Github user lei-xia commented on a diff in the pull request: https://github.com/apache/helix/pull/155#discussion_r176492004 --- Diff: helix-core/src/main/java/org/apache/helix/spectator/RoutingTableSnapshot.java --- @@ -0,0 +1,151 @@ +package org.apache.helix.spectator; + +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +import java.util.Collection; +import java.util.List; +import java.util.Set; +import org.apache.helix.model.InstanceConfig; +import org.apache.helix.model.LiveInstance; + +/** + * The snapshot of RoutingTable information. It is immutable, it reflects the routing table + * information at the time it is generated. + */ +public class RoutingTableSnapshot { --- End diff -- So we add this feature to return a snapshot of routingtable at that time. The routingTable in the provider will keep update, but the snapshot is a read-only view of routingtable at the time it was created.
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