tso: log tso service discovery info on the client side only when the …

…primary is changed (tikv#6511)

close tikv#6508

Skip logging of the tso service discovery info when the secondar list is changed,
because tso servers currently don't have consistent view of the member list due to
remote etcd being used by tso service, which results in changing member list when
the client queries the tso servers in round-robin. We need to improve the server side
so that all tso servers can return the global consistent view of the keyspace groups'
serving or membership info.

Signed-off-by: Bin Shi <[email protected]>

Co-authored-by: ti-chi-bot[bot] <108142056+ti-chi-bot[bot]@users.noreply.github.com>

client/tso_service_discovery.go

@@ -488,17 +488,15 @@ func (c *tsoServiceDiscovery) updateMember() error {
 		}
 	}
 
-	oldPrimary, primarySwitched, secondaryChanged :=
+	oldPrimary, primarySwitched, _ :=
 		c.keyspaceGroupSD.update(keyspaceGroup, primaryAddr, secondaryAddrs, addrs)
 	if primarySwitched {
+		log.Info("[tso] updated keyspace group service discovery info",
+			zap.String("keyspace-group-service", keyspaceGroup.String()))
 		if err := c.afterPrimarySwitched(oldPrimary, primaryAddr); err != nil {
 			return err
 		}
 	}
-	if primarySwitched || secondaryChanged {
-		log.Info("[tso] updated keyspace group service discovery info",
-			zap.String("keyspace-group-service", keyspaceGroup.String()))
-	}
 
 	// Even if the primary address is empty, we still updated other returned info above, including the
 	// keyspace group info and the secondary addresses.