sigram commented on a change in pull request #1684: URL: https://github.com/apache/lucene-solr/pull/1684#discussion_r468379500
########## File path: solr/core/src/java/org/apache/solr/cluster/placement/ReplicaPlacement.java ########## @@ -0,0 +1,29 @@ +/* + * 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; + +/** + * <p>Placement decision for a single {@link Replica}. Note this placement decision is used as part of a {@link WorkOrder}, + * it does not directly lead to the plugin code getting a corresponding {@link Replica} instance, nor does it require the + * plugin to provide a {@link Shard} instance (the plugin code gets such instances for existing replicas and shards in the + * cluster but does not create them directly for adding new replicas for new or existing shards). + * + * <p>Captures the {@link Shard} (via the shard name), {@link Node} and {@link Replica.ReplicaType} of a Replica to be created. + */ +public interface ReplicaPlacement { Review comment: Right, the plugin doesn't need this - but other parts of Solr may need it to simplify error handling if the error is too far away in the code from the original Request. ########## File path: solr/core/src/java/org/apache/solr/cluster/placement/PlacementPlanFactory.java ########## @@ -0,0 +1,52 @@ +/* + * 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; + +/** + * Allows plugins to create {@link PlacementPlan}s telling the Solr layer where to create replicas following the processing of + * a {@link PlacementRequest}. The Solr layer can (and will) check that the {@link PlacementPlan} conforms to the {@link PlacementRequest} (and + * if it does not, the requested operation will fail). + */ +public interface PlacementPlanFactory { + /** + * <p>Creates a {@link PlacementPlan} for adding a new collection and its replicas. + * + * <p>This is in support of {@link org.apache.solr.cloud.api.collections.CreateCollectionCmd}. + */ + PlacementPlan createPlacementPlanNewCollection(CreateNewCollectionPlacementRequest request, String CollectionName, Set<ReplicaPlacement> replicaPlacements); + + /** + * <p>Creates a {@link PlacementPlan} for adding replicas to a given shard of an existing collection. + * + * <p>This is in support (directly or indirectly) of {@link org.apache.solr.cloud.api.collections.AddReplicaCmd}, + * {@link org.apache.solr.cloud.api.collections.CreateShardCmd}, {@link org.apache.solr.cloud.api.collections.ReplaceNodeCmd}, + * {@link org.apache.solr.cloud.api.collections.MoveReplicaCmd}, {@link org.apache.solr.cloud.api.collections.SplitShardCmd}, + * {@link org.apache.solr.cloud.api.collections.RestoreCmd} and {@link org.apache.solr.cloud.api.collections.MigrateCmd}. + * (as well as of {@link org.apache.solr.cloud.api.collections.CreateCollectionCmd} in the specific case of + * {@link org.apache.solr.common.params.CollectionAdminParams#WITH_COLLECTION} but this should be removed shortly and + * the section in parentheses of this comment should be removed when the {@code withCollection} javadoc link appears broken). + */ + PlacementPlan createPlacementPlanAddReplicas(AddReplicasPlacementRequest request, String CollectionName, Set<ReplicaPlacement> replicaPlacements); Review comment: Eh, it looks to me like we need just one method: `PlacementPlan createPlacementPlan(PlacementRequest request, String collectionName, Set<ReplicaPlacement> replicaPlacements)` Also ... I'm not sure how useful this interface is. Do we really need to dictate such granular internal API for the plugins? It's the responsibility of `PlacementPlugin` to create a `PlacementPlan`, and it should be free to do it whichever way it wants, not necessarily going through this factory - it seems like an additional hurdle and not a convenience. ########## File path: solr/core/src/java/org/apache/solr/cluster/placement/PlacementPlugin.java ########## @@ -0,0 +1,41 @@ +/* + * 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; + +/** + * Implemented by external plugins to control replica placement and movement on the search cluster (as well as other things + * such as cluster elasticity?) when cluster changes are required (initiated elsewhere, most likely following a Collection + * API call). + */ +public interface PlacementPlugin { Review comment: Exactly - but where should that data be cached? we don't offer the plugin any way to do it, so implementors will come up with all sorts of nasty ways to circumvent the API sandbox to do it (accessing ZK directly, using external shared FS, or even something worse ;) ). ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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