[2836] Move the actual addition to separate method

Move the actual addition of the data to the memory image to separate
private method. All the allocations from the memory segment should
happen inside this method. Also, the method is mostly exception safe (it
can add some branches in the tree, but they don't bother us and we'll
reuse them).

This'll allow us to retry the addition on the SegmentGrown exception.

src/lib/datasrc/memory/zone_data_updater.cc

@@ -373,6 +373,24 @@ ZoneDataUpdater::addRdataSet(const Name& name, const RRType& rrtype,
 }
 
 void
+ZoneDataUpdater::addInternal(const isc::dns::Name& name,
+                     const isc::dns::RRType& rrtype,
+                     const isc::dns::ConstRRsetPtr& rrset,
+                     const isc::dns::ConstRRsetPtr& rrsig)
+{
+    // Add wildcards possibly contained in the owner name to the domain
+    // tree.  This can only happen for the normal (non-NSEC3) tree.
+    // Note: this can throw an exception, breaking strong exception
+    // guarantee.  (see also the note for the call to contextCheck()
+    // above).
+    if (rrtype != RRType::NSEC3()) {
+        addWildcards(name);
+    }
+
+    addRdataSet(name, rrtype, rrset, rrsig);
+}
+
+void
 ZoneDataUpdater::add(const ConstRRsetPtr& rrset,
                      const ConstRRsetPtr& sig_rrset)
 {
@@ -397,16 +415,7 @@ ZoneDataUpdater::add(const ConstRRsetPtr& rrset,
         arg(rrset ? rrtype.toText() : "RRSIG(" + rrtype.toText() + ")").
         arg(zone_name_);
 
-    // Add wildcards possibly contained in the owner name to the domain
-    // tree.  This can only happen for the normal (non-NSEC3) tree.
-    // Note: this can throw an exception, breaking strong exception
-    // guarantee.  (see also the note for the call to contextCheck()
-    // above).
-    if (rrtype != RRType::NSEC3()) {
-        addWildcards(name);
-    }
-
-    addRdataSet(name, rrtype, rrset, sig_rrset);
+    addInternal(name, rrtype, rrset, sig_rrset);
 }
 
 } // namespace memory

src/lib/datasrc/memory/zone_data_updater.h

@@ -159,6 +159,11 @@ private:
     // contained in 'name' (e.g., '*.foo.example' in 'bar.*.foo.example').
     void addWildcards(const isc::dns::Name& name);
 
+    void addInternal(const isc::dns::Name& name,
+                     const isc::dns::RRType& rrtype,
+                     const isc::dns::ConstRRsetPtr& rrset,
+                     const isc::dns::ConstRRsetPtr& rrsig);
+
     // Does some checks in context of the data that are already in the
     // zone.  Currently checks for forbidden combinations of RRsets in
     // the same domain (CNAME+anything, DNAME+NS).  If such condition is