Add ComparatorFactory

lmdbjava · at055612 · Mar 6, 2025 · Mar 6, 2025 · Mar 6, 2025 · Mar 6, 2025
commit 1acd9711efb752013b6588e5e3d106474afa5822
diff --git a/src/main/java/org/lmdbjava/DbiBuilder.java b/src/main/java/org/lmdbjava/DbiBuilder.java
@@ -49,8 +49,9 @@
    * <p>
    * The name will be converted into bytes using {@link StandardCharsets#UTF_8}.
    * </p>
+   *
    * @param name The name of the database or null for the unnamed database
-   *            (see also {@link DbiBuilder#withoutDbName()})
+   *             (see also {@link DbiBuilder#withoutDbName()})
    * @return The next builder stage.
    */
   public DbiBuilderStage2<T> setDbName(final String name) {
@@ -63,6 +64,7 @@
 
   /**
    * Create the {@link Dbi} with the passed name in byte[] form.
+   *
    * @param name The name of the database in byte form.
    * @return The next builder stage.
    */
@@ -83,6 +85,7 @@
    * <p>Note: The 'unnamed database' is used by LMDB to store the names of named databases, with
    * the database name being the key. Use of the unnamed database is intended for simple applications
    * with only one database.</p>
+   *
    * @return The next builder stage.
    */
   public DbiBuilderStage2<T> withoutDbName() {
@@ -102,7 +105,7 @@
 
     private final DbiBuilder<T> dbiBuilder;
 
-    private java.util.Comparator<T> customComparator;
+    private ComparatorFactory<T> comparatorFactory;
     private ComparatorType comparatorType;
 
