[GitHub] [incubator-druid] himanshug commented on a change in pull request #8038: Making optimal usage of multiple segment cache locations

[GitBox <gi...@apache.org>]

himanshug 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_r326288969
 
 

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 File path: server/src/main/java/org/apache/druid/segment/loading/LeastBytesUsedStorageLocationSelectorStrategy.java
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 @@ -0,0 +1,51 @@
+/*
+ * 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.google.common.collect.ImmutableList;
+import com.google.common.collect.Ordering;
+import org.apache.druid.timeline.DataSegment;
+
+import java.util.Comparator;
+import java.util.Iterator;
+
+/**
+ * A {@link StorageLocation} selector strategy that selects a segment cache location that is least filled each time
+ * among the available storage locations.
+ */
+public class LeastBytesUsedStorageLocationSelectorStrategy implements StorageLocationSelectorStrategy
+{
+  private static final Comparator<StorageLocation> COMPARATOR = Comparator
+      .comparingLong(StorageLocation::currSizeBytes);
+
+  private ImmutableList<StorageLocation> storageLocations;
+
+  @Override
+  public Iterator<StorageLocation> getLocations(DataSegment dataSegment, String storageDirStr)
+  {
+    return Ordering.from(COMPARATOR).sortedCopy(this.storageLocations).iterator();
 
 Review comment:
   @jihoonson @sashidhar  I am ok with it being "best effort" in case of multiple threads. also you can remove the "synchronized" from method. real reason for using "least bytes" was to spread the segments uniformly across locations as much possible and that objective would be fulfilled.

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