gh-249 Remove MDB_UNSIGNEDKEY, let CursorIterable call mdb_cmp

There are now essentially three ways of configuring comparators when creating a Dbi. **null comparator** LMDB will use its own comparator & CursorIterable will call down to mdb_cmp for comparisons between the current cursor key and the range start/stop key. **provided comparator** LMDB will use its own comparator & CursorIterable will use the provided comparator for comparisons between the current cursor key and the range start/stop key. **provided comparator with nativeCb==true** LMDB will call back to java for all comparator duties. CursorIterable will use the same provided comparator for comparisons between the current cursor key and the range start/stop key. The methods `getSignedComparator()` and `getUnsignedComparator()` have been made public so users of this library can access them.
lmdbjava · at055612 · Mar 6, 2025 · Mar 6, 2025 · Mar 6, 2025 · Mar 6, 2025
commit 480e984417c17915b31e33de193ff08e118fcec9
diff --git a/src/main/java/org/lmdbjava/BufferProxy.java b/src/main/java/org/lmdbjava/BufferProxy.java
@@ -16,10 +16,6 @@
 package org.lmdbjava;
 
 import static java.lang.Long.BYTES;
-import static org.lmdbjava.DbiFlags.MDB_INTEGERKEY;
-import static org.lmdbjava.DbiFlags.MDB_UNSIGNEDKEY;
-import static org.lmdbjava.MaskedFlag.isSet;
-import static org.lmdbjava.MaskedFlag.mask;
 
 import java.util.Comparator;
 import jnr.ffi.Pointer;
@@ -70,36 +66,25 @@ protected BufferProxy() {}
    */
   protected abstract byte[] getBytes(T buffer);
 
-  /**
-   * Get a suitable default {@link Comparator} given the provided flags.
-   *
-   * <p>The provided comparator must strictly match the lexicographical order of keys in the native
-   * LMDB database.
-   *
-   * @param flags for the database
-   * @return a comparator that can be used (never null)
-   */
-  protected Comparator<T> getComparator(DbiFlags... flags) {
-    final int intFlag = mask(flags);
-
-    return isSet(intFlag, MDB_INTEGERKEY) || isSet(intFlag, MDB_UNSIGNEDKEY)
-        ? getUnsignedComparator()
-        : getSignedComparator();
-  }
-
   /**
    * Get a suitable default {@link Comparator} to compare numeric key values as signed.
    *
+   * <p>
+   * Note: LMDB's default comparator is unsigned so if this is used only for the {@link CursorIterable}
+   * start/stop key comparisons then its behaviour will differ from the iteration order. Use
+   * with caution.
+   * </p>
+   *
    * @return a comparator that can be used (never null)
    */
-  protected abstract Comparator<T> getSignedComparator();
+  public abstract Comparator<T> getSignedComparator();
 
   /**
    * Get a suitable default {@link Comparator} to compare numeric key values as unsigned.
    *
    * @return a comparator that can be used (never null)
    */
-  protected abstract Comparator<T> getUnsignedComparator();
+  public abstract Comparator<T> getUnsignedComparator();
 
   /**
    * Called when the <code>MDB_val</code> should be set to reflect the passed buffer. This buffer
@@ -140,4 +125,13 @@ protected Comparator<T> getComparator(DbiFlags... flags) {
   final KeyVal<T> keyVal() {
     return new KeyVal<>(this);
   }
+
+  /**
+   * Create a new {@link Key} to hold pointers for this buffer proxy.
+   *
+   * @return a non-null key holder
+   */
+  final Key<T> key() {
+    return new Key<>(this);
+  }
 }
diff --git a/src/main/java/org/lmdbjava/ByteArrayProxy.java b/src/main/java/org/lmdbjava/ByteArrayProxy.java
@@ -104,12 +104,12 @@ protected byte[] getBytes(final byte[] buffer) {
   }
 
   @Override
-  protected Comparator<byte[]> getSignedComparator() {
+  public Comparator<byte[]> getSignedComparator() {
     return signedComparator;
   }
 
   @Override
-  protected Comparator<byte[]> getUnsignedComparator() {
+  public Comparator<byte[]> getUnsignedComparator() {
     return unsignedComparator;
   }
 

diff --git a/src/main/java/org/lmdbjava/ByteBufProxy.java b/src/main/java/org/lmdbjava/ByteBufProxy.java
@@ -114,12 +114,12 @@ protected ByteBuf allocate() {
   }
 
   @Override
-  protected Comparator<ByteBuf> getSignedComparator() {
+  public Comparator<ByteBuf> getSignedComparator() {
     return comparator;
   }
 
   @Override
-  protected Comparator<ByteBuf> getUnsignedComparator() {
+  public Comparator<ByteBuf> getUnsignedComparator() {
     return comparator;
   }
 

diff --git a/src/main/java/org/lmdbjava/ByteBufferProxy.java b/src/main/java/org/lmdbjava/ByteBufferProxy.java
@@ -182,12 +182,12 @@ protected final ByteBuffer allocate() {
     }
 
     @Override
-    protected Comparator<ByteBuffer> getSignedComparator() {
+    public Comparator<ByteBuffer> getSignedComparator() {
       return signedComparator;
     }
 
     @Override
-    protected Comparator<ByteBuffer> getUnsignedComparator() {
+    public Comparator<ByteBuffer> getUnsignedComparator() {
       return unsignedComparator;
     }
 

diff --git a/src/main/java/org/lmdbjava/Cursor.java b/src/main/java/org/lmdbjava/Cursor.java
@@ -196,6 +196,10 @@ public T key() {
     return kv.key();
   }
 
+  KeyVal<T> keyVal() {
+    return kv;
+  }
+
   /**
    * Position at last key/data item.
    *