     private DbiBuilderStage2(final DbiBuilder<T> dbiBuilder) {
@@ -130,7 +133,7 @@
      * If you do not intend to use {@link CursorIterable} then it doesn't matter whether
      * you choose {@link DbiBuilderStage2#withNativeComparator()},
      * {@link DbiBuilderStage2#withDefaultComparator()} or
-     * {@link DbiBuilderStage2#withIteratorComparator(Comparator)} as these comparators will
+     * {@link DbiBuilderStage2#withIteratorComparator(ComparatorFactory)} as these comparators will
      * never be used.
      * </p>
      *
@@ -157,7 +160,7 @@
      * If you do not intend to use {@link CursorIterable} then it doesn't matter whether
      * you choose {@link DbiBuilderStage2#withNativeComparator()},
      * {@link DbiBuilderStage2#withDefaultComparator()} or
-     * {@link DbiBuilderStage2#withIteratorComparator(Comparator)} as these comparators will
+     * {@link DbiBuilderStage2#withIteratorComparator(ComparatorFactory)} as these comparators will
      * never be used.
      * </p>
      *
@@ -186,11 +189,13 @@
      * are stored in the database.
      * </p>
      *
-     * @param comparator for all key comparison operations.
+     * @param comparatorFactory A factory to create a comparator. {@link ComparatorFactory#create(DbiFlagSet)}
+     *                          will be called once during the initialisation of the {@link Dbi}. It must
+     *                          not return null.
      * @return The next builder stage.
      */
-    public DbiBuilderStage3<T> withCallbackComparator(final Comparator<T> comparator) {
-      this.customComparator = Objects.requireNonNull(comparator);
+    public DbiBuilderStage3<T> withCallbackComparator(final ComparatorFactory<T> comparatorFactory) {
+      this.comparatorFactory = Objects.requireNonNull(comparatorFactory);
       this.comparatorType = ComparatorType.CALLBACK;
       return new DbiBuilderStage3<>(this);
     }
@@ -215,15 +220,17 @@
      * If you do not intend to use {@link CursorIterable} then it doesn't matter whether
      * you choose {@link DbiBuilderStage2#withNativeComparator()},
      * {@link DbiBuilderStage2#withDefaultComparator()} or
-     * {@link DbiBuilderStage2#withIteratorComparator(Comparator)} as these comparators will
+     * {@link DbiBuilderStage2#withIteratorComparator(ComparatorFactory)} as these comparators will
      * never be used.
      * </p>
      *
-     * @param comparator The comparator to use with {@link CursorIterable}.
+     * @param comparatorFactory The comparator to use with {@link CursorIterable}.
+     *                          {@link ComparatorFactory#create(DbiFlagSet)} will be called once during the
+     *                          initialisation of the {@link Dbi}. It must not return null.
      * @return The next builder stage.
      */
-    public DbiBuilderStage3<T> withIteratorComparator(final Comparator<T> comparator) {
-      this.customComparator = Objects.requireNonNull(comparator);
+    public DbiBuilderStage3<T> withIteratorComparator(final ComparatorFactory<T> comparatorFactory) {
+      this.comparatorFactory = Objects.requireNonNull(comparatorFactory);
       this.comparatorType = ComparatorType.ITERATOR;
       return new DbiBuilderStage3<>(this);
     }
@@ -267,8 +274,8 @@
       flagSetBuilder.clear();
       if (dbiFlags != null) {
         dbiFlags.stream()
-                .filter(Objects::nonNull)
-                .forEach(dbiFlags::add);
+            .filter(Objects::nonNull)
+            .forEach(dbiFlags::add);
       }
       return this;
     }
@@ -310,7 +317,7 @@
      * </p>
      *
      * @param dbiFlagSet to open the database with.
-     *                 A null value will just clear all set flags.
+     *                   A null value will just clear all set flags.
      */
     public DbiBuilderStage3<T> setDbiFlags(final DbiFlagSet dbiFlagSet) {
       flagSetBuilder.clear();
@@ -359,7 +366,7 @@
     * <p>
     * If you don't call this method to supply a {@link Txn}, a {@link Txn} will be opened for the purpose
     * of creating and opening the {@link Dbi}, then closed. Therefore, if you already have a transaction
     * open, you should supply that to avoid one blocking the other.
     * </p>
     *
     * @param txn transaction to use (required; not closed). If the {@link Env} was opened
@@ -413,7 +420,9 @@
           break;
         case CALLBACK:
         case ITERATOR:
-          comparator = dbiBuilderStage2.customComparator;
+          comparator = Objects.requireNonNull(
+              dbiBuilderStage2.comparatorFactory.create(dbiFlagSet),
+              () -> "comparatorFactory returned null");
           break;
         case NATIVE:
           break;
@@ -465,4 +474,15 @@
     ITERATOR,
     ;
   }
+
+
+  // --------------------------------------------------------------------------------
+
+
+  @FunctionalInterface
+  public interface ComparatorFactory<T> {
+
+    Comparator<T> create(final DbiFlagSet dbiFlagSet);
+
+  }
 }
diff --git a/src/test/java/org/lmdbjava/ComparatorIntegerKeyTest.java b/src/test/java/org/lmdbjava/ComparatorIntegerKeyTest.java
@@ -30,13 +30,10 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.util.Comparator;
-import java.util.LinkedHashMap;
-import java.util.Map;
 import java.util.Random;
 import java.util.stream.Stream;
 import org.agrona.DirectBuffer;
 import org.agrona.concurrent.UnsafeBuffer;
-import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
@@ -98,13 +95,10 @@ void testInt(final ComparatorRunner comparator) {
     assertThat(get(comparator.compare(Integer.MAX_VALUE, 0))).isEqualTo(GREATER_THAN);
   }
 
-  @Test
-  void testRandomLong() {
+  @ParameterizedTest
+  @MethodSource("comparatorProvider")
+  void testRandomLong(final ComparatorRunner runner) {
     final Random random = new Random(3239480);
-    final Map<String, ComparatorRunner> nameToRunnerMap = new LinkedHashMap<>();
-    nameToRunnerMap.put("DirectBufferRunner", new DirectBufferRunner());
-    nameToRunnerMap.put("ByteBufferRunner", new ByteBufferRunner());
-    nameToRunnerMap.put("NettyRunner", new NettyRunner());
 
