murblanc commented on a change in pull request #1684: URL: https://github.com/apache/lucene-solr/pull/1684#discussion_r482422332
########## File path: solr/core/src/java/org/apache/solr/cluster/placement/AddReplicasPlacementRequest.java ########## @@ -0,0 +1,64 @@ +/* + * 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. + */ + +package org.apache.solr.cluster.placement; + +import java.util.Set; + +/** + * <p>Request passed by Solr to a {@link PlacementPlugin} to compute placement for one or more {@link Replica}'s for one + * or more {@link Shard}'s of an existing {@link SolrCollection}. + * The shard might or might not already exist, plugin code can easily find out by using {@link SolrCollection#getShards()} + * and verifying if the shard name(s) from {@link #getShardNames()} are there. + * + * <p>The set of {@link Node}s on which the replicas should be placed + * is specified (defaults to being equal to the set returned by {@link Cluster#getLiveNodes()}). + */ +public interface AddReplicasPlacementRequest extends PlacementRequest { + /** + * The {@link SolrCollection} to add {@link Replica}(s) to. + */ + SolrCollection getCollection(); + + /** + * <p>Shard name(s) for which new replicas placement should be computed. The shard(s) might exist or not (that's why this + * method returns a {@link Set} of {@link String}'s and not directly a set of {@link Shard} instances). + * + * <p>Note the Collection API allows specifying the shard name or a {@code _route_} parameter. The Solr implementation will + * convert either specification into the relevant shard name so the plugin code doesn't have to worry about this. + */ + Set<String> getShardNames(); + + /** + * <p>Replicas should only be placed on nodes in the set returned by this method. + * + * <p>When Collection API calls do not specify a specific set of target nodes, replicas can be placed on any live node of + * the cluster. In such cases, this set will be equal to the set of all live nodes. The plugin placement code does not + * need to worry (or care) if a set of nodes was explicitly specified or not. + * + * @return never {@code null} and never empty set (if that set was to be empty for any reason, no placement would be + * possible and the Solr infrastructure driving the plugin code would detect the error itself rather than calling the plugin). + */ + Set<Node> getTargetNodes(); Review comment: In the implementation in `AddReplicasPlacementRequestImpl.toPlacementRequest()`, when no value is passed, the set of live nodes from `Cluster.getLiveNodes()` is passed here. So no memory allocation. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@lucene.apache.org For additional commands, e-mail: issues-h...@lucene.apache.org
