fix: rollback catchup flow blocking snapshot events

Author: erayarslan

couchbase/observer.go

@@ -122,12 +122,12 @@ func (so *observer) waitRollbackMitigation(seqNo uint64) {
 	}
 }
 
-func (so *observer) canForward(seqNo uint64) bool {
+func (so *observer) canForward(seqNo uint64, isControl bool) bool {
 	if !so.config.RollbackMitigation.Disabled {
 		so.waitRollbackMitigation(seqNo)
 	}
 
-	return !so.needCatchup(seqNo)
+	return isControl || !so.needCatchup(seqNo)
 }
 
 func (so *observer) isBeforeSkipWindow(eventTime time.Time) bool {
@@ -166,7 +166,7 @@ func (so *observer) sendOrSkip(args models.ListenerArgs) {
 }
 
 func (so *observer) SnapshotMarker(event models.DcpSnapshotMarker) {
-	if !so.canForward(event.StartSeqNo) {
+	if !so.canForward(event.StartSeqNo, true) {
 		return
 	}
 
@@ -192,7 +192,7 @@ func (so *observer) IsInSnapshotMarker(seqNo uint64) bool {
 }
 
 func (so *observer) Mutation(event gocbcore.DcpMutation) { //nolint:dupl
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -220,7 +220,7 @@ func (so *observer) Mutation(event gocbcore.DcpMutation) { //nolint:dupl
 }
 
 func (so *observer) Deletion(event gocbcore.DcpDeletion) { //nolint:dupl
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -248,7 +248,7 @@ func (so *observer) Deletion(event gocbcore.DcpDeletion) { //nolint:dupl
 }
 
 func (so *observer) Expiration(event gocbcore.DcpExpiration) { //nolint:dupl
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -288,7 +288,7 @@ func (so *observer) End(event models.DcpStreamEnd, err error) {
 }
 
 func (so *observer) CreateCollection(event gocbcore.DcpCollectionCreation) {
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -308,7 +308,7 @@ func (so *observer) CreateCollection(event gocbcore.DcpCollectionCreation) {
 }
 
 func (so *observer) DeleteCollection(event gocbcore.DcpCollectionDeletion) {
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -328,7 +328,7 @@ func (so *observer) DeleteCollection(event gocbcore.DcpCollectionDeletion) {
 }
 
 func (so *observer) FlushCollection(event gocbcore.DcpCollectionFlush) {
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -348,7 +348,7 @@ func (so *observer) FlushCollection(event gocbcore.DcpCollectionFlush) {
 }
 
 func (so *observer) CreateScope(event gocbcore.DcpScopeCreation) {
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -367,7 +367,7 @@ func (so *observer) CreateScope(event gocbcore.DcpScopeCreation) {
 }
 
 func (so *observer) DeleteScope(event gocbcore.DcpScopeDeletion) {
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -386,7 +386,7 @@ func (so *observer) DeleteScope(event gocbcore.DcpScopeDeletion) {
 }
 
 func (so *observer) ModifyCollection(event gocbcore.DcpCollectionModification) {
-	if !so.canForward(event.SeqNo) {
+	if !so.canForward(event.SeqNo, false) {
 		return
 	}
 
@@ -412,7 +412,7 @@ func (so *observer) OSOSnapshot(event gocbcore.DcpOSOSnapshot) {
 }
 
 func (so *observer) SeqNoAdvanced(advanced gocbcore.DcpSeqNoAdvanced) {
-	if !so.canForward(advanced.SeqNo) {
+	if !so.canForward(advanced.SeqNo, true) {
 		return
 	}