     // 5mil random longs to compare
     final long[] values = random.longs()
@@ -115,40 +109,33 @@ void testRandomLong() {
     for (int i = 1; i < values.length; i++) {
       final long long1 = values[i - 1];
       final long long2 = values[i];
-      for (Map.Entry<String, ComparatorRunner> entry : nameToRunnerMap.entrySet()) {
-        final String name = entry.getKey();
-        final ComparatorRunner runner = entry.getValue();
-        // Make sure the comparator under test gives the same outcome as just comparing two longs
-        final ComparatorTest.ComparatorResult result = get(runner.compare(long1, long2));
-        final ComparatorTest.ComparatorResult expectedResult = get(Long.compare(long1, long2));
-
-        assertThat(result)
-            .withFailMessage(() -> "Compare mismatch for " + name + " - long1: " + long1
-                + ", long2: " + long2
-                + ", expected: " + expectedResult
-                + ", actual: " + result)
-            .isEqualTo(expectedResult);
-
-        final ComparatorTest.ComparatorResult result2 = get(runner.compare(long2, long1));
-        final ComparatorTest.ComparatorResult expectedResult2 = expectedResult.opposite();
-
-        assertThat(result)
-            .withFailMessage(() -> "Compare mismatch for " + name + " - long2: " + long2
-                + ", long1: " + long1
-                + ", expected2: " + expectedResult2
-                + ", actual2: " + result2)
-            .isEqualTo(expectedResult);
-      }
+      // Make sure the comparator under test gives the same outcome as just comparing two longs
+      final ComparatorTest.ComparatorResult result = get(runner.compare(long1, long2));
+      final ComparatorTest.ComparatorResult expectedResult = get(Long.compare(long1, long2));
+
+      assertThat(result)
+          .withFailMessage(() -> "Compare mismatch - long1: " + long1
+              + ", long2: " + long2
+              + ", expected: " + expectedResult
+              + ", actual: " + result)
+          .isEqualTo(expectedResult);
+
+      final ComparatorTest.ComparatorResult result2 = get(runner.compare(long2, long1));
+      final ComparatorTest.ComparatorResult expectedResult2 = expectedResult.opposite();
+
+      assertThat(result)
+          .withFailMessage(() -> "Compare mismatch for - long2: " + long2
+              + ", long1: " + long1
+              + ", expected2: " + expectedResult2
+              + ", actual2: " + result2)
+          .isEqualTo(expectedResult);
     }
   }
 
-  @Test
-  void testRandomInt() {
+  @ParameterizedTest
+  @MethodSource("comparatorProvider")
+  void testRandomInt(final ComparatorRunner runner) {
     final Random random = new Random(3239480);
-    final Map<String, ComparatorRunner> nameToRunnerMap = new LinkedHashMap<>();
-    nameToRunnerMap.put("DirectBufferRunner", new DirectBufferRunner());
-    nameToRunnerMap.put("ByteBufferRunner", new ByteBufferRunner());
-    nameToRunnerMap.put("NettyRunner", new NettyRunner());
 
     // 5mil random ints to compare
     final int[] values = random.ints()
@@ -159,30 +146,26 @@ void testRandomInt() {
     for (int i = 1; i < values.length; i++) {
       final int int1 = values[i - 1];
       final int int2 = values[i];
-      for (Map.Entry<String, ComparatorRunner> entry : nameToRunnerMap.entrySet()) {
-        final String name = entry.getKey();
-        final ComparatorRunner runner = entry.getValue();
-        // Make sure the comparator under test gives the same outcome as just comparing two ints
-        final ComparatorTest.ComparatorResult result = get(runner.compare(int1, int2));
-        final ComparatorTest.ComparatorResult expectedResult = get(Integer.compare(int1, int2));
-
-        assertThat(result)
-            .withFailMessage(() -> "Compare mismatch for " + name + " - int1: " + int1
-                + ", int2: " + int2
-                + ", expected: " + expectedResult
-                + ", actual: " + result)
-            .isEqualTo(expectedResult);
-
-        final ComparatorTest.ComparatorResult result2 = get(runner.compare(int2, int1));
-        final ComparatorTest.ComparatorResult expectedResult2 = expectedResult.opposite();
-
-        assertThat(result)
-            .withFailMessage(() -> "Compare mismatch for " + name + " - int2: " + int2
-                + ", int1: " + int1
-                + ", expected2: " + expectedResult2
-                + ", actual2: " + result2)
-            .isEqualTo(expectedResult);
-      }
+      // Make sure the comparator under test gives the same outcome as just comparing two ints
+      final ComparatorTest.ComparatorResult result = get(runner.compare(int1, int2));
+      final ComparatorTest.ComparatorResult expectedResult = get(Integer.compare(int1, int2));
+
+      assertThat(result)
+          .withFailMessage(() -> "Compare mismatch for - int1: " + int1
+              + ", int2: " + int2
+              + ", expected: " + expectedResult
+              + ", actual: " + result)
+          .isEqualTo(expectedResult);
+
+      final ComparatorTest.ComparatorResult result2 = get(runner.compare(int2, int1));
+      final ComparatorTest.ComparatorResult expectedResult2 = expectedResult.opposite();
+
+      assertThat(result)
+          .withFailMessage(() -> "Compare mismatch for - int2: " + int2
+              + ", int1: " + int1
+              + ", expected2: " + expectedResult2
+              + ", actual2: " + result2)
+          .isEqualTo(expectedResult);
     }
   }
 

