live:ts, then our db entry MUST exist and
+                // must be a ts.
+
                 Entry {
                     valid: EntryIncremental {
                         uuid: db_ent.valid.uuid,
@@ -859,6 +858,36 @@ impl Entry<EntryIncremental, EntryNew> {
                     attrs: db_ent.attrs.clone(),
                 }
             }
+            (State::Tombstone { at: left_at }, State::Tombstone { at: right_at }) => {
+                // WARNING - this differs from the other tombstone check cases
+                // lower of the two AT values. This way replicas always have the
+                // earliest TS value. It's a rare case but needs handling.
+
+                let (at, ecstate) = if left_at < right_at {
+                    (left_at, self.valid.ecstate.clone())
+                } else {
+                    (right_at, db_ent.valid.ecstate.clone())
+                };
+
+                let mut attrs_new: Eattrs = Map::new();
+                let class_ava = vs_iutf8!["object", "tombstone"];
+                let last_mod_ava = vs_cid![at.clone()];
+
+                attrs_new.insert(AttrString::from("uuid"), vs_uuid![db_ent.valid.uuid]);
+                attrs_new.insert(AttrString::from("class"), class_ava);
+                attrs_new.insert(AttrString::from("last_modified_cid"), last_mod_ava);
+
+                Entry {
+                    valid: EntryIncremental {
+                        uuid: db_ent.valid.uuid,
+                        ecstate,
+                    },
+                    state: EntryCommitted {
+                        id: db_ent.state.id,
+                    },
+                    attrs: attrs_new,
+                }
+            }
         }
     }
 }
@@ -2158,6 +2187,14 @@ impl<VALID, STATE> Entry<VALID, STATE> {
         let _ = self.attrs.insert(AttrString::from("last_modified_cid"), cv);
     }
 
+    #[cfg(test)]
+    pub(crate) fn get_last_changed(&self) -> Cid {
+        self.attrs
+            .get("last_modified_cid")
+            .and_then(|vs| vs.to_cid_single())
+            .unwrap()
+    }
+
     #[inline(always)]
     /// Get an iterator over the current set of attribute names that this entry contains.
     pub fn get_ava_names(&self) -> impl Iterator<Item = &str> {

server/lib/src/event.rs

@@ -818,4 +818,12 @@ impl ReviveRecycledEvent {
             filter: filter.into_valid(),
         }
     }
+
+    #[cfg(test)]
+    pub(crate) fn new_internal(filter: Filter<FilterValid>) -> Self {
+        ReviveRecycledEvent {
+            ident: Identity::from_internal(),
+            filter,
+        }
+    }
 }

server/lib/src/repl/consumer.rs

@@ -51,6 +51,8 @@ impl<'a> QueryServerWriteTransaction<'a> {
             e
         })?;
 
+        trace!(?db_entries);
+
         // Need to probably handle conflicts here in this phase. I think they
         // need to be pushed to a separate list where they are then "created"
         // as a conflict.

server/lib/src/repl/supplier.rs

@@ -172,7 +172,8 @@ impl<'a> QueryServerReadTransaction<'a> {
             f_eq("uuid", PVUUID_SYSTEM_CONFIG.clone()),
         ]));
 
-        let entry_filter = filter!(f_and!([
+        let entry_filter = filter_all!(f_or!([
+            f_and!([
                 f_pres("class"),
                 f_andnot(f_or(vec![
                     // These are from above!
@@ -182,6 +183,9 @@ impl<'a> QueryServerReadTransaction<'a> {
                     f_eq("uuid", PVUUID_SYSTEM_INFO.clone()),
                     f_eq("uuid", PVUUID_SYSTEM_CONFIG.clone()),
                 ])),
+            ]),
+            f_eq("class", PVCLASS_TOMBSTONE.clone()),
+            f_eq("class", PVCLASS_RECYCLED.clone()),
         ]));
 
         let schema_entries = self

server/lib/src/repl/tests.rs

@@ -1,6 +1,7 @@
 use crate::be::BackendTransaction;
 use crate::prelude::*;
 use crate::repl::consumer::ConsumerState;
+use crate::repl::entry::State;
 use crate::repl::proto::ReplIncrementalContext;
 use crate::repl::ruv::ReplicationUpdateVectorTransaction;
 use crate::repl::ruv::{RangeDiffStatus, ReplicationUpdateVector};
@@ -750,16 +751,374 @@ async fn test_repl_increment_simultaneous_bidirectional_write(
 // TS on B
 // B -> A TS
 
