split cleanup of old dns urls and new record registration

Author: sudo87

server/src/main/java/org/apache/cloudstack/dns/DnsProviderManagerImpl.java

@@ -1009,26 +1009,31 @@ void handleVmHostnameChanged(long instanceId, String newHostName) {
                 List<DnsNicJoinVO> nicsForThisFqdn = newUrlEntry.getValue();
 
                 try {
+                    Set<String> oldDnsRecordUrls = new HashSet<>();
                     Transaction.execute(new TransactionCallbackWithExceptionNoReturn<DnsProviderException>() {
                         @Override
                         public void doInTransactionWithoutResult(TransactionStatus status) throws DnsProviderException {
-                            if (isDnsCollision(newDnsRecordUrl, targetZoneId, instanceId)) {
-                                return;
-                            }
-
-                            Set<String> oldDnsRecordUrls = new HashSet<>();
                             for (DnsNicJoinVO nic : nicsForThisFqdn) {
                                 if (nic.getNicDnsUrl() != null) {
                                     oldDnsRecordUrls.add(nic.getNicDnsUrl());
+                                    nicDetailsDao.removeDetail(nic.getId(), ApiConstants.NIC_DNS_RECORD);
                                 }
-                                nicDetailsDao.addDetail(nic.getId(), ApiConstants.NIC_DNS_RECORD, newDnsRecordUrl, true);
                             }
-
-                            // NICs for the old URL and cleanly send a DELETE API call to PowerDNS!
                             for (String oldUrl : oldDnsRecordUrls) {
                                 syncDnsRecordsState(instanceId, oldUrl, targetZoneId);
                             }
+                        }
+                    });
 
+                    Transaction.execute(new TransactionCallbackWithExceptionNoReturn<DnsProviderException>() {
+                        @Override
+                        public void doInTransactionWithoutResult(TransactionStatus status) throws DnsProviderException {
+                            if (isDnsCollision(newDnsRecordUrl, targetZoneId, instanceId)) {
+                                return;
+                            }
+                            for (DnsNicJoinVO nic : nicsForThisFqdn) {
+                                nicDetailsDao.addDetail(nic.getId(), ApiConstants.NIC_DNS_RECORD, newDnsRecordUrl, true);
+                            }
                             // This sync call finds the newly written intent and sends an ADD/REPLACE call.
                             syncDnsRecordsState(instanceId, newDnsRecordUrl, targetZoneId);
                         }