[GitHub] [lucene] uschindler commented on a change in pull request #446: LUCENE-10237 : Add MergeOnCommitTieredMergePolicy to sandbox

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

uschindler commented on a change in pull request #446:
URL: https://github.com/apache/lucene/pull/446#discussion_r756423607



##########
File path: lucene/sandbox/src/java/org/apache/lucene/sandbox/index/MergeOnFlushTieredMergePolicy.java
##########
@@ -0,0 +1,138 @@
+/*
+ * 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.lucene.sandbox.index;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import org.apache.lucene.index.MergeTrigger;
+import org.apache.lucene.index.SegmentCommitInfo;
+import org.apache.lucene.index.SegmentInfos;
+import org.apache.lucene.index.TieredMergePolicy;
+
+/**
+ * A simple extension to {@link TieredMergePolicy} to merge all tiny segments (or at least segments
+ * smaller than specified in setSmallSegmentThresholdMB) into one segment on commit.
+ */
+public class MergeOnFlushTieredMergePolicy extends TieredMergePolicy {
+  private double maxSegmentSizeAsProportionOfIndex = 1.0;
+  private long smallSegmentThresholdBytes = Units.mbToBytes(100.0);
+  private long hardMaxSegmentSizeBytes = 5 * 1024 * 1024 * 1024L;
+
+  private static long indexSize(SegmentInfos infos) throws IOException {
+    long totalSize = 0;
+    for (SegmentCommitInfo sci : infos) {
+      totalSize += sci.sizeInBytes();
+    }
+    return totalSize;
+  }
+
+  public double getSmallSegmentThresholdMB() {
+    return Units.bytesToMB(smallSegmentThresholdBytes);
+  }
+
+  /**
+   * @param smallSegmentThresholdMB all segments smaller than this will be merged into a single
+   *     segment before commit completes.
+   */
+  public void setSmallSegmentThresholdMB(double smallSegmentThresholdMB) {
+    this.smallSegmentThresholdBytes = Units.mbToBytes(smallSegmentThresholdMB);
+  }
+
+  public double getMaxSegmentSizeAsProportionOfIndex() {
+    return maxSegmentSizeAsProportionOfIndex;
+  }
+
+  public void setMaxSegmentSizeAsProportionOfIndex(double maxSegmentSizeAsProportionOfIndex) {
+    if (maxSegmentSizeAsProportionOfIndex < 0.0 || maxSegmentSizeAsProportionOfIndex > 1.0) {
+      throw new IllegalArgumentException(
+          "maxSegmentSizeAsProportionOfIndex must be between 0 and 1; got: "
+              + maxSegmentSizeAsProportionOfIndex);
+    }
+    this.maxSegmentSizeAsProportionOfIndex = maxSegmentSizeAsProportionOfIndex;
+  }
+
+  @Override
+  public TieredMergePolicy setMaxMergedSegmentMB(double v) {
+    this.hardMaxSegmentSizeBytes = Units.mbToBytes(v);
+    return this;
+  }
+
+  @Override
+  public MergeSpecification findMerges(
+      MergeTrigger mergeTrigger, SegmentInfos infos, MergeContext mergeContext) throws IOException {
+    double maxSegmentSizeMB =
+        Units.bytesToMB(
+            Math.min(
+                hardMaxSegmentSizeBytes,
+                Math.max(
+                    Units.mbToBytes(getFloorSegmentMB()),
+                    (long) (getMaxSegmentSizeAsProportionOfIndex() * indexSize(infos)))));
+    super.setMaxMergedSegmentMB(maxSegmentSizeMB);
+    return super.findMerges(mergeTrigger, excludeSmallSegments(infos), mergeContext);
+  }
+
+  /**
+   * Returns a SegmentInfos with all segments smaller than smallSegmentThresholdBytes removed.
+   *
+   * @param realSegmentInfos the "real", unfiltered {@link SegmentInfos}
+   * @return a new {@link SegmentInfos} instance containing all {@link SegmentCommitInfo} from
+   *     realSegmentInfos that are at least as large as smallSegmentThresholdBytes.
+   * @throws IOException if unable to load the size of a {@link SegmentCommitInfo}
+   */
+  private SegmentInfos excludeSmallSegments(SegmentInfos realSegmentInfos) throws IOException {
+    SegmentInfos largeSegmentInfos =
+        new SegmentInfos(realSegmentInfos.getIndexCreatedVersionMajor());
+    for (SegmentCommitInfo sci : realSegmentInfos.asList()) {
+      if (sci.sizeInBytes() >= smallSegmentThresholdBytes) {
+        largeSegmentInfos.add(sci);
+      }
+    }
+    return largeSegmentInfos;
+  }
+
+  @Override
+  public MergeSpecification findFullFlushMerges(
+      MergeTrigger mergeTrigger, SegmentInfos segmentInfos, MergeContext mergeContext)
+      throws IOException {
+    List<SegmentCommitInfo> smallSegments = new ArrayList<>();
+    for (SegmentCommitInfo sci : segmentInfos) {
+      if (sci.sizeInBytes() < smallSegmentThresholdBytes) {
+        if (mergeContext.getMergingSegments().contains(sci) == false) {
+          smallSegments.add(sci);
+        }
+      }
+    }
+    if (smallSegments.size() > 1) {
+      MergeSpecification mergeSpecification = new MergeSpecification();
+      mergeSpecification.add(new OneMerge(smallSegments));
+      return mergeSpecification;
+    }
+    return null;
+  }
+  /** Utility class to handle conversion between megabytes and bytes */
+  public static class Units {