+#[qs_pair_test]
+async fn test_repl_increment_basic_bidirectional_lifecycle(
+    server_a: &QueryServer,
+    server_b: &QueryServer,
+) {
+    let ct = duration_from_epoch_now();
+
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    assert!(repl_initialise(&mut server_b_txn, &mut server_a_txn)
+        .and_then(|_| server_a_txn.commit())
+        .is_ok());
+    drop(server_b_txn);
+
+    // Add an entry.
+    let mut server_b_txn = server_b.write(ct).await;
+    let t_uuid = Uuid::new_v4();
+    assert!(server_b_txn
+        .internal_create(vec![entry_init!(
+            ("class", Value::new_class("object")),
+            ("class", Value::new_class("person")),
+            ("name", Value::new_iname("testperson1")),
+            ("uuid", Value::Uuid(t_uuid)),
+            ("description", Value::new_utf8s("testperson1")),
+            ("displayname", Value::new_utf8s("testperson1"))
+        ),])
+        .is_ok());
+    server_b_txn.commit().expect("Failed to commit");
+
+    // Assert the entry is not on A.
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    assert_eq!(
+        server_a_txn.internal_search_uuid(t_uuid),
+        Err(OperationError::NoMatchingEntries)
+    );
+
+    //               from               to
+    repl_incremental(&mut server_b_txn, &mut server_a_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    assert!(e1 == e2);
+
+    server_a_txn.commit().expect("Failed to commit");
+    drop(server_b_txn);
+
+    // Delete on A
+    let mut server_a_txn = server_a.write(ct).await;
+    assert!(server_a_txn.internal_delete_uuid(t_uuid).is_ok());
+    server_a_txn.commit().expect("Failed to commit");
+
+    // Repl A -> B
+    let mut server_a_txn = server_a.read().await;
+    let mut server_b_txn = server_b.write(ct).await;
+
+    repl_incremental(&mut server_a_txn, &mut server_b_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    // They are consistent again.
+    assert!(e1 == e2);
+    assert!(e1.attribute_equality("class", &PVCLASS_RECYCLED));
+
+    server_b_txn.commit().expect("Failed to commit");
+    drop(server_a_txn);
+
+    // At an earlier time make a change on A.
+    let mut server_a_txn = server_a.write(ct).await;
+    assert!(server_a_txn.internal_revive_uuid(t_uuid).is_ok());
+    server_a_txn.commit().expect("Failed to commit");
+
+    // Now move past the recyclebin time.
+    let ct = ct + Duration::from_secs(RECYCLEBIN_MAX_AGE + 1);
+
+    // Now TS on B.
+    let mut server_b_txn = server_b.write(ct).await;
+    assert!(server_b_txn.purge_recycled().is_ok());
+    server_b_txn.commit().expect("Failed to commit");
+
+    // Repl A -> B - B will silently reject the update due to the TS state on B.
+    let mut server_a_txn = server_a.read().await;
+    let mut server_b_txn = server_b.write(ct).await;
+
+    repl_incremental(&mut server_a_txn, &mut server_b_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    // They are NOT consistent.
+    assert!(e1 != e2);
+    // E1 from A is NOT a tombstone ... yet.
+    assert!(!e1.attribute_equality("class", &PVCLASS_TOMBSTONE));
+    // E2 from B is a tombstone!
+    assert!(e2.attribute_equality("class", &PVCLASS_TOMBSTONE));
+
+    server_b_txn.commit().expect("Failed to commit");
+    drop(server_a_txn);
+
+    // Repl B -> A - will have a TS at the end.
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    repl_incremental(&mut server_b_txn, &mut server_a_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    // Ts on both.
+    assert!(e1.attribute_equality("class", &PVCLASS_TOMBSTONE));
+    assert!(e1 == e2);
+
+    server_a_txn.commit().expect("Failed to commit");
+    drop(server_b_txn);
+}
+
 // Create entry on A -> B
 // Recycle on Both A/B
-// Recycle propagates from A -> B, B -> A, keep earliest.
+// Recycle propagates from A -> B, B -> A, keep latest.
-// TS on A
+// We already know the recycle -> ts state is good from other tests.
-// A -> B TS
 