diff --git a/src/test/java/org/lmdbjava/CursorIterableIntegerDupTest.java b/src/test/java/org/lmdbjava/CursorIterableIntegerDupTest.java
@@ -124,11 +124,11 @@
    file = FileUtil.createTempFile();
    final BufferProxy<ByteBuffer> bufferProxy = ByteBufferProxy.PROXY_OPTIMAL;
    env =
        create(bufferProxy)
            .setMapSize(KIBIBYTES.toBytes(256))
            .setMaxReaders(1)
            .setMaxDbs(3)
            .open(file.toFile(), POSIX_MODE, MDB_NOSUBDIR);

    populateExpectedEntriesDeque();
  }
@@ -355,7 +355,7 @@
          bb2.reset();
          return guava.compare(array1, array2);
        };
    final Dbi<ByteBuffer> guavaDbi = env.openDbi(DB_1, comparator, MDB_CREATE);
    populateDatabase(guavaDbi);
    verify(openClosedBackward(bbNative(7), bbNative(2)), guavaDbi, 6, 4, 2);
    verify(openClosedBackward(bbNative(8), bbNative(4)), guavaDbi, 6, 4);
@@ -557,13 +557,13 @@
       final DbiFactory callbackComparatorDb = new DbiFactory("callbackComparator", env ->
           env.buildDbi()
               .setDbName(DB_3)
-              .withCallbackComparator(buildComparator())
+              .withCallbackComparator(MyArgumentProvider::buildComparator)
               .setDbiFlags(DBI_FLAGS)
               .open());
       final DbiFactory iteratorComparatorDb = new DbiFactory("iteratorComparator", env ->
           env.buildDbi()
               .setDbName(DB_4)
-              .withIteratorComparator(buildComparator())
+              .withIteratorComparator(MyArgumentProvider::buildComparator)
               .setDbiFlags(DBI_FLAGS)
               .open());
       return Stream.of(
@@ -574,7 +574,7 @@
           .map(Arguments::of);
     }
 
-    private static Comparator<ByteBuffer> buildComparator() {
+    private static Comparator<ByteBuffer> buildComparator(final DbiFlagSet dbiFlagSet) {
       final Comparator<ByteBuffer> baseComparator = BUFFER_PROXY.getComparator(DBI_FLAGS);
       return (o1, o2) -> {
         if (o1.remaining() != o2.remaining()) {

diff --git a/src/test/java/org/lmdbjava/CursorIterableIntegerKeyTest.java b/src/test/java/org/lmdbjava/CursorIterableIntegerKeyTest.java
@@ -238,9 +238,9 @@
    try (Txn<ByteBuffer> txn = env.txnRead()) {
      try (CursorIterable<ByteBuffer> iterable = db.iterate(txn)) {
        for (KeyVal<ByteBuffer> keyVal : iterable) {
          final String val = getString(keyVal.val());
          final long key = getNativeLong(keyVal.key());
          final int remaining = keyVal.key().remaining();
 //          System.out.println("key: " + key + ", val: " + val + ", remaining: " + remaining);
        }
      }
@@ -309,7 +309,7 @@
  @Test
  public void closedOpenBackwardTest() {
    verify(closedOpenBackward(bbNative(8), bbNative(3)), 8, 6, 4);
    verify(closedOpenBackward(bbNative(7), bbNative(2)), 6, 4);
    verify(closedOpenBackward(bbNative(9), bbNative(3)), 8, 6, 4);
  }

@@ -611,18 +611,16 @@
               .withNativeComparator()
               .setDbiFlags(DBI_FLAGS)
               .open());
-      final Comparator<ByteBuffer> comparator = buildComparator();
-
       final DbiFactory callbackComparatorDb = new DbiFactory("callbackComparator", env ->
           env.buildDbi()
               .setDbName(DB_3)
-              .withCallbackComparator(comparator)
+              .withCallbackComparator(MyArgumentProvider::buildComparator)
               .setDbiFlags(DBI_FLAGS)
               .open());
       final DbiFactory iteratorComparatorDb = new DbiFactory("iteratorComparator", env ->
           env.buildDbi()
               .setDbName(DB_4)
-              .withIteratorComparator(comparator)
+              .withIteratorComparator(MyArgumentProvider::buildComparator)
               .setDbiFlags(DBI_FLAGS)
               .open());
       return Stream.of(
@@ -633,7 +631,7 @@
           .map(Arguments::of);
     }
 
