JournalIndex.truncate() should return last entry

The only time we are calling truncate(), we are following up with a seek
to the appropriate entry.

Return the last indexed position from truncate(), so we can do better
than a linear search.

JIRA: CONTROLLER-2109
Change-Id: I701b0eefbf1f4d83f74ba95b93c41407289d95cb
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit 2a6738b69c763377d1f727da9876ffdd9058262f)

diff --git a/atomix-storage/src/main/java/io/atomix/storage/journal/index/JournalIndex.java b/atomix-storage/src/main/java/io/atomix/storage/journal/index/JournalIndex.java
index ddaef94e377ba2b84eaa97368641ab9fb6b0dfff..8608e00fc6dfe4697fad4e0f10135b7ab1b3b6ca 100644 (file)
--- a/atomix-storage/src/main/java/io/atomix/storage/journal/index/JournalIndex.java
+++ b/atomix-storage/src/main/java/io/atomix/storage/journal/index/JournalIndex.java
@@ -1,5 +1,6 @@
 /*
  * Copyright 2018-2022 Open Networking Foundation and others.  All rights reserved.
+ * Copyright (c) 2024 PANTHEON.tech, s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,32 +16,33 @@
  */
 package io.atomix.storage.journal.index;
 
+import org.eclipse.jdt.annotation.Nullable;
+
 /**
- * Journal index.
+ * Index of a particular JournalSegment.
  */
 public interface JournalIndex {
+    /**
+     * Adds an entry for the given index at the given position.
+     *
+     * @param index the index for which to add the entry
+     * @param position the position of the given index
+     */
+    void index(long index, int position);
 
-  /**
-   * Adds an entry for the given index at the given position.
-   *
-   * @param index the index for which to add the entry
-   * @param position the position of the given index
-   */
-  void index(long index, int position);
-
-  /**
-   * Looks up the position of the given index.
-   *
-   * @param index the index to lookup
-   * @return the position of the given index or a lesser index
-   */
-  Position lookup(long index);
-
-  /**
-   * Truncates the index to the given index.
-   *
-   * @param index the index to which to truncate the index
-   */
-  void truncate(long index);
+    /**
+     * Looks up the position of the given index.
+     *
+     * @param index the index to lookup
+     * @return the position of the given index or a lesser index, or {@code null}
+     */
+    @Nullable Position lookup(long index);
 
+    /**
+     * Truncates the index to the given index and returns its position, if available.
+     *
+     * @param index the index to which to truncate the index, or {@code null}
+     * @return the position of the given index or a lesser index, or {@code null}
+     */
+    @Nullable Position truncate(long index);
 }

diff --git a/atomix-storage/src/main/java/io/atomix/storage/journal/index/Position.java b/atomix-storage/src/main/java/io/atomix/storage/journal/index/Position.java
index c3619364b08090d3bfb834dbfd48799450b283a0..640a8e8f0f14e757ad78bee2b463456371bd1558 100644 (file)
--- a/atomix-storage/src/main/java/io/atomix/storage/journal/index/Position.java
+++ b/atomix-storage/src/main/java/io/atomix/storage/journal/index/Position.java
@@ -16,9 +16,18 @@
  */
 package io.atomix.storage.journal.index;
 
+import java.util.Map.Entry;
+import org.eclipse.jdt.annotation.Nullable;
+
 /**
  * Journal index position.
  */
 public record Position(long index, int position) {
+    public Position(final Entry<Long, Integer> entry) {
+        this(entry.getKey(), entry.getValue());
+    }
 
+    public static @Nullable Position ofNullable(final Entry<Long, Integer> entry) {
+        return entry == null ? null : new Position(entry);
+    }
 }

diff --git a/atomix-storage/src/main/java/io/atomix/storage/journal/index/SparseJournalIndex.java b/atomix-storage/src/main/java/io/atomix/storage/journal/index/SparseJournalIndex.java
index 5fe4280eb00207a9b3b9f719162318cda8eb4489..2b317362c57f3ee6b7637e3fedecbff22e49276d 100644 (file)
--- a/atomix-storage/src/main/java/io/atomix/storage/journal/index/SparseJournalIndex.java
+++ b/atomix-storage/src/main/java/io/atomix/storage/journal/index/SparseJournalIndex.java
@@ -1,5 +1,6 @@
 /*
  * Copyright 2018-2022 Open Networking Foundation and others.  All rights reserved.
+ * Copyright (c) 2024 PANTHEON.tech, s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -15,36 +16,40 @@
  */
 package io.atomix.storage.journal.index;
 
-import java.util.Map;
 import java.util.TreeMap;
 
 /**
- * Sparse index.
+ * A {@link JournalIndex} maintaining target density.
  */
-public class SparseJournalIndex implements JournalIndex {
-  private static final int MIN_DENSITY = 1000;
-  private final int density;
-  private final TreeMap<Long, Integer> positions = new TreeMap<>();
-
-  public SparseJournalIndex(double density) {
-    this.density = (int) Math.ceil(MIN_DENSITY / (density * MIN_DENSITY));
-  }
-
-  @Override
-  public void index(long index, int position) {
-    if (index % density == 0) {
-      positions.put(index, position);
+public final class SparseJournalIndex implements JournalIndex {
+    private static final int MIN_DENSITY = 1000;
+
+    private final int density;
+    private final TreeMap<Long, Integer> positions = new TreeMap<>();
+
+    public SparseJournalIndex() {
+        density = MIN_DENSITY;
+    }
+
+    public SparseJournalIndex(final double density) {
+        this.density = (int) Math.ceil(MIN_DENSITY / (density * MIN_DENSITY));
+    }
+
+    @Override
+    public void index(final long index, final int position) {
+        if (index % density == 0) {
+            positions.put(index, position);
+        }
+    }
+
+    @Override
+    public Position lookup(final long index) {
+        return Position.ofNullable(positions.floorEntry(index));
+    }
+
+    @Override
+    public Position truncate(final long index) {
+        positions.tailMap(index, false).clear();
+        return Position.ofNullable(positions.lastEntry());
     }
-  }
-
-  @Override
-  public Position lookup(long index) {
-    Map.Entry<Long, Integer> entry = positions.floorEntry(index);
-    return entry != null ? new Position(entry.getKey(), entry.getValue()) : null;
-  }
-
-  @Override
-  public void truncate(long index) {
-    positions.tailMap(index, false).clear();
-  }
 }