-// Create + recycle entry on A -> B
+#[qs_pair_test]
+async fn test_repl_increment_basic_bidirectional_recycle(
+    server_a: &QueryServer,
+    server_b: &QueryServer,
+) {
+    let ct = duration_from_epoch_now();
+
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    assert!(repl_initialise(&mut server_b_txn, &mut server_a_txn)
+        .and_then(|_| server_a_txn.commit())
+        .is_ok());
+    drop(server_b_txn);
+
+    // Add an entry.
+    let mut server_b_txn = server_b.write(ct).await;
+    let t_uuid = Uuid::new_v4();
+    assert!(server_b_txn
+        .internal_create(vec![entry_init!(
+            ("class", Value::new_class("object")),
+            ("class", Value::new_class("person")),
+            ("name", Value::new_iname("testperson1")),
+            ("uuid", Value::Uuid(t_uuid)),
+            ("description", Value::new_utf8s("testperson1")),
+            ("displayname", Value::new_utf8s("testperson1"))
+        ),])
+        .is_ok());
+    server_b_txn.commit().expect("Failed to commit");
+
+    // Assert the entry is not on A.
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    //               from               to
+    repl_incremental(&mut server_b_txn, &mut server_a_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    assert!(e1 == e2);
+
+    server_a_txn.commit().expect("Failed to commit");
+    drop(server_b_txn);
+
+    // On both servers, at seperate timestamps, run the recycle.
+    let ct = ct + Duration::from_secs(1);
+    let mut server_a_txn = server_a.write(ct).await;
+    assert!(server_a_txn.internal_delete_uuid(t_uuid).is_ok());
+    server_a_txn.commit().expect("Failed to commit");
+
+    let ct = ct + Duration::from_secs(2);
+    let mut server_b_txn = server_b.write(ct).await;
+    assert!(server_b_txn.internal_delete_uuid(t_uuid).is_ok());
+    server_b_txn.commit().expect("Failed to commit");
+
+    // Send server a -> b - ignored.
+    let mut server_a_txn = server_a.read().await;
+    let mut server_b_txn = server_b.write(ct).await;
+
+    repl_incremental(&mut server_a_txn, &mut server_b_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    server_b_txn.commit().expect("Failed to commit");
+    drop(server_a_txn);
+
+    // They are equal, but their CL states are not. e2 should have been
+    // retained due to being the latest!
+    assert!(e1 == e2);
+    assert!(e1.attribute_equality("class", &PVCLASS_RECYCLED));
+
+    // Remember entry comparison doesn't compare last_mod_cid.
+    assert!(e1.get_last_changed() < e2.get_last_changed());
+
+    let e1_cs = e1.get_changestate();
+    let e2_cs = e2.get_changestate();
+
+    let valid = match (e1_cs.current(), e2_cs.current()) {
+        (
+            State::Live {
+                at: _,
+                changes: changes_left,
+            },
+            State::Live {
+                at: _,
+                changes: changes_right,
+            },
+        ) => match (changes_left.get("class"), changes_right.get("class")) {
+            (Some(cid_left), Some(cid_right)) => cid_left < cid_right,
+            _ => false,
+        },
+        _ => false,
+    };
+    assert!(valid);
+
+    // Now go the other way. They'll be equal again.
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    repl_incremental(&mut server_b_txn, &mut server_a_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    assert!(e1 == e2);
+
+    let e1_cs = e1.get_changestate();
+    let e2_cs = e2.get_changestate();
+    assert!(e1_cs == e2_cs);
+
+    server_a_txn.commit().expect("Failed to commit");
+    drop(server_b_txn);
+}
+
+// Create + recycle entry on B -> A
 // TS on Both,
 // TS resolves to lowest AT.
 
