fix: connecting sibling pointers when leaf node is removed

sepgh · May 25, 2024 · e8e4a57 · e8e4a57
1 parent 618bdcf
commit e8e4a57
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Showing 3 changed files with 48 additions and 0 deletions.
diff --git a/src/main/java/com/github/sepgh/internal/tree/BPlusTreeIndexManager.java b/src/main/java/com/github/sepgh/internal/tree/BPlusTreeIndexManager.java
@@ -471,12 +471,44 @@ private void merge(int table, InternalTreeNode parent, BaseTreeNode child, int i
                 child.setAsRoot();
                 parent.unsetAsRoot();
             }
+            if (child.isLeaf()) {
+                assert child instanceof LeafTreeNode;
+                this.connectSiblings((LeafTreeNode) child, table);
+            }
             TreeNodeIO.update(indexStorageManager, table, child);
             TreeNodeIO.remove(indexStorageManager, table, parent);
         }else{
             TreeNodeIO.update(indexStorageManager, table, parent, child);
         }
+        if (toRemove.isLeaf()) {
+            assert toRemove instanceof LeafTreeNode;
+            this.connectSiblings((LeafTreeNode) toRemove, table);
+        }
         TreeNodeIO.remove(indexStorageManager, table, toRemove);
+    }
+
+    private void connectSiblings(LeafTreeNode toRemove, int table) throws ExecutionException, InterruptedException, IOException {
+        Optional<Pointer> optionalNextSiblingPointer = toRemove.getNextSiblingPointer(degree);
+        Optional<Pointer> optionalPreviousSiblingPointer = toRemove.getPreviousSiblingPointer(degree);
+        if (optionalNextSiblingPointer.isPresent()){
+            LeafTreeNode nextNode = (LeafTreeNode) TreeNodeIO.read(indexStorageManager, table, optionalNextSiblingPointer.get());
+            if (optionalPreviousSiblingPointer.isPresent()){
+                nextNode.setPreviousSiblingPointer(optionalPreviousSiblingPointer.get(), degree);
+            } else {
+                nextNode.setPreviousSiblingPointer(Pointer.empty(), degree);
+            }
+            TreeNodeIO.update(indexStorageManager, table, nextNode);
+        }
+
+        if (optionalPreviousSiblingPointer.isPresent()){
+            LeafTreeNode previousNode = (LeafTreeNode) TreeNodeIO.read(indexStorageManager, table, optionalPreviousSiblingPointer.get());
+            if (optionalNextSiblingPointer.isPresent()){
+                previousNode.setNextSiblingPointer(optionalNextSiblingPointer.get(), degree);
+            } else {
+                previousNode.setNextSiblingPointer(Pointer.empty(), degree);
+            }
+            TreeNodeIO.update(indexStorageManager, table, previousNode);
+        }
 
     }
 

diff --git a/src/main/java/com/github/sepgh/internal/tree/Pointer.java b/src/main/java/com/github/sepgh/internal/tree/Pointer.java
@@ -32,6 +32,14 @@ public static Pointer fromBytes(byte[] bytes, int position){
         );
     }
 
+    public static Pointer empty(){
+        return new Pointer(
+                (byte) 0x00,
+                0,
+                0
+        );
+    }
+
     public static Pointer fromBytes(byte[] bytes){
         return Pointer.fromBytes(bytes, 0);
     }

diff --git a/src/test/java/com/github/sepgh/internal/tree/removing/BPlusTreeIndexManagerTestCase.java b/src/test/java/com/github/sepgh/internal/tree/removing/BPlusTreeIndexManagerTestCase.java
@@ -517,6 +517,14 @@ public void testRemovingRoot() throws IOException, ExecutionException, Interrupt
         Assertions.assertEquals(1, root.getKeyList(degree).size());
         Assertions.assertEquals(10, root.getKeyList(degree).getFirst());
 
+        // Testing next / prev state
+        Pointer lastLeafFromLeftPointer = ((InternalTreeNode) TreeNodeIO.read(fileIndexStorageManager, 1, root.getChildrenList().getFirst())).getChildrenList().getLast();
+        Pointer firstLeafFromRightPointer = ((InternalTreeNode) TreeNodeIO.read(fileIndexStorageManager, 1, root.getChildrenList().getLast())).getChildrenList().getFirst();
+
+        Assertions.assertEquals(lastLeafFromLeftPointer, ((LeafTreeNode) TreeNodeIO.read(fileIndexStorageManager, 1, firstLeafFromRightPointer)).getPreviousSiblingPointer(degree).get());
+        Assertions.assertEquals(firstLeafFromRightPointer, ((LeafTreeNode) TreeNodeIO.read(fileIndexStorageManager, 1, lastLeafFromLeftPointer)).getNextSiblingPointer(degree).get());
+
+
         Assertions.assertTrue(indexManager.removeIndex(1, 10));
         Assertions.assertFalse(indexManager.removeIndex(1, 10));