jihoonson commented on a change in pull request #8038: Making optimal usage of multiple segment cache locations URL: https://github.com/apache/incubator-druid/pull/8038#discussion_r321074058
########## File path: server/src/main/java/org/apache/druid/segment/loading/StorageLocationSelectorStrategy.java ########## @@ -0,0 +1,49 @@ +/* + * 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.druid.segment.loading; + +import com.fasterxml.jackson.annotation.JsonSubTypes; +import com.fasterxml.jackson.annotation.JsonTypeInfo; +import org.apache.druid.timeline.DataSegment; + +import java.util.Iterator; + +/** + * This interface describes the storage location selection strategy which is responsible for ordering the + * available multiple {@link StorageLocation}s for segment distribution. + */ +@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "tier", defaultImpl = LeastBytesUsedStorageLocationSelectorStrategy.class) +@JsonSubTypes(value = { + @JsonSubTypes.Type(name = "leastBytesUsed", value = LeastBytesUsedStorageLocationSelectorStrategy.class), + @JsonSubTypes.Type(name = "roundRobin", value = RoundRobinStorageLocationSelectorStrategy.class) +}) +public interface StorageLocationSelectorStrategy +{ + /** + * Finds the best ordering of the {@link StorageLocation}s to load the given {@link DataSegment} into according to + * the location selector strategy. This method returns an iterator instead of a single best location. The + * caller is responsible for iterating over the locations and calling {@link StorageLocation#reserve} + * method. This is because a single location may be problematic like failed disk or might become unwritable for + * whatever reasons. + * + * @return An iterator of {@link StorageLocation}s from which the callers can iterate and pick a location. + */ + Iterator<StorageLocation> getLocations(DataSegment dataSegment, String storageDirStr); Review comment: None of parameters are in use in any implementations. ---------------------------------------------------------------- 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 With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@druid.apache.org For additional commands, e-mail: commits-h...@druid.apache.org