+#[qs_pair_test]
+async fn test_repl_increment_basic_bidirectional_tombstone(
+    server_a: &QueryServer,
+    server_b: &QueryServer,
+) {
+    let ct = duration_from_epoch_now();
+
+    let mut server_b_txn = server_b.write(ct).await;
+    let t_uuid = Uuid::new_v4();
+    assert!(server_b_txn
+        .internal_create(vec![entry_init!(
+            ("class", Value::new_class("object")),
+            ("class", Value::new_class("person")),
+            ("name", Value::new_iname("testperson1")),
+            ("uuid", Value::Uuid(t_uuid)),
+            ("description", Value::new_utf8s("testperson1")),
+            ("displayname", Value::new_utf8s("testperson1"))
+        ),])
+        .is_ok());
+    // And then recycle it.
+    assert!(server_b_txn.internal_delete_uuid(t_uuid).is_ok());
+    server_b_txn.commit().expect("Failed to commit");
+
+    // Now setup repl
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    assert!(repl_initialise(&mut server_b_txn, &mut server_a_txn).is_ok());
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    assert!(e1 == e2);
+
+    server_a_txn.commit().expect("Failed to commit");
+    drop(server_b_txn);
+
+    // Now on both servers, perform a recycle -> ts at different times.
+    let ct = ct + Duration::from_secs(RECYCLEBIN_MAX_AGE + 1);
+    let mut server_a_txn = server_a.write(ct).await;
+    assert!(server_a_txn.purge_recycled().is_ok());
+    server_a_txn.commit().expect("Failed to commit");
+
+    let ct = ct + Duration::from_secs(1);
+    let mut server_b_txn = server_b.write(ct).await;
+    assert!(server_b_txn.purge_recycled().is_ok());
+    server_b_txn.commit().expect("Failed to commit");
+
+    // Now do B -> A - no change on A as it's TS was earlier.
+    let mut server_a_txn = server_a.write(ct).await;
+    let mut server_b_txn = server_b.read().await;
+
+    repl_incremental(&mut server_b_txn, &mut server_a_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    assert!(e1.attribute_equality("class", &PVCLASS_TOMBSTONE));
+    assert!(e2.attribute_equality("class", &PVCLASS_TOMBSTONE));
+    trace!("{:?}", e1.get_last_changed());
+    trace!("{:?}", e2.get_last_changed());
+    assert!(e1.get_last_changed() < e2.get_last_changed());
+
+    server_a_txn.commit().expect("Failed to commit");
+    drop(server_b_txn);
+
+    // A -> B - B should now have the A TS time.
+    let mut server_a_txn = server_a.read().await;
+    let mut server_b_txn = server_b.write(duration_from_epoch_now()).await;
+
+    repl_incremental(&mut server_a_txn, &mut server_b_txn);
+
+    let e1 = server_a_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access new entry.");
+    let e2 = server_b_txn
+        .internal_search_all_uuid(t_uuid)
+        .expect("Unable to access entry.");
+
+    assert!(e1.attribute_equality("class", &PVCLASS_TOMBSTONE));
+    assert!(e2.attribute_equality("class", &PVCLASS_TOMBSTONE));
+    assert!(e1.get_last_changed() == e2.get_last_changed());
+
+    server_b_txn.commit().expect("Failed to commit");
+    drop(server_a_txn);
+}
+
 // conflict cases.
 
