[yugabyte#11729][DocDB][xCluster] Fix for replication not working if …

…user upgrades to a branch with CDCSDK code changes

Summary:
With the changes for CDCSDK, we have separate `source_type` values i.e. `XCLUSTER` for xCluster replication and `CDCSDK` for the new changes. Similarly there is another option i.e. `checkpoint_type` which can have `IMPLICIT` and `EXPLICIT` values.

If a stream for replication has been created before upgrading, it was unable to continue replication after upgrading to the latest version since the `source_type` and `checkpoint_type` options were missing from it as it has only been introduced with the CDCSDK changes only.

Test Plan:
* Manually tested with a custom build on dev portal

Reviewers: sergei, jhe, mkantimath, skumar, rahuldesirazu

Reviewed By: skumar, rahuldesirazu

Subscribers: rahuldesirazu, iamoncar, sdash, ybase, bogdan

Differential Revision: https://phabricator.dev.yugabyte.com/D15989

ent/src/yb/cdc/cdc_service.cc

@@ -646,6 +646,20 @@ CHECKED_STATUS VerifyArg(const SetCDCCheckpointRequestPB& req) {
   return Status::OK();
 }
 
+// This function is to handle the upgrade scenario where the DB is upgraded from a version
+// without CDCSDK changes to the one with it. So in case, some required options are missing,
+// the default values will be added for the same.
+void AddDefaultOptionsIfMissing(std::unordered_map<std::string, std::string>* options) {
+  if ((*options).find(cdc::kSourceType) == (*options).end()) {
+    (*options).emplace(cdc::kSourceType, CDCRequestSource_Name(cdc::CDCRequestSource::XCLUSTER));
+  }
+
+  if ((*options).find(cdc::kCheckpointType) == (*options).end()) {
+    (*options).emplace(cdc::kCheckpointType,
+                     CDCCheckpointType_Name(cdc::CDCCheckpointType::IMPLICIT));
+  }
+}
+
 } // namespace
 
 template <class ReqType, class RespType>
@@ -2107,6 +2121,9 @@ Result<std::shared_ptr<StreamMetadata>> CDCServiceImpl::GetStream(const std::str
   RETURN_NOT_OK(client()->GetCDCStream(stream_id, &ns_id, &object_ids, &options));
 
   auto stream_metadata = std::make_shared<StreamMetadata>();
+
+  AddDefaultOptionsIfMissing(&options);
+
   for (const auto& option : options) {
     if (option.first == kRecordType) {
       SCHECK(CDCRecordType_Parse(option.second, &stream_metadata->record_type),

ent/src/yb/master/catalog_manager_ent.cc

@@ -210,6 +210,34 @@ class CDCStreamLoader : public Visitor<PersistentCDCStreamInfo> {
  public:
   explicit CDCStreamLoader(CatalogManager* catalog_manager) : catalog_manager_(catalog_manager) {}
 
+  void AddDefaultValuesIfMissing(const SysCDCStreamEntryPB& metadata,
+                                 CDCStreamInfo::WriteLock* l) {
+    bool source_type_present = false;
+    bool checkpoint_type_present = false;
+
+    // Iterate over all the options to check if checkpoint_type and source_type are present.
+    for (auto option : metadata.options()) {
+      if (option.key() == cdc::kSourceType) {
+        source_type_present = true;
+      }
+      if (option.key() == cdc::kCheckpointType) {
+        checkpoint_type_present = true;
+      }
+    }
+
+    if (!source_type_present) {
+      auto source_type_opt = l->mutable_data()->pb.add_options();
+      source_type_opt->set_key(cdc::kSourceType);
+      source_type_opt->set_value(cdc::CDCRequestSource_Name(cdc::XCLUSTER));
+    }
+
+    if (!checkpoint_type_present) {
+      auto checkpoint_type_opt = l->mutable_data()->pb.add_options();
+      checkpoint_type_opt->set_key(cdc::kCheckpointType);
+      checkpoint_type_opt->set_value(cdc::CDCCheckpointType_Name(cdc::IMPLICIT));
+    }
+  }
+
   Status Visit(const CDCStreamId& stream_id, const SysCDCStreamEntryPB& metadata)
       REQUIRES(catalog_manager_->mutex_) {
     DCHECK(!ContainsKey(catalog_manager_->cdc_stream_map_, stream_id))
@@ -245,6 +273,10 @@ class CDCStreamLoader : public Visitor<PersistentCDCStreamInfo> {
     auto l = stream->LockForWrite();
     l.mutable_data()->pb.CopyFrom(metadata);
 
+    // If no source_type and checkpoint_type is present, that means the stream was created in
+    // a previous version where these options were not present.
+    AddDefaultValuesIfMissing(metadata, &l);
+
     // If the table has been deleted, then mark this stream as DELETING so it can be deleted by the
     // catalog manager background thread. Otherwise if this stream is missing an entry
     // for state, then mark its state as Active.