Review comment:
       If this is useful use it at other places,too. And don't make it public. The bug is that it is static only, but you can instantiate. Never allow this.
   
   Better is to make it an interface with static methods or add private ctor.

##########
File path: lucene/sandbox/src/java/org/apache/lucene/sandbox/index/MergeOnFlushTieredMergePolicy.java
##########
@@ -0,0 +1,138 @@
+/*
+ * 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.lucene.sandbox.index;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import org.apache.lucene.index.MergeTrigger;
+import org.apache.lucene.index.SegmentCommitInfo;
+import org.apache.lucene.index.SegmentInfos;
+import org.apache.lucene.index.TieredMergePolicy;
+
+/**
+ * A simple extension to {@link TieredMergePolicy} to merge all tiny segments (or at least segments
+ * smaller than specified in setSmallSegmentThresholdMB) into one segment on commit.
+ */
+public class MergeOnFlushTieredMergePolicy extends TieredMergePolicy {
+  private double maxSegmentSizeAsProportionOfIndex = 1.0;
+  private long smallSegmentThresholdBytes = Units.mbToBytes(100.0);
+  private long hardMaxSegmentSizeBytes = 5 * 1024 * 1024 * 1024L;
+
+  private static long indexSize(SegmentInfos infos) throws IOException {
+    long totalSize = 0;
+    for (SegmentCommitInfo sci : infos) {
+      totalSize += sci.sizeInBytes();
+    }
+    return totalSize;
+  }
+
+  public double getSmallSegmentThresholdMB() {
+    return Units.bytesToMB(smallSegmentThresholdBytes);
+  }
+
+  /**
+   * @param smallSegmentThresholdMB all segments smaller than this will be merged into a single
+   *     segment before commit completes.
+   */
+  public void setSmallSegmentThresholdMB(double smallSegmentThresholdMB) {
+    this.smallSegmentThresholdBytes = Units.mbToBytes(smallSegmentThresholdMB);
+  }
+
+  public double getMaxSegmentSizeAsProportionOfIndex() {
+    return maxSegmentSizeAsProportionOfIndex;
+  }
+
+  public void setMaxSegmentSizeAsProportionOfIndex(double maxSegmentSizeAsProportionOfIndex) {
+    if (maxSegmentSizeAsProportionOfIndex < 0.0 || maxSegmentSizeAsProportionOfIndex > 1.0) {
+      throw new IllegalArgumentException(
+          "maxSegmentSizeAsProportionOfIndex must be between 0 and 1; got: "
+              + maxSegmentSizeAsProportionOfIndex);
+    }
+    this.maxSegmentSizeAsProportionOfIndex = maxSegmentSizeAsProportionOfIndex;
+  }
+
+  @Override
+  public TieredMergePolicy setMaxMergedSegmentMB(double v) {
+    this.hardMaxSegmentSizeBytes = Units.mbToBytes(v);

Review comment:
       If the override is there it requires the return type be this class to allow chaining.




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