 // both add entry with same uuid - only one can win!

server/lib/src/server/recycle.rs

@@ -220,76 +220,17 @@ impl<'a> QueryServerWriteTransaction<'a> {
         Ok(())
     }
 
-    /*
+    #[cfg(test)]
-    #[instrument(level = "debug", skip_all)]
+    pub(crate) fn internal_revive_uuid(&mut self, target_uuid: Uuid) -> Result<(), OperationError> {
-    pub(crate) fn revive_recycled_legacy(
+        // Note the use of filter_rec here for only recycled targets.
-        &mut self,
+        let filter = filter_rec!(f_eq("uuid", PartialValue::Uuid(target_uuid)));
-        re: &ReviveRecycledEvent,
+        let f_valid = filter
-    ) -> Result<(), OperationError> {
+            .validate(self.get_schema())
-        // Revive an entry to live. This is a specialised function, and draws a lot of
+            .map_err(OperationError::SchemaViolation)?;
-        // inspiration from modify.
+        let re = ReviveRecycledEvent::new_internal(f_valid);
-        //
+        self.revive_recycled(&re)
-        //
-        // Access is granted by the ability to ability to search the class=recycled
-        // and the ability modify + remove that class from the object.
-
-        // create the modify for access testing.
-        // tl;dr, remove the class=recycled
-        let modlist = ModifyList::new_list(vec![Modify::Removed(
-            AttrString::from("class"),
-            PVCLASS_RECYCLED.clone(),
-        )]);
-
-        let m_valid = modlist.validate(self.get_schema()).map_err(|e| {
-            admin_error!(
-                "Schema Violation in revive recycled modlist validate: {:?}",
-                e
-            );
-            OperationError::SchemaViolation(e)
-        })?;
-
-        // Get the entries we are about to revive.
-        //    we make a set of per-entry mod lists. A list of lists even ...
-        let revive_cands =
-            self.impersonate_search_valid(re.filter.clone(), re.filter.clone(), &re.ident)?;
-
-        let mut dm_mods: HashMap<Uuid, ModifyList<ModifyInvalid>> =
-            HashMap::with_capacity(revive_cands.len());
-
-        for e in revive_cands {
-            // Get this entries uuid.
-            let u: Uuid = e.get_uuid();
-
-            if let Some(riter) = e.get_ava_as_refuuid("directmemberof") {
-                for g_uuid in riter {
-                    dm_mods
-                        .entry(g_uuid)
-                        .and_modify(|mlist| {
-                            let m = Modify::Present(AttrString::from("member"), Value::Refer(u));
-                            mlist.push_mod(m);
-                        })
-                        .or_insert({
-                            let m = Modify::Present(AttrString::from("member"), Value::Refer(u));
-                            ModifyList::new_list(vec![m])
-                        });
     }
 }
-        }
-
-        // Now impersonate the modify
-        self.impersonate_modify_valid(re.filter.clone(), re.filter.clone(), m_valid, &re.ident)?;
-        // If and only if that succeeds, apply the direct membership modifications
-        // if possible.
-        for (g, mods) in dm_mods {
-            // I think the filter/filter_all shouldn't matter here because the only
-            // valid direct memberships should be still valid/live references.
-            let f = filter_all!(f_eq("uuid", PartialValue::Uuid(g)));
-            self.internal_modify(&f, &mods)?;
-        }
-        Ok(())
-    }
-    */
-}
 
 #[cfg(test)]
 mod tests {

server/lib/src/valueset/cid.rs

@@ -157,7 +157,6 @@ impl ValueSetT for ValueSetCid {
         }
     }
 
-    /*
     fn to_cid_single(&self) -> Option<Cid> {
         if self.set.len() == 1 {
             self.set.iter().cloned().take(1).next()
@@ -165,7 +164,6 @@ impl ValueSetT for ValueSetCid {
             None
         }
     }
-    */
 
     fn as_cid_set(&self) -> Option<&SmolSet<[Cid; 1]>> {
         Some(&self.set)

server/lib/src/valueset/mod.rs

@@ -357,6 +357,11 @@ pub trait ValueSetT: std::fmt::Debug + DynClone {
         None
     }
 
+    fn to_cid_single(&self) -> Option<Cid> {
+        error!("to_cid_single should not be called on {:?}", self.syntax());
+        None
+    }
+
     fn to_refer_single(&self) -> Option<Uuid> {
         error!(
             "to_refer_single should not be called on {:?}",