-    private static Comparator<ByteBuffer> buildComparator() {
+    private static Comparator<ByteBuffer> buildComparator(final DbiFlagSet dbiFlagSet) {
       final Comparator<ByteBuffer> baseComparator = BUFFER_PROXY.getComparator(DBI_FLAGS);
       return (o1, o2) -> {
         if (o1.remaining() != o2.remaining()) {

diff --git a/src/test/java/org/lmdbjava/CursorIterablePerfTest.java b/src/test/java/org/lmdbjava/CursorIterablePerfTest.java
@@ -56,11 +56,11 @@
    file = FileUtil.createTempFile();
    final BufferProxy<ByteBuffer> bufferProxy = ByteBufferProxy.PROXY_OPTIMAL;
    env =
        create(bufferProxy)
            .setMapSize(GIBIBYTES.toBytes(1))
            .setMaxReaders(1)
            .setMaxDbs(3)
            .open(file.toFile(), POSIX_MODE, MDB_NOSUBDIR);

    final DbiFlagSet dbiFlagSet = MDB_CREATE;
    // Use a java comparator for start/stop keys only
@@ -79,7 +79,7 @@
     // Use a java comparator for start/stop keys and as a callback comparator
     dbCallbackComparator = env.buildDbi()
         .setDbName("CallBackComparator")
-        .withCallbackComparator(bufferProxy.getComparator(dbiFlagSet))
+        .withCallbackComparator(bufferProxy::getComparator)
         .setDbiFlags(dbiFlagSet)
         .open();
 
@@ -120,7 +120,7 @@

      for (final Dbi<ByteBuffer> db : dbs) {
        // Clean out the db first
        try (Txn<ByteBuffer> txn = env.txnWrite();
            final Cursor<ByteBuffer> cursor = db.openCursor(txn)) {
          while (cursor.next()) {
            cursor.delete();
@@ -152,7 +152,7 @@
  }

  @Test
  public void comparePerf_sequential() {
    comparePerf(false);
  }


diff --git a/src/test/java/org/lmdbjava/CursorIterableTest.java b/src/test/java/org/lmdbjava/CursorIterableTest.java
@@ -83,7 +83,6 @@ public final class CursorIterableTest {
   private static final BufferProxy<ByteBuffer> BUFFER_PROXY = ByteBufferProxy.PROXY_OPTIMAL;
 
   private Path file;
-  private Dbi<ByteBuffer> db;
   private Env<ByteBuffer> env;
   private Deque<Integer> list;
 
@@ -309,7 +308,11 @@ void openClosedBackwardTestWithGuava() {
           bb2.reset();
           return guava.compare(array1, array2);
         };
-    final Dbi<ByteBuffer> guavaDbi = env.openDbi(DB_1, comparator, MDB_CREATE);
+    final Dbi<ByteBuffer> guavaDbi = env.buildDbi()
+        .setDbName(DB_1)
+        .withDefaultComparator()
+        .setDbiFlags(MDB_CREATE)
+        .open();
     populateDatabase(guavaDbi);
     verify(openClosedBackward(bb(7), bb(2)), guavaDbi, 6, 4, 2);
     verify(openClosedBackward(bb(8), bb(4)), guavaDbi, 6, 4);
@@ -548,13 +551,13 @@ public Stream<? extends Arguments> provideArguments(ParameterDeclarations parame
       final DbiFactory callbackComparatorDb = new DbiFactory("callbackComparator", env ->
           env.buildDbi()
               .setDbName(DB_3)
-              .withCallbackComparator(BUFFER_PROXY.getComparator(DBI_FLAGS))
+              .withCallbackComparator(BUFFER_PROXY::getComparator)
               .setDbiFlags(DBI_FLAGS)
               .open());
       final DbiFactory iteratorComparatorDb = new DbiFactory("iteratorComparator", env ->
           env.buildDbi()
               .setDbName(DB_4)
-              .withIteratorComparator(BUFFER_PROXY.getComparator(DBI_FLAGS))
+              .withIteratorComparator(BUFFER_PROXY::getComparator)
               .setDbiFlags(DBI_FLAGS)
               .open());
       return Stream.of(

diff --git a/src/test/java/org/lmdbjava/DbiBuilderTest.java b/src/test/java/org/lmdbjava/DbiBuilderTest.java
@@ -133,7 +133,7 @@ public void callback() {
 
     final Dbi<ByteBuffer> dbi = env.buildDbi()
         .setDbName("foo")
-        .withCallbackComparator(comparator)
+        .withCallbackComparator(ignored -> comparator)
         .addDbiFlags(DbiFlags.MDB_CREATE)
         .open();